Delineation of Frost Characteristics on Cold Walls by Using a New Formula for Psychrometrics Demarcation Boundary

In this study, a direct new formula that predicts frost formation on cold walls corresponding to psychrometric-subsaturated. The new formula uses data of the entering air dry-bulb temperature and absolute humidity and absolute humidity of air at saturation corresponding to the coil surface temperature. To validate the formula, case studies of demarcation criteria for frost formation on evaporator coil using experimental measured data and on walls of cold storage freezer using measured data from literature are used. Results completely match with the graphic plot of the data on the psychrometric chart. In case of cold storage freezers, results clearly show that a greater demarcation criteria value indicates frost formation under severe condition, as snow-like with low density and thermal conductivity.