Prediction of heat and mass transfer inside 3D frost microstructure

Abstract

In the present study, a CFD model based on 3D frost microstructure is developed. The desublimation phase change coupled with mass transfer of water vapor to ice surface and heat conduction through the tortuous ice crystals are calculated to predict accurate heat transfer process inside the frost microstructure. Air velocity and temperature inside the frost structure after 30 min operation are significantly lower than those inside 10 min operation, which are influenced by the structural change of the ice crystals. Vertical variations in ice crystal surface temperature and ice surface mass flux are also calculated, which varied between the frost structures operated for different periods. At 70 μm height of the frost, the mass flux at the ice crystal surface shows significant decrease from 7.48 × 10−5 kg/m2s for the frost structure at 10 min to 1.82 × 10−5 kg/m2s for that at 30 min. This study provides new and fundamental information to understand the mechanism of frost growth which is very important in refrigeration, cryogenics, and aerospace industry, etc.