Numerical Study on the Flammable Zone of Refrigerant Leaked into Complex Application Environments

The application environment of flammable alternative refrigerants is quite complicated. Once refrigerant leaks into different environments, the diffusion process, distribution, and flammable zone show great differences, which brings challenge to the assessment for the explosion risk. Therefore, R290 and R1234yf were chosen as the research objects, the variation of the flow field of the leakage refrigerant in confined spaces with different temperatures, humidity and pressures were investigated, and the extent of the flammable zone was explored. The results indicated that compared with 40% RH, the extent of the flammable zone generated by R290 in the environment with 60% and 80% RH was reduced by 0.37% and 7.33%, and the extent of the flammable zone generated by leaked R1234yf was increased by 8.57% and 14.28%, respectively. Compared with 278.15 K, the extent of the flammable zone generated by R290 in the environment with 298.15 and 318.15 K was increased by 4.67 and 9.73%, respectively. However, R1234yf leakage into the environment of 278.15 K did not form the flammable zone, and as the ambient temperature increased from 278.15 K to 298.15 and 318.15 K, the flammable zone began to form. After leaked refrigerant returned to the atmospheric pressure, the efrigerant diffusion in low pressure environment was faster, and its concentration was also higher. Compared with the atmospheric environment, the extent of the flammable zone in the environment with pressure of 0.05 MPa increased by 31.17%, and the extent of the flammable zone in the environment with pressure of 0.15MPa decreased by 5.84%.