Thermodynamic analysis of combined ORC-VCR system with recuperator and reheater

Abstract

The trend of utilization of low-grade thermal energy gain huge attention due to increase in energy demand and depletion of conventional resources of energy. Low grade energy can be used in ORC-VCR cycle for refrigeration purpose. In the present work, to improve the performance a modified ORC-VCR cycle, recuperator and reheater are integrated in the cycle. The thermodynamic analysis of the modified system has been conducted with R600a, R600, R290 and R1270 as working fluids under various operating conditions viz. evaporator temperature, condenser temperature, boiler exit temperature. Different parameters evaluated to assess the performance are overall COP, mass flow rate per kW cooling capacity, expansion ratio and compression ratio. From the analysis, butane is found as a best choice for the modified ORC–VCR cycle. It was found that for the modified ORC-VCR cycle at boiler exit temperature of 90°C and condenser temperature 40°C has system COP of 0.5542 with butane, which is 7.1% and 18% higher than that of ORC-VCR cycle with recuperator and simple ORC-VCR cycle, respectively.