A novel organic Rankine cycle-ejector booster refrigeration cycle for low-temperature sources

Abstract

In this study, a detailed comparison was made between the Organic Rankine Cycle-Vapor Compression Refrigeration Cycle (ORC-VCRC) and the novel Organic Rankine Cycle-Ejector Booster Refrigeration Cycle (ORC-EBRC), which was developed as an alternative, using the environmentally friendly refrigerant cyclopentane. Energy and exergy analyses were performed for the ORC-EBRC cycle. A renewable energy source was used for the low-temperature heat source (75 °C–115 °C) on the organic Rankine cycle (ORC) side. The boiler, condenser, evaporator temperatures and isentropic efficiency values of the compressor and turbine were examined over specific ranges, and variations in coefficinet of performance (COP), exergy efficiency, total mass flow rate, compressor compression ratio (CCR), and expander expansion ratio (EER) were obtained. The results indicate that the ORC-EBRC cycle is a more suitable choice in terms of energy and exergy compared to the ORC-VCRC cycle. For a boiler temperature of 100 °C, compared to the ORC-VCRC cycle, the ORC-EBRC cycle achieved increases of 17.56 % in COP_system, 20.21 % in exergy efficiency, and a decrease of 10.04 % in total mass flow rate. For a condenser temperature of 40 °C, the increases were 17.15 % in COP_system, 20.05 % in exergy efficiency, and a decrease of 9.11 % in total mass flow rate. For an evaporator temperature of −15 °C, the increases were 17.91 % in COP_system, 20.13 % in exergy efficiency, and a decrease of 11.35 % in total mass flow rate. It was determined that changes in the isentropic efficiency values of the compressor and turbine increased the COP_system and exergy efficiency values, while decreasing the total mass flow rate values.