Process Simulation And Heat Pumps Of Tablet Frosting Frosting Features

Frost formation is a complex heat and mass transfer process. The thermal conductivity, density and frost surface temperature keep changing during this process. In this paper, a one-dimensional saturated model for cold plate frost was set up. The relations among various characteristic parameters under frost operating mode were studied numerically. The variations of the frost specific heat, the weighting factor and frost thickness were analyzed based on the existed correlations. Meanwhile, a method to calculate the frost thickness based on the supersaturation degree concept and the supersaturation model was proposed.Then, an analysis of the mass transfer on and within frost layer was carried out. The latent heat transfer ratio, the thermal conductivity change ratio and frost growth ratio were analyzed numerically base on a rational tortuosity factor. The result shown that the error for total heat transfer rate with 14% variation of tortuosity factor is less than 3.3%; the frost thermal conductivity changes less than 2% for an hour; and more than 90% of the mass transfer goes to increasing the frost thickness.Finally, a heat transfer analysis for the fin-tube heat exchanger was carried out base on the Perturbation Methods. An equation for predicting the highest heat transfer rate of ribs in fin-tube heat exchanger of the heat pump unit was derived and optimal sizes of the wing pieces were obtained.The results of this paper are of use for understanding frost formation processes and for the optimal design of air-source heat pumps.