Pore network modeling of a solid desiccant for dehumidification applications

Abstract

The development of desiccant-based dehumidification requires a profound understanding of the adsorption–desorption performance and transport properties of porous media. The characterization and modeling of porous media is fundamental to all adsorption and transport studies in porous media. The characteristic properties of porous media, such as pore size distribution (PSD) and connectivity, are usually extracted from complex geometrical and topological information. Pore network modeling (PNM) can also capture these properties without a large computational cost, in contrast to continuum models. In this study, PNM was adopted for the characterization of a silica-based micro sphere gel (M. S. Gel). The PSD of the M. S. Gel was estimated from the adsorption isotherm using a modified Kelvin equation (the Barrett–Joyner–Halenda (BJH) method), which was then corrected by comparison with the PSD obtained from grand canonical Monte Carlo (GCMC) analyses. By contrast, the connectivity was estimated from the desorption isotherm using PNM simulations incorporating the percolation effect, in which the PSD estimated from the adsorption isotherm was employed. Finally, a pore network model of the M. S. Gel with the assigned PSD, connectivity, and porosity without any special pore arrangement was constructed, and the diffusivity of water vapor inside the model was evaluated.