Sensitivity analysis of CFD coupled non-isothermal heat and moisture modelling

Abstract

CFD (Computational Fluid Dynamics) is a useful tool to study air flow patterns in a room. Current CFD models are able to simulate air flow combined with temperature distributions and species distributions. In this paper a coupled CFD–HAM model is discussed. This model combines CFD with a HAM model (Heat, Air and Moisture) for hygroscopic materials. This coupled model is able to simulate air flow around a porous material and combines this with heat and moisture transport in the porous material. Validation with a small scale experiment in which gypsum board was used as a hygroscopic material showed good results. In this paper a further validation of the model is discussed based on a sensitivity analysis of some model parameters. Especially hygrothermal parameters like sorption isotherm and water vapour permeability proved to have a non negligible influence on the modelling outcome. Adding a hysteresis model showed improvement of the model during desorption. The model was also used to compare two modelling strategies. In one strategy the gypsum board was modelled as a uniform material, in a second approach the material was modelled as being layered. The difference between the two approaches showed to be negligible.