Performance investigation of an ejector expansion refrigeration system working on different alternative refrigerants to R134a

Abstract

ABSTRACT In this paper, the performance characteristics of an ejector-expansion refrigeration cycle using six low GWP alternative refrigerants for R134a are presented through the first and second laws of thermodynamics. The ejector is modelled by assuming a constant-mixing pressure. The investigated refrigerants are compared based on the optimum ejector area ratio, discharge temperature, volumetric cooling capacity (VCC), coefficient of performance (COP) and exergy efficiency (ηex). The drop-in analysis is considered based on the same operating/designing parameters, and the VCC, COP and ηex improvements over the conventional refrigeration cycle are presented. The improvements in COP and VCC are between 7.914%–18.46% and 5.712%–22.82%, respectively, for the investigated range of evaporating and condensing temperatures. These values are higher than that of R134a by about 21% and 16%, respectively. The VCC using R1234yf is very close to R134a with a maximum reduction of 6.5%. Therefore, R1234yf refrigerant appears to be the best alternative to R134a in an ejector-expansion system with an appreciable COP and ηex devaluation. R152a outperforms R134a in terms of COP and ηex, thus it is a suitable alternative to R134a except for safety.