Experimental verification of a rolling-piston expander that applied for low-temperature Organic Rankine Cycle

A kilowatt-sized rolling-piston expander is proposed for low-temperature Organic Rankine Cycle power generation system. The main purpose of this paper is to conduct a dynamic test of the proposed expander. A low-temperature ORC system using R245fa as working fluid is established for the performance evaluation of the proposed expander. In the experimental system, a hot-water boiler is applied to supply a low temperature heat source. A variety of working conditions are achieved by varying the feed pump capacity and the generator load. In these tests, experimental data such as the R245fa flow rate, the temperature of expander inlet and outlet, the pressure of expander inlet and outlet, the output power and rotation speed of the expander are measured and analyzed. The experimental results show that the proposed expander normally runs between 350 rpm and 800 rpm with a maximum output power of 0.35 kW when the heat source temperature is below 90 °C. Meanwhile, a maximum expander isentropic efficiency of 43.3% and a stable Rankine cycle efficiency of 5% are also obtained.