Comparing exergy analysis and physical optimum method regarding an induction furnace

Abstract

In order to achieve energy and climate goals, energy and resource efficiency are considered a key measure. Limit-value-oriented methods such as the exergy analysis and the physical optimum method are used to show the limits of efficiency improvement. In this context, the physical optimum represents the theoretical ideal reference process. Despite their similarities, no comprehensive comparison to the exergy analysis has been carried out yet. Thus, the purpose of this study is to close this gap by examining differences and intersections using the example of an induction furnace. The minimum energy input according to the physical optimum method is 1327 MJ/t whereas the exergy of the melting product is 1393 MJ/t, depending on transit flows taken into account. The exergy analysis extends considerably beyond the physical optimum method in terms of the complexity and accuracy of the assessment of material flows by using exergy units. The exergy analysis makes clear which exergy is linked to the losses and thus reveals the potential for coupling processes. This results in different areas of application for the two methods.