An improved cascade mechanical compression–ejector cooling cycle.

Abstract In this paper, a method for improving the efficiency of the cascade mechanical compression–ejector cooling cycle is described. The considered cooling cycle is the combination of the electrically driven carbon dioxide (CO 2) subcritical mechanical compression cooling cycle as a bottoming cycle, and the heat driven ejector cooling cycle as a topping cycle. This cooling cycle is proposed to use superheated CO 2 vapor to preheat the working fluid supplied to the vapor generator, thus improving the whole system's efficiency. This paper provides thermodynamic analysis results for the cascade cooling system in a wide range of evaporating temperatures. Refrigerants R245ca, R600, and R601b were investigated as the working fluids for the ejector cooling cycle, and the results show that the proposed cooling cycle is the most effective at low evaporating temperatures. Highlights • A cascade CO 2 mechanical compression–ejector cooling cycle is studied. • Refrigerants R245ca, R600 and R601b are used for the ejector cooling cycle. • Performance improvement regarding COP, COP THERM and exergy efficiency is evaluated. • The refrigerant preheating has considerable influences on the cascade cycle performance. • The proposed cascade cooling cycle is compared with conventional cycle. [ABSTRACT FROM AUTHOR]