Weipeng Lu

An Improved Generalized Model for Predicting Frost Growth on a Cold Flat Plate

A generalized quasi-steady and one-dimensional model for predicting the frost growth on flat plate was proposed based on the previous theoretical models. To improve the predicting ability of the current model, a modified semi-empirical correlation for calculating initial condition of frost density was presented experimentally. The experiments were conducted in a suction-type open-loop wind tunnel under a series of experimental conditions: air temperature −8°C to 19°C, humidity 42% to 80%, velocity 5m/s and the temperature of cold plate −16°C to −8°C. The numerical results of frost thickness, frost density, frost surface temperature and heat flux rate were compared to the experimental data. The simulation results were found agree with the experimental results in a maximum error of 10%. The presented model was further validated by comparing with the previous published experimental data in a wide range of frosting conditions. It was found that the presented model was a simple but universal one to predict the frost growth on cold flat plate.Copyright

Dynamic frosting characteristics on cold flat surface in different air temperature and humidity conditions

In this paper, the dynamic frosting characteristics on cold flat surface in different air temperature and humidity conditions are investigated numerically. The variation range of air temperature and relative humidity are respectively −10∼10 °C and 50%∼90%, which is the most common frosting condition. The simulation results of frosting characteristics including the parameters of frosting rate, frost thickness, frost density, thermal conductivity of frost layer, frost surface temperature and heat flux variation with the frosting time. These results provide valuable references to design suitable defrost control strategies for air source heat pump used in different areas.