Solar assisted organic Rankine cycle for power generation: A comparative analysis for natural working fluids

Abstract

In this study, a comparative thermodynamic analysis of a solar assisted organic Rankine cycle (ORC) is carried out for different natural working fluids. The required heat energy demand for ORC is supplied by solar energy by means of parabolic trough solar collectors (PTSCs). For the ORC system, eight different natural working fluids those are suitable for low temperature applications such as R170, R1270, R600, R600a, R717, R744, R218 and R161 are analyzed comparatively. Also the analyses are made for R134a in order to compare the system performances. The calculations are made according to the solar flux distribution in Turkey. For the results, the energy and exergy efficiencies and exergy destruction rates of the ORC system for different working natural fluids are compared in detail. From the results of energy and exergy analyses, the best fluid is found to be R744 with a power generation rate of 4.87 kW with an energy and exergy efficiencies of 8 % and 7.1 % respectively. Also it is found that R218 has the highest exergy destruction rate as 76.98 kW. Additionally, the effects of turbine inlet temperature, turbine inlet pressure and condensation temperature on system performance are parametrically analyzed.