Simultaneous process and working fluid optimisation for Organic Rankine Cycles (ORC) using PC-SAFT

Abstract

Organic Rankine Cycles (ORC) have a broad economically attractive application range since they can be tailored to fit specific conditions. The tailor-made design of ORC involves the selection of a suitable working fluid and the optimisation of the process itself. Today, these design steps are usually performed separately. In this paper, the holistic design of ORC processes is rigorously approached employing computer-aided molecular design (CAMD) to select a working fluid and to simultaneously optimise the corresponding process within a single mathematical problem. Herein, the strong molecular picture underlying the PC-SAFT equation of state is exploited using the recently developed continuous-molecular targeting (CoMT) approach. The effectiveness of the CoMT-CAMD approach is demonstrated for the optimisation of both working fluid and process parameters in a waste-heat ORC application.