Water vapour diffusion and condensation in fibrous insulations

An experimental study of the diffusion and condensation of water vapour in fibreglass slab insulations is reported. In the first series of experiments, water is sprayed on the hot face of the slab and it is tested in a heat flow meter apparatus. In the second set of experiments, one of the faces of the slab is exposed to a warm and humid ambient and the other face is maintained at a low temperature. Simple analytical models are developed for the quasi-steady phase of the condensation process in the two experiments. The predicted temperature distribution, heat flux and vapour flux agree well with the measured quantities.