Numerical Modelling of Flow and Coupled Mass and Heat Transfer in an Adsorption Process

In this paper, a detailed 3D modelling of flow and coupled heat and mass transport in a channel coated with adsorbing material is presented. A comparative study between a simplified 1D model and the detailed 3D model is carried out. Both 3D and 1D predictions are compared with experimental data available from literature as well. The time-dependent variation of temperature and heat flux distribution at the interface between the gas channel and the adsorbent layer encourages the development and use of a more detailed 3D model. NOMENCLATURE Aduct cross sectional area of gas duct m Atot total cross sectional area of a channel with adsorbent layer m a half of channel height m b half of channel base m d half of adsorbent wall thickness m Cp specific heat J/(kg∙K) D mass diffusivity m/s DH hydraulic diameter m Jnor peripherally average normal total heat flux of the interface W/m k thermal conductivity W/(m∙K) L channel length m P pressure Pa Pduct wetted perimeter of the crosssection m Ps Saturated vapour pressure Pa rc hydraulic radius m t time s tad adsorption period s tde desorption period s 1,out T mixing cup average temperature at gas channel outlet K g u bulk stream velocity in gas channel m/s uface velocity at inlet face m/s 1,out w mixing cup average pseudo weight fraction at channel outlet kg/kg Greek symbols ε adsorbent porosity νr porous radius m ρ density kg/m σ structural void fraction Aduct/ Atot μ dynamic viscosity Pa∙s τ tortuosity δ equivalent adsorbent layer thickness m w  relative humidity Subscripts and superscripts a dry gas f entire adsorbent material (matrix and pores ) fp pores (inter-particle voids) fm matrix part of the adsorbent material (solid part, adsorbed adsorbate, but excluding pores ) fs dry solid adsorbent material (exclude pores and adsorbed adsorbate) g process stream air M molecular l adsorbed liquid v sorbate vapour eff effective property in, out inlet / outlet of the gas channel s solid