Numerical and Experimental Study on the Diffusion Property of Difluoromethane (HFC-32) in Leakage

Abstract

With the development of industry in China, production and use of dangerous chemicals gradually increased, and as a result leakage accidents caused by that happen more and more frequently. In the field of refrigerants in air conditioner, because of the destruction to the environment from freon(CFC), people are looking for new refrigerants which can replace the freon. And difluoromethane (HFC-32) does no harm to the ozone layer, making it a good substitute. But it's still not widely used. One of the reasons is that difluoromethane is flammable, and its detection technology indoors is not mature. In this study, based on computational fluid dynamics theory and the CFD software FLUENT, the process of leakage of difluoromethane was simulated to study the law of HFC-32 diffusion. And then in a same proportion of entity room experiments were carried out to corroborate the results. From both simulation and experimental results above, we can see that when the leakage point is lower (cabinet air conditioners scene), the difluoromethane cannot easily diffuse to higher places. It will subside to the ground soon and diffuse from the leakage point, and then making it as the centre, spread from the near to the distant. And in the leakage process, the concentration near the leakage point is higher than that in other areas in the same plane. But when the leakage point is located higher (wall-mounted air conditioners scene), there is an obvious effect of sedimentation, in some areas there will be the lowest concentration value at intermediate height. And because of the impact of the initial velocity, the concentration in places closest to the leakage point is not higher than that of the surrounding in the same z plane that is lower than the leakage point.