Explosion risk analysis of R290 leakage into a limited external space

Abstract

R290 is considered as a promising alternative refrigerant to be used in household air conditioners. To promote the safety application of R290 in air conditioners, a numerical model of refrigerant leakage and diffusion in a limited space was developed, and the reliability of the model was verified by the experimental results on the concentration field of refrigerant leakage from a split air conditioner indoor unit. On this basis, the field strength characteristics of R290 leaking from holes with different diameters and shapes to the external space were investigated, and the explosion risk caused by R290 leakage was further analyzed. The results showed that when R290 leaked from circular leakage holes with different diameters or leakage holes with different shapes to the external space, respectively, Mach disks were formed in the flow area, and the location and size of the Mach disks had certain differences. For circular leakage holes, with the increase of the leakage diameter, the diameter of the Mach disk inside the flow area and the distance from the Mach disk to the leakage hole increased, and the range of the flammable area formed by the leaked R290 in the external space did not change significantly in the horizontal direction, but increased significantly in the vertical direction, which were 0.42 m, 0.84 m, 1.26 m, and 1.7 m, respectively. For leakage holes with the same area but different shapes, the diameter of the Mach disk formed by the gas leaking from the circular hole was larger, and the gas was distributed symmetrically in the horizontal direction with the jet axis as the center in the external space. The gas leaking from the triangular hole was approximately distributed in a triangular shape, and then it diffused along the three centerlines of the triangle. The gas leaking from the square hole diffused along the diagonal of the square in the horizontal direction, and finally the flow area gradually changed from a square to a circle. The gas leaking from the rectangular slit was elliptically distributed in the external space, and the gas mainly diffused along the long axis direction of the ellipse, and the diffusion of the short axis direction was not significant. The range of the flammable area formed by the gas leaking from holes of different shapes did not change significantly in the external space.