Theoretical analysis and optimization of a hybrid CO2 transcritical mechanical compression - ejector cooling cycle

The paper provides the results of a design-theoretical study of a hybrid carbon dioxide (CO2) transcritical mechanical compression - ejector cooling cycle. The hybrid cooling cycle is a combination of a CO2 transcritical mechanical compression refrigeration machine (MCRM) powered by electricity, and an ejector cooling machine (ECM) driven by heat rejected from the CO2 cooling cycle. Refrigerants R245ca, R601b (neopentane) and R717 (ammonia) are investigated as the working fluids of ECM in the present study. A method to determine the optimal design parameters and performance of the hybrid cooling cycle is presented. It is shown, that efficiency growth of the transcritical CO2 cooling cycle due to ejector cooling cycle use is higher as evaporating temperatures are lower.