LOWER GWP REFRIGERANTS FOR REFRIGERATION APPLICATIONS

摘要

GWP (Global Warming Potential) of HFCs being used today as non-flammable refrigerants are relatively high [1], therefore, their usage is being reviewed worldwide. F-Gas Regulation came into effect in Europe [2], and HFC regulation is scheduled to be implemented in Japan from 2015. In addition, HFC regulations are also under consideration in the United Nations [3]. In such movements in regulations, the use of lower GWP refrigerant like HFO-1234yf began in the field of automotive air conditioning systems, and the use of alternative refrigerants like R32 began in the field of residential air conditioning systems [4]. On the other hand, several lower GWP refrigerants have been proposed in the field of refrigeration systems, but it is undecided. From the viewpoint of preventing global warming, conversion to a lower GWP refrigerant is getting more attention in this field. This paper describes the performance when various refrigerant blends of which GWPs are 1,500 or lower are applied for the field of refrigeration. We observed that the performance when using lower GWP (300 or less) refrigerant blends is approximately the same as the performance when using middle GWP (1,500) refrigerants. However, a trade-off remains between flammability and GWP of these refrigerant blends. The middle GWP (1,500) refrigerants are non-flammable, and the lower GWP (300 or less) refrigerant blends are slightly flammable. As the result, establishment of appropriate operating conditions of such slightly flammable refrigerant blends is an unavoidable issue for introducing such lower GWP refrigerants. As the burning velocity of these lower GWP refrigerant blends is 10 cm/sec or less, it is considered that these lower GWP refrigerant blends are capable to be handled under the similar operating condition to that of R32 or HFO-1234yf which also has a burning velocity of 10 cm/sec or less.