Modelling heat and moisture transport in porous materials with CFD for building applications

Abstract

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Heat and moisture transport in buildings have a large impact on the building envelope durability, the energy consumption in buildings and the indoor climate. Nowadays HAM (Heat, Air and Moisture) models are widely used to simulate and predict the effect of these transport phenomena in detail. Recently these HAM models are being coupled to CFD (Computational Fluid Dynamics) to study the moisture exchange between air and porous materials on a local scale (microclimates). A direct coupling approach between CFD and HAM is applied. The transport equations for heat and moisture in a porous material are directly implemented into an existing CFD package and the transport equations in the air and in the porous material are solved in one iteration by only one solver. In this paper a model for moisture transport in the hygroscopic range and over-hygroscopic range is developed. This way a broad range of problems can be tackled such as drying phenomena and interstitial condensation in building components. The model is verified and validated with data from literature.