Research on the field strength characteristics and the flammable area of refrigerants leakage into a confined space

Abstract

Some target refrigerants used in refrigeration systems have various flammability. Once the flammable refrigerants leak into a confined space, it is easy to pose safety hazards. Moreover, the leakage refrigerants undergo continuous expansion and compression processes in the near field of the confined space, and the field strength of the refrigerants changes dramatically, which has an impact on the diffusion and the concentration distribution of the refrigerant in the far field of the confined space. The differences in the field strength and the flammable area for different refrigerants are largely determined by the thermophysical parameters of the refrigerants. Therefore, to better assess the hazards of refrigerant leakage, R717, R290, R161, R32, R152a and R1234yf were selected as the targeted leakage refrigerants in this paper, R744 and R134a were selected as the referenced refrigerants, the temperature, velocity and concentration fields of the refrigerants leaking into a confined space were studied, the influence of thermophysical parameters on the field strength of the refrigerants in the near field was further analyzed, and the flammable area formed in the space was explored. The results found that the temperature field was mainly affected by the density and the specific heat of the refrigerant. The velocity field was mainly affected by the density and viscosity of the refrigerant. The concentration field was mainly influenced by the density, viscosity and diffusion coefficient of the refrigerant. When the density was close, Schmidt number could be used to assess the influence of the viscosity and the diffusion coefficient on the concentration field. Under the same leakage pressure, the range of the flammable area formed by the leakage of R290 was the largest, followed by R161 and R152a, the flammable areas of R1234yf and R717 were very close, and the flammable area formed by R32 was the smallest.