Advanced Exergoeconomic Evaluation and Its Application to Compression Refrigeration Machines

Author(s):  
George Tsatsaronis ◽  
Tatiana Morosuk

Splitting the exergy destruction within each component of an energy conversion system into endogenous/exogenous and unavoidable/avoidable parts enhances an exergy analysis and improves the quality of the conclusions obtained from the analysis. The potential for improving each system component is identified and priorities, according to which the design of components should be modified, are established. We call this detailed exergy analysis advanced exergy analysis. For improving the cost effectiveness of an energy conversion system, splitting the investment cost into endogenous/exogenous and unavoidable/avoidable parts is also helpful. The designer should focus on the avoidable thermodynamic inefficiencies (exergy destruction), their costs and the avoidable investment costs. The paper discusses the calculation of these costs in general and the resulting advanced exergoeconomic evaluation that is based on the avoidable endogenous and the avoidable exogenous values for exergy destruction, cost of exergy destruction and investment cost. An application of this methodology to a compression refrigeration machine is presented.

Energetika ◽  
2017 ◽  
Vol 63 (3) ◽  
Author(s):  
Volodymyr A. Voloshchuk

In addition to conventional exergy-based methods, advanced exergetic analyses consider the interactions among components of the energy-conversion system and the real potential for improving each system component. The paper demonstrates the results of application of a detailed advanced exergetic analysis to a wastewater source heat pump providing space heating in the built environment. In order to determine thermodynamic parameters of the refrigeration vapour compression cycle in different operating modes, the simulation model has been used. The analysis includes splitting the exergy destruction within each component of a heat pump into unavoidable, avoidable, endogenous and exogenous parts as well as detailed splitting of the avoidable exogenous exergy destruction. Besides, variabilities of heating demands of a building within both the chosen heating season and also from year to year are taken into account. Distribution of the split exergy destructions during different periods of time is also presented for the analysed cases of the heat pump and built environment. It is shown that in the investigated system only about 50% of the total annual destruction in components of the heat pump can be avoided. About 30…40% of this avoidable thermodynamic inefficiency is caused by interactions among components. Based on the applied advanced exergetic analysis it is possible to receive more precise and useful information for better understanding and improving the design and operation of the analysed energy-conversion system.


2021 ◽  
Vol 11 (23) ◽  
pp. 11535
Author(s):  
Volodymyr Voloshchuk ◽  
Paride Gullo ◽  
Eugene Nikiforovich ◽  
Nadia Buyak

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.


Author(s):  
T. Morosuk ◽  
G. Tsatsaronis

An exergoeconomic analysis identifies the location, magnitude and sources of thermodynamic inefficiencies and costs in an energy conversion system. This information is used for improving the thermodynamic and the economic performance and for comparing various systems. A conventional exergy-based analysis does not consider the interactions among the components of a system nor the real potential for improving the system. These shortcomings can be addressed and the quality of the conclusions obtained from an exergoeconomic evaluation is improved, when for each important system component the values of exergy destruction and costs are split into endogenous/exogenous and avoidable/unavoidable parts. We call the analyses resulting from such splittings advanced exergy-based analyses. The paper demonstrates how an advanced exergoeconomic analysis provides the user with information on the formation processes of thermodynamic inefficiencies and costs and with suggestions for their minimization. In the first part of the paper, the advanced exergy-based analyses are applied to an air refrigeration machine. In the second part of the paper, we demonstrate that the information obtained in the first part can be used to modify the values of the decision variables to reduce the cost of the final product (cold) of the overall system.


Author(s):  
George Tsatsaronis ◽  
Solange O. Kelly ◽  
Tatiana V. Morosuk

One of the roles of exergy analysis is to provide thermal system designers and operators with information useful for the system optimization. An exergy analysis identifies the sources of thermodynamic inefficiencies by evaluating the exergy destruction within each system component. However, care must be taken when using the total exergy destruction within a component to reach conclusions regarding the optimization of the overall energy system. The reason is that the total exergy destruction occurring in a component is not due exclusively to that component but is also caused by the inefficiencies within the remaining system components. The endogenous exergy destruction within a component is defined as that part of the component's exergy destruction that is independent of any change in the exergy destruction within the remaining components. The part of the component's exergy destruction which depends upon the changes of the exergy destruction within the other components is defined as the exogenous exergy destruction. It is apparent that the sum of endogenous and exogenous exergy destruction is equal to the total exergy destruction within the component being considered. Knowledge of the exogenous and endogenous exergy destruction for the most important components can further assist the engineer in deciding whether an adjustment in that component or in the structure of the system (i.e. in the remaining components) is required to improve the overall system. The paper presents the general concept of endogenous and exogenous exergy destruction. Using a graphical approach, the endogenous and exogenous exergy destruction of a simple gas turbine process and simple refrigeration machine are investigated.


2012 ◽  
Vol 2012.87 (0) ◽  
pp. _1-14_
Author(s):  
Tsutomu WAKABAYASHI ◽  
Yoshinori HISAZUMI ◽  
Tsukasa HORI ◽  
Akeshi KEGASA

Author(s):  
H. S. Hamut ◽  
I. Dincer ◽  
G. F. Naterer

In this paper, exergy analysis of a hybrid electric vehicle thermal management system (TMS) is initially investigated in order to find the areas of inefficiencies and exergy destruction within each system component. In the analysis, advanced exergy modeling is utilized to study both endogenous/exogenous and avoidable/unavoidable exergy destructions for each component of the system and further understand the interactions among the TMS components and determine the underlying reasons behind the exergy destructions. Moreover, this approach is also used to enhance exergoeconomic analyses by calculating the endogenous/exogenous and avoidable/unavoidable portion of the investment and exergy destruction costs (so-called advanced exergoeconomic analysis) in order to improve the cost effectiveness of the system and provide information on how much of the cost can be avoided for each component. Based on the analysis, it is determined that exogenous exergy destruction is small but significant portion of the total exergy destruction in each component (up to 40%, in the chiller and thermal expansion valves) and that large portion of the exergy destruction within the components (up to 70%, in the compressor) could be potentially avoided. Moreover, it is determined that electric battery, compressor, and chiller are dominated by investment cost, whereas the condenser and evaporator are dominated by the cost of exergy destruction in the system.


Author(s):  
Lutz Meyer ◽  
Jens Buchgeister ◽  
George Tsatsaronis ◽  
Liselotte Schebek

An exergoenvironmental analysis has been developed that reveals to what extent each component of an energy conversion system is responsible for the overall environmental impact, and identifies the sources of the impact. The approach of the exergoeconomic analysis is modified to deal, instead with an economic problem, with an evaluation of the ecological impact. The basic idea is that exergy represents a proper basis for assigning both costs and environmental impact in energy conversion processes. As a case study, an energy conversion system consisting of a high-temperature solid oxide fuel cell integrated with an allothermal biomass gasification process has been analyzed. The exergoenvironmental analysis allows to identify the environmentally most relevant system components and provides information about possibilities for design improvements. A special focus is laid on the role of exergy destruction. It is shown that the location of the exergy destruction in the process has influence on the resulting environmental impacts. A certain amount of exergy destruction leads to a different extent to environmental impacts depending on the position of the component where the exergy destruction occurs. The exergoenvironmental analysis reveals the thermodynamic inefficiencies that have the greatest environmental impacts.


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