Moisture transport in fibrous clothing assemblies

In this paper, moisture transport in fibrous clothing assemblies is investigated in a one-dimensional setting. A multi-component, multi-phase flow model in a fibrous porous medium with phase change is proposed. The model is a generalization of a single-component model used in a previous study by taking the air resistance to moisture transport into account. Capillary effect on liquid water motion is also included in the model. Using dimensional analysis, it is shown that there exist several different time scales. As a result, the fast-scale moisture transport is coupled with the energy equation while accumulation of liquid water in the pore and absorption of water by the fibers occur at slower time scales. By exploring scale separation, computations can be greatly simplified by decoupling these physical processes. An efficient semi-implicit numerical scheme is proposed for solving the gas (vapor and air) and energy equations, while the water equations are solved separately. At the time scale of experimental measurement, a quasi-steady approximate solution is also derived for gas concentration and temperature as a benchmark for numerical computation. Qualitative comparison between the numerical solutions and experimental measurements are also given. The results show that the new multi-component model proposed in this study gives a better prediction of total water accumulation near the outer boundary of the clothing assemblies.