Key Words:INTERNAL HEAT-EXCHANGER; THERMODYNAMIC PERFORMANCE; SYSTEM; PUMP
Abstract:This paper builds a cascade refrigeration cycle (CRS) system for the requirement of producing ultra-low temperature of -80 to -50 celcius. Taking R404A/R23 CRS as an example, the natural refrigerant NH3 is used to replace the high temperature cycle (HTC) refrigerant R404A, and the environmentally friendly refrigerants R1150, R170, and R41 are used to replace the low temperature cycle (LTC) refrigerant R23. The influence of internal heat exchanger (IHX) on the performance of CRS when using new environmentally friendly refrigerants is analyzed. CRS with two-stage compre intermediate complete cooling method in HTC (CRS with TSC in HTC) is constructed, which not only reduces the discharge temperature of HTC compressor, but also improves the COP and exergy efficiency. According to the basic principles of thermodynamic energy and exergy balance, a system model is established and simulated, the CRS with TSC in HTC used NH3/R1150, R170, R41 and CRS with IHX in HTC used R404A/R23 are comparative analyzed. The results show that optimal COP of the former is 15.79%, 18.58% and 16.17% higher than those of the latter under the given working conditions. The comparison analysis shows that the NH3/R170 CRS had the best refrigeration performance. The research results will provide a reference to the application of cascade refrigeration system using environmentally friendly refrigerants for ultralow temperature in considerations of efficiency and cycle configurations.
Volume:44
Issue:-
Translation or Not:no