[en] This contribution experimentally evaluates and compares the performance of an ORC (organic Rankine
cycle) system for stationary bottoming WHR (waste heat recovery) application operating with two
different working fluids, SES36 and R245fa. The test rig is a regenerative cycle equipped with a single
screw expander modified from a standard compressor characterized by a nominal shaft power of 11 kW.
A total of 36 and 43 steady-state points are collected for SES36 and R245fa respectively, over a wide
range of operating conditions by changing the expander rotational speed, the pump frequency and the
cooling condenser flow rate. The performances of the ORC components are individually evaluated. A
maximum expander isentropic efficiency of 60% is reached using SES36 at 3000 rpm, and a value of 52%
is reached with R245fa at 3000 rpm. However, for a given pressure ratio the expander output power is
higher with R245fa than with SES36. The overall performance of the ORC unit are investigated in terms of
first and second law efficiencies and net output power for the two fluids. The results experimentally
demonstrate the correlation between the working fluid critical temperature and the ORC unit working
characteristics for low temperature waste heat recovery applications. Open experimental data are provided
for both fluids.