Comparative study on a dual temperature transcritical refrigeration cycle with two cascade ejectors.

Paper published in poster form during the conference. This paper presents a comparative study of performance of two natural refrigerants CO2 and N2O on a modified dual temperature transcritical refrigeration cycle using two cascade ejectors to enhance its performance. Thermodynamic analysis using energetic and exergetic methods are carried out. Effect of system performance parameters, namely COP, pressure ratios, entrainment ratios are evaluated for various warm weather operating conditions (heat rejection pressure within range 7 MPa to 12 MPa; heat rejection temperature 35°C to 50°C and evaporator temperatures -40°C to 0°C). Results show that the system using N2O as refrigerants have higher COP and lower heat rejection pressure compared to CO2 system. Exergy destruction is found to be highest in the gas cooler, followed by ejectors. Exergy efficiency of N2O system is found to be about 2.51% to 6.56% higher than CO2 system for the selected operating conditions.