Evaluation of the influence of exergy disaggregation on the results of thermoeconomic diagnosis using exergetic operators

Abstract

Thermoeconomic diagnosis is a tool to locate malfunctions and quantify their impact on thermal system operating costs. Since diagnostic methodologies are mainly based on the iteration of exergy flows within thermal systems, some authors suggest that the results can be improved when exergy is disaggregated into its components. Therefore, a Rankine cycle with intrinsic malfunctions in the condenser and the steam turbine was diagnosed using the thermoeconomic diagnostic methodology with exergetic operators for the thermoeconomic models of total exergy and physical exergy disaggregated into its enthalpic and negentropic portions. To enhance the study, the total exergy and negentropy model was also used. The applied method can identify intrinsic malfunctions, induced malfunctions, and dysfunctions. However, contrary to what would be expected, the results regarding the intrinsic malfunctions were the same for the three thermoeconomic models evaluated. Furthermore, the thermoeconomic model did not affect the value obtained when adding induced malfunctions and dysfunctions. Thus, the fuel impact was divided into its intrinsic and induced parcels. These parcels also remain independent of the thermoeconomic model, allowing the same results to be obtained with less complexity when the methodology is applied directly to the transition structure without needing a productive structure.