Energetic and Exergetic Investigation of a N2O Ejector Expansion Transcritical Refrigeration Cycle

Thermodynamic analysis of a transcritical N2O ejector expansion refrigeration cycle is analysed. A two phase ejector, as an expansion device, is used in place of a conventional expansion valve. Effect of three performance parameters for cycle, namely COP, refrigerating effect, compressor work and two performance parameters of ejectors namely entrainment ratio and pressure recovery ratio are evaluated for various motive nozzle inlet conditions and evaporator temperatures. Further, both energetic and exergetic comparison of the proposed cycle is presented with respect to conventional CO2 ejector expansion refrigeration cycle. The N2O ejector expansion system is found to have higher COP, lower compressor discharge pressure and higher entrainment ratio but have disadvantage of lower volumetric cooling capacity. Maximum COP of N2O ejector cycle is found to be about 10% higher than maximum COP of CO2 ejector cycle. Exergetic output of N2O ejector cycle is higher whereas losses occurred due to irreversibility during expansion is lower.