Formation of Environmental Impacts in Energy Conversion Processes Revealed by a Novel Exergoenvironmental Analysis

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.

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.


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.


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):  
Fatima Zohra ARAMA ◽  
Slimane LARIBI ◽  
Touhami GHAITAOUI

This work presents a field-oriented control (FOC) of active and reactive power applied on Doubly Fed Induction Machine (DFIM) integrated in wind energy conversion system (WECS). The main objective of this work is to compare the performances of energy produced by the use of two types of controllers ( PI regulator and the neural network regulator (NN)) in order to control the wind power conversion system to compare their precision & robustness against the wind fluctuation and the impact on the quality of produced energy. A field oriented control of DEFIG stator is also presented to control the active and reactive power. To show the efficiency of the performances and the robustness of the two control methods those were analyzed and compared by simulation using Matlab/Simulink software. The results described the favoured method.


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