Performance Investigation For A New Near-azeotropic Refrigerant

According to Montreal Protocol and the related revisions, the most commonly used refrigerant in low temperature refrigeration R502 has been the firstly phased out refrigerant as its nonzero ODP and high GWP value. It has been phased out in 1996 in developed countries and will be phased out before 2010 in developing countries. The primary alternative refrigerants of R502 are R404A and R507A, which have zero ODP but high GWP. From the environment protection point of view, these two refrigerants are not perfect for long term alternative. Therefore, to develop a new kind of refrigerant with the close thermodynamic characteristics but more friendly environmental property will be significant.In this work, a new near-azeotropic mixed-refrigerant is investigated and its thermodynamic characteristics and environmental property are compared with R502, R404A, R507A and R290. With the software of REFPROP V8.0, the thermodynamic performance of these proposed refrigerants is calculated in the simplified refrigeration cycle. The result of the calculation shows that at the evaporating temperature around -40℃, the new refrigerant has lower pressure ratio, higher COP and volumetric refrigerating capacity, but the discharge temperature is a little bit higher.Based on related research literature, an experimental system was designed and built according to the state standard of GB/T 5773-2004. The whole system includes three parts: the testing system, the cooling water system and the data acquisition system.All the five refrigerants were tested on this experimental system. The experiments were carried out on different working conditions such as various evaporating temperatures and condensing temperatures. The subcooling and superheating temperature are also changed in the additional tests. The test results show that in the low temperature refrigeration, the new refrigerant have better performance on pressure ratio, discharge temperature, volumetric refrigerating capacity and the COP, compared with R502 and its alternative refrigerants of R404A and R507A.Theoretical analyses as well as the experimental results prove that this new near-azeotropic refrigerant has better cycle performance than that of R502 , R404A and R507. Meanwhile this refrigerant shows friendly to the environment as its zero ODP and much lower GWP. After all, this refrigerant has good potential for the long term substitution of R502 and is worth for further investigation.