Simulation of a cavity insulated by a vertical single band cold air curtain

The cold air curtain used for cavity insulation in the present study is a fundamental idealization of a refrigerated air curtain in display cases. Flow and heat transfer characteristics of vertical single band cold air curtains are studied numerically to investigate the effects of mixed convection and height/width ratios. The results show that for a given Grashof number, the Richardson number must be less than a critical value to assure thermal insulation. From studies of the effect of height/width ratios, it is found that small height/width ratios yield an increased critical Richardson number (thus a reduced critical Reynolds number) and a decreased volumetric infiltration rate. For the cavity whose height/depth ratio equals 2 in the present study, the critical Richardson numbers are 0.62, 0.28 and 0.20 for the height/width ratios of 10, 15 and 20, respectively.