On the solution of coupled heat and moisture transport in porous material

TL;DR

This paper enhances the modeling of heat and moisture transfer in porous materials by incorporating advective processes and a specialized numerical scheme, resulting in improved accuracy and computational efficiency validated against experimental data.

Contribution

It introduces an advective coupled model with the Scharfetter-Gummel scheme, demonstrating better agreement with experiments and analyzing hysteresis effects in moisture capacity.

Findings

The proposed model outperforms pure diffusive models in experimental validation.

The Scharfetter-Gummel scheme improves accuracy and reduces computational time.

Hysteresis effects significantly influence moisture capacity modeling.

Abstract

Comparisons of experimental observation of heat and moisture transfer through porous building materials with numerical results have been presented in numerous studies reported in literature. However, some discrepancies have been observed, highlighting underestimation of sorption process and overestimation of desorption process. Some studies intend to explain the discrepancies by analysing the importance of hysteresis effects as well as carrying out sensitivity analyses on the input parameters as convective transfer coefficients. This article intends to investigate the accuracy and efficiency of the coupled solution by adding advective transfer of both heat and moisture in the physical model. In addition, the efficient Scharfetter and Gummel numerical scheme is proposed to solve the system of advection-diffusion equations, which has the advantages of being well-balanced and asymptotically preserving. Moreover, the scheme is particularly efficient in terms of accuracy and reduction of computational time when using large spatial discretisation parameters. Several linear and non-linear cases are studied to validate the method and highlight its specific features. At the end, an experimental benchmark from the literature is considered. The numerical results are compared to the experimental data for a pure diffusive model and also for the proposed model. The latter presents better agreement with the experimental data. The influence of the hysteresis effects on the moisture capacity is also studied, by adding a third differential equation.