Journal articles on the topic 'Exergy concepts'
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1
Wall, G. "Exergy tools." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 217, no. 2 (January 1, 2003): 125–36. http://dx.doi.org/10.1243/09576500360611399.
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This paper presents a number of exergy-based concepts and methods, e.g. efficiency concepts, exergy flow diagrams, exergy utility diagrams (EUDs), life cycle exergy analysis (LCEA) and exergy economy optimization (EEO). These tools are useful in order to describe, analyse and optimize energy conversion systems.
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Pal, Rajinder. "Chemical exergy of ideal and non-ideal gas mixtures and liquid solutions with applications." International Journal of Mechanical Engineering Education 47, no. 1 (December 29, 2017): 44–72. http://dx.doi.org/10.1177/0306419017749581.
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Exergy or availability, although not a recent concept, is receiving extensive coverage in scientific publications due to its vast applications in different scientific and engineering fields. Exergy of a system consists of two parts: thermo-mechanical exergy and chemical exergy. While thermo-mechanical exergy of systems is covered to a certain extent in modern undergraduate textbooks on engineering thermodynamics, chemical exergy is mentioned only briefly. In particular, the theoretical and conceptual developments related to chemical exergy are not covered in any detail. The focus of this article is the chemical exergy of materials. Special attention is given to the theoretical treatment of non-ideal gas mixtures and liquid solutions. The equations necessary to estimate the chemical exergy of ideal and non-ideal mixtures and solutions are developed from the fundamental concepts. Where necessary, numerical examples are given to illustrate the concepts for the benefit of the students. Finally, a practical problem dealing with the furnace/boiler unit of a practical steam power plant is solved using the concepts of chemical exergy and exergy analysis. As the material presented in this article involves advanced level concepts in thermodynamics, it is most suitable for the second, advanced level, course in engineering thermodynamics in third year, after the students have completed a full one-term course on introductory thermodynamics in their second year.
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O'Toole, F., and Eur Ing J. A. McGovern. "Some Concepts and Conceptual Devices for Exergy Analysis." Proceedings of the Institution of Mechanical Engineers, Part C: Mechanical Engineering Science 204, no. 5 (September 1990): 329–40. http://dx.doi.org/10.1243/pime_proc_1990_204_113_02.
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The main concepts of exergy analysis are outlined with special emphasis on the fact that exergy can be transferred and transported and on the distinction between work and useful work. The exergy transfers associated with work and with heat are described. The relationship between so-called flow exergy and non-flow exergy is explained. Three conceptual devices which can be inserted at an analysis boundary are presented. These achieve mechanical separation between the systems on either side of the boundary so that an exergy transfer equivalent to the net exergy transferred and transported across the boundary can be visualized and evaluated. The first conceptual device can be used where heat transfer occurs at a boundary, the second where a steady flow fluid stream enters and leaves a system, and the third where air and fuel streams enter and flue gases leave a combustion system.
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Wall, Göran, and Mei Gong. "On exergy and sustainable development—Part 1: Conditions and concepts." Exergy, An International Journal 1, no. 3 (January 2001): 128–45. http://dx.doi.org/10.1016/s1164-0235(01)00020-6.
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Gaggioli, Richard A., David H. Richardson, and Anthony J. Bowman. "Available Energy—Part I: Gibbs Revisited." Journal of Energy Resources Technology 124, no. 2 (May 28, 2002): 105–9. http://dx.doi.org/10.1115/1.1448336.
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The concept of available energy, as defined by Gibbs is revisited. Being more general, this concept of available energy differs from that referred to commonly by the same name, or as “exergy” or “availability.” He gave representations of available energy for two circumstances. The first was the available energy of a “body,” for the case when a body, alone, is in a nonequilibrium condition and therefore has energy available. In turn, he presented the available energy of “the body and medium,” for the energy that is available because a body is not in equilibrium with some arbitrarily specified medium or “reference environment.” Gibbs’ did not present formulas to represent available energy. His representations were verbal descriptions regarding surfaces, curves and lines. Although his verbiage was augmented by some graphics, visualization of the geometrical entities he described depended largely on the imagination of the reader. In Part I, we take advantage of modern graphics software to illustrate more vividly not only the available energy he described verbally but also his interesting concepts of “available vacuum” and “capacity for entropy.” We argue that all of these concepts are equivalent. Since Gibbs, representations with formulas have been developed and are common for the “available energy of body and medium.” Gaggioli has developed formulas which are more general, to represent “the available energy of the body (alone)” and to assign an exergy to subsystems of the body as a measure of each subsystem’s contribution to the available energy. In contrast to the available energy, exergy is an additive property, so that balance equations can be written. This exergy is independent of any “reference environment,” which is important both theoretically and practically because of its relevance to proper selection of “the dead state.” In those special cases when the dead state is one in equilibrium with a “reference environment,” this more generalized exergy encompasses that concept called (today) exergy in textbooks and journals.
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Dincer, Ibrahim, and Yunus Cengel. "Energy, Entropy and Exergy Concepts and Their Roles in Thermal Engineering." Entropy 3, no. 3 (August 21, 2001): 116–49. http://dx.doi.org/10.3390/e3030116.
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Patil, Vikram C., and Paul I. Ro. "Energy and Exergy Analysis of Ocean Compressed Air Energy Storage Concepts." Journal of Engineering 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/5254102.
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Optimal utilization of renewable energy resources needs energy storage capability in integration with the electric grid. Ocean compressed air energy storage (OCAES) can provide promising large-scale energy storage. In OCAES, energy is stored in the form of compressed air under the ocean. Underwater energy storage results in a constant-pressure storage system which has potential to show high efficiency compared to constant-volume energy storage. Various OCAES concepts, namely, diabatic, adiabatic, and isothermal OCAES, are possible based on the handling of heat in the system. These OCAES concepts are assessed using energy and exergy analysis in this paper. Roundtrip efficiency of liquid piston based OCAES is also investigated using an experimental liquid piston compressor. Further, the potential of improved efficiency of liquid piston based OCAES with use of various heat transfer enhancement techniques is investigated. Results show that adiabatic OCAES shows improved efficiency over diabatic OCAES by storing thermal exergy in thermal energy storage and isothermal OCAES shows significantly higher efficiency over adiabatic and diabatic OCAES. Liquid piston based OCAES is estimated to show roundtrip efficiency of about 45% and use of heat transfer enhancement in liquid piston has potential to improve roundtrip efficiency of liquid piston based OCAES up to 62%.
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III, Rush D. Robinett, and David G. Wilson. "Exergy and irreversible entropy production thermodynamic concepts for nonlinear control design." International Journal of Exergy 6, no. 3 (2009): 357. http://dx.doi.org/10.1504/ijex.2009.025326.
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Hua, B., Q. Yin, and G. Wu. "Energy Optimization Through Exergy-Economic Evaluation." Journal of Energy Resources Technology 111, no. 3 (September 1, 1989): 148–53. http://dx.doi.org/10.1115/1.3231416.
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This paper deals with total system optimization for energy use in complex process systems based on the premise that the sub-systems or local schemes have been optimally designed. The problem, however, has not been solved so far. Based on the three-links-model established for the energy structure of process systems, this paper advances an evolving optimization strategy, in which the results of quantitative exergy-economic evaluation of the sub-systems are taken as the criteria to guide trade-off among them and lead the total scheme gradually towards optimum. The general concepts, evaluation equations, applying procedure, and examples are presented. Notable economical and energy-saving benefits can be (have been) obtained when used on actual industrial plants.
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Varbanov, Petar Sabev, Hon Huin Chin, Alexandra-Elena Plesu Popescu, and Stanislav Boldyryev. "Thermodynamics-Based Process Sustainability Evaluation." Energies 13, no. 9 (April 28, 2020): 2132. http://dx.doi.org/10.3390/en13092132.
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This article considers the problem of the evaluation of the sustainability of heterogeneous process systems, which can have different areas of focus: from single process operations to complete supply chains. The proposed method defines exergy-based concepts to evaluate the assets, liabilities, and the exergy footprint of the analysed process systems, ensuring that they are suitable for Life Cycle Assessment. The proposed concepts, evaluation framework and cumulative Exergy Composite Curves allow the quantitative assessment of process systems, including alternative solutions. The provided case studies clearly illustrate the applicability of the method and the close quantitative relationship between the exergy profit and the potential sustainability contribution of the proposed solutions. The first case study demonstrates how the method is applied to the separation and reuse of an acetic-acid-containing waste stream. It is shown that the current process is not sustainable and needs substantial external exergy input and deeper analysis. The second case study concerns Municipal Solid Waste treatment and shows the potential value and sustainability benefit that can be achieved by the extraction of useful chemicals and waste-to-energy conversion. The proposed exergy footprint accounting framework clearly demonstrates the potential to be applied to sustainability assessment and process improvement while simultaneously tracking different kinds of resources and impacts.
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Palazzo, Pierfrancesco. "Chemical and Mechanical Aspect of Entropy-Exergy Relationship." Entropy 23, no. 8 (July 28, 2021): 972. http://dx.doi.org/10.3390/e23080972.
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The present research focuses the chemical aspect of entropy and exergy properties. This research represents the complement of a previous treatise already published and constitutes a set of concepts and definitions relating to the entropy–exergy relationship overarching thermal, chemical and mechanical aspects. The extended perspective here proposed aims at embracing physical and chemical disciplines, describing macroscopic or microscopic systems characterized in the domain of industrial engineering and biotechnologies. The definition of chemical exergy, based on the Carnot chemical cycle, is complementary to the definition of thermal exergy expressed by means of the Carnot thermal cycle. These properties further prove that the mechanical exergy is an additional contribution to the generalized exergy to be accounted for in any equilibrium or non-equilibrium phenomena. The objective is to evaluate all interactions between the internal system and external environment, as well as performances in energy transduction processes.
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Oyedepo, S. O., R. O. Fagbenle, S. S. Adefila, and M. M. Alam. "Performance evaluation of selected gas turbine power plants in Nigeria using energy and exergy methods." World Journal of Engineering 12, no. 2 (April 1, 2015): 161–76. http://dx.doi.org/10.1260/1708-5284.12.2.161.
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This study presents thermodynamic analysis of the design and performance of eleven selected gas turbine power plants using the first and second laws of thermodynamics concepts. Energy and exergy analyses were conducted using operating data collected from the power plants to determine the energy loss and exergy destruction of each major component of the gas turbine plant. Energy analysis showed that the combustion chamber and the turbine are the components having the highest proportion of energy loss in the plants. Energy loss in combustion chamber and turbine varied from 33.31 to 39.95% and 30.83 to 35.24% respectively. The exergy analysis revealed that the combustion chamber is the most exergy destructive component compared to other cycle components. Exergy destruction in the combustion chamber varied from 86.05 to 94.67%. Combustion chamber has the highest exergy improvement potential which range from 30.21 to 88.86 MW. Also, its exergy efficiency is lower than that of other components studied, which is due to the high temperature difference between working fluid and burner temperature. Increasing gas turbine inlet temperature (GTIT), the exergy destruction of this component can be reduced.
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Sekret, Robert, and Anna Nitkiewicz. "Exergy analysis of the performance of low-temperature district heating system with geothermal heat pump." Archives of Thermodynamics 35, no. 1 (March 1, 2014): 77–86. http://dx.doi.org/10.2478/aoter-2014-0005.
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Abstract Exergy analysis of low temperature geothermal heat plant with compressor and absorption heat pump was carried out. In these two concepts heat pumps are using geothermal water at 19.5 oC with spontaneous outflow 24 m3/h as a heat source. The research compares exergy efficiency and exergy destruction of considered systems and its components as well. For the purpose of analysis, the heating system was divided into five components: geothermal heat exchanger, heat pump, heat distribution, heat exchanger and electricity production and transportation. For considered systems the primary exergy consumption from renewable and non-renewable sources was estimated. The analysis was carried out for heat network temperature at 50/40 oC, and the quality regulation was assumed. The results of exergy analysis of the system with electrical and absorption heat pump show that exergy destruction during the whole heating season is lower for the system with electrical heat pump. The exergy efficiencies of total system are 12.8% and 11.2% for the system with electrical heat pump and absorption heat pump, respectively.
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Pal, Rajinder. "Quantification of irreversibilities in practical cyclic processes using exergy analysis and Gouy-Stodola theorem." International Journal of Mechanical Engineering Education 46, no. 2 (July 17, 2017): 118–37. http://dx.doi.org/10.1177/0306419017720427.
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The exergy analysis of a process to quantify the irreversibilities is advantageous over the entropy analysis in that it provides the definition of efficiency of a process, referred to as exergetic efficiency (defined as the ratio of exergy recovered to exergy supplied to the process). Unfortunately, the exergy analysis of practical multi-unit cyclic processes is rarely covered adequately in the undergraduate courses in engineering thermodynamics. In this article, the quantification of irreversibilities is illustrated in detail for a practical cyclic steam power plant using exergy analysis and Gouy-Stodola theorem. The efficiencies are determined for the various components and for the whole process. The theoretical background related to exergy, exergy analysis, and Gouy-Stodola theorem is also covered briefly for the benefit of the students. An assessment problem dealing with vapor-compression refrigeration cycle is included at the end in order to assess the intended learning outcomes of this article. The key solution steps along with answers are also provided for the benefit of the readers. As exergy analysis involves advanced level concepts in thermodynamics, the appropriate place for the introduction of the material presented in this article is the second, advanced level, course in thermodynamics.
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Kaiser, Friederike, and Uwe Krüger. "Exergy analysis and assessment of performance criteria for compressed air energy storage concepts." International Journal of Exergy 28, no. 3 (2019): 229. http://dx.doi.org/10.1504/ijex.2019.098613.
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Krüger, Uwe, and Friederike Kaiser. "Exergy analysis and assessment of performance criteria for compressed air energy storage concepts." International Journal of Exergy 28, no. 3 (2019): 229. http://dx.doi.org/10.1504/ijex.2019.10020032.
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Keutenedjian Mady, Carlos Eduardo, Clara Reis Pinto, and Marina Torelli Reis Martins Pereira. "Application of the Second Law of Thermodynamics in Brazilian Residential Appliances towards a Rational Use of Energy." Entropy 22, no. 6 (June 2, 2020): 616. http://dx.doi.org/10.3390/e22060616.
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This article proposes the utilization of the concepts of destroyed exergy and exergy efficiency for equipment and process performance indicators that are related to the current energy planning scenario in Brazil, more specifically with energy-efficiency labelling. Several indicators associated with these concepts are discussed, including one national program that is based on labeling the energy efficiency of several residential, commercial and industrial appliances. The grades are indicated in the equipment using values from A to G. This labeling system is useful for discriminating similar technologies used for the same function; nevertheless produced by different enterprises. For this complementary analysis, two types of refrigeration methods were compared, absorption and vapor compression; however, these energy indexes alone are not sufficient parameters to select among these two technologies, because their performance indexes definition are different. To address this, our research considers the second law of thermodynamics through exergy analysis as a proper sub-index to obtain a systematic comparison between these various indicators. It is significant to highlight that seldom research studies addressed to this problem so explicitly, in an actual governmental working solution, aiming at discussing to the society the advantage of the usage of the “quality of the energy” as a complementary index to governmental and personal choices. Results indicate that it is possible to use the destroyed exergy and exergy efficiency to help select the technology that better utilizes natural resources, considering the energy matrix of the country. Appliances for water heating and air conditioning were compared from energy and exergy viewpoint, where the last gave additional information about the quality of energy conversion process, giving a completely different trend from the energy analysis alone, without the necessity to think about the energy matrix. Later this issue is addressed from both points of view. Future studies may suggest an exergy based index. The energy efficiency suggests that electrical shower (values higher than 95%) are better than gas water heaters (83% ) in using natural resources, whereas the exergy efficiency shares similar magnitudes (about 3%). A related pattern is shown for the theoretical air conditioning systems. The vapor compression systems have an energy index higher than 3, and absorption systems lower than 1. For these circumstances, the exergy efficiency shows figures nearby 30%.
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Yazdi, Behnam, Behdad Yazdi, Mehdi Ehyaei, and Abolfazl Ahmadi. "Optimization of micro combined heat and power gas turbine by genetic algorithm." Thermal Science 19, no. 1 (2015): 207–18. http://dx.doi.org/10.2298/tsci121218141y.
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In this paper, a comprehensive thermodynamic modeling and multi-objective optimization of a micro turbine cycle in combined heat and power generation, which provides 100KW of electric power. This CHP System is composed of air compressor, combustion chamber (CC), Air Preheater, Gas Turbine (GT) and a Heat Recovery Heat Exchanger. In this paper, at the first stage, the each part of the micro turbine cycle is modeled using thermodynamic laws. Next, with using the energetic and exergetic concepts and applying economic and environmental functions, the multi-objectives optimization of micro turbine in combined heat and power generation is performed. The design parameters of this cycle are compressor pressure ratio (rAC), compressor isentropic efficiency (?AC), GT isentropic efficiency (?GT), CC inlet temperature (T3), and turbine inlet temperature (T4). In the multi-objective optimization three objective functions, including CHP exergy efficiency, total cost rate of the system products, and CO2 emission of the whole plant, are considered. Theexergoenvironmental objective function is minimized whereas power plant exergy efficiency is maximized usinga Genetic algorithm. To have a good insight into this study, a sensitivity analysis of the result to the fuel cost is performed. The results show that at the lower exergetic efficiency, in which the weight of exergo-environmental objective is higher, the sensitivity of the optimal solutions to the fuel cost is much higher than the location of the Pareto Frontier with the lower weight of exergo-environmental objective. In addition, with increasing exergy efficiency, the purchase cost of equipment in the plant is increased as the cost rate of the plant increases.
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Streckienė, Giedrė, Vytautas Martinaitis, and Juozas Bielskus. "From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit." Entropy 21, no. 4 (April 3, 2019): 361. http://dx.doi.org/10.3390/e21040361.
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The continuous energy transformation processes in heating, ventilation, and air conditioning systems of buildings are responsible for 36% of global final energy consumption. Tighter thermal insulation requirements for buildings have significantly reduced heat transfer losses. Unfortunately, this has little effect on energy demand for ventilation. On the basis of the First and the Second Law of Thermodynamics, the concepts of entropy and exergy are applied to the analysis of ventilation air handling unit (AHU) with a heat pump, in this paper. This study aims to develop a consistent approach for this purpose, taking into account the variations of reference temperature and temperatures of working fluids. An analytical investigation on entropy generation and exergy analysis are used, when exergy is determined by calculating coenthalpies and evaluating exergy flows and their directions. The results show that each component of the AHU has its individual character of generated entropy, destroyed exergy, and exergy efficiency variation. However, the evaporator of the heat pump and fans have unabated quantities of exergy destruction. The exergy efficiency of AHU decreases from 45–55% to 12–15% when outdoor air temperature is within the range of −30 to +10 °C, respectively. This helps to determine the conditions and components of improving the exergy efficiency of the AHU at variable real-world local climate conditions. The presented methodological approach could be used in the dynamic modelling software and contribute to a wider application of the Second Law of Thermodynamics in practice.
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Gaggioli, Richard A., and David M. Paulus,. "Available Energy—Part II: Gibbs Extended." Journal of Energy Resources Technology 124, no. 2 (May 28, 2002): 110–15. http://dx.doi.org/10.1115/1.1448337.
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Since Gibbs, representations with formulas have been developed and are common, for the “available energy of body and medium.” Gaggioli has developed formulas which are more general, to represent “the available energy of the body (alone)” and to assign an exergy to subsystems of the body as a measure of each subsystem’s contribution to the available energy. In contrast to the available energy, exergy is an additive property, so that balance equations can be written. Moreover, the formulas are independent from any “medium,” which is important both theoretically and practically—because of its relevance to proper selection of “the dead state.” In Part II, these issues are discussed and extended. In the context of Gibbs’ “available energy of the body,” Gaggioli’s development of exergy for subsystems of the body without any reference to a “medium” are reviewed. It is illustrated that the concept of “constraints” underlies available energy, equilibrium and stability, and thermostatic property relations. Furthermore, it is argued that the “availability” and “capacity” concepts of Gibbs are all equivalent to each other. In turn, because of interconvertability, it is shown that available energy is something more fundamental than “maximum useful work.”
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Valero, A., L. Serra, and J. Uche. "Fundamentals of Exergy Cost Accounting and Thermoeconomics Part II: Applications." Journal of Energy Resources Technology 128, no. 1 (July 8, 2005): 9–15. http://dx.doi.org/10.1115/1.2134731.
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Part II of this paper develops the mathematical formulations of three applications of the thermoeconomic analysis methodology described in Part I of the paper: the operation diagnosis study, including new concepts that helps to separate different contributions to those inefficiencies; the local optimization process in case of special conditions for the whole plant, and the benefit maximization (a direct application of the exergy costs accounting analysis). The operation diagnosis, which is the most complex and sophisticated application, is presented with the help of an example: the co-generation plant, as it was described in Part I.
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Gaggioli, R. A., and Y. M. El-Sayed. "A Critical Review of Second Law Costing Methods—II: Calculus Procedures." Journal of Energy Resources Technology 111, no. 1 (March 1, 1989): 8–15. http://dx.doi.org/10.1115/1.3231402.
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The following article completes the review of the development and state of engineering economic applications of the Second Law of Thermodynamics, which was begun in Part I (El-Sayed and Gaggioli, 1989). We began with a historical review, followed by a brief discussion of the relevant cost accounting concepts and, in turn, general descriptions of the different exergy costing methods which are in existence. Then, the various algebraic techniques of exergy costing were analyzed and critiqued, generally by considering successive publications developing and/or based on a technique. This paper, on the other hand, is devoted primarily to calculus methods. Of course the algebraic and calculus techniques do relate to each other, and those relationships are developed here. Furthermore, general concepts, discussion and conclusions which are relevant to both algebraic and calculus methods are presented, along with suggestions regarding further research.
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Hong, Beichuan, Varun Venkataraman, and Andreas Cronhjort. "Numerical Analysis of Engine Exhaust Flow Parameters for Resolving Pre-Turbine Pulsating Flow Enthalpy and Exergy." Energies 14, no. 19 (September 28, 2021): 6183. http://dx.doi.org/10.3390/en14196183.
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Energy carried by engine exhaust pulses is critical to the performance of a turbine or any other exhaust energy recovery system. Enthalpy and exergy are commonly used concepts to describe the energy transport by the flow based on the first and second laws of thermodynamics. However, in order to investigate the crank-angle-resolved exhaust flow enthalpy and exergy, the significance of the flow parameters (pressure, velocity, and temperature) and their demand for high resolution need to be ascertained. In this study, local and global sensitivity analyses were performed on a one-dimensional (1D) heavy-duty diesel engine model to quantify the significance of each flow parameter in the determination of exhaust enthalpy and exergy. The effects of parameter sweeps were analyzed by local sensitivity, and Sobol indices from the global sensitivity showed the correlations between each flow parameter and the computed enthalpy and exergy. The analysis indicated that when considering the specific enthalpy and exergy, flow temperature is the dominant parameter and requires high resolution of the temperature pulse. It was found that a 5% sweep over the temperature pulse leads to maximum deviations of 31% and 27% when resolving the crank angle-based specific enthalpy and specific exergy, respectively. However, when considering the total enthalpy and exergy rates, flow velocity is the most significant parameter, requiring high resolution with a maximum deviation of 23% for the enthalpy rate and 12% for the exergy rate over a 5% sweep of the flow velocity pulse. This study will help to quantify and prioritize fast measurements of pulsating flow parameters in the context of turbocharger turbine inlet flow enthalpy and exergy analysis.
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dos Santos, Rodrigo Guedes, Atilio Barbosa Lourenço, Pedro Rosseto de Faria, Marcelo Aiolfi Barone, and José Joaquim Conceição Soares Santos. "A New Exergy Disaggregation Approach for Complexity Reduction and Dissipative Equipment Isolation in Thermoeconomics." Entropy 24, no. 11 (November 17, 2022): 1672. http://dx.doi.org/10.3390/e24111672.
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Thermoeconomics connects thermodynamic and economic concepts in order to provide information not available in conventional energy and economic analysis. Most thermoeconomicists agree that exergy is the most appropriate thermodynamic magnitude to associate with cost. In some applications, exergy disaggregation is required. Despite the improvement in result accuracy, the modeling complexity increases. In recent years, different exergy disaggregation approaches have been proposed, mostly to deal with dissipative components and residues, despite all of them also increasing the complexity of thermoeconomics. This study aims to present a new thermoeconomic approach based on exergy disaggregation, which is able to isolate dissipative components with less modeling complexity. This approach, called the A&F Model, splits the physical exergy into two terms, namely, Helmholtz energy and flow work. These terms were evaluated from a thermoeconomic point of view, through a cost allocation in an ideal Carnot cycle, and they were also applied and compared with the UFS Model, through a cost allocation analysis, in a case study with an organic Rankine cycle-powered vapor compression refrigeration system. The complexity and computational effort reduction in the A&F are significantly less than in the UFS Model. This alternative approach yields consistent results.
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Lingo, Lowell, Kristin Lingo, and Mark Bomberg. "Merging Geo-Solar Exergy Storage Technology (GEST) and Environmental Quality Management (EQM): A Practical Solution for NZEB Retrofit." E3S Web of Conferences 172 (2020): 16009. http://dx.doi.org/10.1051/e3sconf/202017216009.
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A decade ago, Geo-solar Exergy Storage Technology (GEST) was introduced as a means of utilizing natural, diurnal and seasonal transfers of exergy between a building and its surroundings to significantly decrease heating and cooling requirements. This is accomplished by retrofitting the structure with a dynamic skin to the existing building enclosure that is provided with internal conduits to carry air and fluids, for coupling geothermal storage surrounding the building with the exterior environment. This system was developed by engineers as an affordable, low-tech solution for providing seasonal heat storage in cold climate regions. Meanwhile another holistic but high-tech means to the same goal was initiated by an international group of building scientists by defining concepts for environmental quality management (EQM). Using heat pumps, ‘smart controls’, and newly developed wall coating materials, a fully integrated HVAC (plus moisture control and indoor air quality (IAQ)) system was proposed. The experience gained with GEST methods is now combined with the leading edge of Building Science to permit our international team to re-evaluate the concept of Geo-solar Exergy Storage and Dynamic Building Enclosure incorporated in a system with a heat pump as a new basis for retrofitting buildings in any climate.
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Bejan, Adrian, and George Tsatsaronis. "Purpose in Thermodynamics." Energies 14, no. 2 (January 13, 2021): 408. http://dx.doi.org/10.3390/en14020408.
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This is a review of the concepts of purpose, direction, and objective in the discipline of thermodynamics, which is a pillar of physics, natural sciences, life science, and engineering science. Reviewed is the relentless evolution of this discipline toward accounting for evolutionary design with direction, and for establishing the concept of purpose in methodologies of modeling, analysis, teaching, and design optimization. Evolution is change after change toward flow access, with direction in time, and purpose. Evolution does not have an ‘end’. In thermodynamics, purpose is already the defining feature of methods that have emerged to guide and facilitate the generation, distribution, and use of motive power, heating, and cooling: thermodynamic optimization, exergy-based methods (i.e., exergetic, exergoeconomic, and exergoenvironmental analysis), entropy generation minimization, extended exergy, environomics, thermoecology, finite time thermodynamics, pinch analysis, animal design, geophysical flow design, and constructal law. What distinguishes these approaches are the purpose and the performance evaluation used in each method.
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Kotas, T. J., and D. S. Kibiikyo. "Thermoeconomic Optimization of a Ventilation Air Heater in a Backpressure Combined Heat and Power Plant." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power Engineering 203, no. 4 (November 1989): 255–67. http://dx.doi.org/10.1243/pime_proc_1989_203_036_02.
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In this paper a method of optimization of plant components is demonstrated for the case of a ventilation air heater in a backpressure combined heat and power (CHP) plant. The method, known as thermoeconomic optimization, combines the concepts of exergy analysis with those of economic analysis. The optimization is carried out in two stages. First the heat-exchanger geometry is optimized for a range of different fixed heat-transfer areas using the trade-off between irreversibility due to pressure losses and that due to heat transfer over a finite temperature difference. In the second stage the economically justified cost of the heat-exchanger is determined using a version of thermoeconomic optimization known as the structural method. The concept of the coefficient of structural bonds is discussed and its use in structural investigation and thermoeconomic optimization is explained. Potential for further improvement in the plant efficiency through optimization is discussed with reference to a diagram of exergy flows and irreversibility rates known as the Grass-mann diagram.
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Pal, Rajinder. "Comparison of entropic and exergetic methods of quantification of loss of power due to irreversibilities in real processes using the Gouy–Stodola theorem." International Journal of Mechanical Engineering Education 47, no. 1 (January 4, 2018): 73–96. http://dx.doi.org/10.1177/0306419017749801.
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Thermodynamics offers two methods of quantification of irreversibilities in real processes, namely entropy generation method and exergy destruction method. The engineering students in different disciplines are generally taught only the entropy analysis of processes in their second, advanced level, course in thermodynamics. The exergy analysis of quantification of irreversibilities is rarely covered adequately in the undergraduate courses in thermodynamics, especially when chemical effects are involved where the concept of chemical exergy plays the key role. In this article, the entropy and exergy methods of quantification of irreversibilities are reviewed and are applied to two real processes: steady-state de-mixing of a binary gas mixture into pure components and steady-state combustion of carbon monoxide gas. According to the entropy generation method, the loss of power due to irreversibilities is proportional to the rate of total entropy production (internally and externally). According to the exergy destruction method, the loss of power is equal to the rate of total exergy destruction (internally and externally). Although the calculation procedures involved in the two methods are quite different, the two methods yield the same results in terms of the loss of power due to irreversibilities in the real processes considered in this article. Thus, the detailed calculations carried out in this work confirm that the two methods of quantification of irreversibilities are equivalent. The exergetic method has the advantage that only the knowledge of the exergies of the flowing streams at the inlet and outlet conditions is required in order to calculate the loss of power due to irreversibilities, whereas the entropic method requires a stepwise calculation scheme in going from the inlet conditions to the outlet conditions of the process flow streams. As the material presented in this article involves advanced level concepts in thermodynamics, the appropriate place for the introduction of this material to the engineering students is the second, advanced level, course in thermodynamics.
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Yohana, Eflita, Revki Romadhon, Binawan Luhung, Irwan Fernando, and M. S. K. Tony Suryo Utomo. "Cooling Load and Exergy Destruction Analysis in Air Conditioning Operation Room with Ambient Temperature Variation." E3S Web of Conferences 73 (2018): 01006. http://dx.doi.org/10.1051/e3sconf/20187301006.
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HVAC installations are essential to the operating room to maintain the safety of environmental conditions and provide comfort for patients and medical personnel. Operating room is a room with a class of 10,000 where the maximum number of particles in the room is 352,000 particles per cubic feet for bacteria 0.5-micrometer size (ISO 14644-1). To achieve the desired air conditions in the operating room required an air conditioning tool that is Air Handling Unit (AHU). The AHU determination shall be adjusted to the cooling load of the chamber derived from the sensible load and latent load. Exergy analysis is required to optimize a process and evaluate the device performance. The purpose of this study is to calculate the cooling load and perform the analysis of exergy destruction on Cooling Coil and Electric Heater in AHU. The calculation of cooling load uses the standard air change method. Exergy analysis uses the second law of thermodynamic concepts related to entropy. The results obtained cooling load and exergy destruction increases with the increase of ambient temperature. Maximum exergy destruction in cooling coil 1 and 2 at 35°C is 3.3 kW and 1.6 kW while in the electric heater is 0.52 kW.
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Nielsen, Søren, Felix Müller, Joao Marques, Simone Bastianoni, and Sven Jørgensen. "Thermodynamics in Ecology—An Introductory Review." Entropy 22, no. 8 (July 27, 2020): 820. http://dx.doi.org/10.3390/e22080820.
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How to predict the evolution of ecosystems is one of the numerous questions asked of ecologists by managers and politicians. To answer this we will need to give a scientific definition to concepts like sustainability, integrity, resilience and ecosystem health. This is not an easy task, as modern ecosystem theory exemplifies. Ecosystems show a high degree of complexity, based upon a high number of compartments, interactions and regulations. The last two decades have offered proposals for interpretation of ecosystems within a framework of thermodynamics. The entrance point of such an understanding of ecosystems was delivered more than 50 years ago through Schrödinger’s and Prigogine’s interpretations of living systems as “negentropy feeders” and “dissipative structures”, respectively. Combining these views from the far from equilibrium thermodynamics to traditional classical thermodynamics, and ecology is obviously not going to happen without problems. There seems little reason to doubt that far from equilibrium systems, such as organisms or ecosystems, also have to obey fundamental physical principles such as mass conservation, first and second law of thermodynamics. Both have been applied in ecology since the 1950s and lately the concepts of exergy and entropy have been introduced. Exergy has recently been proposed, from several directions, as a useful indicator of the state, structure and function of the ecosystem. The proposals take two main directions, one concerned with the exergy stored in the ecosystem, the other with the exergy degraded and entropy formation. The implementation of exergy in ecology has often been explained as a translation of the Darwinian principle of “survival of the fittest” into thermodynamics. The fittest ecosystem, being the one able to use and store fluxes of energy and materials in the most efficient manner. The major problem in the transfer to ecology is that thermodynamic properties can only be calculated and not measured. Most of the supportive evidence comes from aquatic ecosystems. Results show that natural and culturally induced changes in the ecosystems, are accompanied by a variations in exergy. In brief, ecological succession is followed by an increase of exergy. This paper aims to describe the state-of-the-art in implementation of thermodynamics into ecology. This includes a brief outline of the history and the derivation of the thermodynamic functions used today. Examples of applications and results achieved up to now are given, and the importance to management laid out. Some suggestions for essential future research agendas of issues that needs resolution are given.
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Farsi, Aida, and Marc A. Rosen. "Assessment of a Geothermal Combined System with an Organic Rankine Cycle and Multi-effect Distillation Desalination." Earth Systems and Environment 6, no. 1 (January 2022): 15–27. http://dx.doi.org/10.1007/s41748-021-00275-w.
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AbstractAn analysis is reported of a geothermal-based electricity-freshwater system in which an organic Rankine cycle is integrated with a multi-effect distillation desalination unit. The system is driven by geothermal hot water extracted from the production well. Mass, energy, entropy, and exergy rate balances are written for all system components, as are energy and exergy efficiency expressions for each subsystem. The exergy destruction rate associated with the temperature and chemical disequilibrium of the freshwater and brine with the reference environment are taken into account to reveal accurate results for irreversibility sources within the desalination process. The developed thermodynamic model is simulated using thermodynamic properties of the working fluids (i.e., ammonia, seawater, distillate, and brine) at each state point. A sustainability analysis is performed that connects exergy and environmental impact concepts. That assessment expresses the extent of the contribution of the system to sustainable development and reduced environmental impact, using exergy methods. Results of the sustainability analysis indicate that, with an increase in the reference environment temperature from 20 to 35 $$^\circ{\rm C}$$ ∘ C , the exergy destruction rate decreases for the multi-effect distillation and organic Rankine cycle systems respectively from 6474 to 4217 kW and from 16,270 to 13,459 kW. Also, the corresponding sustainability index for the multi-effect distillation and organic Rankine cycle systems increases from 1.16 to 1.2 and 1.5–1.6, respectively, for the same increase in reference environment temperature.
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Bhandari, Himanshu. "Understanding the Basic Concepts of Exergy and Real-Time Exergy Analysis of Economiser, Superheater and Reheater of 210MW Coal Fired Boiler in Thermal Power Plant." International Journal for Research in Applied Science and Engineering Technology 6, no. 3 (March 31, 2018): 2331–38. http://dx.doi.org/10.22214/ijraset.2018.3371.
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Haynes, Comas, and William J. Wepfer. "Enhancing the Performance Evaluation and Process Design of a Commercial-Grade Solid Oxide Fuel Cell via Exergy Concepts." Journal of Energy Resources Technology 124, no. 2 (May 28, 2002): 95–104. http://dx.doi.org/10.1115/1.1467647.
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Fuel cell technology is a promising means of energy conversion. As the technology matures, process design and analysis are gaining importance. The conventional measures of fuel cell performance (i.e., gross real and voltage efficiencies) are limited indices-of- merit. Contemporary second law concepts (availability/exergy, irreversibility, exergetic efficiency) have been used to enhance fuel cell evaluation. A previously modeled solid oxide fuel cell has been analyzed using both conventional measures and the contemporary thermodynamic measures. Various cell irreversibilities were quantified, and their impact on cell inefficiency was better understood. Exergetic efficiency is more comprehensive than the conventional indices-of- performance. This parameter includes thermal irreversibilities, considers the value of effluent exergy, and has a consistent formulation. Usage of exergetic efficiency led to process design discoveries different from the trends observed in conjunction with the conventional efficiency measures. The decision variables analyzed were operating pressure, air stoichiometric number (inverse equivalence ratio), operating voltage and fuel utilization.
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Santos, R. G., P. R. Faria, I. C. Belisario, M. A. Barrone, and J. J. C. Santos. "ON THE LOCALIZED PHYSICAL EXERGY DISAGGREGATION FOR DISSIPATIVE COMPONENT ISOLATION IN THERMOECONOMICS." Revista de Engenharia Térmica 19, no. 2 (December 21, 2020): 63. http://dx.doi.org/10.5380/reterm.v19i2.78618.
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Thermoeconomics is a discipline that connects Thermodynamics and Economics concepts, usually used for rational cost allocation to the final products of a thermal plant, by means of a model that describes the cost formation process of the overall system. Generally, exergy or monetary costs of the external resources are distributed to the final products. Exergy is the thermodynamic magnitude used in thermoeconomics and the physical exergy disaggregation has been introduced in thermoeconomics as alternatives for the isolation of the dissipative components and residues allocation. For plants with dissipative equipment, such as condenser or valve, the productive diagram, based on total exergy (E Model), need to merge this dissipative equipment with other productive components. In order to isolate the condenser, the productive diagram must use, at least, the H&S Model and to isolate the valve, the UFS Model has to be considered.Both disaggregation models greatly increase the thermoeconomic modeling complexity. Bearing this in mind, this work aims to evaluate the advantages of combining the E Model with these other models in order to adequately isolate the dissipative equipment. The plants studied herein are two different steam turbine cogeneration systems, with dissipative components (condenser or valve). The different monetary and exergy unit costs obtained for the two final products of each plant are compared and analyzed. The results show that localized physical exergy disaggregation for dissipative component isolation in thermoeconomics is feasible, since it reduces the complexity of the productive structure and is also consistent from the point of view of thermodynamics.
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Kostic, Milivoje M. "Nature of Heat and Thermal Energy: From Caloric to Carnot’s Reflections, to Entropy, Exergy, Entransy and Beyond." Entropy 20, no. 8 (August 7, 2018): 584. http://dx.doi.org/10.3390/e20080584.
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The nature of thermal phenomena is still elusive and sometimes misconstrued. Starting from Lavoisier, who presumed that caloric as a weightless substance is conserved, to Sadi Carnot who erroneously assumed that work is extracted while caloric is conserved, to modern day researchers who argue that thermal energy is an indistinguishable part of internal energy, to the generalization of entropy and challengers of the Second Law of thermodynamics, the relevant thermal concepts are critically discussed here. Original reflections about the nature of thermo-mechanical energy transfer, classical and generalized entropy, exergy, and new entransy concept are reasoned and put in historical and contemporary contexts, with the objective of promoting further constructive debates and hopefully resolve some critical issues within the subtle thermal landscape.
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Schuchardt, Georg K. "Integration of Decentralized Thermal Storages Within District Heating (DH) Networks." Environmental and Climate Technologies 18, no. 1 (December 1, 2016): 5–16. http://dx.doi.org/10.1515/rtuect-2016-0009.
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Abstract Thermal Storages and Thermal Accumulators are an important component within District Heating (DH) systems, adding flexibility and offering additional business opportunities for these systems. Furthermore, these components have a major impact on the energy and exergy efficiency as well as the heat losses of the heat distribution system. Especially the integration of Thermal Storages within ill-conditioned parts of the overall DH system enhances the efficiency of the heat distribution. Regarding an illustrative and simplified example for a DH system, the interactions of different heat storage concepts (centralized and decentralized) and the heat losses, energy and exergy efficiencies will be examined by considering the thermal state of the heat distribution network.
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Bahiraei, Farid, Rahim Khoshbakhti Saray, and Aidin Salehzadeh. "Investigation of potential of improvement of helical coils based on avoidable and unavoidable exergy destruction concepts." Energy 36, no. 5 (May 2011): 3113–19. http://dx.doi.org/10.1016/j.energy.2011.02.057.
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Picallo-Perez, Ana, José María Sala, and Arrate Hernández. "Application of Thermoeconomics in HVAC Systems." Applied Sciences 10, no. 12 (June 17, 2020): 4163. http://dx.doi.org/10.3390/app10124163.
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In order to achieve a sustainable society, the energy consumption in buildings must be reduced. The first step toward achieving this goal is to detect their weak points and analyze the energy-saving potential. to detect the units with higher consumption and cost. Exergy is very useful for analyzing pieces of equipment, systems or entire buildings. It measures not only the quantity of energy but also its quality. If the exergy is combined with economic analysis, this gives rise to thermoeconomics, and the system can be checked systematically and optimized from the perspective of economics. In this work, exergy methods and thermoeconomic analysis were applied to a building thermal system. Due to its complexity, it is necessary to adapt some concepts to translate the exergy application from industry to buildings. The purpose of this work is to overcome these shortcomings and to deal with energy-saving actions for buildings. To this end, a thermoeconomic study of a facility that covers the heating and domestic hot water (DHW) demands of 176 dwellings in Vitoria-Gasteiz (Basque Country) using two boilers and two cogeneration engines was analyzed. The irreversibility associated with each piece of equipment was quantified, and the costs associated with resources, investment and maintenance were calculated for each flow and, consequently, for the final flows, that is, electricity (11.37 c€/kWh), heating (7.42 c€/kWh) and DHW (7.25 c€/kWh). The results prove that the boilers are the lesser efficient components (with an exergy efficiency of 15%). Moreover, it is demonstrated that micro-cogeneration engines not only save energy because they have higher exergy efficiency (36%), but they are also economically attractive, even if they require a relatively high investment. Additionally, thermoeconomic costs provide very interesting information and underscore the necessity to adapt the energy quality in between the generation and demand.
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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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Qian, Hongliang, Weiwei Zhu, Sudong Fan, Chang Liu, Xiaohua Lu, Zhixiang Wang, Dechun Huang, and Wei Chen. "Prediction models for chemical exergy of biomass on dry basis from ultimate analysis using available electron concepts." Energy 131 (July 2017): 251–58. http://dx.doi.org/10.1016/j.energy.2017.05.037.
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Ticu, Ionela, and Elena Gogu. "A POINT OF VIEW ON THE PERCEPTION OF FUTURE PROFESSIONALS ON ENERGY EFFICIENCY OF REFIRGERATION SYSTEMS." Journal of marine Technology and Environment 1, no. 2021 (2021): 38–43. http://dx.doi.org/10.53464/jmte.01.2021.06.
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In the modern times, energy efficiency is of high interest because there is direct link between this concept and energy conservation, economics, environment and sustainable development. The energy efficiency intensification at international level is closely follow by national leaders and worldwide governments and organisations and by top companies as well. Considering this obvious aspects, higher education institutions are deeply involved in involving energy efficiency in the curricula of future professionals, in order to allow them to gain skills that will help in solving challenges specific to this activity. In this international context, Constanta Maritime University introduced in the curricula of the students enrolled in the specialization called Engineering and Environment Protection in Industry a discipline dealing with this very important activity, named Thermal Efficiency of Buildings and Industrial Processes. This paper is investigating the manner in which our students have mastered the tools of energy efficiency assessment of refrigeration systems, throughout a questionnaire applied to them, at the end of the chapter dedicated to these technologies. The students had to write short comments to very specific questions. Analysis of the comments helps the lecturer and the students to take appropriate measures in the next future. Thus, the feedback resulted to be quite positive because most of the students gained the knowledge provided in this respect. Still, delicate concepts, such as entropy, exergy or exergy destruction seem to raise difficulties to some students. In this respect, results that such an intermediary assessment has to be repeated more often, for other kind of technologies discussed during this course, with the involvement of the concepts introduced by the second law- which are essential in energy efficiency assessments.
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Khodak, E. A., and G. A. Romakhova. "Thermodynamic Analysis of Air-Cooled Gas Turbine Plants." Journal of Engineering for Gas Turbines and Power 123, no. 2 (August 1, 2000): 265–70. http://dx.doi.org/10.1115/1.1341204.
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At present high temperature, internally cooled gas turbines form the basis for the development of highly efficient plants for utility and industrial markets. Minimizing irreversibility of processes in all components of a gas turbine plant leads to greater plant efficiency. Turbine cooling, like all real processes, is an irreversible process and results in lost opportunity for producing work. Traditional tools based on the first and second laws of thermodynamics enable performance parameters of a plant to be evaluated, but they give no way of separating the losses due to cooling from the overall losses. This limitation arises from the fact that the two processes, expansion and cooling, go on simultaneously in the turbine. Part of the cooling losses are conventionally attributed to the turbine losses. This study was intended for the direct determination of lost work due to cooling. To this end, a cooled gas turbine plant has been treated as a work-producing thermodynamic system consisting of two systems that exchange heat with one another. The concepts of availability and exergy have been used in the analysis of such a system. The proposed approach is applicable to gas turbines with various types of cooling: open-air, closed-steam, and open-steam cooling. The open-air cooling technology has found the most wide application in current gas turbines. Using this type of cooling as an example, the potential of the developed method is shown. Losses and destructions of exergy in the conversion of the fuel exergy into work are illustrated by the exergy flow diagram.
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Torío, Herena, and Dietrich Schmidt. "Development of system concepts for improving the performance of a waste heat district heating network with exergy analysis." Energy and Buildings 42, no. 10 (October 2010): 1601–9. http://dx.doi.org/10.1016/j.enbuild.2010.04.002.
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Twort, C. T., I. S. Lowndes, and S. J. Pickering. "An application of thermal exermal analysis to the development of mine cooling systems." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 216, no. 8 (August 1, 2002): 845–57. http://dx.doi.org/10.1243/09544060260171465.
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The extraction of minerals and coal at greater depth, employing higher-powered machinery to improve production levels, imposes an increased burden on the ability of a ventilation system to maintain an acceptable mine climate. Hence, mechanical mine cooling systems are often adopted, which can be expensive both in terms of their associated capital and operating costs. Consequently, in order to optimize the costs it is essential to provide the mine operator with a method with which to determine the most cost effective and efficient mine cooling system. The following paper overviews the development of a novel approach to the energy analysis of mine cooling systems using the concepts of thermal exergy analysis. Generic model mine ventilation networks are constructed and the subsurface environments of these mine networks predicted. Models of various cooling system methods are developed and applied to control the underground climate within these mine networks to within pre-set climatic limits. The exergy transfers that are produced by the application of the different cooling methods are compared using performance indices. Models to represent chilled water distribution networks, used to supply the air coolers within the various cooling systems, are designed and balanced. The results of the exergy analyses applied to the operation of the various chilled water pipe networks are discussed and used to assess the exergetic performance of the application of each cooling system to the mine ventilation network.
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Asgari, Sahar, A. R. Noorpoor, and Fateme Ahmadi Boyaghchi. "Parametric assessment and multi-objective optimization of an internal auto-cascade refrigeration cycle based on advanced exergy and exergoeconomic concepts." Energy 125 (April 2017): 576–90. http://dx.doi.org/10.1016/j.energy.2017.02.158.
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Roach, Ty N. F., Peter Salamon, James Nulton, Bjarne Andresen, Ben Felts, Andreas Haas, Sandi Calhoun, Nathan Robinett, and Forest Rohwer. "Application of Finite-Time and Control Thermodynamics to Biological Processes at Multiple Scales." Journal of Non-Equilibrium Thermodynamics 43, no. 3 (July 26, 2018): 193–210. http://dx.doi.org/10.1515/jnet-2018-0008.
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AbstractAn overall synthesis of biology and non-equilibrium thermodynamics remains a challenge at the interface between the physical and life sciences. Herein, theorems from finite-time and control thermodynamics are applied to biological processes to indicate which biological strategies will succeed over different time scales. In general, living systems maximize power at the expense of efficiency during the early stages of their development while proceeding at slower rates to maximize efficiency over longer time scales. The exact combination of yield and power depends upon the constraints on the system, the degrees of freedom in question, and the time scales of the processes. It is emphasized that biological processes are not driven by entropy production but, rather, by informed exergy flow. The entropy production is the generalized friction that is minimized insofar as the constraints allow. Theorems concerning thermodynamic path length and entropy production show that there is a direct tradeoff between the efficiency of a process and the process rate. To quantify this tradeoff, the concepts of compensated heat and waste heat are introduced. Compensated heat is the exergy dissipated, which is necessary for a process to satisfy constraints. Conversely, waste heat is exergy that is dissipated as heat, but does not provide a compensatory increase in rate or other improvement. We hypothesize that it is waste heat that is minimized through natural selection. This can be seen in the strategies employed at several temporal and spatial scales, including organismal development, ecological succession, and long-term evolution. Better understanding the roles of compensated heat and waste heat in biological processes will provide novel insight into the underlying thermodynamic mechanisms involved in metabolism, ecology, and evolution.
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Ahmadi Boyaghchi, Fateme, and Sahar Nazer. "Assessment and optimization of a new sextuple energy system incorporated with concentrated photovoltaic thermal - Geothermal using exergy, economic and environmental concepts." Journal of Cleaner Production 164 (October 2017): 70–84. http://dx.doi.org/10.1016/j.jclepro.2017.06.194.
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Boyaghchi, Fateme Ahmadi, and Mansoure Chavoshi. "Multi-criteria optimization of a micro solar-geothermal CCHP system applying water/CuO nanofluid based on exergy, exergoeconomic and exergoenvironmental concepts." Applied Thermal Engineering 112 (February 2017): 660–75. http://dx.doi.org/10.1016/j.applthermaleng.2016.10.139.
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Li, Rongling, Ryozo Ooka, and Masanori Shukuya. "Theoretical analysis on ground source heat pump and air source heat pump systems by the concepts of cool and warm exergy." Energy and Buildings 75 (June 2014): 447–55. http://dx.doi.org/10.1016/j.enbuild.2014.02.019.
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Deliang, Zeng, Liu Jiwei, and Liu Jizhen. "Data-driven state detection algorithm for multi-scale systems and its application." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 7 (August 27, 2013): 1223–34. http://dx.doi.org/10.1177/0954406213501590.
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To improve the security and reliability of equipment and reduce their failure rate, a data-driven state detection algorithm was proposed. The concepts of multi-scale system, multi-scale entropy and multi-scale exergy were defined. The algorithm is used for multi-scale systems whose state parameters change over time and have the characteristic of increasing monotonically on a dominant scale. An abrasion index for the middle speed roller ring mill was constructed, which was used to monitor the states of the instruments. Noise that affected the accuracy of the results was analyzed. The results of simulation experiments demonstrate the effectiveness of the algorithm, which can provide a technical basis for condition maintenance.