Theoretical investigation of a novel hybrid refrigeration cycle based on the partial thermal isochoric compression

Abstract

The objective of this work is the investigation of a novel refrigeration cycle which utilizes both electricity and heat input. This hybrid cycle compresses the refrigerant by using a conventional compressor in the low-pressure stage and a novel isochoric compression in the high-pressure stage by adding heat in the system. Between the compression devices, there is an intercooler which is vital for reducing the heat input demand. The isochoric process is performed in a closed vessel where refrigerant pressure increases by adding heat, according to the gas laws. Different working fluids are studies like CO2, R134a, R404A, R152a, R290 and R32. According to the final results, the electricity consumption is reduced by the incorporation of the partial thermal compression compared to the conventional system with only mechanical compression. The CO2 and the R32 seem to be the most promising refrigerants for utilization in the novel suggested cycles. For the case with 75% mechanical compression and 25% thermal compression, the electricity savings with CO2 are found 15.61% for the case with the evaporating temperature at −25 °C and the heat rejection temperature at 35 °C. More specifically, in this scenario for 100 kW refrigeration production there is a need for 47.29 kW electricity and 19.72 kW heat input, while the system COP is 1.492 and the exergy efficiency 41.01%.