ALBERT

Description: This installment of Computer's series highlighting the work published in IEEE Computer Society journals comes from IEEE Transactions on Visualization and Computer Graphics. The Web extra at http://youtu.be/E1PVTitj7h0 is a video demonstration of a novel solution to multivariate data visualization that helps users interactively explore data by combining standard presentations, from detailed views to high-level overviews.

Description: The data rearrangement engine (DRE) performs in-memory data restructuring to accelerate irregular, data-intensive applications. An emulation on a field-programmable gate array shows how the DRE could improve speedup, memory bandwidth, and energy consumption on three representative benchmarks.

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Description: License plate recognition is a computer vision method that identifies vehicles from their license plates. The most crucial step of such a system is accurate localization of the plate. The authors propose a system for automatic recognition that has three phases: image capture, plate localization, and license plate number recognition. They tested their methodology on 40 different car models with different types of license plates.

Description: A proposed property-aware name service simultaneously supports what, where, and when properties of each IoT object through unique, text-based, and human-readable identity assignments.

Description: Since its inception, the Internet has been a complex landscape for developers as well as users to negotiate. The new ISO/IEC/IEEE 23026 standard seeks to improve websites' usability and information content and simplify Web service management and maintenance activities.

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Description: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Description: IEEE president-elect candidates address Computer Society concerns.

Description: Events of interest to Computer Society members.

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Description: Although you can't see something that isn't there, you can perceive the powerful effects of its nonexistence. The Web extra at http://youtu.be/vahyX-lM9AI is an audio recording of author David Alan Grier expanding on his Errant Hashtag column, in which he talks about the lack of connection that can exist between two people or organizations.

Description: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Description: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Description: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Description: Irregular applications present unpredictable memory-access patterns, data-dependent control flow, and fine-grained data transfers. Only a holistic view spanning all layers of the hardware and software stack can provide effective solutions to address these challenges.

Description: Computer scientist Anil Jain discusses the evolution of the biometric recognition field. The first Web extra at http://youtu.be/Wb_JbpdFoz4 is a video in which Anil Jain talks with Charles Severance about the evolution of the biometric recognition field. The second Web extra at http://youtu.be/_NdKzKybyQ4 is an audio recording in which author Charles Severance reads his Computing Conversations column that discusses his interview with Anil Jain about the evolution of the biometric recognition field.

Description: A summary of articles recently published in IEEE Computer Society periodicals.

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Description: Emerging data-intensive applications attempt to process and provide insight into vast amounts of online data. A new class of linear algebra algorithms can efficiently execute sparse matrix-matrix and matrix-vector multiplications on large-scale, shared memory multiprocessor systems, enabling analysts to more easily discern meaningful data relationships, such as those in social networks.

Description: Work on human self-awareness is the basis for a framework to develop computational systems that can adaptively manage complex dynamic tradeoffs at runtime. An architectural case study in cloud computing illustrates the framework's potential benefits.

Description: Executing irregular, data-intensive workloads on multithreaded architectures can result in performance losses and scalability problems. Codesigning algorithms and architectures can realize high performance on irregular applications. A codesign study reveals four key lessons learned from implementing matching algorithms on various platforms

Description: The acronym TSA could just as well stand for "tactics to suppress accountability." It's an object lesson in the misuse of technology toward ill-defined ends.

Description: A summary of articles published in Computer 32 and 16 years ago.

Description: Students at the University of Brasília set out to build a better exercise bike. The Web extra at http://youtu.be/NCSb_sDJL7c is a video demonstration of the Bike-X simulator, a virtual cycling experience designed by engineering students at the University of Brasília's Gama Campus.

Description: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Description: The Galois system can automatically parallelize irregular algorithms written in a serial programming model and execute them efficiently on nonuniform memory access (NUMA) machines. Experimental results for five complex irregular algorithms show that the system scales up to 420× on large NUMA systems at 512 threads.

Description: The authors discuss important factors to consider when migrating software to the cloud and offer recommendations to maximize the chance of success.

Description: John Resig discusses the birth of the JavaScript library jQuery and how it came to play a key role in the browser software ecosystem. The first Web extra at http://youtu.be/B7Aut4OUuvs is a video in which jQuery creator John Resig talks with Charles Severance about the birth of the JavaScript library jQuery and how it came to play a key role in the browser software ecosystem. The second Web extra at http://youtu.be/ZRxcFzSqatE is an audio recording of the Computing Conversations column in which Charles Severance discusses his interview with John Resig about the JavaScript library jQuery and how it came to play a key role in the browser software ecosystem.

Description: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Description: Numerical dynamic range analysis combines with architectural simulation to help designers explore algorithmic and architectural tradeoffs that can meet embedded computer vision's demand for precision and high-memory bandwidth.

Description: Students share their impressions of and experiences working with science fiction prototyping at the California College of the Arts. The Web extra at http://youtu.be/c4uYbiH72sI is an audio interview in which Science Fiction Prototyping editor Brian David Johnson talks with California College of the Arts student Gregory Stock about his experience with science fiction prototyping and how it's like exploring dark caves. The second Web extra at http://youtu.be/6XudNL3Cqwo is an audio interview in which editor Brian David Johnson speaks with Leticia Murray, Alida Draudt, and Julia Rose West about their personal experiences working with science fiction prototyping at California College of the Arts. The third Web extra at http://youtu.be/VoJLDiCzH-o is an audio interview in which Science Fiction Prototyping editor Brian David Johnson speaks with California College of the Arts student Jonjozuf Hadley about how science fiction prototyping can give you the space and permission to explore possible futures. The final Web extra at http://youtu.be/xB3RBNT20LM is an audio interview in which Science Fiction Prototyping editor Brian David Johnson speaks with California College of the Arts student Ryan Hogan about one of the most important parts of science fiction prototyping the science fiction.

Description: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Description: Evolving from hybrid clouds to true cloud federations and, ultimately, fog computing will require that cloud platforms allow for--and embrace--local hardware awareness.

Description: The Lunar Atmosphere Dust Environment Explorer (LADEE) software developers incorporated IEEE and other standards to achieve high reliability while adhering to strict budget and schedule guidelines.

Description: Although GitHub has become a great tool for studying the software development process, it poses afundamental problem to those who study work. The Web extra at http://youtu.be/z7aiYedJr8w is an audio recording of author David Alan Grier expanding on his Errant Hashtag column, in which he talks about how GitHub has become a great tool for studying the software development process but poses a fundamental problem to those who study work.

Description: Several intellectual property cases this year raise important patent, copyright, and trademark legal questions--the second part of this two-part series focuses on the trademarkand copyright cases. Part 1 is in the April 2015 issue at 10.1109/MC.2015.112. The Web extra at http://youtu.be/3atq5VwO874 is an audio recording of Brian M. Gaff reading the second installment of a two-part series in his Computing and the Law column, in which he discusses several 2015 intellectual property cases that raise important patent, copyright, and trademark law issues.

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Description: To expand e-commerce, we shouldn't try to fit computing technology into markets, but instead fit markets into technology. The Web extra at http://youtu.be/siTGPpNabHI is an audio recording of author David Alan Grier expanding on his Errant Hashtag column, in which he talks about the disruptive nature of computing and how expanding e-commerce shouldn't mean trying to fit computing technology into markets but instead fitting markets into technology.

Description: An online inference engine monitors and extracts usage cues from wearables and identifies whether the user is busy, alone, happy, or stressed. Experiments show 85 percent identification accuracy with negligible energy cost.

Description: This installment of Computer's series highlighting the work published in IEEE Computer Society journals comes from IEEE Transactions on Mobile Computing.

Description: A summary of articles recently published in IEEE Computer Society periodicals.

Description: An exploration of current discrimination law reveals new opportunities for promoting the public use of wearable assistive technologies, which can be a powerful impetus for both wearable advocates and researchers exploring design alternatives.

Description: Three playful wearable accessories incorporate design principles that promote individuality, natural interaction, ubiquity, and intimacy to encourage spontaneous open-ended social interaction in school-age children. The Web extra at https://youtu.be/LBBe8iDeFrs demonstrates Wearable Sound, an accessory that transforms your movements into sounds. You can play the sound of a bird by moving your arms, the sound of bubbles while walking, or create your personal combination. You only have to wear the sensor, choose a sound, and use all your creativity to play!

Description: A proposed method evaluates eight popular software reliability growth models and selects the one that can best predict the software's remaining faults, providing practical support for project managers who are considering an open source component.

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Description: A student team from NC State designed and built a prototype wireless network to monitor the milking and weighing of cows.

Description: One of the most fundamentally misguided ways to protect a networked infrastructure is to introduce an air gap. The US has been mastering the art of crossing them for more than 30 years.

Description: Vetting a mobile app vendor's processes via a questionnaire is a poor substitute for vetting the app itself, but situations often arise when it's the only or most practical option.

Description: Realizing the full potential of virtualized computation-the cloud-requires rethinking software development. Deployment decisions, and their validation, can and should be moved up the development chain into the design phase.

Description: News of interest to Computer Society members.

Description: Information about upcoming events of interest to Computer Society members.

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Description: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Description: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Description: This installment of Computer's series highlighting the work published in IEEE Computer Society journals comes from IEEE Transactions on Pattern Analysis and Machine Intelligence.

Description: A summary of articles published in Computer 32 and 16 years ago.

Description: Distributed smart cameras exploit smartphone processor performance in their node communication and video metadata exchange, allowing the network to collectively reason in interpreting the scene, generating alerts, and making decisions.

Description: Secure delivery networks can help prevent or mitigate the most common attacks against mission-critical websites. A case study from a leading provider of content delivery services illustrates one such network's operation and effectiveness. The Web extra at https://youtu.be/4FRRI0aJLQM is an overview of the evolving threat landscape with Akamai Director of Web Security Solutions Product Marketing, Dan Shugrue. Dan also shares how Akamai's Kona Site Defender service handles the increasing frequency, volume and sophistication of Web attacks with a unique architecture that is always on and doesn't degrade performance.

Description: A student team from NC State has designed a collar to help control wild elephants that threaten human property and life in Africa and Asia. The Web extra at https://youtu.be/aQV_BkOL4vA is a video showing how students from North Carolina State University designed a collar to keep elephants away from farms and villages. In this field test in South Africa, a buzzing sound from the collar causes an elephant to turn away from the protected area. Video by Emma Besaw. The second Web extra at http://youtu.be/ap1dSwCc6fY is a video in which editor Greg Byrd introduces the new Student Design Showcase column, dedicated to innovative, interesting student projects from computer science and engineering.

Description: In 2011, the US government asked for game-changing research that would fundamentally improve the security, safety, and trustworthiness of the national digital infrastructure. Agencies have responded with novel ideas, from moving target management to tailored trustworthy spaces. The Web extra at https://youtu.be/ZdUDIDolCM4 is a video of Vint Cerf introducing the Honorable Al Gore, 45th Vice President of the United States, who provides the 5 July 2013 keynote for The Impact of NITRD: Two Decades of Game-Changing Breakthroughs in Networking and Information Technology Expanding the Possibilities Ahead. The second Web extra at https://youtu.be/UAVG6mrRs9Q is a video of the NITRD program's panel on Cybersecurity and Cyber-Physical Systems at the 2014 IEEE Symposium on Security and Privacy. Panelists from DHS, NIST, NSF, SRI International, and the University of Connecticut discuss cybersecurity challenges of CPS and prospective research directions for solving those challenges. The third Web extra at https://youtu.be/fzkAtfx6W-g is a video of the NITRD program's panel on Cybersecurity and Cyber-Physical Systems at the 2013 IEEE Symposium on Security and Privacy. The panel comprised Betsy Masiello of Google, Karyn Higa-Smith of the DHS S&T Cyber Security Division, Deirdre Mulligan of the UC Berkeley School of Information, Daniel Weitzner of MIT CSAIL, Vijayalakshmi (Vijay) Atluri of NSF/SaTC, Joan Feigenbaum of Yale University, and Jeannette Wing of Microsoft Research International.

Description: Researchers are making secure multiparty computation--a cryptographic technique that enables information sharing and analysis while keeping sensitive inputs secret--faster and easier to use for application software developers.

Description: Information about upcoming events of interest to Computer Society members.

Description: A two-year study of eight pilot projects to introduce combinatorial testing in a large aerospace corporation found that the new methods were practical, significantly lowered development costs, and improved test coverage by 20 to 50 percent.

Description: As we have done with so many technical systems, we tend to think about functionality first and consider security problems only as an afterthought. The Web extra at http://youtu.be/KXMFLzJq_Bg is an audio recording of author David Alan Grier expanding on his Errant Hashtag column, in which he talks about how we tend to think about functionality first and consider security problems only as an afterthought.

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Description: Ever wondered why really inept executives seem to collect like lint at the top of modern organizations? I have an explanation for your consideration.

Description: Computer Society president Thomas M. Conte looks back on his year in office.

Description: This installment of Computer's series highlighting the work published in IEEE Computer Society journals comes from IEEE Transactions on Software Engineering.

Description: Integrating software developed by third-party organizations into a larger system raises concerns about the software's quality, origin, functionality, security, and interoperability. Addressing these concerns requires rethinking the roles of software's principal supply-chain actors--vendor, assessor, and evaluator.

Description: The complexity necessary for robotics software systems to dynamically respond to or handle a variety of evolving scenarios translates into serious development costs and engineering challenges. Dynamic variability is one new strategy for supporting the dynamic behavior of robotics control systems.

Description: Computing is not about physicality--it's about imagination. The Web extra at https://youtu.be/dv-1OsAL6rI is an audio recording of author David Alan Grier expanding on his Errant Hashtag column, in which he talks about how computing is not about physicality--it's about imagination.

Description: Efficiently supporting the communication needs of systems on chip with tens to hundreds of interacting modules requires a systematic and flexible network-on-chip (NoC) infrastructure. The freely available CONNECT generator lets users quickly navigate a range of design parameters to produce tailored NoC design instances in Verilog. To date, it has generated nearly 4,000 designs.

Description: Processing technology has eclipsed memory technology for the past six decades, but processor-centric architectures are reaching their terminal efficiency. We can reboot computing on the basis of abundant memory enabled by emerging device physics, which will make computation, communication, and memory more efficient. This approach also provides a unique opportunity to address novel security threats with modern, systemic solutions.

Description: Information of interest to Computer Society members.

Description: A recent workshop envisions the impacts that information and communications technology advances will have on warfare by 2050 and the challenges these pose for command and control.

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 196〈/p〉 〈p〉Author(s): Zhendong Zhang, Hui Qin, Yongqi Liu, Liqiang Yao, Xiang Yu, Jiantao Lu, Zhiqiang Jiang, Zhongkai Feng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As a renewable and clean energy, wind energy plays an important role in easing the increasingly serious energy crisis. However, due to the strong volatility and randomness of wind speed, large-scale integration of wind energy is limited. Therefore, obtaining reliable high-quality wind speed prediction is of great importance for the planning and application of wind energy. The purpose of this study is to develop a hybrid model for short-term wind speed forecasting and quantifying its uncertainty. In this study, Minimal Gated Memory Network is proposed to reduce the training time without significantly decreasing the prediction accuracy. Furthermore, a new hybrid method combining Quantile Regression and Minimal Gated Memory Network is proposed to predict conditional quantile of wind speed. Afterwards, Kernel Density Estimation method is used to estimate wind speed probabilistic density function according to these conditional quantiles of wind speed. In order to make the model show better performance, Maximal Information Coefficient is used to select the feature variables while Genetic Algorithm is used to obtain optimal feature combinations. Finally, the performance of the proposed model is verified by seven state-of-the-art models through four cases in Inner Mongolia, China from five aspects: point prediction accuracy, interval prediction suitability, probability prediction comprehensive performance, forecast reliability and training time. The experimental results show that the proposed model is able to obtain point prediction results with high accuracy, suitable prediction interval and probability distribution function with strong reliability in a relatively short time on the prediction problems of wind speed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419306958-ga1.jpg" width="159" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 196〈/p〉 〈p〉Author(s): Homa Hosseinzadeh-Bandbafha, Esmail Khalife, Meisam Tabatabaei, Mortaza Aghbashlo, Majid Khanali, Pouya Mohammadi, Taha Roodbar Shojaei, Salman Soltanian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biodiesel utilization is associated with reduced calorific value and increased nitrogen oxides emissions. Hence, various strategies are implemented to address these challenges such as water addition into diesel/biodiesel fuel blends. In line with that, this study was undertaken to explore the effect of water (3 wt.%) and aqueous carbon nanoparticles (38, 75, and 150 µM), as a novel fuel nanoadditive, on combustion and exhaust emissions of a diesel engine at a fixed engine speed of 1000 rev/min under four different engine loads ranging from 25% to 100% of full load conditions. Overall, the engine performance characteristics were improved by incorporating the aqueous carbon nanoparticles. In particular, the incorporation of carbon nanoparticles into water-emulsified biodiesel/diesel blends generally enhanced brake power and thermal efficiency while lowering specific fuel consumption. The most appealing performance features were observed for the emulsified fuel blend containing 38 µM carbon nanoparticles which increased brake power and brake thermal efficiency by 1.07 kW and 11.58% at full load operation, respectively, while it led to decreased brake specific fuel consumption by about 107.3 g/kWh. The addition of carbon nanoparticles to the water-emulsified fuel blends adversely affected unburned hydrocarbons and carbon monoxide emissions at full load conditions owing to an increase in carbon content of the fuel blends but it lowered nitrogen oxides emissions. The addition of water deteriorated the economic features of the fuel blend (i.e., the cost per kWh of power generated). However, carbon nanoparticles addition into the water-emulsified fuel blend partially neutralized the adverse economic effects of water due to its positive impacts on thermal efficiency. Overall, water-emulsified diesel/biodiesel containing 38 µM carbon nanoparticles could be regarded as the most promising emulsion fuel in terms of engine performance characteristics, nitrogen oxides emissions, as well as fuel economy.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 198〈/p〉 〈p〉Author(s): Chukwuka Odibi, Meisam Babaie, Ali Zare, Md. Nurun Nabi, Timothy A. Bodisco, Richard J. Brown〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study uses the first and second laws of thermodynamics to investigate the effect of oxygenated fuels on the quality and quantity of energy in a turbo-charged, common-rail six-cylinder diesel engine. This work was performed using a range of fuel oxygen content based on diesel, waste cooking biodiesel, and a triacetin. The experimental engine performance and emission data was collected at 12 engine operating modes. Energy and exergy parameters were calculated, and results showed that the use of oxygenated fuels can improve the thermal efficiency leading to lower exhaust energy loss. Waste cooking biodiesel (B100) exhibited the lowest exhaust loss fraction and highest thermal efficiency (up to 6% higher than diesel). Considering the exergy analysis, lower exhaust temperatures obtained with oxygenated fuels resulted in lower exhaust exergy loss (down to 80%) and higher exergetic efficiency (up to 10%). Since the investigated fuels were oxygenated, this study used the oxygen ratio (OR) instead of the equivalence ratio to provide a better understanding of the concept. The OR has increased with decreasing engine load and increasing engine speed. Increasing the OR decreased the fuel exergy, exhaust exergy and destruction efficiency. With the use of B100, there was a very high exergy destruction (up to 55%), which was seen to decrease with the addition of triacetin (down to 29%).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Tingting Xu, Feng Xu, Gift Gladson Moyo, Yaya Sun, Zhihua Chen, Bo Xiao, Xun Wang, Zhiquan Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Syngas is an indispensable chemical raw material, which also can provide heat and power. Chemical looping reforming (CLR) with biofuels is one prospective method to produce syngas. M〈sub〉x〈/sub〉O〈sub〉y〈/sub〉 of 20 wt% (CuO, NiO and Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) supported on dolomite were prepared by the wet impregnation method used as the oxygen carriers (OCs) for syngas production in the CLR process with toluene in the lab-scale fixed bed reactor. The effects of the reduced temperature in FR and mass of OCs on the fuel conversion, syngas production and OCs utilization were studied. The study found that CuO/dolomite (CD) tended to generate CO〈sub〉2〈/sub〉, while Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/dolomite (FD) and NiO/dolomite (ND) were appropriate to syngas production. Although CD achieved the highest oxygen effective conversion of 95.90% at 950 °C and the best selectivity for CO〈sub〉2〈/sub〉, it was not a suitable OC for syngas production in CLR process since the cold gas efficiency, syngas yield and syngas purity for CD remained lowest under different reaction conditions. FD manifested the best performance at 900 °C with 30.0 g, exhibiting the highest cold gas efficiency and syngas yield of 54.23% and 1.16 Nm〈sup〉3〈/sup〉/L, and the corresponding syngas purity was 73.86%. The selection of temperature and mass of FD played a key role in the quality control of syngas. Low syngas purity and rapid deactivation in cyclic tests were main barriers for FD to behave as an excellent OC in the CLR process. Furthermore, ND was the most ideal OC of the three for syngas production with the optimum condition being at 900 °C with 20.0 g, the corresponding cold gas efficiency, syngas yield and syngas purity were 39.30%, 0.93 Nm〈sup〉3〈/sup〉/L and 90.59% respectively. ND exhibited the highest syngas purity of the three, and the satisfied H〈sub〉2〈/sub〉/CO ratios (around 2.0) were achieved under different reaction conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Tan Wu, Long Shao, Xinli Wei, Xinling Ma, Guojie Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The ORC (organic Rankine cycle) system has the advantages of simple structure, environmental friendliness, reliability and low capital cost. The expander is the key device of energy conversion in the ORC system, and its performance has a direct influence on that of the ORC. In this paper, a self-designed and manufactured radial inflow turbine is applied to low temperature waste heat power generation. The numerical model for the internal flow of the radial inflow turbine is established, and the numerical results show a better agreement with the experimental data. Firstly, the influence of blade stagger angles on nozzle performance is studied. The study finds that with the decrement of stagger angles under specific angle ranges, the velocity coefficient increases. However, the efficiency of the nozzle decreases sharply when the stagger angle exceeds 30°. Secondly, the influence of the blade profile on the efficiency of the rotor is investigated. The results indicate that with 〈em〉t〈/em〉 increasing, the efficiency of the rotor firstly increases, then decreases quickly. It increases by 1% compared with that of the original rotor, when the 〈em〉t =〈/em〉 1.95. At last, the performance of the turbine is researched numerically. This paper discovers that total-to-static efficiency of the turbine increases by 1.7% compared with that of the original turbine. This research provides orientation and basis for the improvement of aerodynamic design and performance of radial inflow turbine. As for practical application, the study can provide certain reference for the structure and blade profile design of nozzles and rotors to further improve the performance, and to offer some data for the operational control and tests.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 198〈/p〉 〈p〉Author(s): Johanna Beiron, Rubén M. Montañés, Fredrik Normann, Filip Johnsson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As the share of non-dispatchable energy sources in power systems increases, thermal power plants are expected to experience load variations to a greater extent. Waste-fired combined heat and power has multiple products and is today primarily operated for waste incineration and to generate heat. To consider load variations in the power demand at these plants may be a way to provide system services and obtain revenue, however, the transient interaction between power and district heating generation for the type of steam systems used should be studied. This work describes the transient characteristics and timescales of cogeneration steam cycles to discuss the operational interactions between power and district heating generation. A dynamic model of the steam cycle of a 48 MW waste-fired combined heat and power plant is developed using physical equations and the modeling language Modelica. The model is successfully validated quantitatively for both steady-state and transient operation with data from a reference plant and is shown capable of characterizing the internal dynamics of combined heat and power plant processes. Simulations are performed to analyze steam cycle responses to step changes, ramps and sinusoidal disturbances of boiler load changes and variability in district heating inlet temperature and flow. The results give insight on the process timescales for the specific case studied; for example, with the present design a 10% boiler load change requires up to 15 min for responses to settle, while the corresponding time for a 10% change in district heating flow or temperature show settling times within 5 min. Furthermore, increasing the boiler ramp rate from 2 to 4%/min could reduce the rise time of power generation by 42%, which could be of economic significance in day-ahead power markets.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Guang Li, Zheyu Liu, Fan Liu, Bin Yang, Shuqi Ma, Yujing Weng, Yulong Zhang, Yitian Fang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Exergy-based analysis is a powerful method to evaluate, understand, and improve energy conversion processes. Compared with conventional exergy analysis, advanced exergy analysis can identify the improvement potential of each component and the interactions among components of the whole system. In this paper, the ash agglomerating fluidized bed (AFB) gasification process is simulated in Aspen Plus (version 8.0). Based on the simulation results, advanced exergy analysis is carried out to study the performance of the AFB gasification process. The exergy efficiency of the AFB gasification process is 82.13% and the total exergy destruction is 4670 kW. The result shows that 54.18% of the total exergy destruction can be avoided. The AFB gasifier has the largest potential for reducing exergy destruction. In addition, sensitivity analysis is performed to research the effects of carbon conversion, pressure and temperature on the exergy destruction of the AFB gasifier.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Juliano Pierezan, Gabriel Maidl, Eduardo Massashi Yamao, Leandro dos Santos Coelho, Viviana Cocco Mariani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the past decades, the quantity of researches regarding industrial gas turbines (GT) has increased exponentially in terms of number of publications and diversity of applications. The GTs offer high power output along with a high combined cycle efficiency and high fuel flexibility. As consequence, the energy efficiency, the pressure oscillations, the pollutant emissions and the fault diagnosis have become some of the recent concerns related to this type of equipment. In order to solve these GTs related problems and many other real-world engineering and industry 4.0 issues, a set of new technological approaches have been tested, such as the combination of Artificial Neural Networks (ANN) and metaheuristics for global optimization. In this paper, the recently proposed metaheuristic denoted Coyote Optimization Algorithm (COA) is applied to the operation optimization of a heavy duty gas turbine placed in Brazil and used in power generation. The global goal is to find the best valves setup to reduce the fuel consumption while coping with environmental and physical constraints from its operation. In order to treat it as an optimization problem, an integrated simulation model is implemented from original data-driven models and others previously proposed in literature. Moreover, a new version of the COA that links some concepts from Cultural Algorithms (CA) is proposed, which is validated under a set of benchmarks functions from the Institute of Electrical and Electronics Engineers (IEEE) Congress on Evolutionary Computation (CEC) 2017 and tested to the GT problem. The results show that the proposed Cultural Coyote Optimization Algorithm (CCOA) outperforms its counterpart for benchmark functions. Further, non-parametric statistical significance tests prove that the CCOA’s performance is competitive when compared to other state-of-the-art metaheuristics after a set of experiments for five case studies. In addition, the convergence analysis shows that the cultural mechanism employed in the CCOA has improved the COA balance between exploration and exploitation. As a result, the CCOA can improve the current GT operation significantly, reducing the fuel consumption up to 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si94.svg"〉〈mrow〉〈mn〉3.6〈/mn〉〈mo〉%〈/mo〉〈/mrow〉〈/math〉 meanwhile all constraints are accomplished.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Wei Liu, Cheng Chen, Huijuan Wu, Chunhui Guo, Yuedong Chen, Wenqiu Liu, Zhaojie Cui〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, a cradle-to-grave life cycle assessment was conducted on several typical domestic hot water systems across five climatic regions of China. Variations of the climate and energy supply in these regions and the energy efficiency grade of domestic hot water systems were also taken into consideration. The results suggest that evacuated tube solar systems are highly energy-efficient and low-cost, except in the region with the weakest solar radiation. Electric systems are extremely energy-intensive and uneconomical for domestic hot water use, although they have the least human and ecological toxicity potentials. Solar and air-source energy systems save energy; however, they use more materials and cause more human and ecological toxicity. From the severe cold region to the hot summer and warm winter region, the heat load of domestic hot water increases by 59%, resulting in an increase of 58–230% in primary energy demand. Accordingly, the environmental impacts of domestic hot water systems increase in varying degrees; however, few impacts decrease due to the different emission factors of different power grids. The raw materials used in the manufacture of domestic hot water systems and the energy required for the use of the systems are the most important contributors to all environmental impacts. The scenario analysis indicates that 24.5% of the primary energy demand and 25.7% of greenhouse gas emissions owing to domestic hot water use in China can be reduced by improving the energy efficiency, prompting the use of renewable energy sources, and reducing the usage of materials for domestic hot water systems, as the human and ecological toxicity potentials will increase by 0.1% and 10%, respectively, due to the increasing use of certain materials.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S019689041930946X-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Zhonghe Han, Xiaoqiang Jia, Peng Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Organic Rankine cycle (ORC) is an efficient technique to recycle the low temperature heat sources. The design method of the critical component, radial inflow turbine, is a main focus of research. A preliminary design method was developed to optimize eight critical parameters based on particle swarm optimization (PSO) algorithm. The isotropic efficiency was the objective function of the algorithm. Six working fluids were selected to conduct turbine design based on the design method. The turbine with R245fa was determined to be optimal due to its small geometry size, high exergy efficiency (0.929) and high load coefficient (1.1027). The off-design performance of R245fa turbine was investigated with the variation of pressure ratio (〈em〉PR〈/em〉), stator inlet temperature and power output. The results indicate that the turbine efficiencies increase with the reduction of 〈em〉PR〈/em〉 and turbine inlet temperature and the increase of power output. The exergy efficiency and isotropic efficiency drop slightly with the increase of turbine inlet temperature. So the turbine with R245fa exhibited good off-design performance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Yifan Li, Gaoqiang Yang, Shule Yu, Zhenye Kang, Derrick A. Talley, Feng-Yuan Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The heat generated from electrochemical reactions has been considered one of the most significant issues in terms of the reliability of energy conversion devices. So far, no systematic study on the relation between heat generation and electrochemical reaction exists, especially in the form of experiments. In this study, changes of the temperature distribution and hydrogen evolution reaction (HER) on the catalyst coated membrane (CCM) in proton exchange membrane electrolyzer cells (PEMECs) are 〈em〉in-situ〈/em〉 visualized with the help of a novel PEMEC design, thermal spectroscopy and high-speed visualization system. At the channel-scale, the temperature increases rapidly for most of the active areas, and finally reaches the equilibrium state at 27 °C. The temperature distribution is non-uniform throughout the process. In addition, a series of pore-scale analyses are provided to clarify the relation between the temperature distribution and electrochemical reaction area. More interestingly, the rapid heat generation areas are found to be in a good agreement with the electrochemical reaction areas, which confirms that the heat is released during the reaction processes. Finally, the temperature evolution phenomena on the LGDL surface have also been recorded. These findings could help better understand the correlation between the cathode side electrochemical reaction and heat generation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Jiangjiang Wang, Yuzhu Chen, Noam Lior〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study integrates concentrated photovoltaic/thermal (PV/T) solar collectors into a natural gas combined cooling, heating and power (CCHP) system to both offer efficient use of solar energy and reduce greenhouse emissions. Using exergo-economic analysis based on energy level, an optimization method was proposed and used to configure and determine the PV coverage ratio on the PV/T collector for minimizing the products’ costs of the hybrid CCHP system. The optimization method considers the users’ annual variable energy loads and transforms the off-design operation conditions to the design parameters by employing the heat storage ratio of thermal storage tank and supplemental heat ratio of absorption heat pump. Based on the validated thermodynamic modeling, an exergy and exergo-economic analysis of the hybrid CCHP system are presented to reveal the influences of the PV/T configuration on the exergy efficiency and the products’ cost. As the PV coverage ratio on the PV/T collector was increased, it was found that the specific cost of the CCHP system-generated electricity rose and then slightly dropped, while the specific cost of the heat exergy decreased, and then slightly increased. The optimal coverage ratio, at which the minimal specific cost of the system products was attained, had a value of 1.0. The integration and optimization of the PV/T decreases the specific cost of the system products by 6.4%. Compared to the conventional exergo-economics analysis method, the specific cost of system electricity using the exergo-economic analysis based on energy level is 20.3% higher, and the costs of heat exergy are decreased.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Nicu Bizon〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, a real-time strategy for a fuel cell hybrid power system based on fuel optimization and load-following is analyzed to identify the critical parameters of the optimization problem. Because the dither’s frequency dictates the searching speed of the optimum in the perturbed extremum seeking algorithm, this parameter has been selected from multiple parameters involved in the optimization problem to improve the fuel economy based on sensitivity analysis. The sensitivity analysis reveals the multimodal behavior of the fuel economy, but also the best choice for the dither. The fuel cell hybrid power system is a highly dynamic system, so the optimization and control loops have been designed for a robust but efficient operation of the system based on new perturbed extremum seeking algorithm to track the optimum. Considering the recommended 100 Hz sinusoidal dither, the improvement in fuel economy is of 47.9 L for an 8 kW/12 s load cycle. Also, the electrical efficiency of the fuel cell system increases with 7.83%. Both improvements were estimated compared to a commercial strategy, called in the literature as static feed-forward strategy.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 198〈/p〉 〈p〉Author(s): Minda Ma, Xin Ma, Weiguang Cai, Wei Cai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon-dioxide mitigation in residential building sector (CMRBS) has become critical for China in achieving its emission mitigation goal in the “Post Paris” period with the growing demand for household energy service in residential buildings. This is the first paper to investigate the factors that can mitigate carbon-dioxide (CO〈sub〉2〈/sub〉) intensity and further assess CMRBS in China based on a household scale via decomposition analysis. The core findings of this study reveal that: (1) Three types of housing economic indicators and the final emission factor significantly contributed to the decrease in CO〈sub〉2〈/sub〉 intensity in the residential building sector. In addition, the CMRBS from 2001 to 2016 was 1816.99 MtCO〈sub〉2〈/sub〉, and the average mitigation intensity during this period was 266.12 kgCO〈sub〉2〈/sub〉·(household·year)〈sup〉−1〈/sup〉. (2) Ridge regression indicated that the robustness of the decomposition approach was sufficient for achieving reliable results for the decomposition analysis and CMRBS assessment. (3) The energy-conservation and emission-mitigation strategy caused CMRBS to effectively increase and is the key to promoting a more significant emission mitigation in the future. Overall, this paper covers the CMRBS assessment gap in China, and the proposed assessment model can be regarded as a reference for other countries and cities for measuring the retrospective CO〈sub〉2〈/sub〉 mitigation effect in residential buildings.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉a. Changes of CO〈sub〉2〈/sub〉 emission per household (CO〈sub〉2〈/sub〉 intensity) in the Chinese residential building sector via decomposition analysis; b and c. Total and intensity values of CO〈sub〉2〈/sub〉 mitigation in the residential building sector (2001–2016); d and e. CO〈sub〉2〈/sub〉 mitigation per capita and CO〈sub〉2〈/sub〉 mitigation per floor space in the residential building sector (2001–2016).〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419309069-ga1.jpg" width="406" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Hang Li, Zunlong Jin, Yi Yang, Yaowu Huo, Xiao Yan, Pan Zhao, Yiping Dai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nuclear energy with attractive expectation can be efficiently used by the supercritical carbon dioxide power system. However, amounts of the cooling heat is wasted in the nuclear power plant. Two conceptual designs of combined heat and power systems based on the supercritical carbon dioxide power system are proposed to exploit the waste heat. A comparison research is performed in thermodynamics and economics. Several key physical parameters are selected to investigate their effects on system performance, and multi-objective optimization using the Non-dominated Sorting Genetic Algorithms-II is carried out with the target of gaining maximum system exergy efficiency and minimum total product unit cost. The results of parameter analysis exhibit that there exist optimal values for two target functions with the increasing compressor pressure ratio for three thermal systems, and the system with heat pump needs the highest pressure ratio. Better system performance can be achieved by increasing the turbine inlet temperature and evaporator temperature. The multi-objective optimization results of genetic algorithm display that proposed two systems can gain an improvement by 7.02% and 8.45% for the system exergy efficiency, and 11.95% and 13.48% for the total product unit cost compared with the stand-alone supercritical carbon dioxide system, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 198〈/p〉 〈p〉Author(s): K. Chopra, V.V. Tyagi, Atin K. Pathak, A.K. Pandey, Ahmet Sari〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉In this study, the thermal performance of a novel solar collector integrated with stearic acid as phase change material has been investigated. In this design, the solar radiation was collected by heat pipe equipped evacuated tubes and then stored in manifold integrated with phase change material. The stored thermal energy of phase change material then transferred to water flowing through bundle of finned copper pipes placed inside the manifold. In present study, the design, the operating principle and the experimental investigation of the developed system have been presented. The developed system was investigated with different mass flow rates and also discussed the influence of varying mass flow rate on the thermal performance of system. The experimental investigation of designed and developed system has been carried out for two modes i.e. mid-day charging mode and full-day charging mode. It has been observed that for considered mass flow rates, thermal efficiency of the system was varied in the range of approximately 52–62% for full-day charging mode while for mid-day charging mode, it was varied between 55 and 72%. The maximum value of thermal efficiency was approximately 72.52% at mass flow rate of 24 LPH for mid-day charging mode. The efficiency of phase change material for both modes was varied in the range of approximately 61–64%. The annual cost and annual fuel cost of the developed system are much lower than conventional system. Also, the initial capital cost for the developed system can be recovered after 6 years of operation. However, there is no recovery of initial investment for electricity based water heating system.〈/p〉 〈p〉The proposed system overcomes two problems associated with conventional heat pipe evacuated tube solar collector: elimination of heat pipe overheating problem and low thermal conductivity of phase change materials. By this novel design of manifold, the influence of thermal stratification on the thermal performance of solar collectors can be completely eradicated.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): M.E. Demir, G. Chehade, I. Dincer, B. Yuzer, H. Selcuk〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The synergistic effects of titanium dioxide photocatalysis in combination with Fenton-like reactions for photoelectrochemical based hydrogen production and wastewater treatment is investigated in a newly designed photoelectrochemical reactor. Here, titanium dioxide nanoparticles are coated on the anode to enhance both hydrogen production and wastewater treatment processes. The reactor is tested under 600 W/m〈sup〉2〈/sup〉 of solar irradiance and is characterized using electrochemical, chemical oxygen demand, absorbance, and ultraviolet–visible absorption spectroscopy techniques. The results show that the oxygen evaluation in the anolyte is substituted by iron(II)/iron(III) ions and the presence of hydrogen peroxide forms up the hydroxyl radicals via Fenton like process for degradation of organics in wastewater. While, hydrogen gas production in the catholyte is improved up to 8% by the means of proton reduction at the cathode in an acid medium. Also, 33% chemical oxygen demand removal efficiency of the synthetic textile wastewater (Reactive Black 5) is recorded in 17 h. This new hybrid configuration combines three different photo-assisted advanced oxidation processes such as ultraviolet/Fenton, ultraviolet/titanium dioxide, and ultraviolet/hydrogen peroxide with electrolysis process which increases hydrogen gas production rate and treats the wastewater.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419308945-ga1.jpg" width="347" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 197〈/p〉 〈p〉Author(s): Dechao Wang, Lijun Jin, Yang Li, Baoyong Wei, Demeng Yao, Haoquan Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To understand the effect of reducibility of transition metal oxides (TMOs) on tar conversion, four TMOs including Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, MnO〈sub〉x〈/sub〉, CuO, and NiO were selected and in-situ oxidative catalytic cracking of coal pyrolysis tar on a two-stage fixed bed reactor at 550 °C was performed. The reducibility of TMOs was measured by H〈sub〉2〈/sub〉-temperature programmed reduction (H〈sub〉2〈/sub〉-TPR). The effect of reducibility of TMOs on the pyrolysis products distribution and conversion was investigated. The changes of TMOs before and after reaction were also analyzed by several characterizations. The addition of TMOs results in the decrease of tar yield and heavy tar content, and the increase of gas yield. The reduction temperature of TMOs affects the products distribution and heavy tar conversion. Among these four TMOs, Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 shows the highest reduction temperature (390–700 °C with peak centered on 570 °C) and the largest heavy tar conversion (75.3 wt%). CuO shows the lowest reduction temperature (190–470 °C with peak centered on 326 °C) and heavy tar conversion (45.8 wt%). The main reactions on CuO is complete oxidation with high water yield (12.8 wt%) and CO〈sub〉2〈/sub〉 formation (110 mL/g.coal〈sub〉daf〈/sub〉). The coke formed on the used Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 is amorphous or disordered carbon, and shows the largest yield being 5.5 wt%.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419308532-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 197〈/p〉 〈p〉Author(s): Diego Vittorini, Roberto Cipollone, Roberto Carapellucci〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The full exploitation of the upper thermal source is the key for enhanced energy performances of ORC-based units for medium and low-grade waste heat recovery. The adoption of a dual evaporation pressure cycle layout has the potential to reduce the heat exchange irreversibility at the evaporation section and to assure a higher net power available at the expander shaft, particularly in small scale units and in presence of upper thermal sources with a highly variable heat release characteristic. The adoption of the dual evaporation pressure technology to small scale recovery units represents a major technological breakthrough and an element of novelty, observing that, at present, the possibility to split the evaporation process in multiple pressure levels is considered mostly with reference to steam generators and boilers. The study investigates the potential energy and exergy advantage of a dual pressure heat recovery vapor generator, with respect to a base-single evaporation pressure layout, for a recovery unit with a mechanical power in the 1–15 kW range, for stationary (100 °C–150 °C hot source temperature) and on-board (350 °C–300 °C hot source temperature) applications. A dedicated optimization procedure allows the maximization of either the net power recovered or the cycle energy efficiency, dependently on the final application of the unit. The exergy efficiency of the heat recovery vapor generator is assessed and its dependence on the fluid characteristics and the main cycle variables discussed, along with the relationship between the energy and exergy gain for the enhanced heat exchange. A preliminary economic analysis provides a first indication of the financial merit of the dual evaporation pressure layout with respect to a base single evaporation pressure configuration.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 197〈/p〉 〈p〉Author(s): Seyed Sina Hosseini, Mehdi Mehrpooya, Ali Sulaiman Alsagri, Abdulrahman A. Alrobaian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The object of this paper is to develop and exergetically assess a multi-generation system comprised of a Molten Carbonate Fuel Cell (MCFC) coupled with Steam Methane Reforming (SMR), Methanol Synthesis Process (MSP) with distillation process, and combined heat and power cycle (CHP) including gas turbine, Rankine cycle (RC), Organic Rankine Cycle (ORC) and District Heating (DH) line. The combination of the MCFC, CHP and MSP can be considered as an innovative breakthrough in the field of energy systems, in light of the fact that the reforming compartment can mutually feed both MCFC and MSP, and the whole process can simultaneously produce electricity, pure methanol and hot water. The SMR at 800 kPa and 600 °C was applied to produce synthetic gas required by MCFC and MSP. The simulation was performed by Aspen Hysys, considering several operational conditions and the best was selected according to exergetic performance assessment. The structure produced 110,544 kW net electricity (34% MCFC, 33.4% gas turbine, 18.4% RC and 14.2% ORC), pure methanol (99.9%) at 271.7 kgmole/h, and hot water at 80 °C and 65398.7 kgmole/h. About 23% and 21% of the overall destructed exergy belonged to combustion chamber and MCFC, respectively. The overall exergy destruction, exergy efficiency and energy efficiency of the integrated system were obtained 116,353 kW, 58.4% and 83.7%, respectively. Finally, the performance of the proposed hybrid system was compared with similar studies and it was found that the hybrid MCFC-MSP-CHP system can outstandingly enhance the overall efficiency and reduce CO〈sub〉2〈/sub〉 emissions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S019689041930860X-ga1.jpg" width="357" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉