Energy and Exergy Analyses of a Refrigerant Pump Integrated Dual-Ejector Refrigeration (DER) System

The aims of the present study are to design and perform the analysis of a dual-ejector refrigeration system (DER). The system is constructed by adding a second ejector and a refrigeration pump to the classical single-ejector refrigeration system (SER). In the theoretical analysis, two different refrigerants are employed, R134a and R600, and the cooling coefficient of performance (COP), exergy destruction and exergy efficiency are selected as the performance indices. The performance indices of the DER system are investigated under the variation of the evaporation, and condensing temperatures and results are compared with the SER system operating at the same conditions. In the given conditions, the maximum cooling COP and exergy efficiency are achieved with the DER system by 7.52 and 38.8%, respectively. In the DER system, the minimum exergy destruction occurs with R134a by 9.3 kJ/kg at 10 °C evaporation and 40 °C condensing temperatures. Moreover, 5.3% increments in the cooling COP and exergy efficiency are achieved with R600 when the condenser temperature is 55 °C and the evaporator temperature is 5 °C. The results also showed that the improvements achieved in the cooling COP and exergy efficiency with the DER system are greater at high condensing and low evaporation temperatures.