Modeling of sorbent-based gas filters: Development, verification and experimental validation

Abstract

Adsorption-based air filters/cleaners are often used to remove gaseous contaminants to improve indoor air quality (IAQ) for residential and office buildings. The performance of a sorbent filter is affected by the sorbent filter design parameters (i.e., granular particle size, packing density), the environmental conditions (i.e., flow velocity, challenge gas concentration, temperature, and relative humidity), and the sorbent properties such as sorption isotherm and in-pellet diffusion coefficient. It is the combined effects of all these parameters that determine the performance of the filter. In this study, Convective Mass Transfer (C-MT) model and Convective and Diffusive Mass Transfer (C&D-MT) model were developed and numerically implemented to simulate the fundamental transport and sorption processes in sorbent-based filters. The models’ behaviors were investigated by simulating the effect of different parameters, and were validated by comparison with experimental data. Detailed mechanism analysis was conducted based on both modeled and experimental results, which indicates that the surface diffusion is a much more important mechanism than pore diffusion, and the external convective mass transfer process is a controlling factor compared to pellet diffusion. This model also provides a useful tool for designing, selecting or maintaining sorption-based filter/air cleaner for non-industrial building applications based on the predicted filter performance over its service life.