Experimental study of organic rankine cycle system using scroll expander and diaphragm pump at different condensing temperatures

A small-scale RORC (organic Rankine cycle with a regenerator) system using a scroll expander and a diaphragm pump has been built. By using R123 as the working fluid, the expander, pump, and system performances are measured under different condensing temperatures. The maximum shaft power output of the expander obtained in this work is about 700 W. By increasing the shaft torque of the expander, the isentropic efficiency of the expander first increases and then decreases. The pressure ratio increases with increase of the shaft torque of the expander. The expander shows a highest shaft power output with the filling factor reaching 0.6–-0.7. When T_c increases, both the pump work consumption and the pressure difference of the pump show an increasing trend, leading to an increase in the mass flow rate of the working fluid, which is the main reason for the increase of the shaft power output of the expander. The obtained minimum BWR is about 0.46, the maximum electricity efficiency of the pump is 34.2%. The maximum thermal and exergy efficiencies are 2.4% and 9.3%, respectively.