A Novel Ejector-Expansion Transcritical CO2 Cascade Refrigeration Cycles

In this paper, two new high performance configurations of ejector-expansion transcritical CO2 cascade refrigeration cycles using constant-area mixing model were presented. A gas cooler exergy was utilized by a supercritical CO2 power cycle and cascading with sub-critical CO2 refrigeration cycle to enhance the performance of cycle. Theoretical analysis on the performance characteristics was carried out for the cycles using the first-law of thermodynamics. A parametric study was also conducted to optimize the performance of plant under various operating conditions. It was found that the coefficient of performance and second-law efficiency of the presented novel cycles are on average 32-169 % higher than those of the conventional ejector-expansion transcritical CO2 refrigeration cycle. The proposed cycles could be recognized as a promising refrigeration cycle from the thermodynamic and technical point of views.