Exergy analysis of compressor-expander assisted subcooling refrigeration system

In today's world, refrigeration systems play a crucial role in various sectors. The need for these systems is increasing, especially in many areas such as air conditioning, food production, healthcare sector and chemical industry. Refrigeration technologies are of critical importance to extend the shelf life of food products and ensure the effective storage of medicines. Therefore, effective operation of cooling systems is important to improve quality of life and optimize energy consumption. Any improvements could reduce the energy demand of these systems. A frequently used method to improve system performance is to lower the temperature of the refrigerant at the condenser outlet, known as subcooling. In this study, in addition to the subcooling systems described in the literature, exergy analysis of the compressor expander assisted subcooling vapor compression cycle was performed. In the designed cycle, the refrigerant gas is divided into two parts at the condenser outlet. By using additional refrigerant, it is aimed to reduce the power consumed by the main compressor by switching to another expansion valve, evaporator and an expander compressor to increase the inlet pressure of the compressor. Six different refrigerants were used in the system: R134a, R1234yf, R32, R290, R1270 and R600a, which have low global warming potential. The increase in exergy destruction and exergy efficiency values for each cooler is calculated for different evaporator temperatures and shown in graphs. According to the results obtained, the highest unit exergy destruction at the optimum point was obtained when R290 fluid was used and the least exergy destruction was obtained when R1234yf fluid was used. In the classical system, it was observed that the highest exergy destruction was in the expansion valve and this value decreased in the new system. Total exergy destruction decreased in the expander-compressor system.