Optimization design and working fluid selection for transcritical organic rankine cycle based on particle swarm optimization

In this work, thermodynamic calculations for the transcritical organic Rankine cycle (ORC) were performed, and 10 optimal working fluids were recommended for the transcritical ORC, based on the thermophysical properties, environmental protection performance of the working fluids and the thermodynamic performance of the whole cycle. According to the thermodynamic calculation results and the variation trends of the transcritical ORC exergy efficiency with the expander inlet temperature and the evaporate pressure, it is revealed that there exist optimal values. Thus, an optimization analysis was further performed for the transcritical ORC with the above recommended 10 working fluids, using the Particle Swarm Optimization (PSO) as the optimizer. The optimization results show that the propylene possesses the best overall performance in the no-refrigerant working fluids, which is followed by the propane, while the R134a is standout for its remarkable performance among the refrigerant working fluids.