Dynamic Analysis of Moisture Transport Through Walls and Associated Cooling Loads in the Hot/Humid Climate of Florianopolis, Brazil

Abstract

We describe the use of a dynamic model of combined heat and mass transfer to analyze the effects on cooling loads of transient moisture storage and transport through walls with porous building materials, under varying boundary conditions. The materials studied were brick, lime mortar and autoclaved cellular concrete. The physical properties of these materials, such as mass transport coefficients, thermal conductivity and specific heat, were taken to be functions of moisture content. The simulation results were compared to those obtained by pure conduction heat transfer without moisture effects. Also analyzed were the influence on cooling loads of high moisture content due to rain soaking of materials. and the influence of solar radiation on sunny and cloudy days. The weather used was a hot/humid summer period in Florian6polis (South Brazil). It is shown that neglecting moisture migration or assuming that the physical properties of wall materials do not depend on moisture content can result in large errors in sensible and latent heat transfer.