Simultaneous optimization of working fluid and boiler pressure in an organic Rankine cycle for different heat source temperatures

Abstract Over the last ten years, power generation from the waste heat from industries has become an effective factor in increasing the efficiency of industries. One of the most important ways to improve the efficiency is using the organic Rankine cycles. In this study, the waste heat from industrial complexes with temperature in the range of 120–300 °C was used to generate power through an organic Rankine cycle with different working fluids. In this regard, carrying out energy and exergy analyses on the organic Rankine cycle revealed that for each heat source temperature the maximum efficiency happens when a specific working fluid utilizes at a certain boiler pressure. According to the results, a heat source temperature of 120 °C had the highest energy and exergy efficiencies at a maximum pressure of 624(kPa) for working fluid of R245fa. Also, the optimum working fluids for the heat source temperatures of 150 and 200 °C were R152a and R141b, respectively. These working fluids also had the highest efficiency at the maximum pressures of 2735 and 847.5(kPa). Furthermore, for the heat source temperatures of 250 and 300 °C, Benzene and Water had the highest efficiencies that occurred at the maximum pressures of 398.8 and 452.1(kPa).