Design and preliminary tests of ORC (organic Rankine cycle) with two-stage radial turbine

•An ORC that generates electric power and uses R245fa as the working fluid was designed and developed.•A two-stage radial turbine coupled with a high-speed generator was designed by considering the high expansion ratio.•The performance of the developed ORC and turbine was investigated experimentally.•The manuscript was revised by following the reviewer's comments.

This paper concerns the design and preliminary tests of the ORC (organic Rankine cycle), which generates electric power using R245fa as a working fluid. A two-stage radial turbine expander is designed with an aim of improving the cycle performance by increasing its pressure ratio. The turbine is coupled with a high-speed generator without gear box incurring speed reduction. The turbine is designed in consideration of the thermodynamic properties of the working fluid and the cycle conditions. The design processes of the turbine and cycle are presented in the paper. The performance of the developed cycle and the turbine is examined experimentally, and the factors which influence the performance of the developed ORC are analyzed.