Testing of R245fa and R1233zd(E) in a high temperature waste heat recovery application utilizing a scroll expander.

An organic Rankine cycle (ORC) test setup for high-temperature waste-heat-recovery applications was constructed. The test setup was used to conduct an experimental study of a subcritical ORC architecture working with a high temperature gaseous heat source of approximately 10 kW and to evaluate the feasibility of employing an ORC to recover waste heat from small-scale internal combustion engines. The market affordability of all components including a prototype scroll expander, which contributes heavily to the cycle design, is considered. The cycle consists of a diaphragm pump, a plate heat exchanger as a regenerator, a novel micro-tube evaporator, an air-cooled condenser, and a scroll-type expander. Three expander prototypes of Oldham ring orbiting, idler shaft orbiting, and spinning scroll were evaluated for their performance within this ORC. Focus was given to constraining the high-side temperatures of R1233zd(E) due to its limited thermal stability while decreasing exergy destruction. In this work, a performance comparison between R245fa and R1233zd(E) for varying thermal inputs, expander types, and refrigerant superheating values is reported.