Sizing models and performance analysis of volumetric expansion machines for waste heat recovery through organic Rankine cycles on passenger cars

This paper aims at helping designers of waste heat recovery organic (or non-organic) Rankine cycles on internal combustion engines to best select the expander among the piston, scroll and screw machines, and the working fluids among R245fa, ethanol and water. The first part of the paper presents the technical constraints inherent to each machine through a state of the art of the three technologies. The second part of the paper deals with the modeling of such expanders. Finally, in the last part of the paper, performances of the various Rankine systems are compared and a decision array is built to select the most appropriate couple of fluid and expander.