Performance Investigation of Two Two-Stage Trans-Critical Carbon Dioxide Refrigeration Cycles Ejector and Internal Heat Exchanger

Abstract

In the present work, the performances of improved two-stage multi inter-cooler trans- critical carbon dioxide (CO2) refrigeration cycles with ejector and internal heat exchanger have been examined. In the new improved cycles, an internal heat exchanger is append to the cycles. Also, second inter-cooler in improved cycles, cooled with the refrigeration of the cycle, so that in first cycle it is a branch of saturated vapour flow from separator and in second cycle it is a branch of supersaturated steam from internal heat exchanger as well. Results are validated against those available in the literature. Comparisons of the results indicate that there is an excellent agreement between them. The influences of important operational parameters in the cycle performance such as pressure of gas-cooler, temperature of evaporator and temperature of gas-cooler on the performance of cycle have been analysed. The obtained results present that if the cooling flow for second inter-cooler supply from saturated vapour from separator, maximum coefficient of performance can be improved 25% in comparison with the conventional cycle at the considered specific states for operation.

Keywords

• trans-critical
• refrigeration
• carbon dioxide
• multi inter-cooler
• internal heat exchanger