Two performance indicators for the characterization of the entropy production in a process unit

Two indicators are presented to compare the Second law performances of different design-variants of the same process unit. The first indicator relates the entropy production to quantities like the total transferred thermal energy and the total chemical conversion. This allows a useful comparison, even in the case of different inlets and outlets. An important aspect of the entropy production in a process unit is its distribution. An even distribution, also known as equipartition of entropy production (EoEP), is related to an optimal design. The second indicator is based on the coefficient of variation of a local entropy production profile and allows one to calculate and compare degrees of equipartition of different designs. Both indicators have been used in a study on the entropy production minimization of a plug-flow reactor. A comparison using the first indicator showed that the optimized reactors perform slightly better than a comparison based on the total entropy production alone would suggest. This shows that the total entropy production is not always a good indicator. The second indicator was found to provide an excellent numerical basis for comparing the degrees of EoEP of the different designs.