ALBERT

Description: The skylight on the roof of an atrium can be popular for commercial malls to illuminate the core area of the building. However, the solar radiation and its heat can get into the building together with the daylight, causing excessive cooling load. This paper studies the daylighting and energy performances of skylight coverage area for the air-conditioned atriums in the hot and humid regions. The energy performance with different atrium heights, glass types and the coverage ratios of the skylight are studied. The daylight performance was simulated by the ray-tracing Radiance and was transferred into EnergyPlus for energy evaluations. The finding suggested that, for hot and humid climates, the skylight coverage ratio should be controlled carefully to prevent the excessive solar heat gain. When the on/off lighting control is applied, the total energy consumption of the single-floor cases (or of the top floor for the multi-floor cases) leveled off when the coverage ratio of the skylight reached 9%. Thus, the skylight is favorable to the energy saving of the low-rise or single-floor commercial buildings only under the current assumptions, as the ground of the atrium cannot be well illuminated while the excessive solar radiation gets into the building. The skylight should be shaded in cooling seasons to prevent the excessive solar heat gains.

Description: The production of liquefied natural gas (LNG) is a high energy-consuming process. The study of ways to reduce energy consumption and consequently to reduce operational costs is imperative. Toward this purpose, this study proposes a hybrid system adopting a mixed refrigerant for the liquefaction of natural gas that is precooled with an ammonia/water absorption refrigeration (AR) cycle utilizing the exhaust heat of a molten carbonate fuel cell, 700°C and 2.74 bar, coupled with a gas turbine and a bottoming Brayton super-critical carbon dioxide cycle. The inauguration of the ammonia/water AR cycle to the LNG process increases the cooling load of the cycle by 10%, providing a 28.3-MW cooling load duty while having a 0.45 coefficient of performance. Employing the hybrid system reduces energy consumption, attaining 85% overall thermal efficiency, 53% electrical efficiency and 35% fuel cell efficiency. The hybrid system produces 6300 kg.mol.h−1 of LNG and 146.55 MW of electrical power. Thereafter, exergy and sensitivity analyses are implemented and, accordingly, the fuel cell had an 83% share of the exergy destruction and the whole system obtained a 95% exergy efficiency.

Description: According to the regulation of European Union laws in 2014, it was inevitable to switch to low global warming potential (GWP) fluids in the refrigeration systems where the R404A working fluid is currently used. The GWP of R404A is very high, and the potential for ozone depletion is zero. In this study, energetic and exergetic performance assessment of a theoretical refrigeration system was carried out for R404 refrigerant and its alternatives, comparatively. The analyses were made for R448A, R449A, R452A and R404A. The results of the analysis were presented separately in the tables and graphs. According to the results, the cooling system working with R448A exhibited the best performance with a coefficient of performance (COP) value of 2.467 within the alternatives of R404A followed by R449A and R452A, where the COP values were calculated as 2.419 and 2.313, respectively. In addition, the exergy efficiencies of the system were calculated as 20.62%, 20.22% and 19.33% for R448A, R449A and R452A, respectively. For the base calculations made for R404A, the COP of the system was estimated as 2.477, where the exergy efficiency was 20.71%. Under the same operating conditions, the total exergy destruction rates for R404A, R448A, R449A and R452A working fluids were found to be 3.201 kW, 3.217 kW, 3.298 kW and 3.488 kW, respectively. Furthermore, parametric analyses were carried out in order to investigate the effects of different system parameters such as evaporator and condenser temperature.

Description: Due to the lack of suitable evaluation systems for heating, ventilation, air-conditioning (HVAC) systems with ground source heat pump (GSHP) and energy storage (ES) technologies, it is difficult to design a building HVAC system to achieve optimized design with regard to investment cost, energy saving and environmental protection. This is a study on developing a fuzzy evaluation system by including GSHP and ES with comprehensively determined weights into an HVAC system. A questionnaire method was used and the answers from 21 HVAC experts were analyzed to facilitate the modeling. Taking a commercial integrated project in Nanjing as an engineering case, the evaluation system was tested. If the system with a comprehensive merit value of 0.303 is adopted, the annual operating cost is reduced by 32.5%, the annual total life cycle cost is reduced by 26.5% and the primary energy consumption and carbon emissions are reduced by 10.5%, with the initial investment increased by 6.5%. This study revealed that the newly developed evaluation system is very useful for realizing the optimal design of HVAC systems.

Description: Among non-toxic and inflammable working fluids, carbon dioxide (CO2) proving a possible choice of refrigerant is gaining full status because of its reducing capacity of global warming and ozone depletion. Heat pump (HP) equipment uses energy more rationally to heat water by reducing emissions and global warming caused by conventional refrigerants. HP capability demands an environmentally friendly refrigerant for their full utilization and high energy saving as well to attaining higher coefficient of performance (COP) without much design corrections. CO2 is checked for sustainability to eliminate the standardized refrigerants such as chlorofluorocarbons (CFC) and hydro-CFC. In this work, the performance of CO2 as an alternate refrigerant in HP for heating water at different pressure, flow rates, evaporator fan speed and preheating have been investigated. HP is accommodated with two condensers. The results showed that the increased mass flow rate had increased COP, overall heat transfer (HT) coefficient (U) and HT. However, logarithmic mean temperature difference was decreased for increasing evaporator’s fan speed and pressure. The outlet water temperature (TWO) of second condenser increased with decreasing water flow rate. Improved COP, HT and TWO of HP are observed from the experimental evaluation in case of preheating of water.

Description: By using power electronic devices, photovoltaic grid-connected power generation may inject harmonics into the power system. As the photovoltaic grid-connected inverter has the same basic structure as the active power filter, so the unified control of the photovoltaic grid and active filtering can be achieved. When the current unified control system compensates harmonics of the grid side, it mainly uses ip-iq harmonic detection method, which is based on instantaneous reactive power theory. When the three-phase voltage is unbalanced, the method has a large voltage phase angle detection error and the signal of the low-pass filter tracking system is long, detection time delay and even failure occur. This paper proposes an improved fast harmonic detection method. When phase deviation or amplitude change occurs to the three-phase voltage, the positive and negative-sequence voltages are simultaneously park transformed. The negative-sequence component is filtered by the current average module to obtain the fundamental amount of the voltage, then the phase angle of the positive-sequence voltage is accurately calculated to improve the harmonic current detection accuracy. Through the study of the integral method, it is found that the least common multiple of each harmonic period can be used as the integral interval, and the integral value is also zero, so the detection delay time is reduced by replacing the low-pass filter with an integration module. The simulation results show that the proposed harmonic detection algorithm can accurately detect harmonics when the three-phase voltage is unbalanced, and about 0.057 s improve the harmonic detection speed compared with the commonly used ip-iq method.

Description: Lithium-ion batteries retired from electric vehicles can provide considerable economic benefits when they are retired for secondary use. However, retired batteries after screening and restructuring still face the problem of inaccurate battery pack state-of-charge (SOC) estimation due to the existence of extreme inconsistency. To solve this problem, an adaptive fading unscented Kalman filtering (AFUKF) algorithm based on the cell difference model (CDM) is proposed in this paper for improving the accuracy of SOC estimation of retired lithium-ion battery packs. Firstly, an improved CDM based on a hypothetical Rint model is developed based on a second-order resistor/capacitor equivalent circuit model. Secondly, an AFUKF algorithm is developed to improve the adaptability and robustness of local state estimation against process modelling errors. Finally, characteristic data are obtained by conducting discharge tests on the screened retired lithium-ion batteries under specific operating conditions. The proposed method can improve the accuracy of SOC estimation of retired lithium-ion battery packs and provide a new idea for SOC estimation of retired lithium-ion battery packs, as shown by the simulated real experimental data.

Description: Accurate prediction of electricity sale has a positive effect on power companies in rationally arranging power supply plans, scientifically optimizing power resource allocation, improving power management efficiency, saving energy and reducing consumption. Predicting future electricity sale based on historical electricity sale data can essentially be summarized as a time series forecasting problem. This paper proposes a fast and memory-efficient method, which adopts the expressive power of deep neural networks and the time characteristics of sequence-to-sequence structure (parallel convolution and recurrent neural network) for long range forecasting in electricity sale. Through a large number of experiments and evaluation of real-world datasets, the effectiveness of the proposed method is proved and verified in terms of prediction accuracy, time consuming and training speed.

Description: Nowadays, the global energy and environmental problems are becoming more and more serious, which promotes the development and utilization of renewable and clean energy in various countries. Intelligent car involves many subjects such as electronic technology, artificial intelligence, automatic control technology, sensor technology and computer technology and has become an important part of the application of artificial intelligence. Solar cell is a necessary part of the normal operation of the solar intelligent car, which can provide clean energy for the intelligent car. In this paper, the image recognition technology is used to design the intelligent vehicle control system. According to the intelligent vehicle path recognition, the scale invariant feature transform (SIFT) algorithm is improved to improve the accuracy of intelligent vehicle recognition. Data fusion is used to process the data detected by multi-sensor, and the running state of intelligent vehicle is studied. An evaluation method of intelligent vehicle navigation parameters based on association rules and belief network is proposed. The maximum power point tracking control is realized by using the interference observation method to ensure that the intelligent vehicle can track the maximum power point of the solar cell.

Description: To reveal the flame propagation and CO/CO2 generation characteristics of coal dust explosion, lignite dust cloud is studied through experiment and numerical simulation in a horizontal pipeline apparatus. The result indicated that within 0.5 s after explosion, the flame propagation distance rapidly increases until the explosion reaction is sufficient. FLUENT is used to simulate the flame propagation and CO/CO2 generation characteristics. It is found that the simulation error is acceptable and the simulation result is consistent with the experimental result. The explosion space is divided into five zones by simulating the flame temperature. It also revealed that z = 0.3 ~ 0.6 m in the pipeline generates more CO because it is closed to the ignition zone. As the explosion spreads through the pipeline, the generated CO accumulates to the bottom of the pipeline, and the generated CO2 accumulates more in the upper part of the pipeline.

Description: In city gas pressure reducing stations, in order not to hydrate natural gas after a sudden drop in pressure, the gas temperature is raised by a heater. The increase in temperature is such that after the pressure drop, the gas inside the pipes does not freeze. These heaters are gas burning and very high consumption, and because they use fossil fuels, produce environmental pollution. Accordingly, in this research, solar energy will be used to preheat the gas, which will be used for the most accurate analysis of TRNSYS software. In this regard, the amount of utilization of the sun and the amount of energy required for preheating will be obtained. After the implementation of the TRNSYS program, the highest amount of energy supply by the sun is related to spring, which on this day provides 55% of the thermal energy required by the load by solar energy.

Description: In order to reduce the carbon emission and improve the de-carbonization in distribution of vehicle routing problem with simultaneous delivery and pickup (VRPSDP), a two-stage disruption management method based on the changes of customer demand is proposed in this paper. Firstly, a mathematics model of VRPSDP is established to optimize the parameters and the distribution carbon emission cost and time window deviation. Next, several carbon emission equations in VRPSDP are inducted and designed. Considering the strong global searching ability of quantum particle swarm optimization (QPSO) and combing the advantages of superposition and parallelism of quantum computing, a multi-phase QPSO (MQPSO) is proposed to enhance global searching ability. At last, on the basis of Solomon examples, the validity of the proposed model and MQPSO is tested and compared with the classical algorithms at present. The simulation results show that the proposed method can not only achieve the goal of performance but also meet the practical requirements of reducing carbon emissions in VRPSDP.

Description: Renewable energy sources cannot guarantee long-term and stable output supply when they are given energy consumption at the load end. At the same time, traditional solar and utility power supply systems cannot guarantee the priority of using solar energy to generate electricity, which has certain limitations. In this regard, an energy control strategy for achieving smooth and no backflow switching and prioritizing the use of clean energy solar energy under a joint power supply system of a solar power grid and a municipal power grid is proposed, which is used for a conventional combined power supply system of a contactor switching circuit. A topology of low voltage power grid is proposed, which effectively reduces the impact on the solar power grid and the municipal power grid during the system switching process combined control mode for controlling the current phase and repetitive control at the output end of the solar power grid in the combined power supply mode, and adding a feedforward control method for the grid voltage is adopted to ensure that the solar grid and the municipal power prioritize the use of clean energy solar energy and, at the same time, ensure the maximum utilization of solar energy. This paper chose the combined power supply system with the solar power grid and the municipal power grid as the object of this research. The topology structure and controlling strategy of the power supply system were comprehensively and deeply researched, and on this basis, the combined power supply system prototype was designed on the foundation of DSP28335 and CPLD. Moreover, hardware parameters are designed in the system, and an energy management optimization algorithm based on the system is developed on the corresponding experimental platform. The experimental results show that the proposed energy control strategy can effectively reduce the impact on the solar power grid and the municipal power grid during the system switching process, ensure that the solar power grid and the municipal power grid have no backflow combined power supply and give priority to the use of clean energy solar energy.

Description: Stand-alone hybrid energy systems are an enticing option for electrification in remote areas in several aspects such as grid extension difficulty, economic feasibility and reliability. The use of existing micro-hydropower (MHP) with other renewable resources in rural areas has not been well studied. Moreover, it is challenging to use mathematical optimization algorithms for these kinds of real-world problems, so the derivative-free algorithm is highly sought. In this paper, a methodology has been proposed to perform the optimal sizing, financial and generation uncertainty analysis of solar photovoltaic (SPV) based on an MHP that is proposed to handle the intermittent power output of the SPV. The analysis is performed in two cases: using storage and without storage. The optimal sizing is performed using the least present value cost and reliability constraint using different derivative-free algorithms. The storage-based hybrid system has been found to generate reliable electricity at minimal cost than without a storage-based one. This study would be helpful to propose electrification and existing micro-hydro reinforcement policies to provide reliable electricity in rural areas.

Description: The significance of post-disaster temporary housing for the victims has led to the problem of designing a good model of temporary housing. According to research hypothesis, using the design of Iranian nomads’ housing instead of common forms of temporary housing contributes to energy saving. Investigating the architecture of nomads’ housing indicates that there is a type of indigenous knowledge for designing and constructing this type of housing. After the study, data collection and a review of the types of Iranian nomads’ housing using library and causal method, thermal simulation was conducted to investigate the effect of changing the temporary housing form inspired by the nomads’ housing on energy consumption. Findings showed that using shapes like Kapars of Baluchistan nomads, wigwams of Shahsavan tribe in Ardabil and mudhifs of Khuzestan will save energy for 36%, 24% and 25%, respectively.

Description: The quality and shelf-life of NCS (non-centrifugal sugar) mainly depend on the moisture content present in it. NCS formed by the current practice of open sun drying contains moisture substantially greater than the acceptable level of 3%. This paper presents the work undertaken to design a tunnel dryer to achieve the required moisture content of granular NCS for various load conditions. An experimental investigation was conducted on a laboratory-scale dryer to achieve the required moisture content for various loads. This experimental data was compared with the output of two drying models and a validated one that could be used to design an industrial-scale dryer. For various load conditions on each tray and dryer exit temperature, nine different cases were determined. The number of trucks, drying time, and energy requirements were computed using the validated theoretical model. A tunnel dryer with a length, height and width of 18, 1.2 and 1 m respectively and 18 trucks with 24 trays on each truck is shown to be dry 1 tone of NCS based on the minimum energy requirement of 176.49 MJ, and a drying time of 68 min.

Description: 4-Amino-3-(2-bromo-5-methoxyphenyl)-1H-1,2,4-triazole-5(4H)-thione (ATH) was synthesized and characterized by nuclear magnetic resonance and Fourier-transform infrared as spectroscopical techniques and elemental analysis. ATH was studied for corrosion inhibition of mild steel in corrosive environment by means of weight loss technique, scanning electron microscopy and the adsorption isotherm. ATH demonstrates a superior inhibition efficiency against corrosion of mild steel. Adsorption data fit well to a Langmuir isotherm model.

Description: Hydrogen-fueled combustion systems are becoming popular in recent years. Methane is one of the significant hydrogen supplier in nature. Thus, in the study, the natural gas-fueled reactor-assisted solid oxide fuel-cell system is configured to provide a current to load the battery to turn the propeller of an unmanned aerial vehicle in the large-scale hydrogen-onboard system. The methane-fueled reactor has not been studied under a large-scale case in literature yet. To investigate the amount of products, this paper presents about the steam-reforming performance of natural gas in steady state and transient in the reactor. The influence of vital parameters such as steam/carbon, gas feed temperatures, the amount of heat transferred to the reactor in methane steam reforming for a plug flow reactor, and a continuous stirred tank-type reactor is investigated respectively. Methane conversion, yield of hydrogen gas and H2 gas generation for different medium conditions along the reactor are studied on by using the COMSOL Multiphysics program. The steady-state and time-dependent characteristics of the steam reforming of natural gas are focused on. The high conversion ratio of methane gas is obtained by ranking the steam/carbon ratio. The released hydrogen gas molar flow rate is increasing according to the reactor volume. The achieved power provided by produced gas of H2 is 97 hp supplying the thrust force for an unmanned aerial vehicle.

Description: The corrosion inhibition of Schiff base, namely 2-((2-hydroxy-5-methoxybenzylidene)amino)pyridine (HMAP), for mild steel (MS) in a 1 M hydrochloric acid environment was investigated by means of weight loss and scanning electron microscopy techniques. Quantum chemical calculation based on density functional theory (DFT) was carried out on HMAP. Results illustrated that HMAP is a superior inhibitor for the corrosion of MS in 1.0M hydrochloric acid environment, and inhibition efficiency is higher than 90.0% at 0.5 g/L HMAP. Inhibition performance increases with regard to concentration increase and inhibition performance decreases when raising temperature. Adsorption of the inhibitor on the MS surface followed Langmuir adsorption isotherm and the value of the free energy of adsorption; ΔGads indicated that the adsorption of HMAP was a physisorption/chemisorption process. The DFT refers to perfect correlation with methodological inhibition performance.

Description: Ecological footprint (EF) is an indicator that accounts for human demand in the environment compared with the sizes of the bio-productive land and sea areas. This research was carried out to determine the EF for environmental sustainability in Ilorin Metropolis. Empirical surveying, which involved systematic random sample technique, was used to select residential households in each community for this investigation. The EF indicators, which include food, energy and waste consumptions, were determined empirically. The bio-capacity (BC), ecological stress and deficit were determined, from the land used as environmental sustainable areas in Ilorin, using Google Earth Mapping. The results revealed that energy has the highest EF of 44%, followed by waste and food with the footprint of 25% and 5%, respectively. A deficit of 38% was obtained, and this requires eight times the BC to balance the EF of the population. This implies that people are consuming more of the energy and generating more wastes than they consumed food.

Description: The case study presented in this paper is an innovative ground source heat pump (GSHP) system constituted by a hybrid Photovoltaic Thermal (PVT) solar system for poultry houses. Farmers tend to not to apply GSHPs because of the high prices of excavation and time consumption. The innovative heat pump system assessed in this study comprises of a new type of heat exchangers; a thin-tube solar polyethylene heat exchanger installed between roof tiles and PV panels and a novel vertical ground heat exchanger to utilize the heat stored in the soil. The heating system applied to a poultry house are monitored and evaluated under a variety of environmental and operating conditions to achieve annual/long-term efficiency of the heating system in Kirton, UK. The maximum heating demand of the poultry house is determined 34.4 MWh/PC while the minimum is 11,1 MWh/PC. The monitored results show that the heat pump produced 15.02 MWh of thermal energy per annum. Solar PV and heat pump worked very well together with solar PV covering all the heat pump’s annual electrical energy requirement and generated 8.74 MWh of extra electricity exported to the grid. The seasonal coefficient of performance is found 3.73 through a year. The novel PVT-GSHP heating system is a very promising solution for high fossil fuel consumption in the agriculture industry and the energy savings of the whole system can be noticeably increased dependent up on the system controlling.

Description: This paper introduces an innovative thin film PV vacuum glazing (PV-VG) technology. In addition to electricity generation, the PV-VG glazing can also reduce heat loss from the building in winter and reduce heat gain in summer. In building integrated photovoltaics application, optical characterization of the PV glazing is important in determining the solar ray transmission and thermal transfer process of the glazing. This paper discusses the optical properties of the PV-VG glazing by considering the different layers of the glazing unit that includes a self-cleaning glass, a thin film PV glass and a low-e vacuum glazing. Based on the optical transfer matrix, the transmission coefficients of different film layers were deduced. The theoretical calculations were then validated against the transmission coefficient experiment of the PV-VG using an EDTM SS2450 Solar Spectrum Meter. The calculation error of the transmission coefficient of the single-layer glazing is generally within 5%, the calculation error of the transmission coefficient of the integrated PV-VG glazing is about 6%. The results show that the average visible light transmission coefficient, the average infrared light transmission coefficient and the overall transmission coefficient of PV-VG glazing are 19%, 16% and 12%, respectively. The study is important to optimize the visible light transmission of the PV-VG glazing; the optical model obtained above lays a solid foundation for further study of transmission coefficient analysis of different functional coating of PV-VG glazing.

Description: Renewable energy technologies have been developed in recent years due to the limited sources of fossil fuels, the possibility of depletion of fossil fuels and the related environmental issues. In these types of systems, it is crucial to reach optimum sizing in order to have an affordable system based on solar and wind energy and energy storage. In this study, a powerful optimization scheme based on tabu search, called discrete tabu search, has been proposed for sizing three stand-alone solar/wind/energy storage (battery) hybrid systems. For validating the applied algorithm effectiveness, the results are compared with the results found by the discrete harmony search. The obtained outcomes are compared on the basis of total annual cost. The components of the scheme are analyzed in different operating conditions by applying meteorological data in addition to real time information from three typical regions of Iran. According to the obtained data, applying ‘discrete tabu search’ leads to better outputs on the basis of mean, standard deviation and worst indexes.

Description: Based on 804 samples of farmers in Hubei Province, a typical major grain-producing area in China, this study empirically analyzed the effects of two different policy tools, i.e. economic incentives (subsidies) and order enforcements (regulatory restrictions), as well as the effects of their interaction, on farmers’ chemical fertilizer reduction and substitution behaviors. Samples were grouped according to the degree of concurrent employment to analyze the effects on different groups. The results show that (1) the influences of these policies on the behaviors were significantly positive; (2) after constructing the interactive variables of the policies, the influence of the order enforcement policy was no longer significant, but the influence of the interaction was significantly positive; (3) the low-degree concurrent employment farmers were more likely to be affected by the order enforcement policy, whereas the high-degree ones were more affected by the economic incentive policy; and (4) the behaviors of the low-degree ones were strongly affected by family management characteristics, whereas the high-degree ones were more affected by the farmers’ individual characteristics.

Description: The present study aims to investigate the thermodynamic and financial aspect of concentrated solar power (CSP) plant hybridized with biomass-based organic Rankine cycle (ORC), thermal energy storage (TES), hot springs and CO2 capture systems. The organic working fluids namely R123, R235fa, D4 and MDM are selected for designing the hybrid system at different operating conditions. The nominal power capacities of the CSP and biomass ORC plants are 1.3 MW and 730 kW respectively. Additionally, a parametric study has been carried out to understand the influencing parameters that affect the system’s performance. From the results, it is revealed that the biomass ORC plant with a hot spring system alone can develop a power of 720 and 640 kW for D4 and MDM respectively. Furthermore, the power generation can be increased with addition of TES in the CSP plant. From the economic point of view, the hybrid system with special focus on CO2 capture could be very profitable if the levelized cost of electricity (LCOE) is fixed at 0.24$/kWh. In this scenario, the payback period is 8 years with an internal rate of return (IRR) more than 8%. Therefore, the hybrid system is thermodynamically and financially attractive for dispatchable electricity.

Description: Geothermal energy is a kind of green and non-polluting renewable energy. Medium and low-temperature geothermal energy below 150 °C is usually used directly for heating, industrial and agricultural heating, bathing, etc., and the utilization rate is low. Organic Rankine cycle (ORC) system can be used in a low-temperature geothermal power generation systems. Thermodynamic analysis of the thermal cycle system is carried out in this paper. Based on the principle of exergy analysis, the cycle parameters such as evaporation temperature, condensation temperature, superheating temperature, and supercooling temperature are analyzed. The results show that the exergy efficiency and system output power can improve by increasing evaporation temperature and the exergy loss can decrease in the evaporator. Increasing superheating temperature enhances the output power of the expander and the exergy loss in the condenser, decreases the exergy efficiency simultaneously. Increasing condensation temperature decreases the exergy efficiency of the system and the output power of the expander, and increases the exergy loss of the system. Although the output power of the expander will not be affected by supercooling temperature, the rise of supercooling temperature will reduce the exergy efficiency of the system and increase the exergy loss of the evaporator.

Description: The present work aimed to select the optimum solar tracking mode for parabolic trough concentrating collectors using numerical simulation. The current work involved: (1) the calculation of daily solar radiation on the Earth’s surface, (2) the comparison of annual direct solar radiation received under different tracking modes and (3) the determination of optimum tilt angle for the north-south tilt tracking mode. It was found that the order of solar radiation received in Shanghai under the available tracking modes was: dual-axis tracking 〉 north-south Earth’s axis tracking 〉 north-south tilt tracking (β = 15°) 〉 north-south tilt tracking (β = 45) 〉 north-south horizontal tracking 〉 east-west horizontal tracking. Single-axis solar tracking modes feature simple structures and low cost. This study also found that the solar radiation received under the north-south tilt tracking mode was higher than that of the north-south Earth’s axis tracking mode in 7 out of 12 months. Therefore, the north-south tilt tracking mode was studied separately to determine the corresponding optimum tilt angles in Haikou, Lhasa, Shanghai, Beijing and Hohhot, respectively, which were shown as follows: 18.81°, 27.29°, 28.67°, 36.21° and 37.97°.

Description: Renewable energies could be a good solution to the problems associated with fossil fuels. The storage of wind energy by means of small-scale devices rather than large-scale turbines is a topic that has gained lots of interest. In this study, a compact device is proposed to harvest wind energy and transform it into electrical energy, by means of oscillations of a magnet into a coil, using the concept of vortex-induced vibration (VIV) behind a barrier. For a more comprehensive investigation, this system is studied from two viewpoints of fluid mechanics (without magnet) and power generation (with the magnet). For this purpose, an oscillating plate hinging on one side and three barriers with different geometrical shapes including cylindrical, triangular and rectangular barriers are used. In addition to the effect of barrier geometry, the impacts of various barriers dimensions, the distance between the plate and the barriers as well as inclination angle of the plate with respect to the horizon on the amplitude of oscillations and generated power are investigated. Results showed that in each case, there is a unique Reynolds number in which the frequency of vortex shedding equals to the frequency of plate oscillation and the output power from the energy harvester device is maximum. Besides, by increasing the barrier dimensions, the amplitude of oscillations increases up to three times, which leads to a higher generated power. Finally, by considering the studied parameters, the best conditions for generating energy using the VIV method are presented for design purposes. Among all the considered cases, the cylindrical barrier with the highest diameter and nearest distance to the plate led to the highest efficiency (0.21%) in comparison with other barriers.

Description: In this study, thermodynamic analysis was performed on basic and recuperative transcritical organic Rankine cycles by using five pure and six mixed fluids. The effects of evaporation parameters on the first- and second-law efficiencies (ηI and ηII) as well as power output were investigated. The results indicate that a recuperator had a positive effect on the ηI and ηII and negative effects on the specific power. The total irreversibility of the system was improved by the recuperator. However, the total irreversibility considerably increased with an increase in the expander inlet temperature (Texp,in) due to the significant increase in irreversibility in the condenser, particularly for working fluids with low critical temperatures, namely R134a, R1234yf and R290, and low proportions of R245fa and R600a in mixed fluids. For both the pure and mixed fluids, the specific power linearly increased with an increase in the expander inlet pressure (Pexp,in) and Texp,in. However, with an increase in Pexp,in, the ηI and ηII first increased and then decreased. Finally, for ηI and ηII, the effect of the recuperator increased with an increase in Texp,in even though the recuperator had a relatively small effect on the working fluids with high critical temperature, especially when Pexp,in was high.

Description: In this work, the network data envelopment analysis (DEA) model was used to divide the transformation of scientific and technological achievements in colleges and universities into two stages, which makes up for the lack of process measurement in a single DEA model. Also, the relationship between the transformation efficiency of scientific and technological achievements in universities and the development of a low-carbon economy was quantitatively analyzed. The research results show that: (1) the transformation efficiency of scientific and technological achievements of universities in China is increasing year by year and which is significantly higher in the eastern region than that in the central and western regions. (2) The efficiency of the transformation of scientific and technological achievements of the university promotes the reduction of carbon emission intensity and the development of a low-carbon economy, indicating that the improvement of the transformation efficiency of scientific and technological achievements of the university has a good role in promoting the ecological environment protection. However, compared with the developed countries, the quantity and quality of science and technology supply and ecological environment protection in China’s universities are still insufficient. In this regard, the development suggestions are put forward from the aspects of government policy guidance, professional talent cooperation and strengthening the docking between universities and industrial low-carbon economic development. The purpose of this paper is to promote the development of a low-carbon economy by improving the efficiency of scientific and technological achievements transformation in universities, to achieve the goal of ecological environment protection.

Description: In order to improve the friendliness of the grid connection of new energy power generation, the new energy photovoltaic (PV) unit is equivalent to a synchronous generator in the power system and a virtual synchronous generator (VSG)-controlled PV energy storage complementary grid-connected power generation system model is established and studied to analyze the VSG. When power is supplied to the load together with the power grid, the energy storage unit inside the VSG will release and store the electrical energy according to the fluctuation of the PV output, which plays the role of the adjustment of the prime mover; in the case of load power fluctuations, and power grid assume the corresponding active power regulation according to their capacity. The amount of active power adjustment to jointly and maintain the power balance inside the system under the condition of fluctuating load power. The overall system architecture and control strategy of PV grid-connected inverter based on VSG algorithm are proposed. The PV-VSG proposed here not only takes into account the maximum power point tracking control but also has independent participation in the power supply. A series of characteristics of synchronous generators, such as network frequency modulation voltage regulation and inertia damping, can effectively improve the new energy PV power generation system and promote the new energy consumption. The results of system simulation and field demonstration operation fully show the effectiveness and correctness of the proposed control strategy based on VSG algorithm.

Description: A roof-mounted radiant cooling system incorporating a bypass structure, intended for use on liquid natural gas (LNG)-fueled refrigerated vehicles and offering stable dynamic regulation was designed. A model was established using the TRNSYS software package to simulate the operation of this system, and the effects of various factors on the refrigeration performance were analyzed. The quantitative relationship between the LNG flow rate and the ambient temperature was determined and a dynamic regulation strategy proposed. The results of this work show that, when the vehicle is operated at an economical speed, the cooling capacity provided by the system is greater than 1.2 kW, which meets the requirements for a refrigerated vehicle. The dynamic regulation approach developed in this study was found to allow use of the refrigerated vehicle under different climactic conditions and to improve the stability of the cooling system.

Description: The increasing global energy and environmental problems are encouraging to the development and utilization of renewable and clean energy in various countries. Wind power is one of the major source in large-scale renewable energy applications. However, the frequency regulation becomes a critical issue while the technology is spreading. Research on the frequency modulation (FM) technology of wind turbines and its control strategy for future power grids become significant. The paper proposes a novel coordinated frequency control strategy with the synchronous generator to solve the unmatched state between the output power of the doubly-fed wind turbines (doubly-fed induction generators) and the grid frequency, combined with the frequency response characteristics of the synchronous generator. The FM coordination strategy is formulated by the modulation coefficient from current wind speed and operation mode of each wind turbine. By coordinating the FM output of the doubly-fed wind turbine and the synchronous generator within the allowable range of frequency deviation, it will achieve the dual goal of reducing the frequency regulation pressure of the synchronous generator and indirectly reducing the abandoned wind volume of the wind turbine. The simulation is carried out on the MATLAB/SIMULINK platform. The results show that the presenting variable coefficient frequency modulation strategy could significant smooth the wind power fluctuation, and allow the reserve power of the doubly-fed wind turbine can fully engaged in frequency modulation which will reduces the frequency modulation pressure of the synchronous generator in the system.

Description: The moisture extraction rate (MER) and energy efficiency of domestic gas clothes dryers, heat-pump clothes dryers and electric clothes dryers were assessed. The assessment was performed with regard to five indices: the MER, specific MER, specific thermal energy consumption for dehumidification (mSPC), energy efficiency (ηt) and primary energy efficiency (η1). The effects of the dry mass of clothes (mBD) and the ambient temperature on the performance of the clothes dryers were evaluated. The experiments were divided into two parts. In the first part, the ambient temperature was 20°C, and mBD was set as 1.5, 2.5, 3.5, 4.5 and 6 kg. In the second part, mBD was 3.5 kg, and the performance of the dryers was tested at ambient temperatures of 5, 7.5, 10, 12.5, 15 and 20°C. The experimental results indicated that the gas dryer had the highest MER the heat-pump dryer had the best performance with regard to energy conservation and all three types of dryers had a higher MER and energy efficiency when the ambient temperature increased. The performance of the gas dryer was lower than that of heat-pump dryer when the temperature was 20°C. But when the temperature was

Description: In the current work, the influences of titanium oxide (TO) on nanocomposites using epoxy (EP) resin have been investigated. EP resin was added to various contents in terms of volume of TO (6%). Based on the casting method, the TO-EP nanocomposites were prepared. Mechanical properties in terms of tensile, impact and hardness properties exhibited improvements in the mechanical results of the TO-EP nanocomposites. The experimental results exhibited that the enhancement in the tensile strength, impact, and hardness was found to be 14 MPa, 40.1 J/mm2 and 228.9 HV, respectively. Moreover, the effect of the strength has decreased compared with pointing to brittleness that increased the TO-EP nanocomposites. Field emission scanning electron microscopy (FESEM) analysis was used to perform a microstructure analysis which in turn revealed how TO obstruction the cracks propagation in the nanocomposites. The interface between the TO and the EP nanocomposites was observed using the FESEM images. The results highlighted that the TO-EP nanocomposites can be used a wide range of industrial applications such as biomedical application.

Description: Hotels hold an important role in the energy efficiency policies of the European Union (EU), as they are typically ranked among the top energy consumers in the non-residential sector. However, a significant amount of the energy used in hotels is wasted, leaving ample room for enhancing energy-efficiency and resource conservation. Indeed, energy refurbishment of the hotel building stock is crucial in order to reach the nearly zero energy building (nZEB) status imposed by EU Directives for energy efficiency, and also an important pillar to achieve the energy targets for 2030 and the transition towards climate-neutral levels by 2050. A typical 4-star hotel in operation in Faro (Portugal) was used as a case study in order to establish energy performance indicators for nZEB hotels in three European cities, taking into account the influence of the climatic context, the technical feasibility and cost effectiveness of the best energy retrofit packages. The study started after the calibration of the building energy model by means of an energy audit and measured data, in order to have a baseline model that represents well the actual energy use of the hotel in the reference location. The building energy model was developed by using DesignBuilder/EnergyPlus software. The validated model was then used to assess the effect of the best retrofit interventions (energy efficiency measures and active solar systems) in order to set minimum energy performance requirements and to reach cost-optimal levels and nZEB levels for refurbished hotels. A significant energy-saving potential was found for the cost-optimal benchmarks, and the obtained nZEB levels can be achieved under technically and economically conditions for the selected cities: Faro, London and Athens.

Description: Prefabricated buildings constructed to be used in a specific region cannot be assumed to work unconditionally in different climates around the world. It is important to develop passive house solutions for each location, suitable for the actual climate and geographic conditions. Shelters could be used in different applications such as refugee housing or telecommunication stations. Photovoltaic energy could cover the electricity consumption of these shelters. Shelters for different applications should be usable in all weather conditions, and because of that different climate zones were chosen. A full study about three climate zones was done to study the different factors that play a significant rule in choosing the location of the shelter. In this study, prefabricated housing was designed to ensure thermal comfort by doing structure design changes and using solar energy as an energy source. Three different locations have been chosen to be able to perform the best structure and components design for every location, taking into consideration the assumptions taken in each place. The total photovoltaic system was designed with a capacity of hot, moderate and cold climate zones with 2.0, 1.8 and 3.45 kWp, respectively, along with energy plus the production of 38% in the hot, 47% in the moderate and 28% in the cold climate.

Description: From the last few years, the use of efficient ejector in refrigeration systems has been paid a lot of attention. In this article a description of a refrigeration system that combines a basic vapor compression refrigeration cycle with an ejector cooling cycle is presented. A one-dimensional mathematical model is developed using the flow governing thermodynamic equations based on a constant area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The current model is based on the NIST-REFPROP database for refrigerant property calculations. The model has basically been used to determine the effect of the ejector geometry and operating conditions on the performance of the whole refrigeration system. The results show that the proposed model predicts ejector performance, entrainment ratio and the coefficient of performance of the system and their sensitivity to evaporating and generating temperature of the cascade refrigeration cycle. The simulated performance has been then compared with the available experimental data from the literature for validation.

Description: Cement-based materials have been widely used in bridge construction. In order to further improve their performance, this study analyzed the modification and optimization functions of nano-SiO2 materials, designed test specimens with different content of nano-SiO2 and conducted experiments on their flow performance, compression resistance, bending resistance and impermeability. The results showed that the flow performance of the materials decreased and the impermeability decreased with the increase of nano-SiO2 content. The compressive strength and flexural strength are the best when the content of nano-SiO2 is 1%. On the whole, the best content of nano-SiO2 is 1%; when the content of nano-SiO2 is 1%, all the properties of the specimens are good, which is more conducive to the construction of bridges in various complex environments. The research in this paper has made some contributions to the further application of nano-SiO2 in the optimization of building materials, which is conducive to the better development of building materials.

Description: As one of the most promising and convenient heating service to replace coal-fired boilers and electric heaters due to its high energy efficiency, a heat pump has received more and more attention for the economical application and extensive research. The injection technology can be used to improve the heat pump performance. Currently, the injection ratio and pressure ratio are usually used to characterize the effects of injection styles on its performance. This is not conducive to its practical operation control because of additional cost increase. In this work, the effects of two injection cycles due to two injection paths were characterized with openings of a sub-cooling electronic expansion valve, comparatively tested and analyzed. Test results demonstrate that the heating capacities (Qh), electricity power (EP) and coefficient of performance with the refrigerant injection into compressor (CRI) are more than those with the injection into accumulator (ARI), and the overall effect with the CRI is positive because the Qh improvement outperforms EP increase. For example, the maximum Qh with the CRI at 55, 60 and 85 rps were 8.1%, 7.7% and 18.3% higher than those without the CRI, and 7.3%, 6.7% and 19.0% higher than those with the ARI. The thermodynamic model was used to analyze the experimental results and expound the mechanism of the influence of injection path on the performance of heat pump. This work provides guidance for improving energy efficiency in common areas and enhancing Qh in cold areas.

Description: In order to reduce the cost of central air conditioning, we need to reduce its energy consumption. This paper briefly introduced Internet of Things and the energy-saving and comfort monitoring system of central air conditioning based on the Internet of Things. The system took comfort degree as constraint and energy efficiency as objective to control energy saving of central air conditioning. Company X in Guanghan, Sichuan, China, was taken as an example for analysis. The system was compared with the energy-saving control system which took temperature and power as constraints. Compared with before the energy-saving control, the proportion of air conditioning downtime in the working hours of employees increased after the implementation of the two kinds of energy-saving control systems, and the proportion of downtime under the energy-saving control system designed in this study was larger; in addition, after the control of the two kinds of energy-saving systems, the energy efficiency of the air conditioning significantly improved, and the air conditioning under the control of the energy-saving system proposed in this study had more improvement in energy efficiency and higher energy-saving efficiency. The energy-saving control method proposed in this study can effectively reduce the power consumption of the central air conditioning in the office.

Description: The effect of surface wettability on droplet impact on spherical surfaces is studied with the CLSVOF method. When the impact velocity is constant, with the increase in the contact angle (CA), the maximum spreading factor and time needed to reach the maximum spreading factor (tmax) both decrease; the liquid film is more prone to breakup and rebound. When CA is constant, with the impact velocity increasing, the maximum spreading factor increases while tmax decreases. With the curvature ratio increasing, the maximum spreading factor increases when CA is between 30 and 150°, while it decreases when CA ranges from 0 to 30°.

Description: The non-centrifugal sugar (NCS) industry is one of the oldest small-scale cottage industry in India, whose technological features are not changed for several decades due to which the production and consumption of NCS has reduced significantly. One way to attend this problem is to select the best and sustainable methods among the existing technologies at various stages in the production process. In the production of NCS, juice extraction is the primary and essential process. The present work gives an insight to a logical procedure for selecting a suitable and sustainable juice extraction method for improving the NCS production using multi-criteria evaluation (MCE) technique. The selection process is based on 11 evaluation criteria covering various sustainable factors viz. technological, economic and environmental factors. Fuzzy analytical hierarchical process (FAHP) integrated with elimination et choix traduisant la realité method is the MCE technique considered for selecting the most appropriate crushing method among five alternatives. The results indicated that the power-operated single horizontal crusher is the most suitable and sustainable crushing method for improving the production rate of NCS. The same technique can be used for the other process unit of the NCS production to improve the productivity and sustainability of NCS.

Description: The concept of green buildings has recently arisen in order to contribute to solving some environmental, energy and economic issues. To meet the green building requirements, this paper describes an integrated design approach to improve the energy and water efficiency of the mid-rise residential buildings in Jordan using the eQUEST energy simulation tool. The results show that savings of 77.9% in the annual requirements of electricity, 65.0% in the requirements of diesel oil and 19.5% in the indoor water consumption can be achieved. Finally, the Jordanian green building model had achieved 44 points in the Leadership in Energy and Environmental Design green building rating system and will have the ‘Certified’ classification.

Description: Biogas is deemed as one of the most promising renewable fuels emerging in the past several decades. At present, biogas is mainly applied to cooking for substituting fossil fuels. However, biogas is rarely reported to be used for space heating. In this paper, we designed a biogas-fired partially premixed burner for gas-fired wall-mounted boilers, which has the heat input of 25 kW and can be used for space heating and water heater tank heating. The reference gas was assumed as 60% of methane (CH4) and 40% of CO2, and the burner port area was designed as 4744.5 mm2 according to the calculation. Then, experiments were conducted to study the performance of this burner. Jet diameters were modified in order to investigate their effects on heat input, primary air ratio and flame stability of the burner. The results indicate that the burner shows superior performance when the jet diameter is 2.0 mm. Meanwhile, the primary air ratio (${alpha}^{prime }$) satisfies the design requirement. Moreover, a gas-fired wall-mounted boiler with this burner was examined to investigate the influence of different biogas composition on exhaust emissions and thermal efficiency. The results show that the concentration of CO in the flue gas meets the national standard when CH4 varied from 40% to 60% in the biogas. However, the thermal efficiency of the biogas-fired wall-mounted boiler reduces greatly with the increase of CH4 percentage.

Description: Cooling towers are widely used not only for commercial and industrial purposes but also for cooling power plant. In Korea, coal-fired power plants and nuclear power plants are generally located on the coast, while most combined-power plants are located inland and use cooling towers to condense steam. The operation rate of power plants in Korea highly depends on government energy policies. In the future, it is expected that the need for cooling tower water for inland power plant will increase. Since power plant is one of the massive water-consuming facilities, methods for water saving of cooling tower should be prepared. Also, in the industrial sector, plume is constantly raising social conflicts between residents and manufactures. Basically, similar technologies can be applied to water saving and plume abatement. In this study, the performance of the condensing module (outdoor-air-condensing method) using outside air was tested first. This module has an advantage in that cooling heat source is not necessary. But an excessive increase of fan air volume is required. We tested a membrane-dehumidification method that selectively transfers water vapor by applying a membrane module. The results showed that membrane module required a large amount of energy to generate vapor pressure difference and it had a disadvantage in energy usage. Since the membrane method considered requires a high bypass airflow for higher dehumidification, it also has a disadvantage similar to that of the outdoor air module. Finally, the dehumidification/regeneration module (heat-pump method) gave the best performance in terms of water saving and plume abatement.

Description: Since the reform and opening up, with the development of China’s economy, the demand for tourism has been increased. The traditional agriculture has not been able to satisfy the diversified consumption demand; as a result, the rural ecotourism develops rapidly. Based on such a situation, the data envelopment analysis (DEA) model was used in this study; the relevant data of Guangxi province such as the number of star hotels and number of tourists were referred to. The efficiency of rural ecotourism space was calculated. According to evaluation analysis of spatial dynamic efficiency, it could be found that although the comprehensive technical efficiency of the southeast coastal areas was lower than 1, it was still higher than other regions. The pure technical efficiency of many regions was equal to 1, and the scale benefits were increasing. Regions with moderate political and economic levels had high pure technical efficiency and maintained above the national level, but they were relatively small in scale and needed to increase input indicators. However, the comprehensive technical efficiency of relatively backward areas in northwest China was relatively low, which remained at about 0.3. Therefore, more investment and government support are needed to expand the scale.

Description: With the depth increasing and the improvement of mining mechanization of the coal mine, heat hazard is becoming more and more serious, the ice cooling system is gradually promoted and applied in China for recent years, but the cooling capacity and energy efficiency ratio (EER) test and analysis for such system is seldom reported. The cooling capacity and EER of the refrigerating equipment of an ice cooling system of a coal mine are tested and analyzed in Shandong Province in this paper. The test result indicates that the refrigerating capacity and EER are lower and both the pre-cooling units and the ice making system have a large variable range. It points out that it should not evaluate the ice cooling system by the test data only in this mine but expect more test data and analysis of the ice cooling system in other coal mines to get a more scientific conclusion. And the test, analysis and comparison for different kinds of cooling system are also expected to explore suitable cooling system while a full consideration of the geological conditions and other factors of the mine are taken into consideration.

Description: Solar box cookers draw attention of many researchers across the globe as a promising renewable energy application for cooking purposes. Compared to other types available in literature, solar box cookers are more in the centre of interest owing to their simple and low-cost design, emerging thermodynamic performance figures, high durability and reliable cooking processes without any risk of burning food. On the other hand, cooking power and overall thermal performance of solar box cookers are still somewhat challenging to compete with the conventional cooking systems for the climatic conditions with low solar radiation potential like the Black Sea Region of Turkey. Within the scope of this research, a novel solar box cooker is devised, fabricated and tested to overcome the said shortcomings of traditional solar box cookers through natural and recycled materials. Double-glazed structure having 16-mm-thick air between two 6-mm-thick thermally resistive clear glasses is considered for aperture glazing with an area of 0.16 m2. The oven area has a depth of 350 mm, and it is entirely painted matte black for maximum solar absorption. The oven body made of stainless steel sheets is encountered by a latent heat storage medium filled by natural beeswax product, waste of propolis. Propolis is a resinous mixture that is used for protection of beehives, from either climatic changes or diseases. Polyphenols rich in balsamic part of the structure is extracted by alcohol than used for many apitherapic purposes. The remaining pulp or waste is not considered. In this study, it is used as green chemistry agents. It is found that water temperature in the cooking pot is kept over 40°C till very late hours as a consequence of latent heat storage. First figure of merit is determined to be 0.08, and the thermal efficiency of the cooker varies from 7.47 to 4.54%.

Description: Energy pile group is an important component of ground source heat pumps with foundation piles as ground heat exchangers. Among different energy piles, those with spiral pipes have a large heat exchange area between the pipe and the concrete, achieving good heat exchanging performance and wide applications. To analyze the influence of geometrical parameters (pile layout, pile spacing and pile depth) and external parameter (groundwater velocity) on the heat transfer of spiral-coil energy pile groups, a three-dimensional analytical model of spiral-coil energy pile groups with seepage is used, considering the thermal interaction among different piles, the geometry of spiral pipe and the velocity of groundwater. The soil temperature distribution in the energy pile group is studied under conditions with different factors (pile layouts: 3 × 2, L shape and line shape; pile spacing distances: 3, 5 and 7 m; pile depths: 10, 30 and 50 m; and groundwater velocities: 0, 1.2 × 10−6 and 2.0 × 10−6 m/s). The 3-year outlet fluid temperature of energy pile group affected by the above different factors under different inlet fluid temperatures and velocities or soil thermal exchange ratios is investigated. Results show that for the low fluid velocity inside the piles, the influence of above factors on the thermal performance of energy piles is more obvious. Large groundwater velocity, line shape pile layout, large pile spacing distance and short pile depth can alleviate the long-term temperature variation caused by unbalanced soil heat exchange. This work will facilitate the research, design and application of the energy pile group in ground source heat pumps.

Description: Waste heat is an environmental issue in the world. There are some technologies that can be used to recovery the waste heat, one of which is thermoacoustic cooler technology. Thermoacoustic technology can be divided into two parts: one is thermoacoustic engine and cooler. To design the cooler system having high efficiency and lower onset heating temperature, the effect of mean pressure is investigated. By increasing mean pressure from 0.5 to 3 MPa, the heating temperature generating acoustic power can be decreased from 831 to 580 K. Moreover, 15% of Thermodynamic upper limit value of the whole cooler system is achieved.

Description: In this paper, oblique impact of a single rain droplet on super-hydrophobic surface with randomly distributed rough structures was investigated by lattice Boltzmann method. The effects of the impact angle of the droplet as well as the skewness and kurtosis of rough surface on the bouncing ability of the droplet were in this paper. It was found that the oblique impact can effectively reduce the contact time in the process of droplet bouncing off, because the energy consumption caused by the pinning effect is reduced. Moreover, the contact time most possibly reaches the shortest when the impact angle is 45°. Decreasing the skewness and keeping the kurtosis around 4.0 can enhance the bouncing ability during the droplet oblique impact on randomly distributed rough surfaces. The results are useful for the design of building structures.

Description: At present, higher greenhouse gas (GHG) have triggered global efforts to reduce their level as much as possible for sustainable development. Carbon dioxide is one of the imperative anthropogenic emissions due to its increased excessive accumulation in the environment. Thus, serious attention is required to reduce the level of CO2 using advanced and efficient CO2 capture technologies. Carbon dioxide capture and storage (CCS) technologies may play an important role in this direction. At present, solvent-based sorbents are being utilized in CO2 capture for various industrial processes. In this category, the characters of non-materials are playing a crucial role to improve the CO2 absorption capacity of the process. This study is mainly focused on the role of nanotechnology in the post-combustion CO2 absorption process. The functions of nanomaterials and nanoparticles have been studied in the present work. Additionally, various challenges related to absorption efficiency using nanomaterials have been discussed. The study concludes that the higher thermal stability and exceptional properties of nanomaterials popularized them for use in CO2 capture processes.

Description: : Global climate change has become the greatest threat to mankind, endangering the ecological security of the earth and the long-term development of human society. Therefore, how to effectively reduce greenhouse gas emissions and curb the trend of global warming has become a common challenge facing all countries in the world. Fossil energy combustion is the fundamental cause of climate change. In this paper, the price return series of domestic energy and carbon markets are taken as the research objects. Firstly, the cross-correlation test is used to verify that there is an obvious cross-correlation between the return series of the energy and carbon markets. Based on this, the multifractal characteristics of energy market and carbon market cross-series are empirically studied. The empirical results show that there is an interactive correlation between energy and carbon markets and this relationship has multifractal characteristics; the interactive correlation between return series has multifractal characteristics. The long-range correlation between small fluctuations and large fluctuations and the fat tail distribution of return series are all reasons for the formation of multifractality. These conclusions will help to understand the non-linear dependence and potential dynamic mechanism between energy and carbon markets in China.

Description: This study presents the preparation and property characterization of biomass aerogels as sound absorption materials. Biomasses were chosen to prepare aerogels through the freeze-drying method. Results indicated that four components may have different effects on the aerogel pore structure, and the aerogel formula was thus optimized to reach the best sound absorption. Within the experimental range, biomass aerogel with the optimized formula had an average sound efficiency 0.352, density 0.047 g/cm3 and porosity 94.46 ± 0.04%. It shows better sound absorption performance than traditional sound absorption cotton. These results demonstrate the high sound absorption potential of biomass aerogels for building applications.

Description: Aiming at the problem that the traditional flying capacitor equalization circuit has long equilibrium time and complicated structure, based on the in-depth study of the existing capacitor equalization method, this paper proposes a bidirectional DC-DC equalization circuit topology based on switch matrix. Structure, improve circuit switch network structure, reduce the number of switches and capacitors in the circuit, simplify the equalization structure, combined with the advantages of bidirectional DC-DC converters can be used in both directions, according to the difference between the average voltage of the battery pack and the voltage of each cell. Any two cells in the battery pack areused for equalization purposes. By establishing an experimental test platform verification, the results show that the topology can reduce the equalization time under the premise of simplifying the circuit structure when equalizing any two cells.

Description: In domestic buildings, water is generally heated by an immersion type electric water heater, equipped with a thermostat as one unit, which is fitted at the bottom of the tank. Despite these systems are driven by electric energy, which is not favorable compared to direct solar water heaters, they are still widely used due to the practicality and low installation costs. In current use of electric water heaters, thermostat position and water set-point temperature are crucial and these parameters should be optimized for efficient and economic use of such systems. In this study, the impact of placing the thermostat at three different elevations; namely near the bottom, in the middle and near the top of an EWH is experimentally investigated. In addition, the effect of temperature setting of the thermostat near the bottom of the tank, on the performance of the EWH is experimentally investigated. Data were obtained for 5 L/min discharging rate of the heated water. The discharge efficiencies are found to be higher for the thermostat position at the bottom, while the discharge efficiencies for thermostat positions in the middle and near the top are very close but lower than that of the one near the bottom.

Description: Several passive cooling design techniques are known for reducing solar heat gain through building envelope in summer season. These include the use of phase change materials (PCM), which has received an increased attention over the last years, and the strategy of increasing the above-sheathing ventilation (ASV) in ventilated roofs. However, few studies combine both technologies to maximise the building resilience in hot season. The effect of including a PCM layer into a ventilated roof is numerically analysed here in two different configurations: firstly, laid on the roof deck (PCM1 case) and, secondly, suspended in the middle of the ASV channel (PCM2 case). A computational fluid dynamics model was implemented to simulate airflow and heat transfer around and through the building envelope, under 3 days of extreme hot conditions in summer with high temperatures and low wind speed. Results showed slight differences in terms of mean temperatures at the different roof layers, although temperature fluctuations at deck in the PCM1 case were smaller than half of those estimated for the benchmark case. However, PCM2 configuration achieved a daily reduction of about 10 Wh/m2 (18%) in building energy load with respect to the benchmark case, whilst PCM1 got only 4% due to the lower ventilation at night time. Therefore, a suspended PCM layer in the ASV channel would be a better measure in terms of energy performance than laid on the deck surface, although this last option significantly decreases thermal stress of the insulation layer.

Description: With the increasing pace of urban life, people are yearning more and more for a slow-paced rural life. Rural ecotourism is a new type of tourism produced for people to experience rural scenery. In order to ensure the sustainable development of rural eco-tourism, it is necessary to analyze its planning in many aspects. In this study, Tianjin rural eco-tourism was analyzed using the superiority, weakness, opportunity and threats analysis method. Then, according to the analysis, the superiority, weakness, opportunity and threat were obtained, and they were quantitatively analyzed by means of a questionnaire. The results showed that the development of Tianjin rural eco-tourism had four superiorities, i.e. convenient transportation, rich water resources, rich animal and plant resources and rich eco-tourism resources; three weakness, i.e. homogeneous content, unclear theme and low quality of staff; three opportunities, i.e. government support, effective combination of local culture with tourism activities and increased demand for tourism; and two threats, i.e. fierce competition among peers and diversified demands of tourists. In the comprehensive quantitative analysis, the comprehensive scores of superiorities, weakness, opportunities and threats were 3.6, −2.8, 4.4 and −4.4, respectively. To sum up, Tianjin rural ecotourism has superiorities over weakness and equivalent opportunities and threats; i.e. it is basically in a state of sustainable development.

Description: For areas with hot summer and cold winter, air conditioning is an essential tool to improve the living environment, but the traditional air conditioning needs to consume a lot of energy in cooling and heating, the fan operation noise is large and the sense of blowing will be uncomfortable. This paper briefly introduced the basic structure of a ground-source heat pump-floor radiant air conditioning system and the control strategy which was used for regulating the operation of the air conditioning system. Then, in order to ensure the appropriate comfort and reduce energy consumption, the control strategy was optimized. An experimental room in Xining, Qinghai province, was taken as an example for analysis. The results showed that the thermal comfort under the control strategy proposed in this study was more stable at the moderate degree and the temperature was slightly higher under the traditional control strategy, although the indoor temperature fluctuation under the optimal control strategy was large and the temperature was slightly lower than that under the traditional control strategy; under the control strategy proposed in this study, the air conditioning system had shorter operation time and less power consumption.

Description: The University of Technology in Baghdad addresses problems related to the corrosion of metals. In the present investigation, a thiophene derivative, namely, 2-acetylthiophene thiosemicarbazone (2-AT), was synthesized and examined as a corrosion inhibitor for mild steel in a 1-M hydrochloric acid environment by using weight loss and scanning electron microscopic techniques. The inhibition efficiency of this inhibitor increases with increase in concentration, which offered an inhibition efficiency up to 96%. It was found that the inhibition efficiency decreases with long immersion time. The temperature effect on the inhibition performance was studied at various immersion times and revealed that the inhibition efficiency decreases with increasing temperature. The adsorption of the inhibitor on the surface of mild steel in the corrosive environment followed the Langmuir isotherm. The results of scanning electron microscopy (SEM) reveal that the 2-AT molecules confirmed the presence of a protective layer on the surface of a mild steel sample. The density-functional theory as a quantum modeling technique which is used to study the electronic structure reveals that the obtained findings were found to be consistent with the experimental results.

Description: The development of a low-carbon economy is an inevitable choice for the world to coordinate industrial economic growth and environmental issues actively. At the same time, science and technology are the cornerstones for the development of a low-carbon economy. The equipment manufacturing industry (EMI) in China is known as the base of the low-carbon sector. Still, the research of coordinating industry carbon emission and economic growth from the perspective of science and technology is insufficient. For this reason, this work comprehensively analyzed the economic development and carbon emission of China’s EMI. The DEA (data envelopment analysis) Malmquist method was used to measure the transformation efficiency of scientific and technological achievements of the EMI from 2009 to 2017. The results can show that: (1) the economic benefits of China’s EMI were increasing year by year, but the growth rate is declining. With the optimization of industrial structure, the energy consumption and carbon emission of the industry have improved, but there is still a large gap between different sectors; (2) the achievement transformation of EMI decreases by year due to the influence of technological progress efficiency; and (3) in terms of sector data efficiency in 2017, there is redundancy in the investment of general EMI (B2) and special EMI (B3). This work can provide a reference for the development of countries dominated by industry and to jointly realize the sustainable development of the world economy.

Description: The viscosity and flow rate as rheological characteristics are fundamental in evaluating the nanofillers in processing the polyethylene-nanotube (PE-NT) composite in injecting molding. The purpose of this investigation is to study the rheological conduct of PE-NT composite plastic feedstock through capillary rheometry. For the purpose of obtaining a flawless component, the feedstock is used as a critical parameter, and care must be taken while introducing the raw materials with high solid load and hence perfect flowability. The shear rate viscosity of different feedstocks at an NT ratio extending at 0–3 wt.% has been determined at L/D equal to 10 die and a load extending at 40.0–80.0 KGF at temperatures 140.0, 150.0 and 160.0°C. The three specimens’ viscosity was measured in order to exhibit that the corresponding flow conduct factor varies from 0.40 to 0.70, demonstrating the non-Newtonian behavior of the specimens. The three specimens’ activation energies at the studied temperature degrees were evaluated and turned out to be 36.5–69.88 kJ/mol according to the applied load.

Description: Thermodynamic analysis including energetic and exergetic analysis is carried out employing Engineering Equation Solver for the five modified cycles: dual expansion cycle, internal heat exchanger cycle, work recovery cycle, work recovery with internal heat exchanger cycle and vortex tube expansion cycle. Contours are developed to study the effect of gas cooler temperatures and evaporator temperatures on the system performance and optimum gas cooler pressure. The modified cycle with work recovery turbine offers relatively higher COP and higher exergetic efficiency with lower compressor discharge pressure. The exergy loss in compressor, gas cooler, throttle valve and vortex tube (VT) are considerably higher than that in internal heat exchanger (IHX), evaporator and turbine. It is observed that COP of modified cycle with VT is slightly less than that with IHX, whereas the cycle with work recovery turbine brings the highest COP with the improvement of 25% at the gas cooler exit temperature of 305 K and evaporator temperature of 248 K.

Description: In this study, the impact of social norms on farmers’ behavior of cultivated land protection and the related mechanism was investigated in terms of direct effect and mediating effect and further verified by logistic and mediation effect estimation of different organic fertilizer application behaviors. An empirical analysis of the data collected from Xiajin County of Shandong, China, revealed that (1) perceived social norms can exert significant and positive effects on the behavior of farmers in cultivated land protection; (2) social norms can stimulate farmers to adopt cultivated land protection behaviors by affecting their related value cognition, risk confidence and skills; and (3) the mediating mechanisms varied in the impact of perceived social norms on different cultivated land protection behaviors, with farmyard manure application being significantly moderated by value cognition, risk confidence and skills, in contrast to a major impact of social network on the application of commercial organic fertilizers. This study enriched the theoretical interpretation of the impact of social norms on farmers’ behavior of cultivated land protection and provided useful information on activation of farmers’ cultivated land protection behavior to promote the sustainable development of agriculture.

Description: The ignition and explosion of coal dust are significant hazards in coal mines. In this study, the minimum ignition temperature and energy of non-stick coal dust were investigated empirically at different working conditions to identify the key factors that influence the sensitivity and characteristics of coal dust explosions. The results showed that for a given particle size, the minimum ignition temperature of the coal dust layer was inversely related to the thickness of the coal dust layer. Meanwhile, when the layer thickness was kept constant, the minimum ignition temperature of the coal dust layer decreased with smaller coal dust particle sizes. Over the range of particle sizes tested (25–75 μm), the minimum ignition temperature of the coal dust cloud gradually increased when larger particles was used. At the same particle size, the minimum ignition temperature of the coal dust layer was much lower than that of the coal dust cloud. Furthermore, the curves of minimum ignition energy all exhibited a minimum value in response to changes to single independent variables of mass concentration, ignition delay time and powder injection pressure. The interactions of these three independent variables were also examined, and the experimental results were fitted to establish a mathematical model of the minimum ignition energy of coal dust. Empirical verification demonstrated the accuracy and practicability of the model. The results of this research can provide an experimental and theoretical basis for preventing dust explosions in coal mines to enhance the safety of production.

Description: The demands of specific requirements related to thermal comforts, such as temperature, relative humidity, inside air exchange and other factors required in a hospital operating rooms, have necessitated the development of energy-efficient heating, ventilation and air conditioning (HVAC) systems and efficient heat-recovery system using a heat-pipe heat exchanger (HPHE). The experiment was conducted by using HPHEs having three, six and nine rows, with four heat pipes in each row, arranged in a staggered configuration with a variation of fresh-air inlet temperature and velocity. The theoretical analysis was conducted using the ε-NTU method for predicting the effectiveness, outlet temperature of the evaporator side and energy recovery of the HPHE. The experimental results indicated that increasing the air-inlet temperature in the evaporator section and the number of rows increased the HPHE effectiveness but increasing the air-inlet velocity reduced the effectiveness. The highest effectiveness of 62.6% was obtained at an air-inlet temperature of 45°C with an air-inlet velocity of 2 m/s and a 9-row HPHE. The energy recovery of the HPHE increased with the number of rows, air-inlet temperature and air velocity in the evaporator section. The ε-NTU method can be used as a comparison method in the analysis of heat-recovery systems that apply HPHE air conditioning systems. Heat pipes that utilize cold-air exhaust from a room in an HVAC system can enhance efficiency and reduce emissions.

Description: Urbanization is a global trend determined primarily by excessive population growth, particularly in the developing countries such as Egypt. The configuration and boundaries of urbanization and their model can be observed at a distance of space and time. In this research, geographic information system and remote sensing were used to analyze urbanization and trends in the past 30 years of Mansoura City, which is one of the largest medium-sized cities in Egypt. Four Landsat images, obtained in 1985, 1995, 2005 and 2015, were adjusted and compared using the ArcGIS software. The classified images were analyzed to determine urbanization trends in Mansoura city during the three periods 1985–1995, 1995–2005 and 2005–2015. The results of the change disclosure showed areas and trends in urbanization. The urban area has grown by approximately five times over 30 years. The results showed that the eastern direction was predominant during the periods (1985–1995) and (1995–2005) with 53 and 53% of the city total growth, respectively. During the period (2005–2015), the northern trend was dominant with 38% of the city total growth. This research promotes future urban planning strategies by evaluating temporal spatial transformation and urbanization trends.

Description: Reactive extraction, a novel technique, was experimentally investigated for the removal of propionic acid, which is usually present in low concentrations in aqueous solutions. The experiments were conducted according to statistical design to develop an appropriate regression model. This was aimed at analyzing and optimizing the process variables and extraction efficiency for propionic acid reactive extraction from dilute aqueous streams using trioctylamine as extractant and 1-decanol as organic diluent. Response surface methodology in combination with Box–Behnken design involving 17 experimental runs was utilized for the propionic acid reactive extraction in this study. Three independent process variables were chosen as temperature (T), initial propionic acid concentration (CPAO) in the aqueous phase and trioctylamine composition (CTOA) in the organic phase. The statistical design analysis demonstrated that the propionic acid concentration and TOA composition had a significant effect while temperature had an insignificant effect on the response value as well as an interactive and quadratic effect on the response. The optimum conditions for propionic acid extraction were established as T  =  300.752 K, CTOA  =  18.252 %v/v, CPAO  =  0.408 kmol/m3. Under these optimum conditions, the propionic acid experimental extraction yield was 89.788 %, which was in close conformity with the predicted yield value of 91.939 %.

Description: The volume of Indonesian tea exports to the European Union (EU) decreased by 43% in 2014 because of the EU setting a maximum residue limit of anthraquinone (AQ) for tea as 0.02 mg/kg. The content of AQ in tea leaves increases when there is incomplete combustion in the combustion of firewood for the energy source of withering and drying of tea leaves. This study aims to develop and test a new concept for the direct use of low-temperature geothermal energy with a heat pipe heat exchanger (HPHE) for the withering of tea leaves as a solution for energy sources free from AQ. The geothermal fluid simulators use water, which is heated by heater and flowed by a pump. The HPHE used consists of 42 heat pipes and 181 fins. The heat pipe used has a length of 700 mm with an outer diameter of 10 mm. Each fin is made of aluminum with a thickness of 0.105 mm and a size of 76 × 345 mm2. The results show that the effectiveness of the HPHE varies from 66% to 79.59%. For 100 g of fresh tea leaves, the heating energy produced ranges from 15.21 W to 45.07 W, meaning it can wither tea leaves from 80% (w.b.) to 54% (w.b.) in a variety of 11 h 56 min to only 49.6 min. The Page mathematical model is the best model to represent the behavior of the tea leaves with this HPHE system.

Description: The present study focuses on the organic Rankine cycle (ORC) integrated into an evacuated tube heat pipe (ETHP), whose systems are an alternative solar energy system to low-efficiency planary collectors. In this work, a detailed thermodynamic and artificial neural network (ANN) analysis was conducted to evaluate the solar energy system. One of the key parameters of sustainable approaches focused on exergy efficiency is application of thermal engineering. In addition to this, sustainable engineering approaches nowadays are a necessity for improving the efficiency of all of the engineering research areas. For this reason, the ANN model is used to forecast different types of energy efficiency problems in thermodynamic literature. The examined system consists of two main parts such as the ETHP system and the ORC system used for thermal energy production. With this system, it is aimed to evaluate energy and exergy analysis results by the ANN method in the case of integrating the ORC system to ETHP, which is one of the planar collectors suitable for the roofs of the buildings. Within the scope of this study, the exergy efficiency was evaluated on the developed ANN algorithm. The effect rates of parameters such as pressure, temperature and ambient temperature affecting the exergy efficiency of ORC integrated ETHP were calculated. Ambient temperature was found to be the most influential parameter on exergy efficiency. The exergy efficiency of the whole system has been calculated as ~23.39%. The most suitable BPNN architecture for this case study is recurrent networks with dampened feedback (Jordan–Elman nets). The success rate of the developed BPNN model is 95.4%.

Description: The study on carbon emissions in packaging industry is a very important but easily overlooked field. In order to explore carbon emissions of the packaging life cycle, the wineglass is used as the packaging object to discuss the difference between carbon emissions and costs caused by two new packaging structures and a common packaging structure on the market. The measurement boundary includes raw material collection, raw material processing, packaging manufacturing, transportation and end of life. It was found that reasonable packaging structure instead the buffer function of expanded polyethylene can effectively reduce the carbon emissions and costs.

Description: Currently, there has been an obvious lack of innovation within poultry houses heating, ventilation and air conditioning (HVAC) system design that deals with both energy efficiency and poultry welfare issues. This paper presents an innovative and renewable heating system for poultry house application to meet the welfare living environment requirement for breeding, to improve the energy efficiency of HVAC system and to decrease fossil fuel consumption and harmful gas emissions. The purpose of this study is to design, develop and test the highly efficient hybrid heating system via an integrated photovoltaic/thermal array with polyethylene heat exchanger coupled to geothermal heat pump system based on the East Midlands’ climate conditions in the UK. The numerical model is established based on finite volume method and solved by using Engineering Equation Solver, and a good agreement with less than 15% difference between the numerical and experimental results is achieved. The results indicate that the annual electrical and thermal output are 11867 kWh and 30245 kWh, respectively, which not only could fulfil the poultry house electrical need, but also can provide ~43.5% electricity demand of the heat pump compressor operating.

Description: The purpose of this paper is to present a case study of the latest practice on urban sustainability in China, focusing on the breakdown of city-wide overall indicators to a more controllable spatial level—i.e. individual land plots and individual buildings. We argue the importance of decomposing the indicators to smaller scales by understanding underlying principles such as indicators and their integration in the process of urban governance, i.e. enhancing multi-level policy coordination as an important and effective approach for developing eco-cities. This can provide a common ground of argument to monitor the progress at multiple spatial levels and form a collective effort to move a city towards sustainability. The novelty of this study is to highlight the role of eco-city development at multiple spatial levels and through urban governance. The local government needs to mobilize various stakeholders involved in the urban development process by providing sustainability targets in a transparent way. A collective effort from various stakeholder groups might be formed by linking them to a set of unified but spatial level-based targets.

Description: Human comfort and healthy environments lie at the core of every debate about outdoor spaces nowadays. Thermal comfort is a vital concern for planners and designers in order to produce a healthy and thermally comfortable environment, since the influence of different climates and user groups has been found to greatly alter the range of responses for thermal comfort calculations. This requires Post-Occupancy Evaluation (POE) with an integration of the appropriate outdoor thermal comfort (OTC) index. This paper presents the results of a detailed assessment for the OTC in hot arid zone (HAZ) using the most suitable thermal index. A case study was selected from Effat Campus, Jeddah, Saudi Arabia, to represent the HAZ. Subjective assessment employed the physiological equivalent temperature (PET) and the predictive mean vote (PMV) thermal indices in analysing the results of online and self-directed questionnaires while objective assessment employed a hand-held anemometer that was used to measure wind speed, whereas the wet bulb globe temperature (WBGT) SD Card Logger with a black globe thermometer 75 mm in diameter and emissivity of 0.95 was used to measure the globe temperature. The physical measurements were later used to calculate the mean radiant temperature (MRT) and consequently the PET index using RayMan Software. The results confirmed the significance of the shading strategy on OTC. The study revealed that there is no percentage as shading is permitting people to use the space; otherwise, in hot arid zone, the space would be completely unusable under the sun while the PET is more suitable than the PMV index.

Description: In this paper, a novel photovoltaic/thermal system using micro-channel flat loop heat pipe (PV/T-MCFLHP) is proposed, and the thermal and electrical performance of the system is investigated theoretically and experimentally. The variations of temperatures were analysed, and the efficiency of the system was calculated under different conditions, i.e. simulated solar radiation, water flow rate and refrigerant filling ratio. The maximum overall efficiency of the system was found to be 51.3%, the thermal efficiency 43.8% and the electrical efficiency 7.5% with the refrigerant filling ratio of 25%, simulated solar radiation of 800 W/m2 and water flow rate of 400 L/h. Test results were compared with simulation results, and the recorded average error was 10.2%.

Description: The traditional treatment of coal-gasification wastewater produces high solvent and operation cost, secondary pollution and long processing cycle. The aim of the paper was to attempt an alternative approach of wastewater treatment in coal gasification process. With wastewater being heated and sprayed into the gasifier, water participates in the water–gas shift reaction; meanwhile, organic constituents in wastewater are thermally degraded in specific conditions. In the study, thermal degradation and kinetic analysis of COD and NH3-N from Lurgi coal-gasification wastewater were conducted experimentally. The results showed that COD degradation can be divided into three reaction regions: 200–600, 600–1000 and 1000–1200°C. Also, NH3-N degradation can be divided as 200–400, 400–800 and 800–1200°C. The reaction temperature, oxygen concentration and reaction residence time can improve organic constituents’ degradation rate. The COD and NH3-N degradation rate ranks in the order oxidative 〉 inert 〉 reductive. It is because increasing oxygen concentration indicates more free radical generation and aromatic hydrocarbon polymerization was weakened. In addition, NO conversion with NH3 occurs within a narrow temperature window (800–1000°C). Thus, NO concentration reached the peak 230 mg/m3 at 800°C and then reduced with the increase in reaction temperature. Furthermore, a pseudo-first-order reaction model was implemented to analyse the kinetics of COD and NH3-N degradation rate. The results of the present study indicate that the proposed wastewater treatment is feasible and can be preferable reference for further practical application.

Description: Air conditioning is of the most energy saving potential system in the metro station. This study analyzes the composition and characteristics of air conditioning cooling load in a metro station. The hourly distribution and the proportion of each cooling load are calculated. The results show that cooling load fluctuation of metro air conditioning is large, and the operating time of different load varies greatly. According to the air conditioning cooling load, the coefficient of performance of the fixed frequency screw, variable frequency screw, series countercurrent screw and magnetic bearing centrifugal chiller under the load of 20–100% are tested. The annual operating cost of four chillers is compared. Test results show that the magnetic bearing centrifugal chiller has a much higher coefficient of performance at part load and lower annual operating cost. Increased initial investment can be recovered in less than 2 years. The magnetic bearing centrifugal chiller is suitable as a cold source of air conditioning system in the metro station.

Description: Coupled heat and mass transfer performance of an adiabatic solar-powered liquid desiccant dehumidification and regeneration scheme using lithium bromide(LiBr) solution has been conducted experimentally as well as numerically under subtropical climatic conditions. The application of a vacuum insulated photovoltaic and thermal module to provide desiccant regeneration heat as well as electrical power to drive the air fans and liquid pumps have been explored. A square channelled ceramic cordierite packing with a varying channel density of 20–80 m$^2$/m$^3$ has been used to establish the optimum direct air-LiBr contact ratio for maximum effectiveness. The aggregate crammed vertical dehumidifier and regenerator operational indices featured were effectiveness, moisture removal rate (MRR), heat and mass transfer constants and Lewis number. The influence of solar radiation, humidity and L/G ratios, air–desiccant flow rates and concentration on the indices have been scrutinized in details. A 3D predictive numerical thermal model based on falling liquid stream with constant thickness in counter-flow configuration has been developed and solved by a combination of separative appraisal and stepwise iterative technique. The heat and mass exchange coefficients significantly increased with the increase in Lewis number, air and desiccant flow rates for both the dehumidifier and regenerator vessels. The predicted results of heat and mass transfer coefficients, effectiveness and MRRs have been validated with experimental measurements within a general acceptable conformity of less than $pm $10%.

Description: In the energy performance contracting (EPC) mode, the energy services company (ESCO) involved in energy efficiency retrofitting of existing buildings often faces the parallel construction of multiple tender segments and multi-professional subcontractors. The one-to-many structure for ESCO and subcontractors causes difficulties to the project quality management and directly affects the effect of energy efficiency retrofitting of existing buildings. Therefore, this paper constructs a revenue-sharing incentive model by considering situation where subjects have fairness cognition. Through the social calculation experiment of the model, results show the following: (1) increasing the revenue-sharing coefficient will help to optimize the engineering quality of energy efficiency retrofitting and increase the energy-saving income; (2) in order to get better incentive effect, the engineering quality grade of energy efficiency retrofitting should match with the incentive strength; (3) because of the impact of fairness cognition, the incentive level difference is too large, and the incentive effect will gradually weaken in the subsequent incentive cycle; (4) subcontractor’s effort level changes can prompt ESCO to adjust the corresponding incentive intensity. Finally, some suggestions are put forward to optimize the engineering quality management of energy efficiency retrofitting of existing building, which is of great significance to improve the effect of energy efficiency retrofitting of existing building under EPC mode.

Description: This paper investigates a novel micro-channel flat separated loop heat pipe system for cooling the information technology equipment in the data centres through theoretical and experimental analysis and by assessing the impact of the inlet water temperature on system performance. A computer model is developed to simulate the steady-state performance of the micro-channel flat separated loop heat pipe system. After comparing the experimental and modelling results, the new and conventional system under the same working conditions, the model is validated yielding high accuracy in predicting the performance of the micro-channel flat separated loop heat pipe system with recorded error being limited to 2.16–8.97%. The new system has better performance than the conventional system. Under the operating conditions of heat load intensity of 1,000 W/m2, water flow rate of 0.28 m3/h, refrigerant filling rate of 30%, ambient air temperature of 26°C, and evaporator and condenser height difference of 0.8 m, the performance of the system has been explored at inlet temperature from 15 to 24°C with increments of 3°C. The system’s averaged heat transfer efficiency was found to decrease with the increase in inlet temperature. This research provides valuable insight into the data centre information technology equipment cooling, which is of great significance for energy saving and environmentally friendly operation of data centres.

Description: In order to eliminate the difference of the state of charge (SOC) among parallel battery energy storage systems, an optimization method of power distribution based on available capacity is proposed in this paper. The objective function and constraints are established to realize the optimal power allocation of battery energy storage and to improve the stability of the energy storage system. The simulation and experimental results are presented. The results have proved the corrective and effective of the method.

Description: At present, the environmental quality of urban regions and outdoor spaces has turn out to be one of the main issues facing both climatologists and designers, which could be identified through their research outcomes. It is argued that the urban configuration affects the micro-climate of the urban outdoor spaces. The street’s orientation form was identified as an element, which impacts the urban environment with regards of receiving passive solar, solar radiation and reflection against urban absorption, wind flow and the possible urban cooling techniques. The key purpose of this study is to look into the urban configuration factors affecting the human thermal outdoor comfort in Jeddah city as an example of hot humid climate regions. To accomplish its aim, the research is divided to two sections. The first one illustrates the problem of the research, then generally reviews the literature associated with the outdoor human thermal comfort; in addition, it discusses the relationship between street orientation and micro-climate. The second section highlight the assessments carried out between four different orientations of urban streets from two different districts in Jeddah city, using ENVI-met software. The research adopts three environmental variables to be examined, namely air temperature, wind speed, relative humidity together with pedestrian thermal comfort as indicators for predicted mean vote, during summer and winter seasons. The outcomes of the comparison assist to identify decisions related street networks to achieve the desirable human outdoor thermal comfort in such an urban environment.

Description: Due to the low boiling point of organic fluids, the organic Rankine cycle (ORC) is an effective way to improve the recovery efficiency of low-temperature waste heat. An ORC power plant was established with an actual generating capacity of 16.3 kW. As the ORC technology is in the initial stage of commercial application, a technical and economic analysis has been conducted in this paper. Through analysis of each part investment of the power generation plant, it is found that the ORC system part accounts for 61% of the total initial investment, and the larger the power generation scale, the larger the proportion. An economic model has been proposed to study the economic feasibility of low-temperature industrial waste heat conversion in this plant. The influences of the installation of cooling water system, preheater, superheater, loan ratio, interest rate on electricity production cost (EPC) and profit are analyzed. According to the analysis, the lowest EPC of the plant is 0.46 Yuan/(kW • h).

Description: Continuous application of biodiesel as an alternative fuel for compression ignition (CI) engines has necessitated the need to unearth an optimal mix to enhance engine performance and mitigated emissions. This particular work employed a numerical approach to solve linear equations generated for biodiesel properties using fatty acid (FA) composition for the determination of an optimal fatty acid methyl ester (FAME) candidate. Transesterification of waste vegetable oil employed to experimentally produce the FAME candidate generated through numerical intervention. The gas chromatography-mass spectrometer analysis of the resulting FAME revealed that the type of used vegetable oil, the food the oil was used to fry and catalyst particle size influenced the FA composition of the FAME. Numerical evaluation of the objective function and the constraints yielded a FAME candidate with palmitic and oleic acids at 36.4% and 59.8%, respectively. The outcome of this research indicates that two FA compositions are enough to describe optimized FAME candidate for better engine performance and reduced emissions of an unmodified CI engine.

Description: For reducing the inconsistent state of charges (SOC) of lithium-ion battery cells and making the full use of battery packs, effective battery balancing technology should be used. In order to achieve the goal of balancing any single cell in the battery pack expediently and considering the cost and the balance efficiency, a balanced circuit is proposed. By changing the action state of single-pole double-throw relay connected to each of the single cell battery, the balanced single-cell battery is in a state of non-load power supply, at this point, the balanced battery is in `charging’ state compared with other batteries in the battery pack, thus achieving the balance target of the battery pack. On this basis, this paper also proposes a new balancing control strategy; it is different from the traditional control strategy to balance the SOC of the single cell to the SOC average of the battery pack, considering the different SOC change rates of the cells with different capacity in the battery pack. The balanced control strategy proposed in this paper allows the set condition of the single cell to end the equilibrium process in advance so as to reduce the unnecessary balance time and then improve the equilibrium speed. In order to verify the feasibility of the proposed circuit and control strategy, 18 650 batteries with different initial SOC in series are experimentally verified. The experimental results show that the balanced circuit proposed in this paper can well balance the cell of each single cell and make the battery pack reach a balanced state.

Description: This study assessed through numerical simulations, the technical feasibility of a solar-powered absorption cooling system for a small-scale application in an office building in three different cities with a tropical climate in Ecuador. The model and simulations were performed using the dynamic transient software TRNSYS and were compared and validated using experimental data obtained from a real-life system with main components: 12 m2 vacuum tube solar thermal collector array, a 4.5 kW LiBr/H2O single-effect absorption chiller, a 6 kW fan coil and a 100 l sensible cold store. The results of the simulation showed a good agreement with the experimental data with a deviation of 8.5%. The validated model was used to undertake a parametric study to determine capacities of systems that will be applicable to three Ecuadorian cities: Guayaquil, Manta and San Cristobal. The system capacity predicted by the model for the Ecuadorian cities has the following components: 24 m2 evacuated tube collector field, a 20 kW heat exchanger, a 15 kW single-stage LiBr/H2O absorption chiller, a 35 kW cooling tower and a cold storage tank of 2 m3. The results showed that the proposed system could meet most of the required cooling load (90% for Guayaquil and San Cristobal, and 71% for Manta, considering a set point of 24°C) of a typical single-story office building with.

Description: The brake system of an automobile is composed of disc brake and pad which are co-working components in braking and accelerating. In the braking period, due to friction between the surface of the disc and pad, the thermal heat is generated. It should be avoided to reach elevated temperatures in disc and pad. It is focused on different disc materials that are gray cast iron and carbon ceramics, whereas pad is made up of a composite material. In this study, the CFD model of the brake system is analyzed to get a realistic approach in the amount of transferred heat. The amount of produced heat can be affected by some parameters such as velocity and friction coefficient. The results show that surface temperature for carbon-ceramic disc material can change between 290 and 650 K according to the friction coefficient and velocity in transient mode. Also, if the disc material gray cast iron is selected, it can change between 295 and 500 K. It is claimed that the amount of dissipated heat depends on the different heat transfer coefficient of gray cast iron and carbon ceramics.

Description: The construction of high-rise buildings has attracted human attention at the beginning of human civilizations’ formation. Presently, making tall buildings is considered as a necessary requirement due to the succeeding reasons: the population increase, the tendency to live in urban centers, the land utilization in the most populated centers of the cities, the need to decrease the cost of horizontal development of cities and technological advances. During the last century, issues related to environmental pollution and high energy use have affected these tall buildings. So, it is crucial to apply appropriate methods and patterns in order to adjust their environmental impacts as much as possible. In addition, the building industry accounts for a significant amount of energy consumption in the world. Therefore, energy-saving and efficiency can be mentioned as a significant issue due to the limitation of fossil resources. The importance of this issue has been increased by eliminating subsidies and realizing the price of fuels in Iran. Efforts in the field of high-rise buildings in Iran are chiefly based on general criteria regarding the location and characteristics of urban imagery and the field of urban design knowledge. The efforts contributed to the energy consumption have not been carried out. The present study provides patterns for the aim of designing high-rise buildings with official use in Tabriz and Yazd. The solutions for the opening design of tall buildings with regular forms to reduce energy consumption are proposed in this study.

Description: The analysis of carbon footprint plays an important role in the management of tourism scenic spots. This paper first introduced the calculation method of carbon footprint and ecological efficiency value of tourism scenic spots, then analyzed the general situation of tourism scenic spots in Jiangsu province and collected the data of 2013–17 to calculate the carbon footprint and ecological efficiency value. The results showed that the carbon footprint of tourism scenic spots in Jiangsu province was increasing year by year, of which the traffic carbon footprint accounted for the largest proportion, 60%. The value of ecological benefits of accommodation was the largest, followed by catering, activities and transportation, and accommodation created the highest economic benefits. According to the calculation results, some suggestions were put forward for the ecological efficiency management of tourism scenic spots in Jiangsu province, which is conducive to the better development of tourism scenic spots.

Description: This study aims to investigate the thermal properties of a phase change material (PCM) based on coconut oil for building energy storage applications. Coconut oil is classified as an organic PCM composed of fatty acids made from renewable feedstock. However, low thermal conductivity is one of the major drawbacks of organic PCMs that must be improved. Graphene could be an effective material to enhance the thermal performance of organic PCMs. In this study, coconut oil with a latent heat capacity of 114.6 J/g and a melting point of 17.38°C was used. PCMs were prepared by sonicating graphene into coconut oil, as a supporting material. The mass fractions of the prepared PCMs were 0, 0.1, 0.2, 0.3, 0.4 and 0.5. Thermal conductivity tests were performed using a KD2 thermal property analyser under different ambient temperatures of 5, 10, 15, 20 and 25°C simulated with a circulating thermostatic bath. The latent heat, melting point and freezing point were determined through differential scanning calorimetry, the thermal stability was determined using thermogravimetric analysis (TGA) and the morphology and chemical structure were examined using transmission electron microscopy and Fourier-transform infrared spectroscopy, respectively. The results of this study showed that graphene addition to coconut oil improved the thermal performance, with the highest improvement seen in a 0.3 wt% sample at 20°C. The latent heat decreased by 11% owing to molecular movements within the PCM. However, TGA revealed that the composite PCMs showed good thermal stability in ambient building temperature ranges.

Description: To reduce the efficiency reduction caused by non-uniformity of illumination, a dense-array module with non-uniform sizing of photovoltaic (PV) cells is proposed for dish-type concentrating PV systems. The non-uniform-sized dense-array module has been designed and analyzed theoretically at the ideal irradiance of Gaussian distribution, which consists of 48 silicone solar cells. Using the ZEMAX optical simulation software, the realistic distribution of the Gaussian-like facula on the PV module has been modelled in a dish-type concentrator system. The experiments are done under the conditions of different alignments to imitate the different two-axis tracking accuracy with or without a homogenizer. Besides, the performances of dense-array modules with the classical uniform-sized and the proposed non-uniform-sized PV cells are analyzed under various illumination distributions using ZEMAX, respectively. Results show that when the deviation angle of tracking is 0, 0.02, 0.2, the photoelectric conversion efficiency and output power of the proposed non-uniform size dense-array module considerably exceeds the traditional uniform size module. Furthermore, when the tracking deviation angle is no more than 0.02°, it is a very definite possibility that the dish-type concentrator system with non-uniform-sized dense-array module need not a homogenizer as a secondary optical element, which may hence simplify the system structure.

Description: In this paper, a comprehensive technical review of liquid desiccant (LD) dehumidification and regeneration techniques is presented. The operational features, processes and performance indices of various flow configurations of adiabatic dehumidifier and regenerator are extensively covered. The heat and mass transfer assessment is presented in terms of past experimental and modelling evaluations and procedures. The existing adiabatic dehumidifier/regenerator heat and mass transfer models are categorized into finite difference, effectiveness-number of transfer units and simple empirical correlation models. The respective performance prediction models are critically analysed in details and compared in terms of assumptions, iterative procedures, solution methods, accuracy, computation time, output variables and applications. The solar regenerator models are also highlighted with a focus on the collector module. The ideal settings, formulation procedures, current state-of-the-art and opportunities for improvements are outlined. The review provides meaningful insight into the research status and available opportunities in the LD adiabatic dehumidifier and regenerator modelling and optimization as well as conceptualization of the applicable models. Finally, some very impactful suggestions for improvement and further research are outlined.

Description: The battery charging process has nonlinear and hysteresis properties. PID (Proportion Integration Differentiation) control is a conventional control method used in the battery charging process. The control effect is determined by the PID control parameters ${K}_p$,${K}_i$and${K}_d$. The traditional PID parameter setting method is difficult to give the appropriate parameters, which affects the battery charging efficiency. In this paper, the particle swarm optimization (PSO) is used to optimize the PID parameters. Aiming at the defects of basic PSO, such as slow convergence speed, low convergence precision and easy to be premature, a modified particle swarm optimization algorithm is proposed, and the optimized PID parameters are applied to the battery charging control system. Also, the experimental results show that the battery charging process possesses better dynamic performance and the charging efficiency of the battery has increased from 86.44% to 91.47%, and the charging temperature rise has dropped by 1°C.

Description: Reports by the US Department of Energy in 2014 evaluated membrane heat pump technology as one of the most promising alternatives to conventional vapour compression methods. Vapour compression methods maintain an evaporator temperature lower than the dew point to deal with the latent heat load. In membrane heat pump systems, only the water vapour is transferred and there is no phase change. The migration is caused by the difference in vapour pressure before and after the membrane. A vacuum pump or blower is used to create the pressure difference. However, there is no methodology for predicting dehumidification performance of membranes when used as part of a cooling system. In this study, using the assumption that there is a similarity between heat transfer and moisture pervaporation, the performance indices of the membrane are derived using a well-known heat exchanger method, the ε-NTU models. Performance estimations are calculated for two representative system layouts: bypass and vacuum. Simple relations between design parameters are suggested, giving design guidelines for researchers.

Description: How can command-and-control instruments (CACs) influence consumers’ adoption of energy consumption monitoring technology (ECMT) in public buildings? We attempt to answer this question in an extended theory of planned behaviour in which CACs and energy-saving awareness (ESA) are introduced. Empirical data are collected by a questionnaire survey with 298 respondents, and structural equation modelling (SEM) is used to analyse the research model. The results indicate that ESA has a direct impact on consumers’ adoption of ECMT. The CACs have no direct effect on consumers’ adoption of ECMT but can indirectly affect consumers’ adoption of ECMT through three paths: CAC → ATT (attitudes) → BI (behavioural intention), CAC → ESA → BI and CAC → SN (subjective norm) → BI. Finally, suggestions are proposed, such as optimising the selection and combination of policy instruments, promoting the operation manager’s attitude towards ECMT to a more positive orientation, improving the ESA of the operation manager and providing more support for and pressure on the operation manager who has not adopted ECMT.