Performance comparison of the single-refrigerant cascade refrigerating system
Zhili Sun, Jianhua Quan, Yian Wang, Ruishen Li, Jie Peng, Haoran Zhang, Jiapei Xu, Huan Sun, Shen Tian, Shengming Dong, Kaiyong Hu, Wenxiang Chen
Abstract
In the food refrigeration industry, the single-stage compression refrigerating system cannot meet the operating conditions of a high-pressure ratio when the evaporating temperature decreases. The cascade refrigerating system (CRS) is an alternative technical solution to solving the mentioned problem. This paper studied single-refrigerant pairs used in CRS. The single-refrigerant pairs R32/R32, R125/R125, R1270/R1270, R143a/R143a, R404A/R404A, R407A/R407A, R410A/R410A, and R507A/R507A were adopted to evaluate their operating characteristics compared with those of the traditional R23/R404A CRS. The operation adaptability of the compressor, the optimal operating parameters, the coefficient of performance (COP), and the seasonal energy efficiency ratio (SEER) were analyzed under different single-refrigerant pairs. The results show that the COP of the traditional CRS can be improved by using single-refrigerant pairs. The COP of R32/R32, R125/R125, R1270/R1270, R143a/R143a, R404A/R404A, R410A/R410A, and R507A/R507A were improved by 19.48%, 8.08%, 21.54%, 14.33%, 11.00%, 15.64%, and 12.11%, respectively. In addition, the SEER of the single-refrigerant CRS was higher than that of R23/R404A CRS. This could reduce energy consumption and save energy in typical cities in five major climatic zones of China. Considering COP, flammability, and safety, the application of R1270/R1270 and R32/R32 in a CRS with a low refrigerant charge is recommended. Meanwhile, R410A/R410A may be used in a CRS with a large refrigerant charge. These results provide a theoretical basis for the application of the single-refrigerant CRS.