Disaggregation of the Physical Exergy to Improve the Accuracy of the Results in Thermoeconomics
Pedro Rosseto de Faria1; José Joaquim Conceição Soares Santos2; João Luiz Marcon Donatelli2; Sílvio de Oliveira Júnior3; Rodrigo Guedes dos Santos4
1 Faculdade do Centro Leste (UCL); 2 Universidade Federal do Espírito Santo (UFES); 3 Universidade de São Paulo (USP); 4 Instituto Federal do Espírito Santo (IFES)
doi:10.20906/CPS/COB-2015-1762
Resumo
Thermoeconomics can be considered a new science which, by connecting thermodynamic and economic concepts, provides tools to solve problems in complex energy systems that can hardly or not be solved using conventional energetic and economic analysis. Exergy is the thermodynamic magnitude used in thermoeconomics. Sometimes, under a thermoeconomic analysis, it is necessary to consider the components as a group of subsystems and/or the exergy flows consisting of several components, because the more disaggregated is the system the more accurate are the results. According to Lazzaretto and Tsatsaronis, by considering physical exergy disaggregated into thermal and mechanical components, we improve the accuracy of the results in thermoeconomic analysis and we increase the complexity of the model. However, in the last years, new kinds of physical exergy disaggregation have been introduced in thermoeconomics as consistent alternatives in order to disaggregate the dissipative components of the systems and to allocate the cost of the residues to the final products. At this point, some questions arise related to physical exergy disaggregation in thermoeconomic analysis: What kind of physical exergy disaggregation allows total disaggregation of the systems? The accuracy improvement of the results is significant? The increase in the complexity of the model is considerable? Is physical exergy disaggregation necessary for extracting the main conclusions in thermoeconomic analysis? This paper aims at answering these and others questions, by applying four different level of physical exergy disaggregation, for exergy and monetary cost allocation to the final products in five different cogeneration systems including dissipative components and residues, i.e., steam turbine and gas turbine cogeneration plants.
Palavras-chave: Improvement of the Accuracy of the Results; Physical Exergy Disaggregation; Thermoeconomic Modeling