Experimental Study of a 1-kW Organic Rankine Cycle Using R245fa Working Fluid and a Scroll Expander: A Case Study

In an organic Rankine cycle (ORC), the study of the cycle efficiencies and the turbine is essential to know the performance in the generation of electrical energy. The proper selection of a working fluid is relevant, because it must be environmentally friendly and compatible with the ORC plant. This article presents an experimental study for the analysis of the cycle and thermal efficiencies on a 1-kW ORC system and the isentropic efficiency of its scroll expander. The test was performed on a 1-kW ORC with scroll expander system with R245fa as the working fluid. Furtheremore, it was considered a working temperature below 100 °C, which is used in waste heat recovery systems, to determine the performance of the ORC. The enthalpy is estimated with the Coolprop software. For estimating the cycle and thermal efficiency, the net power and the thermal power, which are supplied to evaporate the working fluid, were considered. The isentropic efficiency of the expander was calculated by the scroll mechanical work and the hydraulic work at the scroll expander. The results show that the mean isentropic efficiency of the fluid in the prototype test for ORC in the generation of 1000 W was about 60%, a promising value for the generation of electrical energy using the residual heat from industry.