Condensation, Evaporation and Moisture Content in Porous Media

There are numerous examples of porous media, both natural ones such as soil and wood as well as synthetic ones such as catalytic converters and filters. At ambient conditions, water vapor tends to condense inside the pores impeding a variety of important transport processes. Hence, it is natural to ask how quickly the moisture can be removed from a porous material. A significant amount of work has been done on diffusive transport of moisture inside the pores. None of the existing model, however, properly account for mass and heat transport, both of which can play an important role under nonequilibrium conditions. We present a comprehensive coarse-grained model of porous media that accounts for the transport of water, in both vapor and liquid form, heat, as well as phase change. A numerical implementation of the model allows us to investigate the dependence of drying time on various parameters such as the initial temperature and moisture content of the porous material as well as the relative humidity and velocity of the air flowing past it.