New refrigerant R450A is used for performance study of ejector refrigeration cycle

New refrigerant R450A is used for performance study of ejector refrigeration cycle

The new refrigerant R450A is a substitute for R134a, which is environmentally friendly and reliable. There are still few studies on it. The limited research mainly focuses on simple vapor compression refrigeration cycles. A mathematical model of ejector was constructed to compare and analyze R450A's refrigeration performance under different ejector characteristics and working conditions in the new ejector refrigeration cycle. The study found that in the ejector refrigeration cycle, the pressure drop of the ejector fluid, the mixing area ratio of the working fluid and the ejector fluid have a parabolic change in the cycle COP, the cooling capacity per unit volume and the ejector compression efficiency, and there is an optimal ejection The fluid pressure drop is 10 kPa and the mixing area ratio of the working fluid and the ejection fluid is 7, and the optimal ejection fluid pressure drop and the mixing area ratio of the working fluid and the ejection fluid increase with the increase of the condensation temperature. In addition, compared with the traditional vapor compression refrigeration cycle, the COP and unit volume refrigeration capacity of R450A in the new jet refrigeration cycle are increased by 14.6%-20.6% and 21.1%-21.7% respectively, and the system performance is significantly improved. At the same time, the ejector nozzle and the efficiency of the diffuser have a significant impact on the system performance, and the efficiency of the diffuser has a stronger effect.

　　 Since the 1990s, R134a has been widely used with its excellent cooling capacity and zero ODP (Ozone Destruction Index) value. However, with the in-depth research on global climate change, R134a is recognized as a greenhouse gas due to its high GWP (Greenhouse Effect Index) value, ranking third among the substances that cause global warming. In order to meet the requirements of the "Kyoto Protocol" and the "Paris Agreement", it is of great significance to find an alternative refrigerant to R134a.

　　 The current research on the substitution of R134a mainly includes natural working fluid and artificial synthesis. In terms of natural working fluids, Ma Yitai, Liu Shengchun, etc. have studied the transcritical cycle of CO 2 and its performance comparison with Freon refrigeration cycle; the research of R1234yf and R1234ze(E) is the most representative in terms of artificial synthesis, Wu et al., Brown et al. , Dong et al. and Chen Qi et al. carried out very thorough experimental studies on the thermophysical properties and transport properties of these working fluids. The new refrigerant R450A is composed of R1234ze(E) and R134a, with mass fractions of 58% and 42%, respectively. It is not easy to burn, and its GWP value is 58% lower than that of R134a. It can be used in heat pumps, air-cooled water-cooled units, automatic beverage vending machines and other medium and low temperature equipment. It is one of the better-performing alternatives to R134a. The US National Environmental Protection Agency SNAP (New Refrigerant Substitution Program) project.

　　 At present, the domestic research on R450A is still relatively lacking. The world's research mainly focuses on the basic cycle performance test comparison of R450A. Mota-Babiloni et al. experimentally measured the refrigeration system with an intermediate regenerator, and compared the cooling capacity, COP, exhaust temperature, etc. of the R450A under different working conditions and the effect of the intermediate heat exchanger on the compressor efficiency, and obtained the R450A cooling capacity 6% lower than R134a, COP is about 1% higher. Mendoza-Miranda et al. [Proposed a compressor prediction model. The measurement results in a basic vapor compression refrigeration system show that the cooling capacity and COP of R450A are slightly lower than R134a.