Journal articles on the topic 'Exergy-based methodology'
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Bou Malham, Zoughaib, Tinoco, and Schuhler. "Hybrid Optimization Methodology (Exergy/Pinch) and Application on a Simple Process." Energies 12, no. 17 (August 28, 2019): 3324. http://dx.doi.org/10.3390/en12173324.
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In the light of the alarming impending energy scene, energy efficiency and exergy efficiency are unmistakably gathering momentum. Among efficient process design methodologies, literature suggests pinch analysis and exergy analysis as two powerful thermodynamic methods, each showing certain drawbacks, however. In this perspective, this article puts forward a methodology that couples pinch and exergy analysis in a way to surpass their individual limitations in the aim of generating optimal operating conditions and topology for industrial processes. Using new optimizing exergy‐based criteria, exergy analysis is used not only to assess the exergy but also to guide the potential improvements in industrial processes structure and operating conditions. And while pinch analysis considers only heat integration to satisfy existent needs, the proposed methodology allows including other forms of recoverable exergy and explores new synergy pathways through conversion systems. A simple case study is proposed to demonstrate the applicability and efficiency of the proposed method.
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Doty, John H., José A. Camberos, and David J. Moorhouse. "Benefits of Exergy-Based Analysis for Aerospace Engineering Applications—Part I." International Journal of Aerospace Engineering 2009 (2009): 1–11. http://dx.doi.org/10.1155/2009/409529.
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This paper compares the analysis of systems from two different perspectives: an energy-based focus and an exergy-based focus. A complex system was simply modeled as interacting thermodynamic systems to illustrate the differences in analysis methodologies and results. The energy-based analysis had combinations of calculated states that are infeasible. On the other hand, the exergy-based analyses only allow feasible states. More importantly, the exergy-based analyses provide clearer insight to the combination of operating conditions for optimum system-level performance. The results strongly suggest changing the analysis/design paradigm used in aerospace engineering from energy-based to exergy-based. This methodology shift is even more critical in exploratory research and development where previous experience may not be available to provide guidance. Although the models used herein may appear simplistic, the message is very powerful and extensible to higher-fidelity models: the 1st Law is only anecessarycondition for design, whereas the 1st and 2nd Laws provide thesufficiencycondition.
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Eydner, Matthias, Lu Wan, Tobias Henzler, and Konstantinos Stergiaropoulos. "Real-Time Grid Signal-Based Energy Flexibility of Heating Generation: A Methodology for Optimal Scheduling of Stratified Storage Tanks." Energies 15, no. 5 (February 28, 2022): 1793. http://dx.doi.org/10.3390/en15051793.
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Heat pumps coupled with thermal energy storage (TES) systems are seen as a promising technology for load management that can be used to shift peak loads to off-peak hours. Most of the existing model predictive control (MPC) studies on tariff-based load shifting deploying hot water tanks use simplified tank models. In this study, an MPC framework that accounts for transient thermal behavior (i.e., mixing and stratification) by applying energy (EMPC) and exergy (XMPC) analysis is proposed. A case study for an office building equipped with an air handling unit (AHU) revealed that the MPC strategy had a high load-shifting capacity: over 80% of the energy consumption took place during off-peak hours when there was an electricity surplus in the grid. An analysis of a typical day showed that the XMPC method was able to provide more appropriate stratification within the TES for all load characteristics. An annual exergy analysis demonstrated that, during cold months, energy degradation in the TES is mainly caused by exergy destruction due to irreversibility, while, during the transition to milder months, exergy loss dominates. Compared to the EMPC approach, the XMPC strategy achieves additional reductions of 18% in annual electricity consumption, 13% in operating costs, and almost 17% in emissions.
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Sejkora, Christoph, Lisa Kühberger, Fabian Radner, Alexander Trattner, and Thomas Kienberger. "Exergy as Criteria for Efficient Energy Systems—A Spatially Resolved Comparison of the Current Exergy Consumption, the Current Useful Exergy Demand and Renewable Exergy Potential." Energies 13, no. 4 (February 14, 2020): 843. http://dx.doi.org/10.3390/en13040843.
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The energy transition from fossil-based energy sources to renewable energy sources of an industrialized country is a big challenge and needs major systemic changes to the energy supply. Such changes require a holistic view of the energy system, which includes both renewable potentials and consumption. Thereby exergy, which describes the quality of energy, must also be considered. In this work, the determination and analysis of such a holistic view of a country are presented, using Austria as an example. The methodology enables the calculation of the spatially resolved current exergy consumption, the spatially resolved current useful exergy demand and the spatially resolved technical potential of renewable energy sources (RES). Top-down and bottom-up approaches are combined in order to increase accuracy. We found that, currently, Austria cannot self-supply with exergy using only RES. Therefore, Austria should increase the efficiency of its energy system, since the overall exergy efficiency is only at 34%. The spatially resolved analysis shows that in Austria the exergy potential of RES is rather evenly distributed. In contrast, the exergy consumption is concentrated in urban and industrial areas. Therefore, the future energy infrastructure must compensate for these spatial discrepancies.
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Voloshchuk, Volodymyr, Paride Gullo, Eugene Nikiforovich, and Nadia Buyak. "Simulation and Exergy Analysis of a Refrigeration System Using an Open-Source Web-Based Interactive Tool—Comparison of the Conventional Approach and a Novel One for Avoidable Exergy Destruction Estimation." Applied Sciences 11, no. 23 (December 6, 2021): 11535. http://dx.doi.org/10.3390/app112311535.
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Avoidable endogenous/exogenous parts of the exergy destruction in the components of an energy conversion system can be computed by applying advanced exergy analysis. Their calculation is crucial for the correct assessment of the real thermodynamic enhancement achievable by the investigated energy conversion system. This work proposes a new approach to estimate the avoidable exergy destruction rates of system components, being more rigorous compared to the conventional method due to the elimination of the need for the implementation of theoretical assumptions associated with the idealization of processes. An open-source web-based interactive tool was implemented to contrast the results of the conventional advanced exergy analysis to those involving the new approach for avoidable exergy destruction estimation. The comparison was based on the same case study, i.e., a refrigeration system selected from the literature. It was observed that the developed tool can be properly employed for comparing the two approaches within exergy analyses, and the results obtained presented some differences for the compressor and the condenser. Compared to the new approach, the existing methodology of advanced exergy analysis suggests lower values of the avoidable part of exergy destruction, which can be reduced by improving the efficiency of the compressor and the condenser. Moreover, the avoidable parts of exergy destruction, which could be removed within these components by improving the efficiencies of the remaining components, were higher in the case of the application of the existing advanced exergetic analysis as compared with the findings obtained by the proposed approach. These differences were due to the impossibility of the existing advanced exergy analysis to implement complete thermodynamic “idealization” for the condenser and evaporator.
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Voloshchuk, Volodymyr, and Mariya Polishchuk. "EXERGY-BASED CONTROL STRATEGY IN A DWELLING VENTILATION SYSTEM WITH HEAT RECOVERY." Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska 10, no. 2 (June 30, 2020): 44–47. http://dx.doi.org/10.35784/iapgos.933.
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The paper presents energy and exergy analysis of a typical dwelling ventilation system with heat recovery for Ukrainian climatic conditions using a quasi-steady state approach over 24-hour time-steps. Evaluation of such systems on the base of the first law of thermodynamics demonstrates that heat recovery is beneficial for the whole variety of operational modes. Such methodology identifies as a thermodynamic inefficiency only energy losses to the surroundings with the exhaust air. The exergy-based analysis can detect additional inefficiencies due to irreversibilities within the components of the system. As a result the exergetic investigations show that for the ventilation systems there are operating conditions for which heat recovery increases exergy of fuel expended to provide the ventilation air compared to cases without bringing any recovery of heat and additional power consumption to drive the air flow by the fans. For the specified system, in case of switching ventilation unit to the operation mode of lower values of spent fuel exergy it is possible to provide annual saving of the primary energy sources from 5 to 15%.
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Salahshoor, Karim, and M. H. Asheri. "A new exergy-based model predictive control methodology for energy assessment and control." Journal of Natural Gas Science and Engineering 21 (November 2014): 489–95. http://dx.doi.org/10.1016/j.jngse.2014.08.024.
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Kallio, Sonja, and Monica Siroux. "Exergy and Exergy-Economic Approach to Evaluate Hybrid Renewable Energy Systems in Buildings." Energies 16, no. 3 (January 17, 2023): 1029. http://dx.doi.org/10.3390/en16031029.
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Hybrid renewable energy systems (HRES) combine two or more renewable energy systems and are an interesting solution for decentralized renewable energy generation. The exergy and exergo-economic approach have proven to be useful methods to analyze hybrid renewable energy systems. The aim of this paper is to present a review of exergy and exergy-economic approaches to evaluate hybrid renewable energy systems in buildings. In the first part of the paper, the methodology of the exergy and exergo-economic analysis is introduced as well as the main performance indicators. The influence of the reference environment is analyzed, and results show that the selection of the reference environment has a high impact on the results of the exergy analysis. In the last part of the paper, different literature studies based on exergy and exergo-economic analysis applied to the photovoltaic-thermal collectors, fuel-fired micro-cogeneration systems and hybrid renewable energy systems are reviewed. It is shown that the dynamic exergy analysis is the best way to evaluate hybrid renewable energy systems if they are operating under a dynamic environment caused by climatic conditions and/or energy demand.
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Dinc, Ali, Yasin Şöhret, and Selcuk Ekici. "Exergy analysis of a three-spool turboprop engine during the flight of a cargo aircraft." Aircraft Engineering and Aerospace Technology 92, no. 10 (July 29, 2020): 1495–503. http://dx.doi.org/10.1108/aeat-05-2020-0087.
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Purpose This study aims to introduce exergy analysis of a three-spool turboprop engine during the complete flight. Design/methodology/approach In this study, a flight scenario of the aircraft is assumed. Operating parameters of the aircraft and its engine are modelled based on the assumed flight scenario with the aid of a genuine code. And then performance analysis of the engine is performed for each flight path point with the aid of exergy. Findings At the end of the study, major exergy parameters of the engine are calculated during the complete flight of a cargo aircraft three-spool turboprop engine. Practical implications Findings of the study may be beneficial for industry and practitioners to improve performance of the evaluated engine. Originality/value To the best of authors’ knowledge, this paper presented the exergy analysis of a three-spool turboprop engine during the complete flight for the first time. It was shown how the exergy destruction rate depends on the altitude and manoeuvre.
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Jane, Robert, Tae Young Kim, Emily Glass, Emilee Mossman, and Corey James. "Tailoring Mission Effectiveness and Efficiency of a Ground Vehicle Using Exergy-Based Model Predictive Control (MPC)." Energies 14, no. 19 (September 23, 2021): 6049. http://dx.doi.org/10.3390/en14196049.
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To ensure dominance over a multi-domain battlespace, energy and power utilization must be accurately characterized for the dissimilar operational conditions. Using MATLAB/Simulink in combination with multiple neural networks, we created a methodology which was simulated the energy dynamics of a ground vehicle in parallel to running predictive neural network (NN) based predictive algorithms to address two separate research questions: (1) can energy and exergy flow characterization be developed at a future point in time, and (2) can we use the predictive algorithms to extend the energy and exergy flow characterization and derive operational intelligence, used to inform our control based algorithms or provide optimized recommendations to a battlefield commander in real-time. Using our predictive algorithms we confirmed that the future energy and exergy flow characterizations could be generated using the NNs, which was validated through simulation using two separately created datasets, one for training and one for testing. We then used the NNs to implement a model predictive control (MPC) framework to flexibly operate the vehicles thermal coolant loop (TCL), subject to exergy destruction. In this way we could tailor the performance of the vehicle to accommodate a more mission effective solution or a less energy intensive solution. The MPC resulted in a more effective solution when compared to six other simulated conditions, which consumed less exergy than two of the six cases. Our results indicate that we can derive operational intelligence from the predictive algorithms and use it to inform a model predictive control (MPC) framework to reduce wasted energy and exergy destruction subject to the variable operating conditions.
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Nwodo, Martin N., and Chimay J. Anumba. "Exergetic Life Cycle Assessment: A Review." Energies 13, no. 11 (May 26, 2020): 2684. http://dx.doi.org/10.3390/en13112684.
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Exergy is important and relevant in many areas of study such as Life Cycle Assessment (LCA), sustainability, energy systems, and the built environment. With the growing interest in the study of LCA due to the awareness of global environmental impacts, studies have been conducted on exergetic life cycle assessment for resource accounting. The aim of this paper is to review existing studies on exergetic life cycle assessment to investigate the state-of-the-art and identify the benefits and opportunity for improvement. The methodology used entailed an in-depth literature review, which involved an analysis of journal articles collected through a search of databases such as Web of Science Core Collection, Scopus, and Google Scholar. The selected articles were reviewed and analyzed, and the findings are presented in this paper. The following key conclusions were reached: (a) exergy-based methods provide an improved measure of sustainability, (b) there is an opportunity for a more comprehensive approach to exergetic life cycle assessment that includes life cycle emission, (c) a new terminology is required to describe the combination of exergy of life cycle resource use and exergy of life cycle emissions, and (d) improved exergetic life cycle assessment has the potential to solve characterization and valuation problems in the LCA methodology.
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WANG, C., C. GUANG, Z. S. ZHANG, and J. GAO. "DESIGN AND OPTIMIZATION OF HEAT EXCHANGE NETWORK AND EXERGY ANALYSIS FOR METHANATION PROCESS OF COAL-GAS." Latin American Applied Research - An international journal 49, no. 1 (January 31, 2019): 47–54. http://dx.doi.org/10.52292/j.laar.2019.284.
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It has the significant meaning to design an energy-efficient heat exchange network (HEN) for the methanation process in the coal-gas industry in China. In this work, HENs are set up to produce multiple saturated steams with different pressure levels by software design and manual retrofit methodology based on pinch analysis, and evaluated from the economic and exergetic viewpoints. The result shows that high pressure steam (312℃, 10Mpa, 13000kg/h) and medium pressure saturated steam (175℃, 0.9Mpa, 500kg/h) can be cogenerated by the optimal HEN with lower exergy loss and economic cost as well as higher exergy efficiency.
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Fernández Bandera, Carlos, Ana Muñoz Mardones, Hu Du, Juan Echevarría Trueba, and Germán Ramos Ruiz. "Exergy As a Measure of Sustainable Retrofitting of Buildings." Energies 11, no. 11 (November 13, 2018): 3139. http://dx.doi.org/10.3390/en11113139.
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This study presents a novel optimization methodology for choosing optimal building retrofitting strategies based on the concept of exergy analysis. The study demonstrates that the building exergy analysis may open new opportunities in the design of an optimal retrofit solution despite being a theoretical approach based on the high performance of a Carnot reverse cycle. This exergy-based solution is different from the one selected through traditional efficient retrofits where minimizing energy consumption is the primary selection criteria. The new solution connects the building with the reference environment, which acts as “an unlimited sink or unlimited sources of energy”, and it adapts the building to maximize the intake of energy resources from the reference environment. The building hosting the School of Architecture at the University of Navarra has been chosen as the case study building. The unique architectural appearance and bespoke architectural characteristics of the building limit the choices of retrofitting solutions; therefore, retrofitting solutions on the façade, roof, roof skylight and windows are considered in multi-objective optimization using the jEPlus package. It is remarkable that different retrofitting solutions have been obtained for energy-driven and exergy-driven optimization, respectively. Considering the local contexts and all possible reference environments for the building, three “unlimited sinks or unlimited sources of energy” are selected for the case study building to explore exergy-driven optimization: the external air, the ground in the surrounding area and the nearby river. The evidence shows that no matter which reference environment is chosen, an identical envelope retrofitting solution has been obtained.
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Maghsoudi, Peyman, Sadegh Sadeghi, Qingang Xiong, and Saiied Mostafa Aminossadati. "A multi-factor methodology for evaluation and optimization of plate-fin recuperators for micro gas turbine applications considering payback period as universal objective function." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 5 (July 19, 2019): 2411–38. http://dx.doi.org/10.1108/hff-04-2019-0333.
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Purpose Because of the appreciable application of heat recovery systems for the increment of overall efficiency of micro gas turbines, promising evaluation and optimization are crucial. This paper aims to propose a multi-factor theoretical methodology for analysis, optimization and comparison of potential plate-fin recuperators incorporated into micro gas turbines. Energetic, exergetic, economic and environmental factors are covered. Design/methodology/approach To demonstrate applicability and reliability of the methodology, detailed thermo-hydraulic analysis, sensitivity analysis and optimization are conducted on the recuperators with louver and offset-strip fins using a genetic algorithm. To assess the relationship between investment cost and profit for the recuperated systems, payback period (PBP), which incorporates all the factors is used as the universal objective function. To compare the performance of the recuperated and non-recuperated systems, exergy efficiency, exergy destruction and corresponding cost rate, fuel consumption and environmental damage cost rates, capital and operational cost rates and acquired profit rates are determined. Findings Based on the results, optimal PBP of the louvered-fin recuperator (147 days) is slightly lower than that with offset-strip fins (153 days). The highest profit rate is acquired by reduction of exergy destruction cost rate and corresponding decrements for louver and offset-strip fins are 2.3 and 3.9 times compared to simple cycle, respectively. Originality/value This mathematical study, for the first time, focuses on introducing a reliable methodology, which covers energetic, exergetic, economic and environmental points of view beneficial for design and selection of efficient plate-fin recuperators for micro gas turbine applications.
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Camberos, José A., and David J. Moorhouse. "Systems Engineering in Terms of Exergy." International Journal of Aerospace Engineering 2009 (2009): 1–7. http://dx.doi.org/10.1155/2009/735680.
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We address the design of a flight vehicle from the viewpoint of a system of systems and we discuss the integration of the individual technical disciplines. Then a conceptual fundamental methodology and tools required for the analysis, design, and optimization of aerospace vehicles in terms of the efficient use of on-board energy are discussed. This suggests changing the design paradigm to the optimization of a system of energy systems. We propose a foundation for system-level design with optimization based on minimum exergy destruction.
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Peters, Jens F. "Reinventing exergy as indicator for resource depletion impacts in LCA." Matériaux & Techniques 108, no. 5-6 (2020): 504. http://dx.doi.org/10.1051/mattech/2021003.
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While resource aspects are gaining increasing importance for the sustainability assessment of new technologies, the question of how to assess the depletion of abiotic resources is still controversially discussed. Different methodologies exist for their quantification within life cycle assessment (LCA). Among them, thermodynamic approaches have the advantage of considering aspects of absolute quantity (reserves or amount of a substance contained in total in earth’s crust) and of quality (concentration of the target element in the mined resource), making them a potentially appealing approach for assessing resource depletion. However, existing approaches are either far from the original thermodynamic idea of exergy or far too complex and not applicable for resource accounting. This work briefly discusses the suitability of exergy-based approaches for resource assessment, and then suggests a simple but comprehensive methodology for quantifying resource depletion related with the concept of chemical concentration exergy (MDPces). It provides a calculation approach for quantifying the MDPces and estimates the corresponding values for some representative key metals.
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Esfandyari, Alireza, Aarief Syed-Khaja, Mark Horvath, and Jörg Franke. "Energy Efficiency Analysis of Vapor Phase Soldering Technology through Exergy-Based Metric." Applied Mechanics and Materials 805 (November 2015): 196–204. http://dx.doi.org/10.4028/www.scientific.net/amm.805.196.
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In electronics production, the condensation based soldering technologies are known for reproducible solder profiles and efficient heat transfer methodology. The recent advancements in lead-free soldering and requirements for absolute void-free interconnections to increase the reliability and lifetime of the product needs optimization of the soldering process. The vacuum assisted vapor phase soldering process addresses the requirements with respect to mass production and parallelly resource efficient production which is also the motivation for the present work. This study is devoted to quantify the resource consumption and qualify this consumption through exergy flows in a vacuum vapor phase reflow soldering technology in electronics manufacturing.The analysis implies on the saving potential for energy consumption specifically during the vacuum process which also defines the void reduction quality of solder joints. Exergy efficiency analysis of a temperature profile depicts the influence of the materials used in the demonstrator. Shortening the production lead‑time, and increasing the production rate increase the efficiency of exergy and prevents wastage of usable energy. Furthermore, the set-up improvements for the temperature profiles processes are necessary, and the changes toward developing new, transformational technologies in pre-heating and vacuum zones are mandatory if a high efficiency of resources used is aimed.
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Fialko, N., A. Stepanova, R. Navrodskaya, and S. Shevchuk. "EXERGIC EFFICIENCY OF THE HEAT RECOVERY UNIT FOR WASTE GASES OF A HEAT ENGINE OF A COGENERATION PLANT." Thermophysics and Thermal Power Engineering 42, no. 3 (June 19, 2020): 56–60. http://dx.doi.org/10.31472/ttpe.3.2020.6.
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The paper presents the results of a study of the efficiency of a heat recovery unit for waste gases of a heat engine of a cogeneration plant. The possibilities of using for this purpose the discrete-modular principle and complex methods of analyzing the efficiency of heat recovery systems, which are based on the methods of exergo-dissipative functions and exergic balances, are analyzed. The design features of the heat exchanger are considered and a conclusion is made about the possibility of presenting it as a system of eight discrete modules. The results of calculating the exergy characteristics for each of the eight heat exchanger modules, performed within the framework of the indicated methods, are presented. A regular decrease in exergy losses and heat-exergy criterion of efficiency is observed during the transition from the first to the eighth module of the heat recovery unit. However, exergy characteristics for the third and fourth modules of the heat exchanger are somewhat higher than the indicated dependence suggests. This indicates the thermodynamic imperfection of these modules. The main exergy losses in all heat exchanger modules are associated with losses due to heat transfer from flue gases to the wall. An insignificant discrepancy between the values of the total exergy losses calculated within the framework of the methods used indicates that both methods can be used in various heat recovery schemes. However, in each specific case, it is necessary to choose a methodology with which it is possible to identify individual elements that need optimization or constructive improvement. Particular attention is paid to the comparative analysis of the selected techniques and consideration of the advantages and disadvantages of their use in various cases. It is noted that the technique based on the integral balance method of exergy analysis can be considered effective due to the small number of initial parameters and the simplicity of the analytical and calculation methods. The advantage of the technique using exergo-dissipative functions is that it allows one to differentiate exergy losses in a heat exchanger and establish the causes and areas of their localization.
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Gunasekar, P., S. Manigandan, Venkatesh S., R. Gokulnath, Rakesh Vimal, and P. Boomadevi. "Effect of hydrogen addition on exergetic performance of gas turbine engine." Aircraft Engineering and Aerospace Technology 92, no. 2 (October 26, 2019): 180–85. http://dx.doi.org/10.1108/aeat-05-2019-0095.
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Purpose The depletion of fossil fuel and emissions of harmful gases forced the pioneers in search of alternate energy source. The purpose of this study is to present an effective use of hydrogen fuel for turbojet engines based on its exergetic performance. Design/methodology/approach This study was performed to measure the assessment of exergetic data of turbojet engines. Initially, the test was carried out on the Jet A-1 fuel. Then, a series of similar tests were carried out on turbojet engines with hydrogen fuel to measure their performance results. Finally, the exergetic values of both were compared with each other. Findings The introduction of hydrogen fuel reduced the exergy efficiency, and a 10 per cent reduction was observed in exergy efficiency. Simultaneously, the waste exergy rate increased by 9 per cent. However, because of the high specific fuel exergy, hydrogen fuel was better than Jet A-1 fuel. Note that parameters such as environmental effect factor and ecological effect witnessed an increase in their index owing to the addition of hydrogen. Practical implications Introduction of alternative blends is necessary for achieving lower emission of gases such as CO, NOx and CO2 from gas turbine engines without compromising on performance. The Jet A fuels were replaced by blends to obtain better emission characteristics. Originality/value The use of hydrogen in turbojet engines showed an adverse effect on exergetic performance. However, it was very impressive to see a 200 per cent reduction in emissions. From the comparison of exergy efficiency results of inlet, combustion and nozzle, it is evident that the combustion chamber has the largest values of exergy ratio, waste exergy ratio, cost flow, ecological factor, environmental factor and fuel ratio owing to irreversibility in the combustion process.
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Gopalsamy, Vijayan, Ramalingam Senthil, Muthukrishnan Varatharajulu, and Rajasekaran Karunakaran. "Application of Response Surface Methodology to Predict the Optimized Input Quantities of Parabolic Trough Concentrator." International Journal of Renewable Energy Development 9, no. 3 (July 5, 2020): 393–400. http://dx.doi.org/10.14710/ijred.2020.30092.
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This work carries out a numerical investigation on aluminum oxide/de-ionized water nanofluid based shield-free parabolic trough solar collector (PTSC) system to evaluate, validate, and optimize the experimental output data. A numerical model is developed using response surface methodology (RSM) for evaluation (identifying influencing parameters and its level) and single objective approach (SOA) technique of desirability function analysis (DFA) for optimization. The experimental data ensured that global efficiency was enhanced from 61.8% to 67.0% for an increased mass flow rate from 0.02 kg/s to 0.06 kg/s, respectively. The overall deviation between experimental and numerical is only 0.352%. The energy and exergy error is varied from 3.0% to 6.0%, and the uncertainty of the experiment is 3.1%. Based on the desirability function analysis, the maximum and minimum efficiencies are 49.7% and 84.9%, as per the SOA technique. This numerical model explores the way to enhance global efficiency by 26.72%.©2020. CBIORE-IJRED. All rights reserved
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Hagi, Hayato, Yann Le Moullec, Maroun Nemer, and Chakib Bouallou. "Performance assessment of first generation oxy-coal power plants through an exergy-based process integration methodology." Energy 69 (May 2014): 272–84. http://dx.doi.org/10.1016/j.energy.2014.03.008.
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Golpour, Iman, Mohammad Kaveh, Ana M. Blanco-Marigorta, José Daniel Marcos, Raquel P. F. Guiné, Reza Amiri Chayjan, Esmail Khalife, and Hamed Karami. "Multi-Response Design Optimisation of a Combined Fluidised Bed-Infrared Dryer for Terebinth (Pistacia atlantica L.) Fruit Drying Process Based on Energy and Exergy Assessments by Applying RSM-CCD Modelling." Sustainability 14, no. 22 (November 16, 2022): 15220. http://dx.doi.org/10.3390/su142215220.
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The present investigation aimed to perform an optimisation process of the thermodynamic characteristics for terebinth fruit drying under different drying conditions in a fluidised bed-infrared (FBI) dryer using response surface methodology (RSM) based on a central composite design (CCD) approach. The experiments were conducted at three levels of drying air temperature (40, 55, and 70 °C), three levels of drying air velocity (0.93, 1.765, and 2.60 m/s), and three levels of infrared power (500, 1000, and 1500 W). Energy and exergy assessments of the thermodynamic parameters were performed based on the afirst and second laws of thermodynamics. Minimum energy utilisation, energy utilisation ratio, and exergy loss rate, and maximum exergy efficiency, improvement potential rate, and sustainability index were selected as the criteria in the optimisation process. The considered surfaces were evaluated at 20 experimental points. The experimental results were evaluated using a second-order polynomial model where an ANOVA test was applied to identify model ability and optimal operating drying conditions. The results of the ANOVA test showed that all of the operating variables had a highly significant effect on the corresponding responses. At the optimal drying conditions of 40 °C drying air temperature, 2.60 m/s air velocity, 633.54 W infrared power, and desirability of 0.670, the optimised values of energy utilisation, energy utilisation ratio, exergy efficiency, exergy loss rate, improvement potential rate, and sustainability index were 0.036 kJ/s, 0.029, 86.63%, 0.029 kJ/s, 1.79 kJ/s, and 7.36, respectively. The models predicted for all of the responses had R2-values ranging between 0.9254 and 0.9928, which showed that they had good ability to predict these responses. Therefore, the results of this research showed that RSM modelling had acceptable success in optimising thermodynamic performance in addition to achieving the best experimental conditions.
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Alvarez, José C., Kazuo Hatakeyama, Monica Carvalho, Roberto C. Marçal, Jorge Inche, and Norma de Melo. "A model for renewable energy-based product innovation based on TRIZ methodology, exergy analysis and knowledge management: Case study." Energy Reports 8 (November 2022): 1107–14. http://dx.doi.org/10.1016/j.egyr.2022.07.110.
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Budnik, Michał, and Wojciech Stanek. "Exergetic cost of steam power plant operation." Archives of Thermodynamics 32, no. 2 (August 1, 2011): 39–54. http://dx.doi.org/10.2478/v10173-011-0008-2.
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Exergetic cost of steam power plant operation The paper is devoted to the problems of exergetic cost determination. A brief description of theoretical fundamentals of exergetic cost determination and its application are presented. The applied method of calculations is based on the rules of determination of cumulative exergy consumption. The additional possibilities ensured by the exergetic cost analysis in comparison to the direct exergy consumption analysis are discussed. The presented methodology was applied for the analysis of influence of operational parameters on exergetic cost indices of steam power plant. Results of calculations concern one of the modern Polish power plant unit. Basing on the obtained results several conclusions have been formulated that show advantages of application of exergetic cost analyses.
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Zheng, Guozhong, and Youyin Jing. "Thermodynamics Performance Study on Water Source Heat Pump in Variant Operating Condition." Energy & Environment 20, no. 4 (August 2009): 517–32. http://dx.doi.org/10.1260/095830509788707284.
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Water source heat pumps have outstanding advantages: significant energy conservation, working stability and notable pollution reduction. In this paper, the benefits and features of the water source heat pump are described. Then the methodology for studying the thermodynamics performance in variant conditions is described and the thermodynamics analysis of a specific water source heat pump is presented based on the first law of thermodynamics and exergy analysis theory to study the thermodynamics performance in variant condition. Coefficient of Performance (COP) and exergy efficiency in variant operating condition are calculated. The relation of COP and exergy efficiency with the outlet temperature of the chilled water and the inlet temperature of the cooling water are respectively studied. The operating strategies of both summer and winter condition are then concluded. Finally, the thermodynamics performance of the water source heat pump is compared with the other common refrigerating and heating equipments. It is concluded that the water source heat pump has great advantage over others in terms of energy saving. It is expected that the study would be beneficial to the researchers and engineers.
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Khaliq, A., and K. Choudhary. "Combined First and Second-Law Analysis of Gas Turbine Cogeneration System With Inlet Air Cooling and Evaporative Aftercooling of the Compressor Discharge." Journal of Engineering for Gas Turbines and Power 129, no. 4 (May 1, 2007): 1004–11. http://dx.doi.org/10.1115/1.2747257.
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A conceptual gas turbine based cogeneration cycle with compressor inlet air cooling and evaporative aftercooling of the compressor discharge is proposed to increase the cycle performance significantly and render it practically insensitive to seasonal temperature fluctuations. Combined first and second-law approach is applied for a cogeneration system having intercooled reheat regeneration in a gas turbine as well as inlet air cooling and evaporative aftercooling of the compressor discharge. Computational analysis is performed to investigate the effects of the overall pressure ratio rp, turbine inlet temperature (TIT), and ambient relative humidity φ on the exergy destruction in each component, first-law efficiency, power-to-heat ratio, and second-law efficiency of the cycle. Thermodynamic analysis indicates that exergy destruction in various components of the cogeneration cycle is significantly affected by overall pressure ratio and turbine inlet temperature, and not at all affected by the ambient relative humidity. It also indicates that the maximum exergy is destroyed during the combustion process, which represents over 60% of the total exergy destruction in the overall system. The first-law efficiency, power-to-heat ratio, and second-law efficiency of the cycle significantly vary with the change in the overall pressure ratio and turbine inlet temperature, but the change in relative humidity shows small variations in these parameters. Results clearly show that performance evaluation based on first-law analysis alone is not adequate, and hence, more meaningful evaluation must include second-law analysis. Decision makers should find the methodology contained in this paper useful in the comparison and selection of advanced combined heat and power systems.
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Wang, Ligang, Zhiping Yang, Shivom Sharma, Alberto Mian, Tzu-En Lin, George Tsatsaronis, François Maréchal, and Yongping Yang. "A Review of Evaluation, Optimization and Synthesis of Energy Systems: Methodology and Application to Thermal Power Plants." Energies 12, no. 1 (December 27, 2018): 73. http://dx.doi.org/10.3390/en12010073.
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To reach optimal/better conceptual designs of energy systems, key design variables should be optimized/adapted with system layouts, which may contribute significantly to system improvement. Layout improvement can be proposed by combining system analysis with engineers’ judgments; however, optimal flowsheet synthesis is not trivial and can be best addressed by mathematical programming. In addition, multiple objectives are always involved for decision makers. Therefore, this paper reviews progressively the methodologies of system evaluation, optimization, and synthesis for the conceptual design of energy systems, and highlights the applications to thermal power plants, which are still supposed to play a significant role in the near future. For system evaluation, both conventional and advanced exergy-based analysis methods, including (advanced) exergoeconomics are deeply discussed and compared methodologically with recent developments. The advanced analysis is highlighted for further revealing the source, avoidability, and interactions among exergy destruction or cost of different components. For optimization and layout synthesis, after a general description of typical optimization problems and the solving methods, the superstructure-based and -free concepts are introduced and intensively compared by emphasizing the automatic generation and identification of structural alternatives. The theoretical basis of the most commonly-used multi-objective techniques and recent developments are given to offer high-quality Pareto front for decision makers, with an emphasis on evolutionary algorithms. Finally, the selected analysis and synthesis methods for layout improvement are compared and future perspectives are concluded with the emphasis on considering additional constraints for real-world designs and retrofits, possible methodology development for evaluation and synthesis, and the importance of good modeling practice.
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Noh, Yeelyong, and Daejun Chang. "Methodology of exergy-based economic analysis incorporating safety investment cost for comparative evaluation in process plant design." Energy 182 (September 2019): 864–80. http://dx.doi.org/10.1016/j.energy.2019.06.028.
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Linnhoff, B. "Pinch Technology for the Synthesis of Optimal Heat and Power Systems." Journal of Energy Resources Technology 111, no. 3 (September 1, 1989): 137–47. http://dx.doi.org/10.1115/1.3231415.
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Over recent years a new methodology for the analysis and design of heat exchanger networks, called pinch technology, has led to significant energy savings in the chemical and process industries. The methodology has later been extended to apply to integrated heat and power systems (Townsend and Linnhoff, 1983). This paper shows that pinch technology is firmly based in Second Law Analysis. In contrast to conventional Second Law Analysis, however, it does not require a base case design. Rather, it performs true synthesis. Also, it is capable of a methodical distinction between “inevitable” and “avoidable” exergy losses.
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Sayed, Enas Taha, Hegazy Rezk, Abdul Ghani Olabi, Mohamed R. Gomaa, Yahia B. Hassan, Shek Mohammad Atiqure Rahman, Sheikh Khaleduzzaman Shah, and Mohammad Ali Abdelkareem. "Application of Artificial Intelligence to Improve the Thermal Energy and Exergy of Nanofluid-Based PV Thermal/Nano-Enhanced Phase Change Material." Energies 15, no. 22 (November 14, 2022): 8494. http://dx.doi.org/10.3390/en15228494.
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Photovoltaic-thermal (PVT) technologies have demonstrated several attractive features, such as higher power and comparative efficiencies. Improving the thermal recovery from the PVT system would further improve the power output and the efficiency of the PVT system. This paper identifies the best operating factors of nanofluid-based PV thermal/nano-enhanced phase change material using artificial intelligence. The target is the maximization of thermal energy and exergy outputs. The suggested approach combines ANFIS modelling and particle swarm optimization (PSO). Four operating factors are taken into consideration: PCM (phase change material) layer thickness, HTF (heat transfer fluid) mass flow rate, MFNPCM (“mass fraction of nanoparticles in PCM”) and MFNfluid (“mass fraction of nanoparticles in nanofluid”). Using a dataset, an “adaptive neuro-fuzzy inference system” (ANFIS) model has been established for simulating the thermal energy and exergy outputs in terms of the mentioned operating factors. Then, using PSO, the best values of PCM thickness, mass flow rate, MFNPCM and MFNfluid are estimated. The proposed model’s accuracy was examined by comparing the results with those obtained by response surface methodology and the experimental dataset.
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Ural, Tolga, Gülşah Karaca Dolgun, Onur Vahip Güler, and Ali Keçebaş. "Performance analysis of a textile based solar assisted air source heat pump with the energy and exergy methodology." Sustainable Energy Technologies and Assessments 47 (October 2021): 101534. http://dx.doi.org/10.1016/j.seta.2021.101534.
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Zhao, Hongbin, Yu Cao, Chang Liu, and Xiang Qi. "A thermodynamic performance analysis on influence parameters of COG-CCHP based on exergy." World Journal of Engineering 15, no. 6 (December 3, 2018): 771–85. http://dx.doi.org/10.1108/wje-12-2017-0416.
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PurposeThe purpose of this paper is to investigate the performance of coke oven gas (COG)-combined cooling, heating and power (CCHP) system and to mainly focus on studying the influence of the environmental conditions, operating conditions and gas conditions on the performance of the system and on quantifying the distribution of useful energy loss and the saving potential of the integrated system changing with different parameters.Design/methodology/approachThe working process of COG-CCHP was simulated through the establishment of system flow and thermal analysis mathematical model. Using exergy analysis method, the COG-CCHP system’s energy consumption status and the performance changing rules were analyzed.FindingsThe results showed that the combustion chamber has the largest exergy loss among the thermal equipments. Reducing the environmental temperature and pressure can improve the entire system’s reasonable degree of energy. Higher temperature and pressure improved the system’s perfection degree of energy use. Relatively high level of hydrogen and low content of water in COG and an optimal range of CH4volume fraction between 35 per cent and 46 per cent are required to ensure high exergy efficiency of this integration system.Originality/valueThis paper proposed a CCHP system with the utilization of coke oven gas (COG) and quantified the distribution of useful energy loss and the saving potential of the integrated system under different environmental, operating and gas conditions. The weak links of energy consumption within the system were analyzed, and the characteristics of COG in this way of using were illustrated. This study can provide certain guiding basis for further research and development of the CCHP system performance.
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Wenzel, Paula M., and Peter Radgen. "Multi-Criteria Comparison of Energy and Environmental Assessment Approaches for the Example of Cooling Towers." Applied System Innovation 5, no. 5 (September 5, 2022): 89. http://dx.doi.org/10.3390/asi5050089.
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Cooling towers remove economically or technically unusable heat using considerable amounts of electricity and, in many cases, water. Several approaches, which vary in methodology, scope, and level of detail, are used for environmental evaluations of these cooling systems. Although the chosen approach has a significant impact on decisions made at the plant level, no methodology has yet been standardized for selecting the approach that best serves the objectives of the evaluation. Thus, this paper provides comparison criteria for the systematic selection of suitable evaluation methods for cooling towers and classifies how the methods score in this respect. These criteria, such as ‘life cycle thinking’, ‘inventoried physical quantities’, ‘temporal resolution’, ‘formalization’, and ‘data availability’, are grouped by overall evaluation objectives such as ‘thoroughness’, ‘scientific soundness’, and ‘usability’. Subsequently, these criteria were used to compare material flow analysis, energy analysis, environmental network analysis, life cycle inventory, life cycle assessment, environmental footprint methods, emergy analysis, exergy analysis, and the physical optimum method. In conclusion, material flow analysis is best suited for the analysis of cooling towers when impact assessment is not required; otherwise, life cycle assessment meets most of the defined criteria. Moreover, only exergy-based methods allow for the inclusion of volatile ambient conditions.
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Atta, Uzma, Majid Hussain, and Riffat Naseem Malik. "Environmental impact assessment of municipal solid waste management value chain: A case study from Pakistan." Waste Management & Research: The Journal for a Sustainable Circular Economy 38, no. 12 (August 19, 2020): 1379–88. http://dx.doi.org/10.1177/0734242x20942595.
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The present study quantified environmental impacts of the Rawalpindi Waste Management Company (RWMC) value chain in Pakistan for three consecutive years (2015–2018) using a cradle-to-grave life cycle assessment (LCA) approach. Energy potential from municipal solid wastes (MSW) was also predicted till the year 2050. Based on a functional unit of 1.0 tonne of MSW, the study analyzed inputs and outputs data through SimaPro v.8.3 applying CML 2000 methodology and cumulative exergy demand indicator (CExD). LCA revealed that operational activities of RWMC mainly contributed to marine aquatic ecotoxicity, i.e. 8962.83 kg1,4-DBeq t−1 MSW, indicating long-range transport of petrogenic hydrocarbons from the company’s fleet gasoline combustion. Similarly, human toxicity potential, global warming potential and freshwater aquatic ecotoxicity potential were also found to be significant, i.e. 18.14 kg1,4-DBeq t−1 MSW, 15.79 kgCO2eq t−1 MSW and 6.22 kg1,4-DBeq t−1 MSW, respectively. The CExD showed that company activities consumed 827.14 MJ t−1 MSW exergy from nature, and gasoline used in MSW transport was the most exergy-intensive process, using 634.47 MJ exergy per tonne MSW disposed of. Projections for energy generation potential up to the year 2050 showed that MSW of Rawalpindi city will have the potential to produce 3901 megawatt of energy to fulfill the energy needs of the country. Possible stratagems to reduce environmental impacts from the municipal solid waste management (MSWM) value chain of RWMC include curtailing dependency on petrogenic and fossil fuels in mobile sources, optimization of waste collection methods and dumping routes, inclining attention toward suitable wastes-to-energy conversion technology and opting for a holistic approach of MSWM in Pakistan.
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Almeida, G. S., F. V. S. Tavares, W. M. P. B. Lima, and A. G. Barbosa de Lima. "Energetic and Exergetic Analysis of the Clay Bricks Drying in an Industrial Tunnel Dryer." Defect and Diffusion Forum 369 (July 2016): 104–9. http://dx.doi.org/10.4028/www.scientific.net/ddf.369.104.
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The purpose of this paper is to present a theoretical study of industrial hollow bricks drying in across flow tunnel dryer. The theoretical model is based on the 1st and 2nd laws of Thermodynamic applied to the system. To validate the methodology, numerical and experimental data of the moisture content of the brick during the drying in an industrial scale are compared and a good agreement was obtained. Results of moisture content and temperature of the product and air, and energy and exergy efficiencies are presented and analysed.
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Li, Bin, Chengjie Li, Junying Huang, and Changyou Li. "Exergoeconomic Analysis of Corn Drying in a Novel Industrial Drying System." Entropy 22, no. 6 (June 20, 2020): 689. http://dx.doi.org/10.3390/e22060689.
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The improvement of the design and operation of energy conversion systems is a theme of global concern. As an energy intensive operation, industrial agricultural product drying has also attracted significant attention in recent years. Taking a novel industrial corn drying system with drying capacity of 5.5 t/h as a study case, based on existing exergoeconomic and exergetic analysis methodology, the present work investigated the exergetic and economic performance of the drying system and identified its energy use deficiencies. The results showed that the average drying rate for corn drying in the system is 1.98 gwater/gdry matter h. The average exergy rate for dehydrating the moisture from the corn kernel is 345.22 kW and the exergy efficiency of the drying chamber ranges from 14.81% to 40.10%. The average cost of producing 1 GJ exergy for removing water from wet corn kernels is USD 25.971, while the average cost of removing 1 kg water is USD 0.159. These results might help to further understand the drying process from the exergoeconomic perspective and aid formulation of a scientific index for agricultural product industrial drying. Additionally, the results also indicated that, from an energy perspective, the combustion chamber should be firstly optimized, while the drying chamber should be given priority from the exergoeconomics perspective. The main results would be helpful for further optimizing the drying process from both energetic and economic perspectives and provide new thinking about agricultural product industrial drying from the perspective of exergoeconomics.
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Parekh, A. D., P. R. Tailor, and Nirav Sutaria. "Thermoeconomic Optimization of Cascade Refrigeration System Using Refrigerant Pair R404A-R508B." Applied Mechanics and Materials 110-116 (October 2011): 677–84. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.677.
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In present work, an exergy based thermoeconomic optimization is applied to an actual cascade refrigeration system. The advantage of using exergy method of thermoeconomic optimization is that various elements of the system i.e. condenser, evaporator, compressor and cascade condenser can be optimized separately. A simplified cost minimization methodology based on thermoeconomic concept is applied to calculate the economic costs of all internal flows and products of the system by formulating thermoeconomic cost balance. Once these costs are determined, the system is thermoeconomically evaluated to identify the effects of the design variables on cost of the flows and products. This enables to suggest changes of the design variables that would make the overall system cost effective. Finally, an approximate optimum design configuration is obtained. The result shows that the increase in Coefficient of Performance and exergetic efficiency of the system by 13.76% and 16.20% respectively. The cost of the product and total investment cost are decreased by 19.71% and 19.18% respectively. This shows significant improvement in system performance as well as reduction in the cost of product and total investment cost. The reduction in cost and improvement in performance suggest the commercial acceptability of the cascade refrigeration system in a best efficient way.
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Ivančić, Aleksandar, Joaquim Romaní, Jaume Salom, and Maria-Victoria Cambronero. "Performance Assessment of District Energy Systems with Common Elements for Heating and Cooling." Energies 14, no. 8 (April 20, 2021): 2334. http://dx.doi.org/10.3390/en14082334.
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District energy systems, especially those integrating renewables or low exergy sources, have multiple elements for generating heating and cooling. Some of these elements might be used for both purposes: heating and cooling, either simultaneously or alternatively. This makes it more complex to separate the assessment and have a clear picture on performance of cooling service on one side, and heating services on the other, in terms of energy, environmental, and economic results. However, a correct comparison between different district energy configurations or among district energy and conventional solutions requires split assessment of each service. The paper presents a methodology for calculating different district heating and cooling system key performance indicators (KPIs), distinguishing between heating and cooling ones. A total of eleven indicators are organized under four categories: energy, environment, economy and socio-economy. Each KPI is defined for heating service and for cooling service. According to this, the methodology proposes a demand-based and an investment-based share factors that facilitate the heating and cooling KPI calculation.
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Fialko, N., A. Stepanova, R. Navrodska, and S. Shevchuk. "Optimization of geometric parameters and analysis of exergy efficiency of heat recovery units glass furnaces." Energy and automation, no. 3(55) (June 23, 2021): 5–17. http://dx.doi.org/10.31548/energiya2021.03.005.
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The paper presents the results of optimization of the geometric parameters of the heat exchange surface of water and air-heating heat exchangers of glass-making furnaces and an analysis of their exergy efficiency. Ensuring the efficient operation of heat recovery units in various thermal circuits is an urgent problem of heat power engineering. The aim of the work is to establish the optimal areas of the geometric parameters of the heat exchange surface of heat recovery units of glass-melting furnaces and to analyze their exergy efficiency. The paper presents the results of solving the tasks necessary to achieve the goal: - using statistical methods for planning the experiment, determine the levels of variation of the parameters of the geometric surface of heat transfer for the heat recovery units under study and calculate the values of the criteria for evaluating the efficiency at the points of the central orthogonal compositional plan; - to obtain the regression equations for the investigated heat exchangers, to determine the optimal areas of change in the geometric parameters of the heat exchange surface and the corresponding exergy efficiency criteria. To determine the optimal areas of geometric parameters of the heat exchange surface, a complex methodology is used based on the methods of exergy analysis and statistical methods of the theory of experiment planning. It has been established that when designing heat recovery schemes for heating water in heat supply systems and for heating blast air, heat recovery units with the following values of the areas of variation of the geometric parameters of the heat exchange surface can be used: - the values of the area of variation of the distance between the panels for heat recovery units with a staggered and corridor arrangement of pipes in a bundle s1 = 58.0-62.0 mm. - the values of the areas of change in the diameter of pipes for a hot water heat exchanger with a corridor arrangement of pipes d = 41.0-43.0 mm and for an air heating heat exchanger with a staggered and corridor arrangement of pipes d = 29.0-31.0 mm. - the use of the values of the ranges of change of other parameters is carried out taking into account additional technological factors. It has been established that the exergy efficiency of hot water heat recovery units is in all cases higher than the exergy efficiency of air heating units. For hot water heat exchangers, the values of exergy criteria are lower than for air heating ones: k – 2.0 times, ε – by 7.5%, m0 – 1.9 times. The expediency of using the investigated heat recovery units in heat recovery circuits of glass melting furnaces has been established, taking into account the results obtained and in the presence of certain technological factors. The results obtained and further developments in the field of optimization of the operating parameters of heat recovery units for glass-melting furnaces will provide an increase in the efficiency of heat recovery equipment for power plants.
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Bhaskaran Anangapal, Hari. "Energy and exergy analysis of fuels." International Journal of Energy Sector Management 8, no. 3 (August 26, 2014): 330–40. http://dx.doi.org/10.1108/ijesm-04-2013-0012.
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Purpose – The purpose of this study is to carry out energy and exergy analysis of fuels. Production of power and heat in industrialized countries is almost entirely based on combustion of fuels. Usually, combustion takes place in boilers or furnace; well-designed boilers have high thermal efficiencies of > 90 per cent. Even very high efficiencies, close to 100 per cent can be achieved depending on the applied fuel and boiler type. These high thermal efficiencies do suggest that combustion processes are highly optimized and do not need further improvements with regard to their thermodynamic performance. Second law (entropy or exergy) evaluations, however, shows that thermodynamic losses of boiler and furnaces are much larger than the thermal efficiencies do suggest. During combustion, air is predominantly used. When using air, the adiabatic combustion temperature depends only on the properties of fuel and air. The determining parameters for optimal fuel utilization are the fuel type, their composition and moisture content, the air temperature and air factor at combustion inlet. Design/methodology/approach – Following assumptions are made for the analysis: calculation on the basis of 100 kg of dry and ash free fuel entering the control volume; fuel entering the control volume at T0, P0 and reacting completely with air entering separately at T0, P0 to form CO2, SO2, N2 and H2O, which exit separately at T0, P0 (T0 = 298 K; P0 = 1 atm); all heat transfer occurs at temperature T0; and the chemical exergy of the ash has been ignored The availability change and the irreversibility for chemical reactions of hydrocarbon fuels were studied because fuel and dry air composed of O2 and N2 react to form products of combustion in the restricted dead state, and fuel and dry air composed of O2 and N2 react to form products of combustion which end up in the environmental (unrestricted) dead state. The difference between the above two statement, is the chemical availability of the product gases as they proceed from the restricted to the unrestricted dead state. These evaluations were made in terms of enthalpy and entropy values of the reacting species. T0 extend these concepts to the most general situation, it is considered a steady-state control volume where the fuels enters at the restricted dead state, the air (oxidant) is drawn from the environment, and the products are returned to the unrestricted dead state. Findings – It is evident from the analysis that an air factor of 1.10-1.20 is sufficient for liquid fuels, whereas solid fuels will require air factors of 1.15–1.3. When the temperatures of the products of combustion (Tp) are cooled down to that of T0, the maximum reversible work occurs. From the analysis, it is clear that the rather low combustion temperature and the need for cooling down the flue gases to extract the required heat are the main causes of the large exergy losses. The maximum second law efficiency also occurs when Tp is set equal to T0. The maximum second law efficiency per kilo mole of fuel is found to be 73 per cent, i.e. 73 per cent of the energy released by the cooling process could theoretically be converted into useful work. It is evident that reducing exergy losses of combustion is only useful if the heat transferred from the flue gas is used at high temperatures. Otherwise, a reduction of exergy loss of combustion will only increase the exergy loss of heat transfer to the power cycle or heat-absorbing process. The exergy loss of combustion can be reduced considerable by preheating combustion air. Higher preheat temperatures can be obtained by using the flue gas flow only for preheating air. The remainder of the flue gas flow can be used for heat transfer to a power cycle or heat-absorbing process. Even with very high air preheat temperatures, exergy losses of combustion are still > 20 per cent. The application of electrochemical conversion of fuel, as is realized in fuel cells, allows for much lower exergy loses for the reaction between fuel and air than thermal conversion. For industrial applications, electrochemical conversion is not yet available, but will be an interesting option for the future. Originality/value – The outcome of the study would certainly be an eye-opener for all the stakeholders in thermal power plants for considering the second law efficiency and to mitigate the irreversibilities.
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Herrera, R., and F. Méndez. "An advanced exergy analysis based on the dysfunction and malfunction methodology for a combined cycle power plant: a Mexican case study." International Journal of Exergy 27, no. 1 (2018): 105. http://dx.doi.org/10.1504/ijex.2018.093902.
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Herrera, R., and F. Méndez. "An advanced exergy analysis based on the dysfunction and malfunction methodology for a combined cycle power plant: a Mexican case study." International Journal of Exergy 27, no. 1 (2018): 105. http://dx.doi.org/10.1504/ijex.2018.10014872.
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Jahromi, Farid Sadeghian, Masoud Beheshti, and Razieh Fereydon Rajabi. "Comparison between differential evolution algorithms and response surface methodology in ethylene plant optimization based on an extended combined energy - exergy analysis." Energy 164 (December 2018): 1114–34. http://dx.doi.org/10.1016/j.energy.2018.09.059.
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Voloshchuk, V., and Eu Nikiforovich. "MODELING OF THERMAL INSTALLATIONS BASED ON THERMODYNAMIC APPROACHES." Journal of Numerical and Applied Mathematics, no. 1 (135) (2021): 53–58. http://dx.doi.org/10.17721/2706-9699.2021.1.06.
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The most widespread approaches to the study of thermal systems involve the iterative implementation of the following steps: thermodynamics, heat and mass transfer, hydrodynamics, economics and ecology. Such methodology cannot combine economic, environmental and thermodynamic aspects from the beginning of the analysis. It does not provide information concerning not only external, but also internal, caused by thermodynamic inefficiencies of system components, impact factors on economic and ecological characteristics. Modeling methods based on the combined application of the First and Second Laws of Thermodynamics (methods of entropy and exergetic analysis), and their combination with economic and environmental assessment make it possible to identify the location, magnitude, causes, costs and environmental impact of thermodynamic inefficiencies in an energy conversion system. The paper proposes the improvement of methods for modeling thermal systems on the base of exergy analysis. It has been shown that combining exergetic, economic and ecological assessment can significantly simplify tasks of finding parameters and structure of the studied system. Examples of implementation of such studies have been presented.
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Ghannadzadeh, Ali, and Amir Hossein Tarighaleslami. "Exergy-aided environmental life cycle assessment of propylene oxide production." International Journal of Life Cycle Assessment 27, no. 1 (December 9, 2021): 20–37. http://dx.doi.org/10.1007/s11367-021-01969-z.
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Abstract Purpose Propylene oxide (PO) is one of the useful chemicals that is predicted to experience a compound annual growth rate of 3.9% from 2020 through 2027. The environmental burdens of the current PO production process and its corresponding utility system including power generation system need to be determined quantitatively as a response to increasing demands for its environmentally sustainable production process in the energy transition period from fossil fuels towards renewable energy resources. Methods A new methodology is proposed to study the PO production process called exergy-aided environmental life cycle assessment (EELCA), using the US National Renewable Energy Laboratory’s database known as life cycle inventory (LCI) database. EELCA is dedicated to LCA studies of processes in the energy transition period and is aided by Monte Carlo simulation (MCS) as a tool for discernibility analysis which brings another dimension to the EELCA because MCS was often used to assess uncertainty in LCA studies. EELCA impact categories are classified into two classes: (i) emission-dependent impact categories addressed by ReCiPe and (ii) resource-dependent impact categories covered by cumulative exergy demand (CExD). The alternative energy like bioenergy is evaluated through the stepwise scenarios assisted by MCS, which are employed in openLCA with 10,000 iterations. Results and discussion The cumulative exergy depletion of the base scenario is 6.1898 MJ (CExD). The human health and ecosystem impacts are 3.65E-06 DALY and 1.58E-08 species.yr, respectively. Human health-total (2.7E-4 DALY) is the most important category, where the power generation system by residual fuel oil (33.19%) is on top of the list. By analysing statistically discernible scenarios using EELCA, it has been proven that natural gas is not a proper choice for energy mix in the energy transition period. This is because natural gas-based scenarios present more burden compared to residual fuel oil-based scenarios especially regarding human toxicity, freshwater ecotoxicity, marine ecotoxicity, terrestrial acidification, and particulate matter formation. This study shows that the reduction in environmental impacts without changes in the production process technology is feasible through implementing bioenergy scenarios. Conclusions Having applied successfully EELCA, this study shows that PO production in the present configuration is not sustainable at all. The statistically discernible scenarios regarding energy mix selection help to enhance sustainability of the PO production process. Moreover, by examining the application of CExD along with LCA analysis, it is proved that by using the concept of CExD, we were able to represent the environmental impacts of the entire system with one figure, which tremendously facilitates the calculations in MCS.
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Leal, Elisângela M., and Jack Brouwer. "A Thermodynamic Analysis of Electricity and Hydrogen Co-Production Using a Solid Oxide Fuel Cell." Journal of Fuel Cell Science and Technology 3, no. 2 (September 29, 2005): 137–43. http://dx.doi.org/10.1115/1.2173669.
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This paper presents the electricity and hydrogen co-production concept, a methodology for the study of SOFC hydrogen co-production, and simulation results that address the impact of reformer placement in the cycle on system performance. The methodology is based on detailed thermodynamic and electrochemical analyses of the systems. A comparison is made between six specific cycle configurations, which use fuel cell heat to drive hydrogen production in a reformer using both external and internal reforming options. SOFC plant performance has been evaluated on the basis of methane fuel utilization efficiency and each component of the plant has been evaluated on the basis of second law efficiency. The analyses show that in all cases the exergy losses (irreversibilities) in the combustion chamber are the most significant losses in the cycle. Furthermore, for the same power output, the internal reformation option has the higher electrical efficiency and produces more hydrogen per unit of natural gas supplied. Electrical efficiency of the proposed cycles ranges from 41 to 44%, while overall efficiency (based on combined electricity and hydrogen products) ranges from 45 to 80%. The internal reforming case (steam-to-carbon ratio of 3.0) had the highest overall and electrical efficiency (80 and 45% respectively), but lower second law efficiency (61%), indicating potential for cycle improvements.
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Méndez-Cruz, Ladislao Eduardo, Miguel Ángel Gutiérrez-Limón, Helen Lugo-Méndez, Raúl Lugo-Leyte, Teresa Lopez-Arenas, and Mauricio Sales-Cruz. "Comparative Thermodynamic Analysis of the Performance of an Organic Rankine Cycle Using Different Working Fluids." Energies 15, no. 7 (April 1, 2022): 2588. http://dx.doi.org/10.3390/en15072588.
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Today, the study of thermal systems that take advantage of residual thermal sources in the power generation sector is of great importance to mitigate environmental impact and promote sustainable alternatives in this sector. Among these alternatives, the organic Rankine cycle (ORC) is of great relevance since it allows taking advantage of residual energy sources at low temperatures. This work presents a methodology to evaluate the feasibility of using a refrigerant as a working fluid in an organic Rankine cycle based on an exergetic viability index. As a case study, R134a, R600a, R245fa, and R123 refrigerants were considered. A residual thermal source was used that came from the Hybrid Cycle Plant of the Valley of Mexico. Thermodynamic analysis was performed to determine generated power, thermal efficiency, refrigerant mass flow, pinch point temperature difference, specific steam consumption, unused thermal exergy flow, exergy efficiency, and total heat transfer requirement. The weighted average of the differences between these indicators, the global warming index, and the ozone depletion potential relative to the most favorable indicator corresponded to the definition of the exergetic viability index of the refrigerant. The results indicate that the ORC operating at condensing temperatures of 25, 35, and 45 °C with R245fa shows the highest rate of exergetic viability despite not generating the greatest amount of power and being one of the refrigerants with the highest total heat transfer requirement. Finally, at condensing temperatures above 45 °C, it is observed that R600a is exergetically the most viable refrigerant used in the ORC.
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Santo, Denilson Boschiero do Espirito. "An energy and exergy analysis of a high-efficiency engine trigeneration system for a hospital: A case study methodology based on annual energy demand profiles." Energy and Buildings 76 (June 2014): 185–98. http://dx.doi.org/10.1016/j.enbuild.2014.02.014.
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Walker, H. A., and J. H. Davidson. "Second-Law Analysis of a Two-Phase Self-Pumping Solar Water Heater." Journal of Solar Energy Engineering 114, no. 3 (August 1, 1992): 188–93. http://dx.doi.org/10.1115/1.2930004.
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Entropy generated by operation of a two-phase self-pumping solar water heater under Solar Rating and Certification Corporation rating conditions is computed numerically in a methodology based on an exergy cascade. An order of magnitude analysis shows that entropy generation is dominated by heat transfer across temperature differences. Conversion of radiant solar energy incident on the collector to thermal energy within the collector accounts for 87.1 percent of total entropy generation. Thermal losses are responsible for 9.9 percent of total entropy generation, and heat transfer across the condenser accounts for 2.4 percent of the total entropy generation. Mixing in the tempering valve is responsible for 0.7 percent of the total entropy generation. Approximately one half of the entropy generated by thermal losses is attributable to the self-pumping process. The procedure to determine total entropy generation can be used in a parametric study to evaluate the performance of two-phase hot water heating systems relative to other solar water heating options.
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Priambodo, Dedy, Erlan Dewita, and Ign Djoko Irianto. "ANALISIS ENERGI DAN EKSERGI PADA SISTEM HTR-10 SIKLUS TURBIN UAP." Jurnal Pengembangan Energi Nuklir 17, no. 1 (June 14, 2015): 33. http://dx.doi.org/10.17146/jpen.2015.17.1.2561.
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ABSTRAK ANALISIS ENERGI DAN EKSERGI PADA SISTEM HTGR SIKLUS TURBIN UAP. Reaktor tipe HTGR merupakan reaktor yang rencana akan dibangun sebagai Reaktor Daya Eksperimental (RDE) pertama di Indonesia. Reaktor HTGR merupakan reaktor dengan suhu pendingin keluar reaktor tinggi (686°C ~ 950°C), efisiensi termal tinggi serta mempunyai sistem keselamatan pasif dan melekat. Untuk mengetahui ketepatan efisiensi suatu pembangkit dipandang tidak cukup jika hanya mengacu pada efisiensi energi saja seperti yang didasarkan pada Hukum I Termodinamika, namun perlu dikombinasikan dengan pendekatan eksergi yang berdasarkan Hukum II Termodinamika. Karena itu, tujuan studi adalah melakukan analisis energi dan eksergi pada sistem HTGR siklus turbin uap untuk mengetahui kerugian/ kehilangan panas yang terjadi dalam komponen sistem pembangkit, sehingga dapat diketahui potensi-potensi kerugian dan dapat dilakukan perbaikan. Metodologi yang digunakan adalah perhitungan menggunakan program cycle tempo dengan input data dari reaktor HTR-10. Hasil studi analisis dan evaluasi terhadap ireversibilitas sistem reaktor HTGR menggunakan siklus turbin uap menunjukkan bahwa reaktor merupakan komponen yang paling tidak efisien diantara seluruh komponen yang ada dalam sistem. Hal ini disebabkan ireversibilitas yang terjadi dalam transfer energi hasil reaksi pembelahan ke pendingin helium. Pembangkit uap, turbin, kondensor, adalah komponen penyumbang kerugian terbesar berikutnya. Hasil studi juga menunjukkan bahwa efisiensi sistem HTGR siklus turbin uap mempunyai potensi besar untuk dilakukan perbaikan sehingga mampu memberikan efek yang signifikan terhadap perbaikan efisiensi sistem. Kata kunci: energi, eksergi, HTGR, analisis, turbin uap ABSTRACT ENERGY AND EXERGY ANALYSIS ON THE STEAM TURBINE CYCLE OF HTGR SYSTEM. HTGR type reactor is planned to be built reactors as the first Experimental Power Reactor (RDE) in Indonesia. HTGR tipe reactor is a reactor with a high reactor outlet temperature (~ 900 ° C), high thermal efficiency and also it have inherent and passive safety systems. To determine the accuracy of the efficiency of a power plant is not enough if it merely refers to the energy efficiency just as it is based on the first law of thermodynamics, but it needs to be combined with exergy approach that is based on the second law of thermodynamics. Therefore, the purpose of the study is to analyze the energy and exergy of HTGR-steam turbine cycle system to determine the loss / heat loss that occurs in the power system components, so it can be seen the potential loss and can be repaired. The methodology used is a calculation using the program cycle due to the data input of the HTR-10 reactor. The results of analysis and evaluation of the irreversibility of HTGR reactor system using a steam turbine cycle shows that the reactor is a component of the least efficient among all components in the system. This is due to the irreversibility of energy transfer that occurs in the cleavage reaction proceeds to the helium coolant. Steam generators, turbines, condensers, is a component of the next largest contributor kerugia. The study shows that the efficiency of the steam turbine cycle HTGR system has great potential to be improved so it can provide a significant effect on the improvement of the efficiency of the system. Keywords: energy, exergy, HTGR, analysis, steam turbine