Coupled Adsorption Two-Fluid Modelling of H2 Adsorption in Solid Sorbents

In the present work, a CFD model for simulating adsorption of H2/CO2 on a solid sorbent using ANSYS Fluent is developed and validated. The developed model is based on two-fluid Euler-Euler equations such that solid phase follows the Kinetic Theory of Granular Flow (KTGF) equations and continuous gas phase is laminar. Adsorption is calculated using modified Dubinin–Astakhov (DA) isotherm while Linear Driving force (LDF) model is used for mass transfer between gas and the solid phase. The mass transfer between phases due to adsorption has been included in the numerical model through User Defined Functions (UDF). To validate the developed model, a benchmark case of hydrogen adsorption on activated carbon is simulated. The predicted temperature profiles across the activated carbon bed are found to be strongly influenced by the characteristic thermal properties of the sorbent, i.e. specific heat capacity, thermal conductivity and the thermal boundary condition. The temperature profiles showed a build-up of high temperature zone (~350 K) at the centre of bed. The numerical results of transient variation in local temperature in the bed, pressure drop and breakthrough curve compared well with the experimental values reported in the literature.