ALBERT

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Jingqi Tan, Jianjian Wei, Tao Jin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Onset and damping processes that characterize the transition of a thermoacoustic engine between the stationary and periodic oscillating states have attracted much research effort. In this work, the onset and damping characteristics of a closed two-phase thermoacoustic engine are investigated, where a regenerator is inserted between the cold and hot heat exchangers to reduce the irreversible loss caused by heat transfer. Additionally, a branch resonator, which consists of a load tube and a gas reservoir, is introduced to form the closed system and to adjust the acoustic field. A lumped parameter model is proposed to quantitatively analyze the performance of the thermoacoustic engine. Upon optimization, an onset temperature difference as low as 8.2 °C can be achieved in the experiments with R134a as the working fluid, which is the lowest one ever reported in the literatures. Besides, hysteresis phenomenon is found during the onset and damping processes. The present work aims to provide better understanding of the onset and damping behaviors of a two-phase thermoacoustic engine.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Bin Zou, Yiqiang Jiang, Yang Yao, Hongxing Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Since various optical factors, including sunshape and optical errors, coexist in practice, their coupling effects on the PTC’s optical performance deserve in-depth explorations. Previous studies mainly focused on individual effects of several typical optical errors or simple description of optical errors using a unified Gaussian model. Thus, this study is committed to investigating the coupling effects of multiple optical factors on the PTC’s optical performance based on the theoretically individual characterization of each optical factor. The Monte Carlo Rays Tracing method was adopted, and the effective sunshape model was established for sampling of incident rays by convolving the incident sunshape model with the specularity error model. It is revealed that larger circumsolar ratio and specularity error produced more uniform heat flux distribution on the absorber. The advantage of high optical quality reflectors in improving optical efficiency was more outstanding in clearer weather. As circumsolar ratio was more than 0.2, improving specular quality to very high degree (〈3 mrad) reduced instead the optical efficiency. When tracking error and slope error were maintained respectively less than 4 mrad and 2 mrad, the weakening of optical efficiency was limited. The optical efficiency was more sensitive to slope error than to tracking error. The offset direction along positive Y-axis caused at maximum 2.19 times increase in heat flux density than that without optical errors, which causes threat of overheating to the absorber. When alignment error and tracking error were in the opposite direction, the optical loss could be compensated, whereas that in the same direction enlarged the optical loss. The slope error weakened the compensation effect and aggravated the weakening effect.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Jiaxu Wang, Xuefeng Liu, Siwei Chen, Hanghang Jiang, Guanyu Fang, Wenjing Chen, Shiming Deng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The current work study the heat dissipation characteristics and airflow distribution in a power cabin. By simplifying the cable structure, a 1:5 reduced-scale model was constructed based on the Archimedes number. Computational fluid dynamics (CFD) simulations were applied to the prototype power cabin. The 3D steady-state Reynolds average Navier-Stokes (RANS) equation is used to solve the ventilation flow, where the turbulence model is realizable k–ε. The CFD simulation of the prototype has been verified by the reduced-scale model. On this basis, several conclusions were drawn. The airflow distribution in the power cabin and cable arrangement cause a difference in the temperature distribution between the cables. The strong turbulence at the air inlet causes a significant temperature drop. The mechanical fan can effectively cool the cable to a certain extent, but cable temperature control should take into account the effects of ampacity and ventilation, as well as cable location.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Wenwu Zhou, Lin Yuan, Xin Wen, Yingzheng Liu, Di Peng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present study explored and examined the piezoelectric (PE) jet: an active cooling concept that can be actuated in demand, which had an oscillating flow and extremely low power consumption. The heat transfer and flow characteristics of the PE jet were quantified at various Reynolds numbers (〈em〉Re〈/em〉 = 5000, 10,000, 18,000) and spacings (〈em〉H〈/em〉/〈em〉D〈/em〉 = 4.5, 5.5, 6.5; corresponding gap 〈em〉G〈/em〉/〈em〉D〈/em〉 = 0.1, 1.1, 2.1). The temperature sensitive paint technique was used to study the heat transfer, and the particle image velocimetry technique was applied to resolve the flow characteristics and to further correlate the heat transfer results. Measured results show that the impingement cooling of the PE jet increased as the 〈em〉Re〈/em〉 increased and as the 〈em〉H〈/em〉/〈em〉D〈/em〉 decreased. Compared with a circular jet, the PE jet exhibited a greatly improved heat transfer at 〈em〉H〈/em〉/〈em〉D〈/em〉 = 4.5 (i.e., 〈em〉G〈/em〉 = 0.1〈em〉D〈/em〉), with a maximum of 20% enhancement in area-averaged 〈em〉Nu〈/em〉. Due to the fan oscillation, the turbulent kinetic energy level in the PE jet was significantly higher than in the circular jet, which greatly promoted the heat transfer at a narrow gap. In general, the new PE jet can provide superior heat transfer performance at a small gap and a high Reynolds number.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Sanaz Tabasi, Hossein Yousefi, Younes Noorollahi, Mohamad Aramesh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, the performance of a photovoltaic panel integrated with a reflecting mirror is investigated. In this regard, the effects of panel and mirror tilt angles, and the mirror length on the system performance are modeled. The cell temperature rises have also been considered. Moreover, by a 3D model, the lighting and shading statuses are studied in detail, and all the possible conditions are presented and modeled. The resulting model can calculate the amount of incident solar energy on the panel and the generated electrical power in every moment during a year. This amount is dependent on the system configuration and capacity and its location. A 250-W photovoltaic panel and the city of Tehran have been considered the basics of calculations to assess the model results. By employing the genetic algorithm method, the optimum configuration has been found to have 69.084° and 0° tilt angles for the panel and the mirror, respectively, at the mirror length of 2 m. This configuration can generate 2.38 GJ (613.89 kWh) of electrical energy annually. It was also found that the optimum configuration had 0.024 GJ of annual energy losses due to the effects of cell temperature rise.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Su Min Hoi, An Liang Teh, Ean Hin Ooi, Irene Mei Leng Chew, Ji Jinn Foo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The flow across the plate-fin heat sink under the influence of 2D planar space-filling square fractal grid-induced turbulence at Reynolds number 〈em〉Re〈sub〉Dh〈/sub〉〈/em〉 of 2.0 × 10〈sup〉4〈/sup〉 is numerically characterized. Fractal thickness ratio 〈em〉t〈sub〉r〈/sub〉〈/em〉, plate-fin inter-fin distance 〈em〉δ〈/em〉 and grid-fin separation 〈em〉ℓ〈/em〉 are numerically explored and optimized via Response Surface Optimization (RSO) with the objective of maximizing the Nusselt number 〈em〉Nu〈/em〉. Results reveal that, thanks to highly interactive, small and comparable turbulence length scale 〈em〉L〈sub〉t〈/sub〉〈/em〉, strong turbulence intensity 〈em〉T〈sub〉u〈/sub〉〈/em〉 and high velocity adjacent to the fin surfaces, thermal dissipation of plate-fin heat sink enhances significantly. An optimum fractal grid and plate-fin geometrical combination having 〈em〉t〈sub〉r〈/sub〉〈/em〉 = 9.77, 〈em〉δ〈/em〉 = 0.005 m and 〈em〉ℓ〈/em〉 = 0.01 m is proposed. It delivers 〈em〉Nu〈/em〉 of 3661.0 which is 6.1% and 16.3% greater than the reference case and least favorable configuration, respectively. Sensitivity analysis discovered that 〈em〉δ〈/em〉 effectively dominates the thermal dissipation improvement while 〈em〉t〈sub〉r〈/sub〉〈/em〉 contributes the most on the pressure drop. Interestingly, fractal grid may not necessarily augmenting plate-fin forced convective heat transfer. Without proper-tuning the fluid flow structures within the fins may worsen the thermal dissipation instead of strengthening it. In short, the interaction between plate-fin heat sink and the fluid flow structures within the fins contributes greatly to heat transfer performance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Mark Baldry, Victoria Timchenko, Chris Menictas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Metal additive manufacturing technologies are increasingly being adopted for rapid prototyping and to build geometrically complex designs for thermal management. This paper develops and experimentally validates a numerical model to design a high performance, small-scale heat sink for use with a thermoelectric cooling cap. The design was constrained by a heat load of 2.15 W, and a target average base temperature of 45 °C as a compromise between avoiding burn injury and reducing heat dissipation requirements. Over successive numerical iterations, an optimal natural convection heat sink was developed with an estimated thermal resistance of 10.9  K·W〈sup〉−1〈/sup〉 and base temperature of 44.4 °C. This design featured an internal cavity in a tapered pin array, and was able to achieve a steady state base temperature that was 11.7 °C cooler than a conventional design, with 51% less surface area and significantly less material.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Nae-Hyun Kim, Cheol-Hwan Kim, Yousaf Shah, Wei Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In a parallel flow heat exchanger, significant mal-distribution of flow occurs due to phase separation. In this study, various insert devices (perforated tube, perforated tube with perforated plate, orifice and perforated tube, concentric perforated tube) were investigated to obtain an improved flow distribution in a 36 channel parallel flow heat exchanger. The test section was made to closely simulate an actual heat exchanger. Tests were conducted for upward flow for the mass flux from 57 to 241 kg m〈sup〉−2〈/sup〉 s〈sup〉−1〈/sup〉 and quality from 0.2 to 0.4 using R-410A. Of the investigated insert devices, concentric perforated tube yielded the best flow distribution. Insertion of the concentric perforated tube reduced the thermal degradation from 61% to 14%. Furthermore, the preferred number of holes of the concentric perforated tube was dependent on the mass flux. At a low mass flux, an insert having small number of holes was preferred, whereas the reverse was true at a high mass flux. At a low mass flux, the effect of inlet vapor quality on flow distribution was significant. At a high mass flux, however, the effect of vapor quality on flow distribution was minimal. Possible explanations on the flow distribution behavior were provided through flow visualization in the header.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): Yadan Guo, Chenxi Li, Yiqin Guo, Xuegang Wang, Xiaomeng Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Graphitic carbon nitride (g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉) is a new type of nonmetal polymeric semiconductor photocatalyst for removal of pollutants. To overcome the low BET surface and the low electron–hole recombination rate of the g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 photocatalysts, we successfully synthesized g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/Na-bentonite composites using an ultrasonic-assisted method. The XRD showed that the composite was composed of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 and Na-bentonite. The analyses of TEM and XPS indicated that graphite carbon nitride was successfully intercalated on Na-bentonite via the ultrasonic-assisted strategy, and the g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/Na-bentonite nanocomposites presented remarkable light absorption capacities and mesoporous structure observed by UV–vis DRS and BET method. In addition, the as-prepared composites can be used for the photocatalytic removal of single RhB or Cr(VI), and the efficiencies of the Cr(VI) reduction are increased from 53.2% to 88.6% in RhB/Cr(VI) mix-system. Superior stability and high efficiencies of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/Na-bentonite composites were also exhibited for up to 4 cycles. The photocatalytic enhancement was due to the strong adsorption and the higher charge separation efficiency of as-prepared g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/Na-bentonite composites.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719306065-ga1.jpg" width="219" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): Lifeng Chen, Zhen Qian, Liang Li, Meilong Fu, Hui Zhao, Lipei Fu, Gang Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Water production is getting worse along with the continuous water injection in the reservoir with fracture, but common hydrogels cannot be successfully applied for water shutoff due to its poor resident ability in fracture. In this work, an interpenetrating network hydrogel has been developed innovatively by polyvinyl alcohol (PVA) fiber and common polyacrylamide (PAM) hydrogel. Plugging ability, long-term thermal stability and the interaction between PVA fiber and hydrogel were detailedly studied. Results show that PVA fiber is beneficial to the stability of the PAM hydrogel, and the syneresis rate can be decreased from 30% to 3% on the 120〈sup〉th〈/sup〉 day. PVA fiber accelerates the hydrogel gelation, and the high concentration of fiber leads to good hydrogel strength. PVA fiber increases the amount of the bound water in hydrogel, leading the hydrophilcity increase of hydrogel. An interpenetrating network is formed on the micrometer level, resulting from the three-group crosslinking among polymer, cross-linker and fiber. Compared with common PAM hydrogel, the interpenetrating network hydrogel has better water shutoff effect and EOR performance. Core flow experiment and micromodel test show that the interpenetrating network hydrogel forms an effective bridge in fracture, and it is hard to be moved due to the water washing. The introduction of fiber to hydrogel is an innovative research, which not only improves the water shutoff effect of hydrogel in fracture, but also provides reference to increase the performance of drilling fluid, fracturing solution and EOR polymer utilized in petroleum engineering.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Micropresentation of synergistic effect of PVA fiber on PAM solution (A, B) and hydrogel (C, D).〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719305928-ga1.jpg" width="252" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): Krzysztof Kolman, Zareen Abbas〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Molecular dynamics (MD) simulations provide molecular level information about the interaction of organic molecules with the solid surfaces. There has been much development of this method to simulate the interaction of organic molecules with neutral surfaces but relatively less information is available regarding the interactions with charged surfaces. In this study we have developed MD model for the charged silica surface and have investigated the interactions of different benzoic acid derivatives with the charged silica surface in pure and saline water at acidic, neutral and basic pH. The investigated molecules were 2,3-dihydroxybenzoic acid (23DHBA), 3,4-dihydroxybenzoic acid (34DHBA), 1,2,4-benzenetricarboxylic acid (BTCA) and phthalic acid (PHTHA). To simplify the analysis of results, three different simulation systems were considered. Clustering simulations showed how molecules aggregate in solution, pulling simulations provided quantitate information regarding the interactions of single molecule with the silica surface, whereas adsorption simulations focused on the adsorption of multiple molecules on the surface. In general, at pH 2–3, all investigated molecules were clustering and were attracted towards the surface. At pH 7, due to arising electrostatic repulsion, the interactions became weaker which prevented 23DHBA, 34DHBA and BTCA from clustering, however, they continued to adsorb on the silica surface. The adsorption of 23DHBA and 34DHBA decreased significantly at pH 9–10 due to electrostatic repulsion between the molecules and charged silica surface, while BTCA adsorbed slightly stronger due to interactions with ions close to the surface. PHTHA molecules behaved differently by clustering stronger and adsorbing weaker at higher pH. The results of MD simulations presented in this work by using pulling and adsorption approaches provide possibility to compare the results with experimental data.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719301748-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): José G. Parra, Héctor Domínguez, Yosslen Aray, Peter Iza, Ximena Zarate, Eduardo Schott〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Structural characteristics, interfacial distribution and molecular interactions of the components of the CO〈sub〉2〈/sub〉(gas)/SDS/water/SDS/CO〈sub〉2〈/sub〉(gas) systems as a function of the CO〈sub〉2〈/sub〉(gas)/water interface coverage by the SDS surfactant to different amounts of the CO〈sub〉2〈/sub〉 were studied with molecular dynamics simulations and the NVT ensemble. Initially, the repulsive nonbonding parameter between the water oxygen and CO〈sub〉2〈/sub〉 oxygen was adjusted to improve the prediction of the solvation free energy, solubility of the CO〈sub〉2〈/sub〉 gas in water and the behavior of the CO〈sub〉2〈/sub〉(gas)/SDS/water/SDS/CO〈sub〉2〈/sub〉(gas) systems at molecular level. Our results show that the stability of the studied foams can be improved incrementing of the vapor/water interface coverage with the SDS surfactant and the amount of CO〈sub〉2〈/sub〉 in the system. With the highest interface coverage, the sulfate group has a molecular array more compact at the interface. Furthermore, CO〈sub〉2〈/sub〉 gas have a reduction of the diffusion across of the hydrocarbon chains to the water layer with an increment of the number of CO〈sub〉2〈/sub〉 molecules in the system, indicating a behavior more hydrophobic of the CO〈sub〉2〈/sub〉 gas. The tendencies obtained of the simulations are consistent with the reported experimental results.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719305989-ga1.jpg" width="239" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): M. Jinish Antony, C. Albin Jolly, K. Rohini Das, T.S. Swathy〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report here the synthesis of polyaniline (PANI) nanomaterials using sodium bis (2-ethylhexyl) sulfosuccinate (AOT) micelles assisted chemical oxidative interfacial polymerization. We have employed two interfaces (chloroform-water and hexane-water) and two oxidizing agents (ammonium persulfate and ferric chloride). The anionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate (AOT) forms normal micelles in aqueous solution and reverse micelles in hydrophobic solvents like hexane or chloroform. The factors influencing the properties and morphologies of polyaniline nanomaterials such as monomer: surfactant ratio, monomer: oxidant ratio, types of interfaces and oxidants used have been studied. Powder X-ray diffraction of the polyaniline nanomaterials have revealed that polyaniline samples were semi-crystalline in nature. Morphology of polyaniline samples studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have revealed that most of the polyaniline nanomaterials synthesized using ferric chloride possess spherical nature, whereas polyaniline samples synthesized using ammonium persulfate (APS) possess short nanofibers especially at lower aniline/AOT mole ratio in feed (12.5–6.5). The four probe electrical conductivity of the samples were found to be of the order of 1.8 × 10〈sup〉−1〈/sup〉 to 8.6 × 10〈sup〉−1〈/sup〉 S/cm. Thermal stability of the polyaniline samples recorded by thermogravimetric analysis (TGA) have revealed that polyaniline samples were thermally stable up to 275 °C for 10% weight loss. Interfacial polymerization of aniline monomer using reverse micelles of AOT in hexane phase and ammonium persulfate as oxidizing agent in aqueous phase have been proved to be efficient method for the synthesis of short polyaniline nanofibers.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719306090-ga1.jpg" width="316" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): Feng Zhao, Shibin Wang, Xin Shen, Jianchun Guo, Yuxuan Liu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Inhibiting acid-rock reaction rate is an important key in the field of acid fracturing. Based on the acid-rock reaction mechanism and the performance characteristics of surfactant, the surfactant is applied to cover the rock surface for forming an adsorption layer, which can keep H〈sup〉+〈/sup〉 from contacting the surface of rock during acid fracturing. In this paper, a series of cationic Gemini surfactants with different hydrophobic chain length are synthesized (C〈sub〉n〈/sub〉-4-C〈sub〉n〈/sub〉, n = 12, 14, 16).The surface tension, adhesion work, and AFM are used to investigate the effect of hydrophobic chain length and concentration of surfactant on surface activities, adsorption morphology and adsorption capacities. The static acid-rock reaction rate is measured and the surface of the rock plate is digitally characterized by 3D scanning. The results show that Gemini surfactants have the high surface activities. It can be recognized from AFM that as the length of the carbon chain increases, the aggregation of Gemini surfactants on the surface to form micelles becomes more and more obvious, resulting in a decrease in the density and area of the adsorption. However there are few differences for adsorption capacities. Therefore, 12-4-12 can restart H〈sup〉+〈/sup〉 most efficiently. This conclusion is proved by static acid-rock reaction. In addition, H〈sup〉+〈/sup〉 only reacted with the rock from the micro fractures of the adsorption layer formed by 12-4-12, the surface morphology of the rock plate after etching is the best rugged. In conclusion, it is believed that using the Gemini surfactant to form an adsorption layer on the rock surface is a new approach for inhibiting acid rock reaction rate and has great potential in oil field application.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Inhibiting acid-rock reaction rate is an important key in the field of acid fracturing. The morphology of the surfactant on the rock controls the rate between acid and rock. The properties of the different chain length surfactant form different layered structure on the substrate. 12-4-12 can play an efficacious role to adsorb on the rock surface to prevent H〈sup〉+〈/sup〉 from contacting the surface of rock.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719306119-ga1.jpg" width="295" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): Zhao Mu, Jianhao Hua, Sai Kumar Tammina, Yaling Yang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In current investigation, we synthesized a new Cu, N co-doped carbon dots/Ag〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉 (Cu, N-CDs/Ag〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉) nanocomposite by one-step thermolysis and precipitation method. In addition, we evaluated the activity of Ag〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉 and Cu,N-CDs/Ag〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉 nanomaterials in degrading an environmental pollutant called neutral red under visible radiations. Compared to the pure Ag〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉, Cu, N-CDs/Ag〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉 had shown high degradation efficiency by more than 25% and shown good recyclability. The synthesized nanocomposite was characterized by XRD, HRTEM, FT-IR, Raman and XPS techniques. The optical property of Cu, N-CDs/Ag〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉 nanocomposite was examined with UV–vis DRS (Diffuse Reflectance Spectroscopy). And the excellent photocatalytic performance of this Cu, N-CDs system was ascribed to the increased conversion of ·O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 under visible light irradiations and effective separation of electron-hole pairs, results in inhibited photocorrosion of the system. Also, this nanocomposite could successfully degrade the neutral red dye (mention the concentration) about 95.5% under LED irradiations within 60 min.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719306193-ga1.jpg" width="222" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): Juan David Beltrán, Camilo Eduardo Sandoval-Cuellar, Katherine Bauer, María Ximena Quintanilla-Carvajal〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Liposomes are spherical vesicles which can be used as encapsulation systems for transporting and releasing many biocomposites which can be affected by conditions in the gastrointestinal tract; such affectation means that the dominant degradation mechanisms and the factors influencing such degradation must be identified by means of digestion studies. This study was thus aimed to evaluate the physical stability and intestinal digestibility of nanoliposomes (NLs) produced by microfluidization (MF) and ultrasound (US) for high oleic palm oil (HOPO) encapsulation. A standardized 〈em〉in vitro〈/em〉, three-stage (〈em〉i.e.〈/em〉 oral, gastric and intestinal) static model of the gastrointestinal tract was used which had been published by the INFOGEST research network. No statistically significant changes were observed concerning any of the properties regarding stability during the oral phase; however, both types of NL studied here became destabilized during the gastric phase by environmental conditions, such as acid pH and high ion concentration. This was reflected by increased average particle size, the polydispersity index and the Z potential. Decreased particle size was observed during intestinal digestion regarding both technologies compared to gastric phase. MF-produced NLs were larger than US-produced ones during this phase. Intestinal enzymes degraded the system’s triglycerides, leading to 116.04 ± 2.62%w MF and 80.39 ± 2.26%w US free fatty acid release.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719305862-ga1.jpg" width="389" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): Chengwei Wang, Lili Ma, Qingkun Wen, Baoxiang Wang, Rongjiang Han, Chuncheng Hao, Kezheng Chen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, an electrorheological (ER) fluid containing titanium oxide@ H〈sub〉2〈/sub〉Ti〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanotube core/shell nanocomposite was prepared via the combination of hydrothermal and solvo-thermal method. The morphological evolution was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Furthermore, the structural characteristics of the as-obtained core/shell nanoparticles were confirmed by x-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) and nitrogen adsorption measurements respectively. Titanium oxide@H〈sub〉2〈/sub〉Ti〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanotube core/shell nanocomposite is showed to possess tube-like and core-shell structure and enhanced ER properties under external electric fields.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092777571930617X-ga1.jpg" width="235" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Rohit Singla, Kanchan Chowdhury〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cryogenic air separation plants producing pressurized gaseous oxygen (PGOX) near 40 bara at purities 99.8% and 95% and gaseous nitrogen at 5 bara above 99.99% purity are analyzed. Oxygen is compressed either by external compression process (EC) or by internal compression (IC). IC is gasification of pumped liquid oxygen in the main heat exchanger (MHX). IC plants require appropriate combinations of pressure and flow of air and size of the MHX to vaporize PGOX with reasonable specific power consumption (SPC). Based on exergy and economic analyses of the ASU after simulating the plant in Aspen HYSYS®™8.6, the values of parameters which give high exergy efficiency with low capital and operating expenditures are determined. SPC of IC is 7–8% higher than that of EC. Addition of crude argon column improves the purity of oxygen from 96.3% to 99.8%. Recovery of oxygen improves by 5% with 3–4% reduction of SPC for both types of plants. Capital requirement for both EC and IC plants is about 50% higher with argon separation than without it. HP air between 33% and 31% of total air flow at 70 bara and 80 bara respectively is the most preferred range of operation of IC plants for 95% purity of oxygen. The corresponding flow of HP air is 5% lower for 99.8% purity of oxygen.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Medhat M. Sorour, Wael M. El-Maghlany, Mohamed A. Alnakeeb, Amgad M. Abbass〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An experimental investigation was conducted in order to study heat transfer between a vertical free surface jet and a horizontal stainless steel heated plate. The jet was composed of water-〈em〉SiO〈sub〉2〈/sub〉〈/em〉 nanofluid with an average particle size of 8 nm delivered from a fixed nozzle diameter of 6 mm. The results covered a wide range of jet Reynolds number up to 40000, ten nanoparticle volume fractions (0% ≤ 〈em〉φ〈/em〉 ≤ 8.5%), five jet aspect ratios (〈em〉z/d〈/em〉 = 0.5, 1, 2, 4 and 8) and plate radius to jet diameter ratio (〈em〉r/d〈/em〉) up to 12.5. The experimental results illustrated that the enhancement of the average Nusselt number increases with the volume fraction and Reynolds number. Therefore, the volume fraction can significantly provide a heat transfer enhancement of the average Nusselt number up to 80% for a volume fraction of 8.5% compared to pure water. Conversely, the effect of nozzle to plate aspect ratio (〈em〉z/d〈/em〉) is not significant. Finally, a new heat transfer correlation has been proposed for the average Nusselt number as a function of Peclet number, a nanoparticle volume fraction, a plate to jet diameter ratio and a nozzle to plate aspect ratio.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Grayson Lange, Luca Carmignani, Subrata Bhattacharjee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Radiative emission from a flame is an important component of the heat transfer balance between flame and surroundings. When the residence time of the oxidizer increases radiation plays an important role, and a practical example is given by microgravity flames where the lack of buoyancy creates larger time scales of the problem. With a strong opposed-flow, however, radiation could become a secondary effect. This study presents experimental measurements of thermal radiation from downward spreading flames over thin sheets of PMMA (polymethyl methacrylate) in a normal gravity environment and no forced flow. Radiation data from these downward spreading flames can serve as a baseline for future microgravity experiments. The presented experiments are performed in an apparatus called Flame Stabilizer where a spreading flame is turned stationary in laboratory coordinates by moving the sample upwards at the same velocity as the downward spreading flame. A radiometer, capable of line of sight measurement, is mounted on a x-y-z position controller and used to map the radiation emitted by the flame and the burning solid perpendicular to the fuel surface. After establishing repeatability and consistency of the results, a family of radiation profile curves is generated to map the radiation field. The experiments are then repeated by varying fuel thickness; larger fuel thicknesses are found to generate stronger radiation signals as the flame size becomes bigger. Furthermore, the radiative response to the presence of char in a flame is illustrated by comparing the PMMA results with a cellulosic fuel. With the unburnt solid in the flame region, radiative emissions significantly increase.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): X. Zheng, Z. Lin, B.Y. Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Desiccant coated aluminum fins are an important part of desiccant coated heat exchangers (DCHEs). The overall performance of DCHE-based systems benefits from improved heat and mass transfer characteristics of desiccant coated aluminum fins. In this paper, a new type of nano-silver powder supported FAPO-34 composite fin is proposed. Samples with different mass percentages of nano-silver powder were fabricated and related characteristics including thermal conductivity, cycle water uptake and adsorption/desorption performance were investigated. Our experimental results show greatly improved thermal conductivity of nano-silver powder supported composite sheets. Analysis of the adsorption testing confirmed that the nano-silver powder improved dynamic adsorption performance, and adsorption rate coefficients of composite sheets increasing by 6–103% compared with that of a pure FAPO-34 coated sheet. The composite samples also exhibited better dynamic desorption performance, in that their desorption rate coefficients increased to be 1.3–2.3 times as great as those of the pure FAPO-34 sample.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Xinpeng Zhao, Sohrab A. Mofid, Majed R. Al Hulayel, Gabriel W. Saxe, Bjørn Petter Jelle, Ronggui Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Highly transparent and low thermal conductivity materials have attracted great interest for the applications in window insulation in recent years. Accurate characterization of the thermal properties including thermal transmittance (U-value) and thermal conductivity of window insulation materials is very important for developing next-generation materials. The conventional hot box method, which is commonly used to measure the U-values of building materials, requires sample sizes 〉 1.0 m〈sup〉2〈/sup〉 to minimize the influence of parasitic heat loss on the measurement accuracy. This characterization challenge hinders the development of novel window materials which are not yet available for large-scale deployment. To address this issue, a reduced-scale hot box system (RHS) was designed to measure both the U-value and the thermal conductivity of specimens that can be more readily made, with sizes 〈 0.2 m × 0.2 m. The developed reduced-scale hot box system has a very simple testing system and can avoid the challenging thermal insulation requirement of the conventional hot box. The fast turnaround of the reduced-scale hot box system can help facilitate the development of novel insulating materials for energy-efficient windows.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Thi-Thao Ngo, Chi-Chang Wang, Jin H. Huang, Van-The Than〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents an inverse method for predicting the heat source and temperature during Gas Metal Arc Welding (GMAW). A combination of finite element thermal model and optimized technique is used to give inverse solutions. Simulated results show that the estimated temperatures and heat source are in good agreement with the exact solutions. Experiments are then performed to measure real temperature data which are further utilized for inversely predicting the heat source and temperature field. The experimental inverse results indicate that the predicted temperatures have a good correlation with the measured data, and the heat source is carried out for different welding conditions. To verify accuracy of the inverse results, a comparison of temperature at validated point is implemented. In addition, the temperatures at the welding area which are difficult to directly measure are also obtained. The proposed method may be applied to optimize welding condition for other welding processes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 578〈/p〉 〈p〉Author(s): Jincheng Mao, Jizhen Tian, Wenlong Zhang, Xiaojiang Yang, Heng Zhang, Chong Lin, Yang Zhang, Zhaoyang Zhang, Jinzhou Zhao〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Gemini cationic surfactants, which have two cationic surfactant molecules connected by a spacer, have received increased attention in recent years as very good thickeners for clean fracturing fluids. We synthesized four Gemini cationic surfactants with three, four, five, and six methylene groups in the spacers. Salts can promote micelle aggregation of viscoelastic surfactants (VESs) and affect their performance and we used potassium chloride (KCl) to study the performance differences of the surfactants with different spacer lengths. The results showed that the surfactant with three methylene groups in its spacer had the lowest critical micelle concentration, and when combined with KCl in solution, it had the best salt tolerance and apparent viscosity in KCl concentrations ranging from 0.2 wt% to 2.6 wt%. In addition, the solution also exhibited an excellent viscoelasticity and a tighter network microstructure, which was confirmed by SEM observation and oscillatory measurement. We conducted rheological measurements for the four Gemini cationic surfactant fracturing fluid formulations with a shear rate of 170 s〈sup〉−1〈/sup〉 at up to 100 °C. The solution with KCl and the surfactant with the shortest spacer had distinctly superior rheological properties, and its viscosity could be maintained above 58 mPa.s after 120 min. Finally, we did proppant suspension tests, gel breaking property tests, and core matrix permeability damage rate tests on the four optimized fracturing fluid systems. The solution prepared by KCl and the surfactant with the shortest spacer was found to have the most favorable properties for fracturing fluids. These results demonstrate that decreasing the spacer length of a Gemini cationic surfactant leads to better performance in fracturing fluids.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The effect of counter-ion salt (KCl) concentrations on 21-(3,4,5,6)-21 surfactants that the surfactant solutions were transparent at low salt concentrations, but with increasing counter-ion concentrations above a peak viscosity, the phase separation occurred in all surfactant solutions. Meanwhile, this also shows that increasing the number of carbon atoms on the spacer of the surfactants lead to a greater sensitivity to the phase separation phenomenon.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719306016-ga1.jpg" width="227" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Mingyue Ding, Chenzhen Liu, Zhonghao Rao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to enhance the heat transfer performance of phase change material (PCM) for thermal energy storage (TES) in tiny devices, such as battery thermal management, light-emitting diode and electronic device cooling, TiO〈sub〉2〈/sub〉-H〈sub〉2〈/sub〉O nanofluids and the microchannel were combined in this paper. Two crystal forms of TiO〈sub〉2〈/sub〉-H〈sub〉2〈/sub〉O nanofluids were prepared by using a two-step method. And paraffin was used as PCM. The stability and thermophysical properties of the above two nanofluids were tested and compared. It can be found that R TiO〈sub〉2〈/sub〉-H〈sub〉2〈/sub〉O nanofluid has better stability, and its thermal conductivity increases maximally by 3.27%, while the value is 2.88% of A TiO〈sub〉2〈/sub〉-H〈sub〉2〈/sub〉O. Besides, R TiO〈sub〉2〈/sub〉-H〈sub〉2〈/sub〉O nanofluid increases the viscosity by a maximum of 4.87%, while A TiO〈sub〉2〈/sub〉-H〈sub〉2〈/sub〉O increases by 7.45%. Considering these properties, R TiO〈sub〉2〈/sub〉-H〈sub〉2〈/sub〉O nanofluid was chosen to study the heat transfer characteristics in the microchannel within a TES unit. The results indicate that R TiO〈sub〉2〈/sub〉-H〈sub〉2〈/sub〉O nanofluid with 1.0 wt% increases Nu by 19 ∼ 41% and 6 ∼ 14% during the melting process and solidification process respectively. In addition, the melting time of paraffin decreases by a maximum of 32.90% and the solidifying time of paraffin decreases by a maximum of 22.57%. During the whole TES process, there is an increase in pressure drop of no more than 8%.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Amir Sharafian, Paul Blomerus, Walter Mérida〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fugitive methane emissions from the liquefied natural gas (LNG) supply chain have revealed uncertainty in the overall greenhouse gas emissions reduction associated with the use of LNG in heavy-duty vehicles and marine shipping. Methane is the main constituent of natural gas and a potent greenhouse gas. Recent measurements have shown that the LNG offloading process had the largest contribution to methane emissions in the refueling portion of the supply chain. However, there are limited studies analyzing the LNG offloading process for small-scale applications. This study investigates six methods used to offload LNG from a tanker truck to an LNG refueling station and their contribution to methane emissions. A verified thermodynamic model is created by comparing numerical results with the experimental data collected from an LNG offloading process in a refueling station. The modeling results show that the LNG transfer by using a pressure buildup unit causes methane emissions as high as 104 g/kg LNG. In contrast, LNG transfer by using a pump and controlled pressure buildup unit provides the lowest risk of methane venting. Also, the results of parametric study indicate that rigid foam insulation can be considered as an economical alternative to vacuum jacketed pipes in LNG refueling stations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Cheng Zeng, Shuli Liu, Liu Yang, Xiaojing Han, Ming Song, Ashish Shukla〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For some renewable energy such as solar energy, the mismatch between the side of generation and demand should be tackled by thermal energy storage techniques with high energy density and low thermal losses. Thermochemical energy storage is a promising technology to meet these requirements. Within a thermochemical energy storage system, reactor is one of the critical components to achieve the optimal performance. While few studies have investigated the three-phase reactor applied in open thermochemical system in building’s application. This study presents a numerical description of a three-phase thermochemical reactor with air, solid thermochemical material and water flow. Zeolite 13X has been selected as the working thermochemical material and experimental tests have been conducted to obtain the temperature profiles in both the charging and discharging processes. A two dimensional numerical model of the reactors has been developed, verified and validated. A good agreement has been obtained by comparing the numerical and experimental results with the root mean square percent error ranging from 6.02% to 12.29%. Additionally, parameters sensitivity analysis has been conducted for reference diffusivity, heterogeneity factor, and initial water uptake of the zeolite. The numerical model and the investigation provide the tool for reactor design optimisation, charging and discharging processes evaluation and reactor performance improvement.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Dan Dan, Chengning Yao, Yangjun Zhang, Hu Zhang, Zezhi Zeng, Xiaoming Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An effective battery thermal management system is crucial for electric vehicles because the performance of lithium ion battery is sensitive to its operating temperature. In this study, a thermal management system equipped with micro heat pipe array (MHPA) is designed. An equivalent thermal resistance model is developed for MHPA based on thermal circuit method. The accuracy of the proposed model is validated by comparing the simulation results with experimental data under steady and dynamic and operating condition. A validated lumped thermoelectric model is adopted for prismatic lithium ion battery. The proposed thermal resistance model is combined with the battery model in order to predict the transient temperature distribution of a battery pack based on MHPA cooling. Simulations are conducted for air-cooled MHPA thermal management system. Temperature rise and temperature gradients of the designed cooling system are compared with direct forced convection. Simulation results demonstrate that the MHPA-based battery thermal management provides a quick response to ensure the temperature stability during rapid changing operating condition.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Farkhondeh Jabari, Behnam Mohammadi-ivatloo, Mousa Mohammadpourfard〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recently, seawater desalination and power generation units are optimally co-scheduled because of interconnection between electricity and water networks. A typical water-energy hub grid consists of the conventional thermal power plants and the combined water and power (CWP) generating units. In the CWP plants, the waste heat of the flue gases exhausted from the power generation process is utilized for water treatment. If the water and power generation company aims to maximize its daily profit, the electricity price uncertainty will affect the optimum operating point of the generating units. In other words, the fluctuations of the energy prices cause the power generation patterns of thermal and CWP units to change. Hence, this paper implements a robust optimization strategy on water-power nexus model to handle the uncertainty of the electricity price with no need for its probability distribution and membership functions. The lower and upper bounds and the forecasted prices are used for solving the robust mixed-integer non-linear program and making the risk-averse decisions against the uncertainty. It is indicated that the proposed approach is suitable for the price taker water-power cogeneration companies, which seek the optimal schedule of their thermal and CWP units for a certain operating period.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects〈/p〉 〈p〉Author(s): Zechen Liu, Yangchao Xia, Qingteng Lai, Maoyan An, Yinfei Liao, Yongtian Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this investigation, a mixed collector (MC) of dodecane and n-valeric acid was used to improve low rank coal flotation. Fourier transformation infrared spectroscopy (FTIR) measurements and contact angle measurements were conducted to explain flotation responses. Furthermore, using a molecular dynamics (MD) simulation, the changes of water/collector (dodecane or MC)/coal systems were studied before and after adsorption to indicate the absorption behavior and mechanism. The results showed that a better flotation performance of low-rank coal was obtained using the MC compared to a conventional collector of dodecane. The hydroxyl (-OH) or carbonyl (C = O) or carboxyl (COOH) migration of the coal with the MC was stronger than that with dodecane as a solo collector, and the MC can enhance the hydrophobicity and lipophilicity of the coal surface. MD simulation results revealed the adsorption behavior of the MC on low-rank coal surfaces. Dodecane was mainly adsorbed on the hydrophobic surface of coal, and n-valeric acid was more inclined to act on the oxygen-containing functional group of coal, i.e., a hydrophilic surface. The mobility of = dodecane molecules on the coal surface was reduced owing to the presence of n-valeric acid, which increased the lipophilicity and hydrophobicity of the low-rank coal surface, thus attracting dodecane molecules of the MC and restricting their movement, and accelerating the departure of water molecules from the low-rank coal surfaces. There was also a higher interaction energy between the MC and low-rank coal. The simulation results are in good agreement with the measured results; this effectively explains the flotation results.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308283-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Xing-An Luo, Pei Zhao, Hai Zhang, Shu-Yi Feng, Ke-Xian Chen, Zhong-Xiu Chen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dietary macromolecules are often used for food formulation. Most of the published literature usually focuses on a certain polysaccharide reducing lipid digestion, but the non-specific physical effects such as the excluded volume effect of the surrounding macromolecules, which will possibly enhance the hydrolysis of lipids, is rarely discussed. As the influence of polysaccharides on the gastrointestinal fate of α-tocopherol acetate (VE-A) encapsulated in emulsion have not been conducted so far, in this research, we study the effect of crowded medium created by polysaccharides (Ficoll400) on the hydrolysis of VE-A and its bioaccessibility. The results show that the presence of Ficoll400 increased the bioaccessibility and conversion of VE-A 1.6 times that of a dilute buffer. An enzyme-catalyzed kinetic reaction rate of VE-A hydrolysis is increased up to 3.5 times. Both the improved thermodynamic conversion yields and kinetic rates of the hydrolysis of the VE-A emulsion was further observed in a synthetic macromolecule PEG2000 medium. This research improves our understanding of the crowding effect of macromolecules on VE-A/lipid emulsion digestion.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308258-ga1.jpg" width="323" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Zhiyao Yang, Ming Qu, Omar Abdelaziz, Kyle R. Gluesenkamp〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Liquid desiccant systems (LDS) have recently seen an increase in research interest as they can utilize low-grade heat resources and separate the sensible and latent cooling loads by efficiently removing moisture in the air without cooling it to the dew point. However, simulation and analysis of LDS had remained complex and demanding due to the limited resources of LDS simulation tools. This work presents the new LDS module developed in the Sorption system Simulation program (SorpSim), which is an open-source and flexible platform for steady-state simulation and analysis of various sorption systems. First, the new LDS module containing a finite-difference model and an effectiveness-NTU model for the heat and mass transfer in LDS dehumidifier/regenerator component was introduced. Then the simulation results of the new module were verified using data from the literature. Finally, a case study was carried out in SorpSim where an LDS cycle was built and simulated using the new module. The impacts of design and operating parameters on the simulated LDS performance were investigated. The parametric study revealed that a high source temperature improved moisture removal rate (MRR) but reduced the system coefficient of performance (COP); the COP increased monotonically with the desiccant solution recirculation ratio, while the MRR peaked at a ratio of 85%; and an internal solution heat exchanger with UA of 800 W/K was found to be sufficient for optimal performance under high recirculation ratios. The case study demonstrated the LDS module’s capability to facilitate the analysis of LDS design and operation. The LDS module can be further coupled with other component models in SorpSim to simulate and analyze various liquid-desiccant-based systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Mohammad Parhizi, Ankur Jain〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Phase change materials (PCMs) are used commonly for thermal energy storage and thermal management. Typically, a PCM utilizes its large latent heat to absorb and store energy from a source. The rate of energy stored (W) and energy storage density (J/m〈sup〉3〈/sup〉) over a certain time period are both important performance parameters of a phase change based energy storage system. While significant experimental research has been carried out to improve thermal conductivity of PCMs, there is a lack of theoretical understanding of how thermal conductivity and other thermophysical properties affect these performance parameters. This paper presents a theoretical heat transfer model to predict the rate of energy storage and energy storage density as functions of PCM thermal properties. Using perturbation method based techniques, expressions for these parameters are derived for two geometries, first for a simplified assumption of constant temperature at the source-PCM interface, and then for a more realistic scenario of time-dependent interface temperature. Results indicate that while increasing thermal conductivity results in improvement in rate of energy stored, the energy storage density does not change for a Cartesian system and actually decreases for cylindrical system. This shows that using a high thermal conductivity PCM may not be ideal when energy must be stored compactly because while this increases the total energy absorbed, it also results in greater rate of melting, which reduces the energy storage density. Results also provide guidelines for material selection for phase change based energy storage systems. For example, a trade-off in the choice between materials of disparate thermal properties is identified in terms of whether the rate of energy stored or energy storage density is paramount. Differences in the performance of Cartesian and cylindrical systems is investigated. Theoretical results presented in this work highlight various performance trade-offs related to the thermal properties of the PCM and help understand the impact of thermal conductivity enhancement on phase change energy storage performance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects〈/p〉 〈p〉Author(s): Ping Ding, Serafim Bakalis, Zhibing Zhang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Foaming in high viscous and non-Newtonian aqueous phase is generally difficult to be realised. In this work, a surfactant (Sodium Linear Alkylbenzene Sulphonate with alkyl chain lengths varying from C10 to C16) named LAS paste mixed with a co-polymer solution of acrylic acid and maleic acid denoted by Polymer solution was used to generate foam under conditions of sparging without or with agitation, which aims to be used as a coating material of detergent powders. The foam structure/morphology, bubble size, gas holdup and liquid drainage in such surfactant-copolymer system were investigated. It was found that two different types of foam were generated: 1) dispersed spherical air bubbles in highly viscous mixtures of LAS paste and Polymer solution with median size d50 in a range of 20 – 50 μm and gas holdup of 0.20 - 0.44 depending on LAS concentration, 2) bubbles with polyhedral structure in a mixture of LAS paste and Polymer solution diluted with water and size d50 = 7.0 ± 0.4 mm and gas holdup of 0.93 ± 0.05. The generated foam structures depended on the energy input, air superficial velocity, surfactant concentration and the liquid viscosity. Besides, they even depended on liquid mixing procedures before the foam was generated, resulting from different transfer rates from LAS paste phase to Polymer solution. The comparison of foam behaviours in such complex system and in single-phase liquid was made. For dispersed spherical bubbles, the median size has been correlated to energy input whilst for bubbles with polyhedral structure the characteristic size has been predicted by considering the balance between their buoyancy and viscous forces generated in the system. Based on the results, the mechanism of foam stabilisation is proposed.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308052-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Xudong Wang, Daqian Zhang, Xiaojia Wang, Zhiwei Kong, Yali Shao, Baosheng Jin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the increasing thermal input of chemical looping combustion (CLC) reactor, the monitoring and diagnosis of its internal boundary conditions become important issues for operation safety. Based on the discrete heat transfer model of reactor wall, Kalman filter and fuzzy inference were combined as fuzzy inference-based augmented Kalman filter (FI-AKF) and fuzzy inference-based Kalman filter coupled with weighted recursive least squares algorithm (FI-KFW) for the real-time monitoring of CLC reactor. Simulations were carried out to validate the feasibility of these two methods. Under both normal and abnormal conditions, the FI-KFW could exhibited satisfying performances for the internal heat flux monitoring. Number of the measurement points and intensity of measurement noises were changed numerically to investigate their effects on the monitoring results of FI-KFW. Results demonstrated that FI-KFW had strong ability to resist the ill-posedness of the monitoring process and it was capable for the real-time monitoring of the chemical looping combustion reactor, which could offer reliable information for operation diagnosis.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Yongming Han, Chenyu Fan, Meng Xu, Zhiqiang Geng, Yanhua Zhong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The production data of complex chemical processes are multi-dimensional, uncertain and noisy, and it is difficult to directly control raw materials consumption and measure the product quality. Therefore, this paper proposes a production capacity analysis and energy saving model using long short-term memory (LSTM) based on attention mechanism (AM) (AM-LSTM). The weights of the results sequence in the hidden layer, which have great influence on final results in the output layer, are calculated by the AM. Then the production prediction model is built using the LSTM to extract features of the input data and multiple time series results of the hidden layer. Compared with the common LSTM, the multi-layer perceptron (MLP) and the extreme learning machine (ELM), the applicability and the effectiveness of the proposed model is validated based on University of California Irvine repository (UCI) datasets. Finally, the proposed model is applied to analyze the production capacity and the energy saving potential of the purified terephthalic acid (PTA) solvent system and the ethylene production system of the complex chemical process. The experimental results verify the practicability and accuracy of the proposed model. Furthermore, the results offer the operation guidance for production capacity improvement through saving energy and reducing the energy consumption.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359431118343485-ga1.jpg" width="170" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Natalya Sankova, Viktoriya Semeykina, Ekaterina Parkhomchuk〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we have studied the growing mechanism of polystyrene microspheres with a small amount of cross-linking agent (0.2–2 wt%) during dispersion polymerization (DP) in 1-butanol in presence of PVP-40 steric stabilizer. Scanning electron microscopy and dynamic light scattering showed that particles take anomalous form at first several hours due to the growth predominantly by homo- and hetero-coagulation mechanism. The duration of the coagulation process is estimated to be of about a minute. Understanding of the mechanism of particle formation in the above systems will help to overcome the problem of irreproducibility, control the preparation of anisotropic particles during DP and extend the application of these particles.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307332-ga1.jpg" width="496" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Sabino Caputo, Federico Millo, Giulio Boccardo, Andrea Piano, Giancarlo Cifali, Francesco Concetto Pesce〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper investigates the potential of coated pistons in reducing fuel consumption and pollutant emissions of a 1.6 l automotive diesel engine. After a literary review on the state-of-the-art of the materials used as Thermal Barrier Coatings for automotive engine applications, anodized aluminum has been selected as the most promising one. In particular, it presents very low thermal conductivity and heat capacity which ensure a high “wall temperature swing” property. Afterwards, a numerical analysis by utilizing a one-dimensional Computational Fluid Dynamics engine simulation code has been carried out to investigate the potential of the anodized aluminum as piston Thermal Barrier Coating. The simulations have highlighted the potential of achieving up to about 1% in Indicated Specific Fuel Consumption and 6% in heat transfer reduction. To confirm the simulation results, the coated piston technology has been experimentally evaluated on a prototype engine and compared to the baseline aluminum pistons. Despite the promising potential for Indicated Specific Fuel Consumption reduction highlighted by the numerical simulation, the experimental campaign has indicated a slight worsening of the engine efficiency (up to 2% at lower load and speed) due to the slowdown of the combustion process. The primary cause of these inefficiencies is attributed to the roughness of the coating.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Xiaobo Nie, Wei Jiang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A facile method is introduced to tune the aggregate morphologies of ABC triblock copolymer in selective media by combining the self-assembly and hydrogen bonding. Poly(styrene)-〈em〉block〈/em〉-poly(1,4-butadiene)-〈em〉block〈/em〉-poly(2-vinyl pyridine), abbreviated for PS-〈em〉b〈/em〉-PBd-〈em〉b〈/em〉-P2VP and used as an ABC triblock copolymer, self-assembles in toluene and methanol mixture to form discoid micelles with PBd as the disk containing part of PS domains in the core, other PS as bumps and P2VP as corona, respectively. When oleic acid (OA) is added in the assembly system, supramolecular polymer PS-〈em〉b〈/em〉-PBd-〈em〉b〈/em〉-P2VP(OA) is prepared by the hydrogen bonding between OA and P2VP of triblock copolymer. As a result, biscuit-like and mushroom-like micelles are formed with assistance of hydrogen bonding. Interestingly, the biscuit-like and mushroom-like micelles can transform reciprocally by fission and fusion mechanism through varying the volume ratio of toluene and methanol. Thus, it provides a simple and convenient approach to control the aggregate morphologies of block copolymers by tuning the hydrogen bonding and selective solvent content. The multicompartment micelles from ABC triblock copolymer may present potential applications in drug delivery, targeting, catalysis and others.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308271-ga1.jpg" width="247" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects〈/p〉 〈p〉Author(s): Badr M. Thamer, Ali Aldalbahi, Meera Moydeen A, Abdullah M. Al-Enizi, Hany El-Hamshary, Mandeep Singh, Vipul Bansal, Mohamed H. El-Newehy〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Activated electrospun carbon nanofibers (A-ECNFs) with micro/mesoporous structures and high surface areas (1615 m〈sup〉2〈/sup〉 g〈sup〉-1〈/sup〉) were prepared using an electrospinning technique followed by carbonization and alkali activation. The adsorption of Congo red (CR) and methylene blue (MB) dyes by A-ECNFs from aqueous solutions was investigated and compared with those of pristine ECNFs. The textural characteristics and morphology of the prepared pristine and activated ECNFs were characterized using various techniques. The adsorption performance was found to be associated to the surface area, porosity, and surface charges of the prepared adsorbents; the nature and molecular size of the dyes; and the pH and temperature of the solution. Six nonlinear isotherm models were applied to analyze the adsorption equilibrium data, and the results showed that the adsorption behavior could be appropriately described using the Redlich–Peterson isotherm model. The kinetic results for the adsorption of CR and MB onto A-ECNFs were fitted reasonably well to the Elovich model and were fitted by a pseudo-second order (PSO) model onto the pristine ECNFs. According to the thermodynamic results, the adsorption of CR and MB onto the A-ECNFs was endothermic and spontaneous. In addition, the reusability of the A-ECNFs was evaluated over five adsorption-desorption cycles.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308234-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Zilong Wang, Hua Zhang, Binlin Dou, Guanhua Zhang, Weidong Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heat storage tanks are one of the key components in solar thermal utilisation systems. In this study, the effect of the inlet stratifier on the thermal stratification in a heat storage tank with phase-change materials (PCMs) was investigated. A heat storage tank with a volume of 60 L and aspect ratio of 1.68 was developed based on the phase-change temperature of 331.15 K for sodium acetate trihydrate. The thermodynamic characteristics of the heat storage tank were measured at an initial temperature of 353.15 K and inlet water temperature of 278.15 K. Moreover, a computational fluid dynamics (CFD) model of the heat storage tank was established to simulate the discharge process. In addition, the CFD model was verified with experimental data. The impact of the PCM position on thermal stratification was thoroughly analysed for various flow rates. Furthermore, performance parameters including the Fill Efficiency (FE), Richardson number (Ri), and MIX number were considered. The results show that the equalizer enhances the thermal stratification effectively in the phase-change heat storage tank and stabilises the heat output characteristics of the water tank. Furthermore, in the water discharge process (t* = 0.1–0.7), the distances between the isothermal surfaces (279.15 K) and isothermal surfaces (352.15 K) in PCM4, PCM3, PCM2, and PCM1 increase by 6.56, 7.2, 8.98, and 12.34 cm, respectively. Thus, the mixing of hot and cold water strengthens with higher PCM position, which improves the thermal stratification in a heat storage tank. The half-life of the PCMs (melting rate reaches 50%) is prolonged with increasing inlet flow rate. For an inlet flow rate of 1 L/min, the half-life of PCM4 is t* = 0.5. For an inlet flow rate of 5 L/min, the half-life of PCM4 is t* = 0.95. Moreover, the simulated results of the FE and Ri are slightly higher than the experimental values, whereas the simulated MIX number results are below the experimental values. Finally, the simulated and experimental root mean-squared error results increase with lower PCM positions and increasing inlet flow rates.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Y.H. Diao, L.L. Yin, Z.Y. Wang, Y.H. Zhao, L. Liang, F.W. Bai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present study, the thermal performance of a latent heat thermal energy storage device based on flat miniature heat pipe arrays with straight rectangular fins during the charging process is numerically investigated using porous media to reduce computational resources and time. Air is selected as the heat transfer fluid (HTF). The influence of a thermal storage unit (TSU) with one heat transfer component (HTC) on the melting rates of the phase change material (PCM) is simulated at different inlet temperatures and flow rates of HTF. The heat transfer between two HTCs that form a tandem is analyzed and compared, and the effect of different arrangements of the two HTCs on the charging process is then studied. Results indicate that the inlet temperature and the volume flow rate of the TSU influence the charging process. The average outlet temperature and charging power, which grow in a power function relationship with the volume flow rates, increase linearly with the inlet temperatures. The average charging power of the HTF through HTC-2 is reduced by approximately 63.71% compared with HTC-1 when the two HTCs form a tandem. The average charging power of the TSU with two HTCs connected in tandem is higher than that of the parallel TSU at the same inlet temperature and volume flow rate.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Bruno Marcotte, Michel Bernier〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents an experimental validation of a thermal resistance and capacitance (TRC) model for double U-tube boreholes with two independent circuits. In the TRC model, the borehole cross-section is divided into four quadrants each with two nodes representing the fluid and the grout, respectively. Ground heat transfer is evaluated in each of the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.svg"〉〈mi〉n〈/mi〉〈/math〉 vertical sections using the infinite cylindrical source analytical solution with appropriate temporal superposition. Finally, internal tube-to-tube and tube-to-borehole thermal resistances are evaluated with the multipole method. The TRC model is validated against results obtained using a small-scale borehole (90.39 cm long with a 9.45 cm diameter) positioned in a sand tank of known properties. The borehole is made of ceramic which enabled the precise positioning of thermocouples at the mid-height cross-section. Data are acquired at a high frequency (1 s) to capture transient effects. In the first set of results obtained for a quasi-steady state, isotherms over the mid-height cross-section compare favorably well with the ones obtained using the multipole method. In the other two tests, the borehole is subjected to varying inlet (flow rate and temperature) conditions. It is shown that the TRC model is in good agreement with the experimental data except when there is a severe steep change in inlet temperature or when there is no flow.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Taehoon Kim, Donghwan Kim, Sungwook Park〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In engine simulation, coarse mesh size is usually used to analyze a variety of cases utilizing chemistry which consists of many species and reactions. However, it is difficult to predict spray morphology exactly with coarse mesh. In this study, a model to predict structure deforming flash boiling spray even for the coarse mesh has been developed. A flash breakup model combined with a modified version of a gas-jet model was utilized to analyze propane flash boiling spray. The gas-jet direction was calculated by averaging the directions of spray from each nozzle. A high-velocity region near the axis of gas-jet flow confined the plumes to form a single plume. Gasoline spray was analyzed to determine proper Kelvin-Helmholtz-Rayleigh-Taylor (KH-RT) model constants. Gasoline spray characteristics such as spray tip penetration and morphology were captured using the final model constants. Using the KH-RT model constants, the flash breakup model was validated for propane flash boiling spray. Sauter mean diameter (SMD) of simulation and experiment showed similar results. However, spray morphology could not be captured by the simulation using only the flash breakup model. A modified gas-jet model was applied to the simulation along with the flash breakup model to improve spray morphology. Using the modified gas-jet and flash breakup models, spray structure penetrating through the central axis was successfully predicted and this resulted in a better spray tip penetration prediction. SMD trend depending on ambient pressure was captured and maximum error between experimental and simulation results was 11%.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Ruikang Wu, Yiwen Fan, Tao Hong, Hao Zou, Run Hu, Xiaobing Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heat removal of high-power electronic devices has become the bottleneck that restricts the working performances. For ultrahigh heat flux density, even a thin layer of thermal interface material will dominate the temperature rise along the whole heat dissipation path. The existing liquid cooling only consider the cooling of the top surface of the electronic devices/chips, causing insufficient utilization of the cooling potential. In this paper, an immersed jet array impingement cooling device with distributed returns was designed, fabricated, and tested. In the proposed cooling device, the chip is immersed in the coolant and the coolant is ejected onto all the immersed surface of the electronics through the impinging jets, enabling to provide body cooling for high-power electronics. To prevent the jet interference between adjacent jets, distributed extraction returns were set between the adjacent jets for coolant to exit the impingement domain without flowing past the surrounding jets. The measured average temperature of the high-power chip with input heat power 550 W and flow rate 1000 ml/min is 77.0 °C, where the effective heat flux is 110 W/cm〈sup〉2〈/sup〉, and the inlet coolant temperature is maintained to be 40 °C. The average temperature of the high-power chip under the input heat power of 800 W (160 W/cm〈sup〉2〈/sup〉) is 78.7 °C with the flow rate reaching 2000 ml/min. The effective heat transfer coefficient of 41,377 W/m〈sup〉2〈/sup〉·K in maximum was achieved. The present body cooling is expected to provide high heat removal ability and be used for ultrahigh heat flux density electronics.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Manoj Kumar, Debashis Panda, Suraj K. Behera, Ranjit K. Sahoo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As a major component of cryogenic turboexpander, the design and performance estimation of a radial inflow turbine determines the effectiveness of the system. To explore the performance, this paper focuses on to investigate the effect of mass flow rate and operating temperature on isentropic efficiency, temperature drop, enthalpy drop, pressure variation, and power output of a cryogenic turboexpander. Firstly, the mean-line design of a radial inflow turbine is conducted by considering different loss models. Sobol sensitivity analysis is performed to identify the major geometrical parameters which have a significant effect on the performance of the turbine. Based on the geometrical data sets, an 〈em〉ANN〈/em〉 and 〈em〉ANFIS〈/em〉 models are developed to predict the ranges in which maximum efficiency of the turbine is obtained with minimum losses. The designed turbine is validated with available data in the literature. Secondly, an experimental set-up with extended measuring points for data collection is developed to investigate the performance of a turboexpander at cryogenic temperature. A detailed experimental analysis is carried out to compare the temperature drop, isentropic efficiency, and power output of the turboexpander for mass flow rate in the range of 0.03–0.08 kg/s and the inlet temperature of 130, 140, and 150 K. It is noticed that the highest temperature drop is obtained for the inlet temperature of 150 K. Thirdly, based on the experimental data, an 〈em〉ANN〈/em〉 and 〈em〉ANFIS〈/em〉 model is developed to predict the optimal range in which the turboexpander have maximum isentropic efficiency and temperature drop. The results deduce some valuable experimental data and also accumulate the design methodology of radial inflow turbine for cryogenic applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Kaswar Ali Al-Ameri, Shohel Mahmud, Animesh Dutta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work proposes a new configuration of solar still system and includes three experimental comparative studies on a 17 cm high longitudinal distillation unit with one distillation partition. The study targets to figure out the optimum conditions that maximize the productivity of the distillation partition. Also, the work includes determining the amount of the rejected waste energy from the unit with respect to the input energy for the optimum case obtained in the study. The investigated comparative cases include gravitational effect vs. Capillary effect of brackish water flow in the distillation partition wick, the performance when the unit is insulated vs. uninsulated, and using single wick vs. double wick layer inside the distillation partition. The work was conducted indoor, and electrical power (30 W, 50 W, 70 W, 90 W, and 110 W) was supplied to the unit separately. The results show that the gravitational brackish water flow, insulating the unit with 1″ thickness styrofoam, and using double cotton wick layer are the optimum operating conditions that maximize the productivity of the distillation partition. Under these conditions and when 110 W is supplied inside the distillation unit, the distillation efficiency of the unit is 15.64%, the distillation partition efficiency is 16.48%, and the heat supply efficiency of the unit is 19.61%. Also, the study proves that the distillation efficiency of the unit, the distillation efficiency of the distillation partition, and the efficiency of heat supply of the unit increases with increasing the input power to the unit.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Xiao Qian, Dongji Xuan, Xiaobo Zhao, Zhuangfei Shi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The excessively high temperature of lithium-ion battery greatly affects battery working performance. To improve the heat dissipation of battery pack, many researches have been done on the velocity of cooling air, channel shape, etc. This paper improves cooling performance of air-cooled battery pack by optimizing the battery spacing. The computational fluid dynamics method is applied to simulate the flow field and temperature field of the battery pack for different battery spacing. The battery spacing and corresponding CFD simulation outputs (maximum temperature and temperature difference) are used to train the Bayesian neural network. Compared with CFD simulation results, the relative errors are 0.08% and 3.2%. With this neural network model, the optimal battery spacing arrangement is found which is [17,24,22,0.22,0.23,0.176,0.176] and the temperature difference and the maximum temperature of the batteries are respectively 5.986(K) and 300.511(K). The results show this neural network model can accurately describe the relationship between the battery spacing and the battery temperature. This optimization process represents an effective and time-saving method to design the battery spacing distribution to improve the cooling performance of battery pack.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Evaldas Greiciunas, Duncan Borman, Jonathan Summers, Steve J. Smith〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A Concept Heat Exchanger (HE) design manufactured using the Additive Layer Manufacturing (ALM) technique Selective Laser Melting (SLM) is proposed and numerically evaluated. It is composed of a HE corrugation which introduces inter-layer flow conduits between the parallel HE layers of the same fluid. These pathways are provided by hollow elliptical tubes which serve several functions: to disturb the flow to promote heat transfer, to provide additional heat transfer area and to minimise flow maldistribution inside the HE core. The corrugation is incorporated into a counter-flow prototype HE unit model meaning to exploit the installation volume and design freedom made possible via ALM. Three Computational Fluid Dynamics (CFD) models are utilised to evaluate the performance of the proposed HE unit. Firstly, a traditional two step HE design methodology is utilised which works by initially evaluating a fully symmetric channel of the proposed HE corrugation (termed single channel). Then the results this model are incorporated into a simplified HE unit model. The second approach evaluates the HE unit performance based on a fully detailed CFD analysis that fully resolves flow and heat transfer inside the HE core. The third modelling approach involves splitting the inter-layer HE unit model into parts, which results in HE header models and allows simplification of the HE core into a single corrugation period width HE core model (termed superchannel). The results of these models are then compared to a conventional pin–fin HE unit model, formed by blocking the elliptical inter-layer conduits. It was found that in all the HE unit models the pressure drop is similar whilst the heat transfer was enhanced by between 7% and 13% in terms of the overall 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si68.svg"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈mi〉T〈/mi〉〈/mrow〉〈/math〉 by the inter-layer channels (increasing with the Reynolds number). All simulations were completed using a CFD package OpenFOAM.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 160〈/p〉 〈p〉Author(s): Ehsan Sourtiji, Yoav Peles〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A concept to power micro synthetic jets using bubble growth and collapse is introduced and studied over a range of operating frequencies (0.1–2.5 Hz) and heating powers (3–4.5 W). The microfluidic device has no moving parts and uses the interfacial layer between the vapor and liquid phases which substitutes the requirement for a physical flexible membrane. A micro heater inside a chamber (3.5 mm in radius and a height of 220 µm) was connected to a main microchannel through a nozzle with a 300 µm opening. Periodically powering the micro-heater triggered bubble explosion and implosion in the chamber, which in turn generated the synthetic jet. Sequential images of bubble nucleation, growth and collapse were captured using high-speed camera photography and a microscope. A momentum coefficient was used to characterize the synthetic jet. It was found that its average value exceeds unity for a large range of operating frequencies suggesting that this synthetic jet can improve the performance of a range of micro-system performance, such as micro-mixing in microfluidic devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Hitomi Kobara, Kaoru Nakatsuka, Akihiro Wakisaka〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Size selected synthesis of gold nanoparticle (AuNP) was carried out by use of an ultra-fine liquid droplet as a reaction field. The ultra-fine liquid droplets were generated by electrospraying in a liquid medium. The electrospraying in the liquid medium had a great advantage over the conventional electrospraying in the air. The size of electrosprayed liquid droplets can be varied with the supplied electric voltage beyond the range of the electrospraying in the air. When the AuNPs synthesis through the chemical reduction of Au〈sup〉3+〈/sup〉 was carried out by use of this electrospraying in the liquid medium for the mixing of Au〈sup〉3+〈/sup〉 solution and the reducing agent solution, the size of AuNPs was controlled by the supplied electric voltage. Two types of reaction field equipped with a single and double electrospray nozzles were designed to be demonstrated.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The size distribution of gold nanoparticles was controlled in the ultra-small reaction field generated by the electrospray in a liquid medium.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308246-ga1.jpg" width="440" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Kenji Aramaki, Misaki Fujii, Yuichi Sakanishi〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One of the major drawbacks of ionic-surfactant-based wormlike micelles (WLMs) is their poor low-temperature stability, which severely limits their application. Generally, an ionic surfactant with a linear C12–C16 alkyl chain has a Krafft point around or above room temperature. Therefore, there is a demand for ionic-surfactant-based WLMs with greater lowtemperature stability. Silicone surfactants have flexible hydrophobic chain structures. Hence, they are expected to be suitable candidates for WLMs that can be stable at low temperatures. Sodium trimethylsilyl tetra(dimethylsiloxane) decyl sulfate (Si〈sub〉5〈/sub〉C〈sub〉10〈/sub〉SO〈sub〉4〈/sub〉Na) and benzyltrimethylammonium chloride (BTAC) were used as surfactant and electrolyte, respectively, to obtain the WLM system with desired properties. No precipitation of surfactant crystals was observed in the WLM system obtained in this study when temperature was decreased to as low as 0 °C, indicating excellent low-temperature stability. Steady rheological measurements on the viscous solutions show shear thinning corresponding nearly to a power law relation (viscosity ∝ [shear rate]〈sup〉−1〈/sup〉). Zero shear viscosity (〈em〉η〈/em〉〈sub〉0〈/sub〉) increased with increase in 〈em〉R〈/em〉, reaching a maximum at around 〈em〉R〈/em〉 = 0.3 and decreasing thereafter. Oscillatory shear measurements for the viscoelastic samples, formed around the maximum-viscosity composition, show that the storage modulus (〈em〉G′〈/em〉) and the loss modulus (〈em〉G′′〈/em〉), with respect to the oscillation frequency (〈em〉ω〈/em〉), cross each other and fit the Maxwell model very well in the low-〈em〉ω〈/em〉 region. The normalized Cole-Cole plot of 〈em〉G′′〈/em〉 / 〈em〉G′′〈/em〉〈sub〉max〈/sub〉 against 〈em〉G′〈/em〉 / 〈em〉G′′〈/em〉〈sub〉max〈/sub〉 was obtained as a semicircle centered at 〈em〉G′〈/em〉 / 〈em〉G′′〈/em〉〈sub〉max〈/sub〉 = 1, as is typical for WLM systems.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308295-ga1.jpg" width="356" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects〈/p〉 〈p〉Author(s): Jian Xiao, Honglin Luo, Haiyong Ao, Yuan Huang, Fanglian Yao, Quanchao Zhang, Yizao Wan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Although recombinant human bone morphogenetic protein-2 (rhBMP-2) has been widely applied for bone regeneration, finding an ideal delivery system with optimal dose and minimal side effects is still a challenge. In this context, a novel mesoporous bioactive glass nanotubular (MBG-NT) scaffold loaded with rhBMP-2 was developed using a template-assisted sol-gel method. The obtained MBG-NT scaffold showed a notable 3D network structure and the nanotubes had an outer diameter of approximately 45 nm and a wall thickness of 15 nm. X-ray photoelectron spectroscopy (XPS) certified that the rhBMP-2 was successfully loaded into the MBG-NT scaffold with a quantity of 184.3 〈strong〉±〈/strong〉 5 ng mg〈sup〉-1〈/sup〉, and the MBG-NT scaffold exhibited a sustained release of rhBMP-2 for 28 days due to the presence of mesoporous structures. Moreover, the rhBMP-2-loaded MBG-NT scaffold exhibited enhanced proliferation, alkaline phosphatase (ALP) activity and osteogenic-related gene expression of human bone marrow stromal cells (hBMSCs) when compared to bare MBG-NT scaffold. We believe that the rhBMP-2-loaded MBG-NT scaffold can be a promising scaffold for regeneration of large bone defects.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092777571930826X-ga1.jpg" width="285" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Haobing Zhou, Fei Zhou, Qian Zhang, Qianzhi Wang, Zebin Song〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To maintain the maximum temperature within the optimum range and to improve the temperature uniformity of cylindrical lithium-ion battery, a liquid cooling method based on the half-helical duct was proposed. The effects of inlet mass flow rate, pitch and number of helical duct, fluid flow direction and diameter of helical duct on the thermal performance of battery at 5 C discharge rate were analyzed numerically. The results showed that the maximum temperature and temperature difference decreased with an increase in the inlet mass flow rate. When the pitch and the number of helical duct changed at the optimal inlet mass flow rate of 3 × 10〈sup〉−4〈/sup〉 kg/s, there was no obvious improvement in the cooling performance. If the flow direction was varied according to six kinds of cases, the maximum temperature and the temperature difference for the Case4 all displayed the lowest values. If the diameter of half-helical duct varied from 2.0 mm to 3.8 mm, the temperature difference would retain within 4.3 °C, but the maximum temperature would approach to 30.9 °C, slightly higher than 30.5 °C. In comparison to the thermal management with jacket liquid cooling method, the thermal management with half-helical duct liquid cooling method might be better and more effective owing to the low fluid volume and no stagnant zone.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Jingtang Peng, Zhili Chen, Taojie Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new solar heat collecting and snow melting device for purified water utilization was originally designed and developed. The heat and mass transfer model was established and verified by experiments. Results show that the snow melting efficiency of the cases at 100% and 80% of the system volume is higher than other amount cases. The heat conducting working medium filling level has relatively large influence on the snow melting efficiency of the device, and the optimal working medium filling level is above 3/4 of total volume of the circulating system. In actual use, replenishment of working medium in the system shall be conducted in time before the working medium level decreases to 1/2. The water outflow and snow feeding mode has evident influence on the snow melting efficiency. When the 2-h water outflow mode is used, the snow melting efficiency is the highest, reaching 39.2%. The heat and mass transfer model of the device performs better in simulation calculation and is useful for estimation of snow melting efficiency.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): Naeem Abas, Ali Raza Kalair, Mehdi Seyedmahmoudian, Muhammad Naqvi, Pietro Elia Campana, Nasrullah Khan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉CO〈sub〉2〈/sub〉 is becoming increasingly important as a mediating fluid, and simulation studies are indispensable for corresponding developments. In this study, a simulation-based performance investigation of a solar water heating system using CO〈sub〉2〈/sub〉 as a mediating fluid under sub-zero temperature condition is performed using the TRNSYS® software. The maximum performance is achieved at a solar savings fraction of 0.83 during July. The as lowest solar savingss fraction of 0.41 is obtained during December. The annual heat production of the proposed system under Fargo climate is estimated to be about 2545 kWh. An evacuated glass tube solar collector is designed, fabricated and tested for various climate conditions. Moreover, a detailed comparison of the system’s performance at sub/supercritical and supercritical pressures shows that the annual heat transfer efficiency of the modeled system is 10% higher at supercritical pressure than at sub/supercritical pressures. This result can be attributd to the strong convection flow of CO〈sub〉2〈/sub〉 caused by density inhomogeneities, especially in the near critical region. This condition resuls in high heat transfer rates.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359431119301450-ga1.jpg" width="267" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): Hadi Sadeghi, Masoud Rashidinejad, Moein Moeini-Aghtaie, Amir Abdollahi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Today’s world energy-related challenges, ranging from anthropogenic climate change to continuous growth of demand for different energy forms, have enforced planners of energy systems (ESs) to concentrate on more optimal and eco-friendly operation and/or expansion planning methodologies. In this context, increased interdependencies of gas, heat and electricity ESs have recently encouraged the planners to design operation and/or expiation strategies in an integrated manner in favor of a new concept, the so-called “Energy Hub” (EH). Although this concept has been employed so far in a multitude of studies, but its real nature, advantages, difficulties, importance or inevitability aspect, and eventually, its application areas in power industries have remained as open questions from various viewpoints. On the other hand, the difference in the planners’ perceptions of the EH concept has caused emerging various definition and models for this. At this point, it is worth reviewing the frameworks proposed for planning the ESs based on the EH approach, while understanding the application areas of the EH, its components, the nature behind presented definitions, and the hierarchy of events/factors drawing the planners attention to this approach, can help to find the answers of the questions. In doing so, this paper presents a state-of-the-art review of existing research works focusing on the operation and/or expansion planning problems of ESs in the context of EH. Reviewing results and findings can be helpful for both researchers new to this field of study by extraction of the distinguishing borders between underlying concepts and presenting an in-depth review on the latest studies, and experts in this research field by summarizing the details of a wide range of relevant works and extracting research gaps.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Razieh Zahedi, Zahra Asadi, Fahimeh Dehghani Firuzabadi〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel heterogeneous catalyst was developed via the immobilization of a copper complex by covalent anchoring of the ligand on the surface of magnetic nano particles. The catalyst was characterized by various techniques including Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron micrograph (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), a vibrating sample magnetometer (VSM) and inductively coupled plasma (ICP) spectroscopy. The prepared catalyst demonstrated high catalytic activity, stability, reproducible dispersibility, and recycability in the O-arylation reactions. Moreover, the catalyst could be easily recovered under the outside magnetic field and reused without noticeable decreasing in its catalytic performance upon five consecutive runs.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307162-ga1.jpg" width="271" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Akram Abbasi, Arijit Bose〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The high electrical conductivity of multilayer graphene (MLG) and their sheet like morphology results in a low percolation threshold, and makes it an attractive filler for inducing electrical conductivity in an insulating polymer at small filler loadings. However, strong van der Waals forces between the flat faces of multilayer graphene cause agglomeration, making it difficult to disperse them in a polymer. The loading required for forming a percolating network of these MLGs then increases dramatically, and the advantage of their sheet-like morphology is lost. To enhance the dispersion of MLGs, carbon black nanoparticles (CB) were added as secondary fillers to a polystyrene (PS) matrix containing 2.5 vol% MLG. The electrical conductivity of the composite increased from 10〈sup〉−9〈/sup〉 S/m with no CB to 10〈sup〉-4〈/sup〉 S/m with 1.5 vol% CB, asymptoting to 10〈sup〉3〈/sup〉 S/m at ∼12 vol% CB. Using Raman spectroscopy and wide-angle X-ray diffraction, we confirmed that the CB particles act as dispersion aids and prevent MLG restacking, reducing agglomeration and enhancing dispersion of the MLG sheets in PS. This leads to an increase of several orders of magnitude in electrical conductivity.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307150-ga1.jpg" width="269" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Jiaoyuan Lian, Suxia Zheng, Cong Liu, Zhongbin Xu, Xiaodong Ruan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We propose a co-flowing step emulsification strategy for the on-line control of micro-droplet generation. The effects of four parameters including wall contact angle, plateau length, channel distance and diameter are investigated numerically and experimentally in this study. The results indicate that the wall contact angle, whose applicable range can be expanded to 90°–180° by co-flow, is critical to droplet formation. The effect of the plateau length on droplet generation is reduced by the co-flow, and the droplet diameter is almost independent of the plateau length, which ranges from 0.7 to 1.5 mm. In addition, the droplet diameter increases significantly with increasing channel distance and diameter. Combining these results with those of our previous study, we derived an explicit equation for droplet diameter prediction. The predicted droplet diameter based on this equation has good agreement with the simulation and experimental results. Furthermore, we proposed a coefficient 〈em〉α〈/em〉 as a function of physical and dimensional parameters to predict the regimes and modes in the co-flowing step emulsification process. The conclusion of this study not only provides an important reference for the design and improvement of step emulsification chips, but also offers a new idea and a scientific basis for tuneable monodisperse micro-droplet production.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307216-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Biao Zhang, Xiaojuan Li, Yang Zhao, Hua Song, Huan Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxygen doped mesoporous graphitic carbon nitride(O-mpg-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉) was innovatively prepared through facile two-step synthesis and characterized through different characterization tools, such as XRD、SEM、XPS etc. These characterizations confirm that the as-prepared sample has separated plate-like structure with lots of gaps and oxygen atoms have been successfully doped into them. Evaluated by photodegradation of Rhodamine B and Methyl Orange, the O-mpg-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 photocatalyst exhibits higher photocatalytic degradation efficiency, which is attributed to the added active spots, shorter electronic transmission distance and wider range of light absorption. In addition, the photocatalytic activity of the as-prepared catalysts didn’t decrease significantly after five photodegradation cycles, showing a high photocatalytic stability.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Oxygen doped mesoporous g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 was firstly prepared by a facile calcination-solvothermal method and exhibits excellent photocatalytic degradation performance, which is ascribed to the change of morphology and intrinsic electronic structure.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307241-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Wenjie Liu, Kun Yuan, Peipei Liu, Ming Chen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this article, magnetically responsive catalysts were successfully synthesized by host-guest chemistry and self-assembly strategy. Firstly, β-cyclodextrin (β-CD) was bound directly to the surface of core/shell magnetic Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@C (MFC) using chemical bonding methods. Then, in view of the host-guest recognition, p-aminothiophenol (pATP) was captured by β-CD to form inclusion complex on the surface of MFC. Lastly, pre-synthesized gold, silver, platinum nanoparticles (AuNPs, AgNPs, PtNPs) could be adsorbed on the surface of MFC@β-CD-pATP through self-assembly strategy to fabricate ternary composites MFC@β-CD-pATP@metal nanoparticles. Catalytic reduction reaction of methylene blue using NaBH〈sub〉4〈/sub〉 as reducing agent evaluates the catalytic performance of three as-prepared magnetic nanocomposites. MFC@β-CD-pATP@AuNPs catalyst showed the fast catalytic reaction rate constant. Significantly, we have explored the separation of magnetic supports and novel metal nanoparticles under mild conditions. This strategy will become a green and environmental way for highly efficient separation of precious metals catalysts, and recycle and reuse of catalyst carriers.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307174-ga1.jpg" width="362" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Piero De Leonardis, Francesco Cellesi, Nicola Tirelli〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We explored a versatile enzyme nanoencapsulation process based on the synthesis of silica gel nanoparticles, decorated with a dense hydrophilic poly(glycerol monomethacrylate) (PGMMA) shell for biological and therapeutic applications. These hybrid enzyme-SiO〈sub〉2〈/sub〉-polymer nanoparticles were obtained through an aqueous sol-gel process, followed by the adsorption of cationic macroinitiators by electrostatic complexation. Surface-initiated Atom Transfer Radical Polymerisation (ATRP) was applied to obtain a dense hydrophilic (protein repellent) PGMMA layer of tunable size, under conditions which are compatible with the nanoencapsulation of horseradish peroxidase. The sol-gel synthetic procedure, the composition and molecular weight of the macroinitiators, the polymer adsorption and purification methods, and the final ATRP conditions, were optimised to control the properties of these nanoparticles, in terms of particle size, Z-potential, PGMMA decoration, while preserving enzymatic activity.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307228-ga1.jpg" width="489" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈p〉Enzyme-SiO〈sub〉2〈/sub〉-polymer nanoparticle obtained by enzyme (HRP) nanoencapsulation in silica gel nanoparticles, adsorption of a cationic macroinitiator, and final polymer shell generation (PGMMA) by ATRP.〈/p〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): F. Salerni, D. Orsi, E. Santini, L. Liggieri, F. Ravera, L. Cristofolini〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉We employ Diffusing Wave Spectroscopy (DWS) to characterize microscopic structure, internal dynamics and rheological properties of a paradigmatic emulsion formed by water and dodecane stabilized by the anionic surfactant Sodium Dodecyl Sulfate (SDS).〈/p〉 〈p〉We focus on ageing and stability in the regime of low surfactant concentration, well below the Critical Micellar Concentration (CMC). In the long-time ageing regimes differentiate in stable and unstable, depending on surfactant concentration. For the stable case, ageing affects the dynamics following a power law with an exponent independent on surfactant concentration, presumably related to the late stages of the water drainage process. On the contrary, at constant ageing, the dependence of the dynamics from surfactant concentration shows a slowdown, corresponding to a maximum in the bulk shear mechanical modulus, around 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si25.svg"〉〈mo〉[〈/mo〉〈mi〉S〈/mi〉〈mi〉D〈/mi〉〈mi〉S〈/mi〉〈mo〉]〈/mo〉〈mo〉=〈/mo〉〈mn〉2〈/mn〉〈mi〉m〈/mi〉〈mi〉M〈/mi〉〈/math〉 which is reminiscent of a similar maximum found by drop tensiometry in the dilational modulus of the single interface.〈/p〉 〈p〉This suggests a consistent picture of the mechanisms (de)stabilizing the emulsion, explained in terms of elementary process at the interface. These results show furthermore that DWS can be a reliable diagnostic for the study of the aging and of the mechanical properties of concentrate emulsions. This might be relevant to control stability of emulsions when a low concentration of surfactant is desired, e.g. for economical or environment reasons.〈/p〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719301876-ga1.jpg" width="334" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Huijian Ye, Xuanhe Zhang, Chunfeng Xu, Lixin Xu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The polymer film capacitor has been widely applied in electronics and stationary power system due to the large power density and graceful dielectric reliability. The current requirements for flexible film capacitor are mainly on the development of polymer nanocomposite with high energy density and charge-discharge efficiency during applied electric field. Here we employed the fluoro hyperbranched polyethylene-graft-poly(trifluoroethyl methacrylate) (HBPE-〈em〉g〈/em〉-PTFEMA) copolymer to exfoliate the boron nitride nanosheets (BNNSs) in low-boiling-point solvent, and then, the flexible poly(vinylidene fluoride-trifluoroethylene) (P(VDF-CTFE)) nanocomposite film incorporated with BNNSs was prepared by the simple solution casting. The stable BNNSs dispersion was obtained with assistance of fluoro hyperbranched copolymer as the stabilizer, which was adsorbed on the nanosheets via the noncovalent CH-π interaction against aggregation. The presence of fluoro segments improves the compatibility of BNNSs/P(VDF-CTFE) nanocomposite, which contributes to the large interfacial polarization. The energy density in 0.4 wt% nanocomposite achieves 6.8 J/cm〈sup〉3〈/sup〉 with charge-discharge efficiency of 66% at 300 MV/m, which is ascribed to the large content of electroactive phase and the enhanced interfacial polarization. The fluoro hyperbranched copolymer functionalized BNNSs/P(VDF-CTFE) nanocomposite film exhibits high electric storage capability as well as lightweight feature and flexibility, which is benefit to potential applications for portable and implantable electrical devices where both the weight and size are primary concerns.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092777571930723X-ga1.jpg" width="287" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Mohammad M. Hassan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, multifunctional wool fabrics were produced by treating them with silver (Ag) nanoparticles in a single-stage treatment using trisodium citrate (TSC) as a reducing and capping agent. The effects of treatment parameters, such as Ag〈sup〉+〈/sup〉 concentration, pH, temperature and time on the colour strength, antibacterial and antistatic properties, and UV radiation absorption by the treated fabric were carried out. It was found that the wool fabric treated with Ag nanoparticles formed by using Ag〈sup〉+〈/sup〉 concentration of less than 1.11% on the weight of wool fibres produced very pale shade. The colour strength and UV radiation absorption capacity of the treated wool fibres increased with an increase in the concentration of Ag〈sup〉+〈/sup〉, and Ag〈sup〉+〈/sup〉 to citrate anion ratio, and also with a decrease in the treatment pH. The treatment temperature had a great effect on the colour strength of the treated fabrics and the size of Ag nanoparticles. The colour strength increased from 1.59 for the fabric treated at 55 °C to 7.74 for the fabric treated at 95 °C. The surface resistance of the treated wool fibres decreased with an increase in the concentration of Ag〈sup〉+〈/sup〉, while the colour fastness to washing decreased for the fabric treated at a higher pH. The treated fibres showed excellent antibacterial activity, UV radiation absorption capacity, and also very good antistatic properties along with an excellent colourfastness to washing. Moreover, the developed treatment is highly durable to washing as after 20 washes the treated fibres lost their colour and antibacterial activity only marginally.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308076-ga1.jpg" width="415" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 17 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects〈/p〉 〈p〉Author(s): Yixing Wang, Taijun He, Mengyun Liu, Jianqi Ji, Yu Dai, Yang Liu, Longbo Luo, Xiangyang Liu, Jiaqiang Qin〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fast and efficient oil-water separation materials under harsh conditions become urgent requirement for eliminating destruction of environment from offshore oil spill, oily wastewater produced in industry and life. Here, we designed and prepared polyimide (PI) aerogel with strong hydrogen bond by introducing benzimidazole structure. The hydrogen bond increases the intermolecular interactions to overcome the expansion force and capillary force during ice crystal growth and sublimation. The obtained PI aerogel has a mutually interleaved sheet three-dimensional network structure of thin pore walls (about 85 nm), interconnected pores and tortuous channels with a low shrinkage (about 7.8%). Moreover, due to the high hydrophobicity and morphological characteristics, the PI aerogel can be used for oil-water separation continuously under different harsh conditions, such as high viscosity oil (above 570 mPa·s), oil in cold/hot water (0 °C/120 °C), corrosive solution and emulsion. The separation efficiency and maximum oil flux can reach 99. 9% and 14320 L·m〈sup〉-2〈/sup〉 h〈sup〉-1〈/sup〉, respectively. Because of their fast and efficient oil-water separation performance in harsh environments, this PI aerogel shows great potential in the field of petroleum, municipal and industrial wastewater treatment.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307976-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 13 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects〈/p〉 〈p〉Author(s): Junmei Tian, Zhijia Zhu, Baojiang Liu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photocatalysts with heterojunctions had attracted much attention in the field of photocatalysis due to their strong charge separation and transfer capabilities. In this work, a novel Bi〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉/Bi〈sub〉2〈/sub〉WO〈sub〉6〈/sub〉/MWCNTs Z-scheme photocatalyst was firstly prepared by one-step hydrothermal method. A series of characterization results showed that the ternary flower-like Bi〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉/Bi〈sub〉2〈/sub〉WO〈sub〉6〈/sub〉/MWCNTs photocatalyst was successfully synthesized. The photocatalytic property of Bi〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉/Bi〈sub〉2〈/sub〉WO〈sub〉6〈/sub〉/MWCNTs composite was evaluated by photo-degradation of reactive blue 19 (RB-19) dye under visible light irradiation. The results manifested that Bi〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉/Bi〈sub〉2〈/sub〉WO〈sub〉6〈/sub〉/MWCNTs composite presented the better photocatalytic property than pure Bi〈sub〉2〈/sub〉WO〈sub〉6〈/sub〉 and Bi〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉/Bi〈sub〉2〈/sub〉WO〈sub〉6〈/sub〉. Additionally, in the photocatalytic process free radical and hole scavenging experiments indicated that h〈sup〉+〈/sup〉 and ·O〈sub〉2〈/sub〉- played an indispensable role. Finally, possible mechanisms for the photocatalytic enhancement of the composite were put forward.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307861-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Chao Zhang, Siyao Liu, Shuangxi Li, Yue Tao, Panpan Wang, Xinyue Ma, Lanzhou Chen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The magnetic chitosan microspheres immobilized 〈em〉Aspergillus sydowii〈/em〉 (MCMAs) was prepared and characterized by SEM, BET, XRD and VSM analyses, and used to adsorb Cu(II) from aqueous solution under different influence factors such as contact time, initial Cu(II) concentration and biosorbent dose. Characterization results showed that MCMAs had large specific surface area and were rapidly separated from aqueous solution by using an adscititious magnetic field. Batch adsorption experiments showed that Cu(II) adsorption capacity of MCMAs was up to 119.21 mg g〈sup〉−l under the optimal condition. The CO, OH and NH〈/sup〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉 groups played an important role in Cu(II) chelation observed from FTIR spectra. Cu(II) adsorption onto MCMAs was well described by pseudo-second-order kinetics and Langmuir isotherm, and the adsorption process involved surface and intra-particle diffusion. In addition, MCMAs showed good recyclable efficiency after four adsorption-desorption cycles.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308015-ga1.jpg" width="334" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Suvendu Manna, Snigdha Prakash, Papita Das〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This article presents the process of synthesizing a value added product from a carbonaceous industrial waste. For this a carbonaceous industrial waste was coated with graphene oxide (GO) and then thermally activated at 800 °C. The GO and the GO-coated biochar were characterized with atomic force microscope, raman spectroscope, fourier transform infrared spectroscopy, field-emission scanning electron microscope, x-ray Diffraction and transmission electron microscope. This GO-coated biochar was then utilized to investigate removal capacity of phenol present in wastewater. The data indicated that the GO-coated biochar showed better phenol removal efficacy then that of the GO itself. The isotherm analysis indicated that the data could be described best with Langmuir isotherm indicating that the phenol separation was a monolayer surface adsorption. The kinetic analysis indicated that the phenol separation process was followed by pseudo second order kinetics. Also, it was evident from the intra-particle diffusion kinetic analysis that diffusion plays a significant role in phenol separation. From thermodynamic analysis it was evident that the phenol separation process was endothermic as well as spontaneous in nature. The GO-coated biochar showed better separation efficacy in the presence of salt.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308064-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Yong-li Yan, Qi Xi, Christian-chibuike Una, Bing-cheng He, Chun-sheng Wu, Long-long Dou〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The serious fingering and nonuniform injectivity profile of acid liquid result from the features of heterogeneity in most carbonate reservoir, leading to a poor effect on the acidizing process. In the present contribution, for the first time, we report a novel diversion acidizing strategy that uses acid-rock reaction between the acidizing fluid itself and carbonate core to produce CO〈sub〉2〈/sub〉 at supercritical state. Under the action of a mixture of foaming agent and stabilizer contained in this working fluid, a CO〈sub〉2〈/sub〉 foamed acid fluid is in-situ formed in the acidizing layer, which would play a diverting role in carbonate matrix acidizing operations. Experiments on in-situ formation of CO〈sub〉2〈/sub〉 microfoams (emulsions) were performed utilizing a visible acid-rock reaction simulation device and a self-made high pressure and temperature foam generator. A series of divided-flow experiments were undertaken by the core displacement setup.〈/p〉 〈p〉Results based on these experiments indicate that with 0.5% SDBS as a foaming agent and 0.15% CMC as a stabilizing agent, the supercritical CO〈sub〉2〈/sub〉 microfoams (emulsions) could be created in-situ in the process of acidizing through the carbonate reservoirs. The foamed acid has the accumulating and plugging effects, with divided-flow selectivity not only in the parallel cores of oil saturation and water saturation, but also in the parallel cores of different permeability. This foamed acid fluid could provide better diversion acidizing operations for heterogeneous carbonate formation. Finally, the mechanism of this novel diversion acidizing technology was uncovered in detail. It is suggested that the whole working process is actually an interface effect in the dynamic system of gas/liquid/solid multiphase fluid. Such findings are potentially important for a better understanding on the mechanisms of in-situ formation of CO〈sub〉2〈/sub〉 foamed acid and its self-diversion. Looking out to the future, our report attempts to provide a new and efficient technology for the improvement of acid stimulation in the carbonate reservoirs.〈/p〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉A novel diversion acidizing technology using in-situ microfoams to meet the challenge of serious fingering and poor backflow of acid liquid existing in application of diverting acid technology in heterogeneous formations. This technology uses a chemical reaction between conventional acid and carbonate cores to produce CO〈sub〉2〈/sub〉 at supercritical state. Under the action of a mixture of foaming agent and stabilizer, a CO〈sub〉2〈/sub〉 foam fluid was in-situ formed, which would play a diverting role in carbonate matrix acidizing operations. It is suggested that the whole working process is actually an interface effect in the dynamic system of gas/liquid/solid multiphase fluid.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307757-ga1.jpg" width="200" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Tao Ma, Haishun Feng, Hairong Wu, Zhe Li, Jiatong Jiang, Derong Xu, Ziyu Meng, Wanli Kang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Gemini surfactant has a good application prospect in the field of enhanced oil recovery (EOR) due to the advantages of high interfacial activity, low critical micelle concentration (CMC) and good wettability alteration. In this paper, ethylenediamine, sodium 2-bromoethanesulphonate and fatty alcohol polyoxyethylene ether are used as raw materials to synthesize a new kind of anionic-nonionic gemini surfactant which hydrophilic group consists of two parts nonionic and anionic groups through a mild reaction of amination. The surface tension, interfacial tension, wettability and oil displacement of the synthesized anionic-nonionic gemini surfactants were evaluated. Parameters of surfactant the saturated adsorption amount 〈em〉Γ〈/em〉〈sub〉max〈/sub〉 and the minimum molecular occupied area 〈em〉A〈/em〉〈sub〉min〈/sub〉 were calculated. The structures of the optimal product were characterized by IR and 〈sup〉1〈/sup〉H-NMR. The results showed that the critical surface tension of the synthesized anionic-nonionic gemini surfactant was as low as 28.94 mN/m, and the critical micelle concentration was 4.9 × 10〈sup〉−5〈/sup〉 mol/L. An interfacial tension between the aqueous solution of 600 mg/L optimal surfactant and Dagang crude oil was 0.0804 mN/m. 1500 mg/L aqueous solution can reduce the surface contact angle of lipophilic low permeability core from 144.5° to 71.5°. The anionic-nonionic gemini surfactant (1000 mg/L; 0.4 PV) can improve oil displacement efficiency by 7.03%. The current study opens a new pathway for designing enhancing oil recovery applicable gemini surfactants with excellent performance, wide source of raw materials and low dosage.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307885-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Zengzi Wang, Runtao Hu, Gaihuan Ren, Gongrang Li, Shangying Liu, Zhenghe Xu, Dejun Sun〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The application of conventional alkalis (NaOH or Na〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉) in alkali/surfactant/polymer (ASP) flooding is rather limited due to their intrinsic drawbacks, including precipitating during injection into formation water with a high divalent ion concentration and enhancing the dispersibility of clays (e.g., montmorillonite (MMT) or kaolinite) in water, which lead to damage to reservoir formations and bring about difficulties in treating produced fluids. Here, we propose polyetheramine D 230 as an alternative alkali to avoid these problems. D 230 is a diamine linked by poly(oxypropylene) backbones. Interfacial tension and emulsification measurements proved that D 230 can neutralize the acidic components in crude oil to generate surface-active soaps, which facilitate oil emulsification in water. Contact angle measurements indicated that an oil-contaminated quartz surface treated with D 230/SP blends was successfully altered from oil-wet to water-wet. Sand pack flooding measurements demonstrated that a D 230/SP injection was able to mobilize 19.23% of the original oil in place (OOIP) after thorough water flooding. Rheograms of alkali/polymer blends showed a reduced impact of D 230 on viscosity. Static bottle tests indicated that no precipitation occurred after D 230 was injected into formation water with a high Ca〈sup〉2+〈/sup〉 concentration. Colloidal stability measurements of clay dispersions suggested that D 230 can inhibit clay dispersibility. As an alternative alkali in ASP flooding, D 230 not only facilitates enhanced oil recovery (EOR) but also solves problems such as precipitation, high biotoxicity, reduced fluid viscosity and enhanced clay dispersibility brought about by conventional inorganic and organic alkalis. These advantages make D 230 an eco-friendly choice as an alkali for ASP flooding.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308088-ga1.jpg" width="362" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Mohsin Ali Marwat, Bing Xie, Yiwei Zhu, Pengyuan Fan, Kai Liu, Meng Shen, Malik Ashtar, Suwadee Kongparakul, Chanatip Samart, Haibo Zhang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The sandwich-structured barium titanate/poly(ether imide) (BT/PEI) nanocomposites are fabricated layer-by-layer, with outer two insulation layers (ILs) for high breakdown strength and a middle polarization layer (PL) for high dielectric constant, using solution casting technique. Consequently, the sandwich-structured BT/PEI nanocomposites with optimum BT NPs concentration in ILs and PL showed tremendously enhanced discharge energy density (〈em〉U〈/em〉〈sub〉e〈/sub〉) of 5.7 J/cm〈sup〉3〈/sup〉, which is ∼256% and ∼307% higher than the pristine PEI (with 1.6 J/cm〈sup〉3〈/sup〉) and its single-layered counterpart, i.e., 9 wt.% BT/PEI (with 1.4 J/cm〈sup〉3〈/sup〉), respectively. The similar sandwich structure also displayed a significantly higher discharge efficiency of ∼62% at very high electric field. In addition, the high-temperature hysteresis loops for optimal sandwich structure nanocomposites revealed considerably high-temperature endurance until 150 °C at 200 MV/m. The present work paves the way for using sandwich-structured linear nanocomposites in thermally stable energy storage devices.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307903-ga1.jpg" width="267" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Sabrina Matos de Carvalho, Carolina Montanheiro Noronha, Cleonice Gonçalves da Rosa, William Gustavo Sganzerla, Ismael Casagrande Bellettini, Michael Ramos Nunes, Fabiano Cleber Bertoldi, Pedro Luiz Manique Barreto〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Natural antioxidants can be incorporated into polymers to the production of active packaging, preventing the formation of off-flavors and undesirable textures in foods, increasing the foods shelf life. In this study was developed polymeric films based on poly (vinyl alcohol) (PVA) incorporated with 30, 50 and 70% of solid lipid nanoparticles entrapped α-tocopherol. PVA films were produced by the casting technique and characterized by their physicochemical, morphological, thermal and antioxidant characteristics. PVA films with nanoparticles demonstrated higher hydrophilic compared to the control film. Thermal analysis of the films showed that nanoparticles incorporation has changed the structure, decreasing the crystallinity. Moreover, films with solid lipid nanoparticles entrapped α-tocopherol demonstrated a higher antioxidant capacity, and the α-tocopherol controlled release confirmed the possibility of its use as active packaging to application in food conservation.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307812-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 19 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects〈/p〉 〈p〉Author(s): Yudai Chizawa, Yayoi Miyagawa, Mao Yoshida, Shuji Adachi〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mayonnaise is a preferred dressing that is routinely used in many regions. Distribution of products containing frozen mayonnaise is highly desirable due to the development of cold chain and changing lifestyle. However, freezing and thawing of mayonnaise result into separate oil and aqueous phases. A detailed mechanism of this phenomenon is still unknown. In this study, the destabilization of frozen emulsions, using rapeseed, safflower, olive, rice bran, and soybean oils as the oil phase was examined, in which these oil phases crystallize at lower temperature than the aqueous one. The vegetable oils exhibit different crystallization behavior. Irrespective of the type of vegetable oil, it was found that smaller the difference between the storage temperature and the melting point of the oil, which was estimated from the fatty acid composition, quicker was the destabilization of the emulsion prior to the growth of the oil crystal. We consider that the change in the crystallization process of the oil phase increases the energy at the oil–water interface and destabilizes the emulsion.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092777571930812X-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Pablo Llombart, Mauricio Alcolea Palafox, Luis G. MacDowell, Eva G. Noya〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Controlled CTAB self-assembly is an essential prerequisite for the formation of gold nanorods with tailored shape and monodispersity. In this paper, we exploit the use of salt concentration and co-surfactant decanol for the preparation of CTAB aggregates with different morphologies. To this end we use a model of CTAB recently developed by ourselves, and perform electronic structure calculations in order to improve current point charge parametrization of decanol. Using molecular dynamics simulations with the new models, we find a sequence of structural transitions of CTAB aggregates induced by salt concentration and added cosurfactant. In pure solutions, CTAB aggregates form spherical micelles with a compact ionic shell and a diffuse double layer that can be qualitatively described with Poisson–Boltzmann theory. Addition of decanol as a cosurfactant induces a sequence of dramatic structural transitions at low surfactant concentration and allows the stabilization of compact ordered bilayers in a well defined range of intermediate decanol/CTAB ratios. At low and high decanol/CTAB ratios spherical micelles are transformed into wormlike cylindrical micelles. At intermediate decanol/CTAB ratios, fully formed bilayers are observed, with surfactants exhibiting a compact structure with strong positional and orientational order. We discuss how the controlled self-assembly of compact CTAB bilayers at low global CTAB concentration can pave the way for the selective passivation of gold facets and the controlled formation of monodisperse gold nanorods.〈/p〉〈/div〉 〈div〉 〈h6〉Graphical abstract〈/h6〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307186-ga1.jpg" width="275" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Zeng Deng, Jun Shen, Wei Dai, Ke Li, Qinglu Song, Wenchi Gong, Xueqiang Dong, Maoqiong Gong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, a hybrid microchannel and slot jet array heat sink is designed and fabricated to achieve a better thermal performance of the high-power laser diode arrays. A standard commercial laser bar with wavelength of 808 nm is packaged on the heat sink and experiments are performed to assess the cooling performance of the hybrid heat sink. In the experiments, the forward voltage method is used to measure the chip temperature and the structure function method is applied to obtain the thermal resistance of the heat sink. Using the deionized water as coolant, the heat sink deals with a heat flux of up to 506 W/cm〈sup〉2〈/sup〉 and the thermal resistance of the heat sink is only 0.23 K/W when the flow rate is 0.8 L/min (The average jet velocity is 13.3 m/s). The optical power can be up to 135.5 W corresponding to the wall plug efficiency of 64.2%. Compared with the published solutions related to cooling similar laser chips, the thermal resistance reduces by over 15%, indicating that this hybrid heat sink is an interesting solution to improve the cooling of the high-power laser diode arrays.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Tülin Gürkan Polat, Kayhan Ateş, Süleyman Bilgin, Osman Duman, Şükrü Özen, Sibel Tunç〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, gelatin-based conductive hydrogels doped with carbon nanotube (CNT), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and silver (Ag) nanoparticle were prepared for use in biopotential measurements. Gelatin was modified by various concentrations of methacrylic anhydride (MA) to obtain photo-crosslinkable gelatin methacrylate (GelMA) polymer with low (21%), medium (44%) and high (78%) methacrylation degree. Chemical modification of gelatin was characterized by 〈sup〉1〈/sup〉H-NMR spectroscopy. It was observed that mechanical properties of the GelMA hydrogels were highly dependent on methacrylation degree. Ultimate compressive stress of low, medium and high methacrylated gelatin hydrogel was measured to be 9.97 ± 0.14 kPa, 17.83 ± 1.73 kPa and 38.23 ± 2.96 kPa, respectively. Surface morphology of hydrogels was visualized by scanning electron microscope (SEM). The pore size of methacrylated gelatin hydrogel significantly reduced with the addition of CNT, PEDOT:PSS and Ag nanoparticle into the hydrogel matrix. The results of thermal gravimetric analysis showed that conductive hydrogels were of higher thermal stability than nonconductive GelMA hydrogel. The suitability of the prepared hydrogels for biopotential measurements was determined by equivalent impedance measurements. Impedance values of hydrogel samples were obtained in the frequency range of 20 Hz–500 Hz. The hydrogel materials prepared in this study exhibited high impedance at low frequencies and low impedance at high frequencies. The results of this study showed that the hydrogels produced with Ag nanoparticle are more suitable electrode materials for physiological measurement systems such as electrocardiography (ECG) and electroencephalography (EEG).〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307393-ga1.jpg" width="438" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Siddhesh Kamat, Runxing Lin, Yee C. Chiew〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Reduction of interfacial tension caused by surfactants at oil/water interfaces plays a crucial role in many technological processes and industrial applications such as detergency, food processing, cosmetics and personal care, wastewater treatment, pharmaceutical and oil industries. The properties and behavior of dispersions, foams, and emulsions are determined by the interfacial properties stabilized by the surfactants. We carried out molecular dynamics simulations to study the interfacial properties, structure and dynamics of dodecanedioic dicarboxylic acids at hexane/water interface over a wide range of surface coverage (area per molecule). Unlike monocarboxylic acid whose hydrocarbon tail points to the oil phase normal to the oil/water interface, the two carboxyl groups of the dicarboxylic acid are attached to the aqueous phase while its slightly curved carbon backbone lies parallel to the interface. The dodecanedioic dicarboxylic acid adopts a slightly curved linear conformation in the interfacial region. The adsorbed acids undergo a first-order gas-to-liquid phase transition as the density of acid increases. The characteristic thickness of the acid layer remains practically constant at large area per molecule (or, low surface density) until surface coverage reaches a “critical” value above which the thickness of the acid layer increases markedly deviating from its low density value. This layering transition has a significant influence on the spreading pressure, interfacial structure, and lateral diffusion coefficient of the acids. Additionally, we modeled a system of fully deprotonated negatively charged acids balanced by positively charged sodium counterions. We found that the interfacial tension of the charged acid interface is consistently lower than uncharged acid at moderate to higher surface density; however, at low densities, we observe little difference in interfacial tension between these two systems within the accuracy of the MD results. Additionally, we found that the rotational relaxation of the charged acids is significantly slower than that of uncharged acids owing to strong electrostatic interactions between the carboxyl groups COO〈sup〉−〈/sup〉and sodium Na〈sup〉+〈/sup〉cations which restrain the rotational motion of the acid. This molecular dynamics study has provided information and insights at the molecular level on the structure, equilibrium, and dynamic properties of dicarboxylic dodecanedioic acids at hexane/water interface.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307137-ga1.jpg" width="494" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): Xiaojia Li, Guangqiao Xu, Guilong Peng, Nuo Yang, Wei Yu, Chengcheng Deng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Solar steam generation technology can utilize abundant and renewable solar energy for many applications. In this work, we proposed a low-cost high-efficiency solar steam generator by using wick materials with wrapped graphene nanoparticles, and the energy efficiency can reaches up to 80%. Instead of traditional smearing method, the chemical wrapping method was used for better coating the graphene nanoparticles on the wick materials. Through the SEM morphological results, the graphene nanoparticles are shown to be evenly wrapped across the fibres of the wick material, which have better dispersity and stability. The evaporation rate, instantaneous energy efficiency and the solar absorptivity of three wick materials with/without nanoparticles under different conditions were compared and analyzed. Among the three different wick materials, the fine fluffy cloth can provide more three-dimensional contact area for wrapping graphene nanoparticles and thus contribute to better evaporation. Additionally, the influence of two different reduction methods and different concentrations of graphene oxide solution on the energy efficiency was also analyzed. Our work offers a simple and effective way of using nanotechnology in practical application for better solar-to-heat conversion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): Juan C. Tudon-Martinez, Alberto Cantu-Perez, Andrea Cardenas-Romero, Jorge de J. Lozoya-Santos〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A zero dimensional thermodynamic model (0D-model) is used to represent the conservation equations of energy in an industrial box furnace for designing purposes. Thus, this paper proposes a 0D model-based design approach for industrial box furnaces which results very processing time efficient, minimizing the design analysis time period that can exist when two-dimensional (2D) or Computational Fluid Dynamics (CFD) modeling is used. 2D or CFD models can be highly accurate but with also high computational load; the time spent in an industrial design from the concept to the prototype can take several months where the bottleneck is the simulation phase. The modeling results in the proposed approach consists on analyzing the fuel energy power requirement required to achieve a desired temperature profile, given the most important design parameters such as physical furnace dimensions, composition material in the insulation section, thermal load properties, fuel/air ratio conditions, etc. In this case, the proposed approach for a 0D-model based furnace design has been validated with different operation set-ups and compared with simulation data provided by a complex 2D model as well as with experimental data from an industrial box furnace. Quantitatively, the modeling result was up to 96.77% of fit with respect to the simulator behavior, taking less than 5% of processing time considered by the complex 2D model.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): R. Anish, V. Mariappan, Mahmood Mastani Joybari〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Renewable energy sources are incapable of supplying continuous power due to their intermittent availability. To tackle this, energy storage systems incorporating phase change materials can be utilized. Among the several techniques, shell-and-finned-tube configurations show promising heat transfer performance and have greater engineering applicability. This study experimentally investigated the heat transfer mechanism in a horizontal shell-and-multi-finned-tube energy storage unit. Variation of average temperature and storage effectiveness as well as effects of inlet heat transfer fluid temperature and flow rate on the phase change of erythritol were experimentally investigated. It was found that the effect of inlet temperature was more significant than the flow rate (12–32% and 7–17%, respectively). Moreover, natural convection was found to significantly influence the heat transfer during melting where the melted material initially occupied the upper region of the unit and then moved from top to bottom. The outcomes of the present work help understand the effect of natural convection to be effectively utilized for the design and optimization of such storage configurations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Xinyu Zheng, Huaili Zheng, Yuhao Zhou, Yongjun Sun, Rui Zhao, Yongzhi Liu, Shixin Zhang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Wastewater containing dyes poses a severe threat to human health and to environmental safety. Hence, finding an effective way to treat this wastewater has attracted wide attentions. In this study, quaternary ammonium group-rich magnetic nanoparticles (MNPs), Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@SiO〈sub〉2〈/sub〉-MPS-g-DAC (FSMD), were facilely prepared by grafting polymerization and served as a cationic adsorbent to remove anionic dye Orange G from aqueous solutions. Being compared with Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@SiO〈sub〉2〈/sub〉-MPS MNPs, the adsorption capacity of FSMD MNPs was notably enhanced and it could be maintained in a high level under a wide solution pH range. The dependency on pH and the sensitivity to ionic strength indicated that the main adsorption mechanism was the electrostatic interaction. The adsorption kinetics followed the pseudo-second-order model, and the adsorption isotherms were well described with the Langmuir model. According to the thermodynamic analysis, the adsorption process was spontaneous and endothermic. FSMD MNPs were proved to have advantages of fast adsorption rate, high adsorption capacity, easy separation ability under external magnetic field, and satisfactory reusability, therefore they can be applied in the removal of anionic dyes from wastewater.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307344-ga1.jpg" width="370" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Du Ren, Yujie Chen, Hua Li, Hafeez Ur Rehman, Yunli Cai, Hezhou Liu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Shape memory assisted self-healing polymeric networks have been numerously explored due to their multi-functionality and sustainability. In this study, we prepare a kind of electrical and thermal dual-responsive shape memory assisted self-healing polymeric composites fabricated with polycaprolactone/thermoplastic polyurethane (PCL/TPU) and carbon nanotubes (CNTs) via a facile method. The CNTs/PCL/TPU composites use PCL/TPU blend as shape memory polymer matrix, PCL as healing agent and CNTs as reinforcement networks. CNTs greatly enhance mechanical strength of the composites with good electrical and thermal conductivity. Interestingly, the CNTs/PCL/TPU composites can be healed via electricity and heating respectively in tens of seconds with corresponding optimal healing efficiencies about 96% and 94%. Meanwhile, the composites can exhibit remarkable electro-active shape recovery property that assist to diminish the crack openings and then the healing agent would be molten to fill in the crack. Therefore, the proposed materials can offer great potential applications in biomedical, aerospace and microelectronics.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307198-ga1.jpg" width="343" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): Peng Xiao, Zhong Yifeng, Wang Peng, Luo Dan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As a lightweight building material, hollow-glass-beads-filled cement-based composites (HGB-CBCs) have important applications in building energy saving and fireproofing. In order to reveal the mechanism of thermal conduction in HGB-CBCs, a heat conduction micro-model of HGB-CBCs was established based on the variational asymptotic homogenization method (VAHM). Then, the heat conduction micro-model was used to quantitatively investigate the influence of the micro-structural parameters and constituent properties on the effective thermal conductivity of HGB-CBCs with two different types of unit cells. Numerical results show that the heat flux fields recovered by VAHM perfectly agree with those by RVE-based FEM, but more smooth. The heat flux will drop slowly and almost linearly far away from the glass bead, while the heat flux in HGB will drop sharply, indicating HGB has great thermal resistance. HGB-CBCs with greater volume fraction and smaller wall thickness of HGB provides better thermal insulation effect. The longer and more complicated heat transfer paths around the wall of HGB are beneficial to the decrease of effective thermal conductivity, which can provide guidance for engineers who want to use HGB-CBCs as thermal-insulating composite materials in the civil engineering.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): Chunmeng Xu, Lukas Graber〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to improve the electric current rating of a vacuum-insulated disconnect switch, a copper-water thermosyphon has been embedded into an electrical bushing to achieve significantly higher effective thermal conductivity and lower hotspot temperatures of the bushing. The temperature profiles of a thermosyphon bushing conductor under different heat loads and filling ratios have been characterized by experiments. For the purpose of estimating the performances of any thermosyphon bushing with various dimensions, working fluids and filling ratios, a thermal network model with lumped thermal capacitors has been established. Characteristic features of thermosyphon bushings like the thick pipe walls and the distributed Joule heat sources are represented in the model. This model successfully predicted the effective thermal conductivity and hotspot temperatures of a thermosyphon bushing prototype designed for a vacuum-insulated disconnect switch. Because of the compact designs of thermosyphon bushings, they can be implemented in a wide range of power equipment, such as vacuum switchgear, disconnect switches, plasma chambers, and high-power physics experiments.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): Xiaofei Yue, Weidong Liu, Yuan Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Water droplet freezing and melting on three micro- or hierarchically-structured silicon surfaces and a smooth silicon wafer were studied experimentally. The surface temperature was kept at −13.8 °C during freezing and increased gradually to room temperature after turning off the bath circulator. The freezing behaviors including the freezing delay, solidification front movement, and the droplet profile were obtained through the photographic method. The results show that the tiny black silicon particles on hierarchical structures facilitate a longer freezing delay. The solidification stage lasted for 5–17 s depending on the surface structures, during which the freezing rate was larger in the initial seconds. Droplet on three micro-structured surfaces formed a tip with the angle of 122 ± 2°, smaller than that on the smooth silicon which was 136 ± 3°. The melting onset temperature for samples 1–3 was about 4.4 °C while melting happened on smooth silicon needed a smaller degree of superheat.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): T.I. Bhaiyat, S. Schekman, H.Y. Lim, Y.H. Jeon, T. Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Louvered fin-and-tube heat exchanger cores, operating inside of an automotive climate control system (ACCS), are used to control temperature and humidity in a passenger cabin. The thermal performance of these cores is typically sensitive to flow features inside the core, which have been well studied for uniform flow fields as well as some non-uniform and inclined flow-fields upstream of the core. The compact geometry of an ACCS unit results in the flow-fields upstream of the core being different from those used in previous studies. When measuring the performance of a louvered fin-and-tube heater core inside a commercially manufactured ACCS unit, up to a 60% reduction in the core’s thermal performance compared to the performance when exposed to a uniform upstream flow is detected. Such a drastic performance reduction has not been reported in the literature. As such a systematic breakdown is made to elaborate how some key and specific ACCS unit features designed for the sake of compactness could play a detrimental role in reducing the overall thermal performance of a given louvered fin-and-tube heater core. By mimicking the actual ACCS features the performance deterioration in the commercial unit could be largely replicated. The individual contributing effects of the various fluidic features such as flow separation and recirculation are determined. Only 50% of the measured 60% deterioration, however, could be accounted for, suggesting that other ACCS unit properties not assessed in detail in this study may also adversely affect the core’s performance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): Hang Li, Xiangbang Kong, Chaoyue Liu, Jinbao Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The nickel-rich silicon-graphite lithium-ion cells, for example the LiNi〈sub〉0.8〈/sub〉Mn〈sub〉0.1〈/sub〉Co〈sub〉0.1〈/sub〉O〈sub〉2〈/sub〉/Silicon-carbon (NMC811/Si@C), have been used in the commercial power batteries to meet the higher capacity requirements now. However, the battery with higher energy is more destructive as thermal runaway occurs. In order to improve the safety of the battery, it is essential to study the thermal stability of this kind of battery. In this work, the differential scanning calorimetry (DSC) and adiabatic rate calorimetry (ARC) have been used to conduct a detail thermal stability analysis for this type of battery of different charge state, the thermal stability mutation of Si@C material has been observed firstly when the SOC is great than 55%. Besides, a reasonable thermal runaway reaction sequence of the battery of NMC811/Si@C is proposed. Moreover, based on the time to maximum reaction rate (TMR), the effective recommendations for the use of NMC811/Si@C lithium ion battery are provided.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): J. Carneiro, J.B.L.M. Campos, J.M. Miranda〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study reports the generation and characterization of polydimethylsiloxane (PDMS) microparticles. Droplets are produced in the jetting regime by hydrodynamic flow focusing technique in a PDMS square-section microchannel and afterwards thermally cured. Both the droplets and microparticles size distributions are characterized and compared. During the curing process, there is no appreciable shrinking of the droplets/microparticles. Droplets are generated with a maximum frequency of 1.3 kHz and their diameter ranges from 27 to 59 μm depending on the flow rate ratio. After the cure, the microparticles are chemically and optically characterized. The results show that the droplet generation method and the curing process are able to produce PDMS microparticles with low size, low dispersity and optimal optical properties for visualization and velocimetry experiments.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307253-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Li Duan, ChenChen Qin, Anhe Wang, Shengtao Wang, Jieling Li, Shuo Bai〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, uniform and porous gelatin microgels with various functional nano-objects (platinum nanoparticles and magnetic nanoparticles) were prepared by a ‘casting’ strategy in a controllable manner. During the microgels fabrication, two kinds of nanoparticles can be simultaneously introduced into the microgels without mutual influence, endowing the microgels with the combined functionality of nano-objects. Experimental data showed that the microgels with various nano-objects are stable enough in strong base or acidic solution, and can be taken as an efficient catalysis system and conveniently separated from the reaction medium by magnetic field. The method proposed here is certified to be facile, efficient and low cost to fabricate stable multifunctional microgels.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307472-ga1.jpg" width="259" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Yaya Ma, Cuiqing Zhang, Chengyu Li, Feng Qin, Lin Wei, Changyuan Hu, Quanhong Hu, Shuwang Duo〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 is a newly found semiconductor photocatalyst with visible-light response property; however, due to its large particle size, the photocatalytic efficiency is greatly limited. Reducing the particle size down to nanoscale is an efficient way to enhance the photocatalytic ability, but still challenging. Herein, the firework-shaped hierarchical TiO〈sub〉2〈/sub〉 microsphere was used as the framework to spatially confine the growth of Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉. SEM characterization results reveal nanosized Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 particles are successfully inserted into the TiO〈sub〉2〈/sub〉 microsphere, forming enormous Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 heterojunctions. Benefitted from the nanoscaled Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 and the formation of Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 type II heterojunction, both the separation efficiency of charge carriers and the quantum yield are improved. As a result, Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 heterojunctions show much higher photocatalytic activity than that of pristine Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 in the degradation of methyl orange and tetracycline under visible light. Radical capture experimental results imply that hole is the dominant reactive species for the degradation of methyl orange. The present work paves the way for designing nanosized photocatalyst via the space-confined effect.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉A space-confined strategy is developed to restrict the size of Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 down to nanoscale level and as-constructed Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 heterojunctions display superior photocatalytic performance than pure Bi〈sub〉2〈/sub〉O〈sub〉4〈/sub〉.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307459-ga1.jpg" width="283" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 161〈/p〉 〈p〉Author(s): Xin Ma, Chenghui Zhang, Ke Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple, yet accurate hybrid model of scroll compressor (SC) used in micro-compressed air energy storage system (MCAES) is put forward in this paper. The modeling process starts with basic thermodynamic and fundamental physical principles but captures only few key operational characteristic parameters to predict the exhaust temperature, exhaust flow rate and the input torque of the SC, and then the appropriate input and output variables are selected according to the control demands of the system. Compared to the existing models, the hybrid model is more streamlined, and is better to meet the control requirements of the system, considering both accuracy and practicability. The developed model is identified and corrected based on both the experimental data and manual. The testing results show that the maximum error between the predicted results and the experimental data is less than 10%, indicating that the model can predict the system performance accurately. Finally, further efficiency analysis is advanced based on the proposed hybrid model, and the optimal operation range of the compression process is suggested. The hybrid model proposed in this paper lays the foundation for the subsequent capacity design, performance analysis and optimization control of MCAES.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): A.M. Hezma, A. Rajeh, Mohammed A. Mannaa〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Zinc oxide nanoparticles were prepared by a sol-gel method and characterized by XRD, SEM, TEM and EDX. A series of chitosan and polyvinyl alcohol (Cs/PVA) blend films doped with various concentrations of Zinc oxide nanoparticles (ZnO NPs) were prepared by solution casting method. These samples were characterized by various analytical techniques. XRD patterns of the prepared samples showed increasing in amorphousity of the polymer blend with increasing the content of ZnO NPs in Cs/PVA blend. The FT-IR analysis confirmed the complexation between Cs/PVA blend and ZnO NPs. From the UV–vis results, the optical energy gap was calculated. The TGA analysis displayed that the thermal stability of all the samples improved after the addition of the ZnO NPs. By the tensile universal testing machine, the mechanical properties of the prepared films were determined. The antimicrobial analysis showed that all nanocomposite films exhibited enhanced antimicrobial efficacy as compared to pure Cs/PVA film and it is linearly related to the amount of ZnO nanoparticles in the matrix. The sample containing 10 and 15 wt.% ZnO NPs exhibited the highest thermal stability, mechanical strength, and antibacterial activity. This nanocomposite with excellent thermal stability, tensile and antibacterial properties can be potentially utilized for antimicrobial packaging purposes and can be widely used in medical applications.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092777571930809X-ga1.jpg" width="256" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 581〈/p〉 〈p〉Author(s): Ya Di, Kunling Lu, Yaling Tian, Yan Liu, Yunwang Zhao, Yue Zheng〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two-phase synthesis is an advantageous alternative to the traditional synthetic method, due to its less toxicity, controllable, mild synthetic conditions and easy large-scale synthesis. However, meeting novel synthesis, the conventional trial-and-error approach could not provide a clear understanding. We herein report synthesis and mechanism investigation of CdS quantum dots in octadecene/glycerol two-phase system. The effects of different reaction parameters and conditions including reaction temperature, reaction time, reactant concentrations, and synthesis routes (one-step and two-step approach) on both nucleation and particle growth were investigated. It was found that the synthesis course was a growth dominated process depending on both CdS(monomer) and CdS(nuclei), and controlled by the interface of ODE/glycerol. The present work provided a new and clear understanding about two-phase system synthesis on semiconductor quantum dots, noble metal nanocrystals and some alloy nanomaterials.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719308003-ga1.jpg" width="377" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Huey-Shan Hung, Da-Tian Bau, Chun-An Yeh, Mei-Lang Kung〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉〈strong〉Gold〈/strong〉nanoparticles (AuNPs) have well applied in imaging and carriers of drugs and/or biomolecules for diseases and cancers therapeutics, due to their tunable physicochemical properties, easy functionalized with biomolecules and biocompatibility. AuNPs conjugated with biopolymer such as collagen has been demonstrated that increased the cell proliferation, migration and cell differentiation. Avemar (Ave) is a nutraceutical from natural components and dietary supplement for healthcare of tumor related anorexia/cachexia. Moreover, Ave has revealed the excellent bio-efficacy of anti-proliferation, cell cycle disturbing and apoptosis induction in numerous types of tumor cells in 〈em〉in vivo〈/em〉 and 〈em〉in vitro〈/em〉. However, the effects of Ave on cellular uptake mechanisms still unclear. In this study, we fabricate the Ave-deposited AuNP-collagen nanocarrier (AuNP-Col-Ave) and investigate their endocytic mechanisms in transformed SCC oral cancer cells and non-transformed BAEC and HSF cell lines. By using DLS assay, Ave-deposited AuNP-Col have shown a particle size of 303 ± 35.2 nm. Both UV–vis absorption assay and FTIR spectrum analysis were also demonstrated that the Ave conjugated onto AuNP-Col. Further, both MTT assay and Calcein AM assay were revealed that AuNP-Col-Ave induced a significant cytotoxicity in cancerous SCC cells and showed nontoxicity and biocompatibility for non-transformed BAEC and HFS cells. In addition, AuNP-Col-Ave has showed an excellent uptake capacity in all these cell lines as compared to AuNP-Col group. Further uptake mechanisms analysis demonstrated that the macropinocytosis seems to be the favorite endocytic mechanism during AuNP-Col-Ave internalized into these transformed and non-transformed cell lines. Altogether, this study is first validating the endocytic mechanisms of AuNP-Col-Ave in transformed and non-transformed cell lines. Our findings will provide a novel insight for endocytic mechanisms of cellular uptake nutraceuticals during nutrition therapy and cancer prevention.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Schematic diagram illustrated that AuNP-Col-Ave-mediated cellular uptake mechanisms and cell fates in both transform and non-transformed cell lines.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307794-ga1.jpg" width="217" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Allan Gomez-Flores, Scott A. Bradford, Lei Wu, Hyunjung Kim〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Particles of various shapes (e.g., spheres or rods), sizes (e.g., nm to microns), interiors (e.g., solid or hollow), and materials are used in many industrial and environmental applications. The Derjaguin–Landau–Verwey–Overbeek (DLVO) theory has commonly been used to calculate and predict the adhesive interaction of these particles with solid surfaces. However, DLVO theory treats these particles as equivalent spheres for simplicity ignoring shape in numerous cases. The surface element integration (SEI) approach allows DLVO theory to be extended for different particle shapes, orientations, and interiors. In this study, the SEI approach was applied to calculate the interaction energy between hollow and solid cylinders with a flat surface. The effect of aspect ratio and particle orientation on interaction energies was investigated under different solution chemistry conditions. Our study is relevant for an extensive range of particle aspect ratios, ranging from nanosized particles such as carbon nanotubes or nanowires, which have high aspect ratios, to micron-sized particles such as bacteria, which have low aspect ratios. The energy barrier tended to increase when the angle that the larger axis of the particle made with the normal to the surface changed from perpendicular (0 rad) to parallel (π/2 rad). The aspect ratio did not affect the trend of the energy barrier for solid (200–1000) and hollow (25–1000) cylinders of relatively high aspect ratios, but it produces a non-monotonic trend for solid (2–100) and hollow (2–10) cylinders of low aspect ratios. The present study advances our understanding of adhesive interactions for particles having a wide range of aspect ratios and interior properties at various orientations with the surface.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307691-ga1.jpg" width="310" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 580〈/p〉 〈p〉Author(s): Xiaoqin Huang, Yanli Niu, Zeping Peng, Weihua Hu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Core–shell structured BiOCl@polydopamine (BiOCl@PDA) hierarchical hollow microspheres were synthesized as an efficient photocatalyst towards degradation of pollutants under visible light. As-prepared BiOCl@PDA features hierarchical hollow microsphere structure formed by aggregated BiOCl nanosheets with PDA thin film coated on their surface. It exhibits excellent photocatalytic activity and recycling durability for photodegradation of pollutants under visible light illumination. Detail investigation suggests that the introduction of PDA significantly improves the specific surface areas and enhances the light absorption and interfacial separation, together to improve the photocatalytic efficiency. This work may provide a valuable strategy for the synthesis of highly efficient photocatalysts.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0927775719307356-ga1.jpg" width="222" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Thermal Engineering, Volume 162〈/p〉 〈p〉Author(s): Dietmar Siegele, Fabian Ochs, Wolfgang Feist〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents the detailed steady-state measurement results of a novel speed-controlled exhaust-air to supply-air heat pump combined with a ventilation system. Compared with conventional systems, the heating power can be more than doubled to approximately 2.5 kW using recirculation air. Therefore, such cost-effective systems can be utilized not only in high-energy-efficient buildings but also in buildings with higher heating loads, such as in case of renovations. A functional model was developed and tested in the laboratory. The measurement results demonstrated an overall system performance of over 4.5 for minimal heating power at +10 °C and 2.5 for maximum heating power at −7 °C. A simplified physical model for refrigerant cycle was presented and validated. It provided results with a measurement accuracy of 8%. The model was used to demonstrate further optimization potential. According to these results, a 5% improved system performance can be achieved by increasing the condenser size.〈/p〉〈/div〉 〈/div〉