Coupled heat and moisture transfer in building material with freezing and thawing process

A mathematical model is proposed for coupled heat and moisture transfer in building material with freezing and thawing process in this paper. The temperature gradient and the water content gradient in the material are used as the driving potentials of the transport process. The effects of the phase transition of vapor, water and ice on heat and moisture transfer are simultaneously considered in the present model. The energy equation takes into account not only the influence of the latent heat of freezing (or thawing) and condensation (or evaporation), but also the energy change caused by moisture transfer. The model is verified experimentally with respect to the temperature, relative humidity, and frozen moisture content (ice, water and vapor). The comparison of all results shows that the proposed model can significantly improve the prediction accuracy of the coupled heat and moisture transfer in building material with freezing and thawing process.