Study of the Performance Parameters in an Organic Rankine Cycle Power System Operating in Low Temperature Conditions

The working fluid normally used in Organic Rankine Cycle (ORC) systems is R245fa. However, due to stricter regulations for emission control, this type of fluid will be phased out. Due to the above, in this research, the performance parameters of ORC systems operating at low temperatures with different working fluids are analyzed. The research was carried out by numerical simulation using MATLAB® software and the CoolProp® database. The working fluids investigated were R245fa, R1233zd(E), and R1336mzz(Z), respectively. The analysis of the performance parameters involves the net power, thermal efficiency, and exergetic efficiency of the ORC system. From the results obtained, it was shown that the net power obtained with the working fluid R1233zd(E) and R1336mzz(Z) are 3.5% and 6% lower compared to R245fa. However, the higher evaporation temperature of R1233zd (E) allows achieving a higher thermal and exergetic efficiency of the thermal cycle. R1233zd(E) enables a 3.8% and 4.8% improvement in thermal and exergetic efficiency compared to R245fa working fluid. R1336mzz(Z) working fluid is not recommended as a replacement for R245fa. In general, R1233zd(E) has the potential to replace R245fa, which is one of the main working fluids used despite its high level of CO2 emissions.