Performance Analysis of Supercritical Organic Rankine Cycles

Abstract

Supercritical Rankine cycles using organic fluids as working fluids in converting low-grade energy to high-grade power energy are investigated in the study. The main purpose is to identify suitable working fluids which may yield high system efficiencies in a supercritical Organic Rankine Cycle (ORC) system. R123, R134a, R152a, R22, and R245fa are used for the research. Results show that: at a constant superheating of expansion outlet, system efficiency improves with the increasing of evaporation pressure for all the working fluids and supercritical ORC has a higher efficiency than sub-ORC process. Furthermore, R152a performs the best compared with other refrigerants and is suitable for SORC system.