Thermodynamic and exergoeconomic analysis of two-stage organic rankine cycle using different refrigerants

In this study, A two-stage Organic Rankine Cycle (ORC) was analyzed by using engineering equation solver (EES). Twelve Organic working fluids used in R32, R227ea, R410a, R290, R134a, RC318, R407c, R22, R23, R116, R218 and R245fa are used as the working fluids for given temperature limits. Suitable choice of refrigerant or refrigerant couple for the ORC's cycle efficiency, exergy and net work output has a vital importance. The results showed that the highest net power output and the highest thermal efficiency were obtained from the R23 + R23 pair at 425K. R227ea + R410a couple gives the highest thermal efficiency at 355K. For R245fa + R245fa refrigerant at 425K, 14.11kW exergy destruction is obtained in Pump-1, higher than other components. The smallest exergy destruction of 0.133kW is observed in Turbine-2 at 400K temperature. As a result, this study showed us R245fa is the most suitable working fluid because of higher condensation temperature for environmental conditions.