Two-Phase Mass and Heat Flow Model

Abstract

AbstractA brief history of the coupled moisture and heat transport theory is presented, accompanied by the discussion on the doubt about the enhanced vapor transport mechanism put forward by Philip and de Vries [62] (PdV model). The discussion points out that apart from a diffusion mechanism, vapor transport in the soil may also include advection and dispersion mechanisms. To check this, a two-phase mass and heat transport model has been developed based on the PdV model. The difference between the proposed model and the PdV model is discussed. Furthermore, the specific items added to the PdV model to take the airflow into consideration, are explained. The constitutive equations are introduced to link the independent variables (unknowns) and the dependent variables. The finite element formulation for the model is briefly described. The accuracy of the proposed model is assessed through comparison with analytical work for coupled mass and heat transfer and experimental work for isothermal two-phase flow (moisture/air transfer). The influence adding airflow has on the coupled moisture and heat transfer is further investigated, clearly identifying the importance of including airflow in the coupled mass and heat transfer. How the isothermal two-phase flow is affected by considering heat flow is also investigated, showing the influence of heat flow only to be significant if the air phase plays a significant role in solving the equations of the water phase.KeywordsSaturated Hydraulic ConductivityVapor FluxVolumetric Heat CapacityUnsaturated Hydraulic ConductivityAdvective FluxThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.