Performance optimization of organic rankine cycle based on simulated annealing algorithm

First, a procedure to select working fluids for the Organic Rankine Cycle (ORC) was introduced. Fourteen working fluids of better overall performance were selected based on their better environmental characteristics, thermal efficiency and net power output. Then, the performance of the Basic Organic Rankine Cycle (BORC) and the Organic Rankine Cycle with Inner Heat-exchanger (ORCIH) were optimized for the selected fourteen working fluids, by the simulated annealing algorithm. And the performance of these two cycles under the optimized condition were compared and analyzed. Furthermore, the performance of the BORC was analyzed as heat source temperature changed. The results show that the thermal efficiency and the exergy efficiency of the ORCIH are 0.80%~3.34% and 3.20%~10.22% larger than that of the BORC, respectively. The thermal efficiency, the working fluid mass flow rate and the net power output of both the BORC and the ORCIH increase with an increase in the temperature of the heat source. Among these selected working fluids, benzene from the non-refrigerants shows the best cycle performance while R245ca and R245fa from the refrigerants show better overall performance.