Simulation and experiments on an ORC system with different scroll expanders based on energy and exergy analysis

An Organic Rankine Cycle (ORC) with a scroll expander with varying displacement is studied. First, to obtain the isentropic efficiency of the scroll expander modified from an automobile air-condition compressor with a displacement of 66 ml/r, the performance is investigated by experiments on a test rig driven by the compressed air. Second, based on the experimentally obtained isentropic efficiency, thermodynamic and heat transfer models of ORC are established on the basis of sub-models of the main apparatuses. Consequently, energy and exergy efficiencies are analyzed. Based on the simulation, an ORC system is constructed and investigated. Experiments show that for a given heat source temperature of 105 °C, the energy efficiency of the system ranges from 1.7% to 3.2% and the exergy efficiency of the system is 8.6%-16.9%. Additionally, another scroll expander with a displacement of 86 ml/r is utilized to investigate how displacement of the scroll expander influences performance of the ORC system. Finally, experiments also show that the IHX deteriorates the performance of ORC system, which is significantly different from simulation results.