Adsorption of H2 in porous solid sorbents using a two-phase modelling approach

Abstract

The increasing energy demand, depleting fossil fuel reserves and increasing greenhouse gas emissions have initiated the search for cleaner and more affordable energy sources. Hydrogen is considered a major energy source due to its high calorific value. The physisorption of H2 on a porous material is an attractive alternative for its storage. This paper presents a two-fluid equation-based model benchmarked against an experimental work on hydrogen storage in an activated carbon packed bed reported in the literature. The computational model is implemented in Ansys Fluent 21.1.0 to solve the hydrodynamic and thermal interaction between the gas and solid phases along with the mass transfer due to adsorption. Adsorption isotherm is calculated from the modified Dubinin-Astakhov (D-A) equation, while the resultant mass transfer is determined from the Linear Driving Force (LDF) model. These equations are incorporated into the model with the help of User Defined Functions (UDF). The predicted pressure, local bed temperature, and adsorption values show a good match with the experimental results. In addition, the sensitivity of different thermal and material properties revealed that a denser adsorbent bed and a high value of thermal properties improve the performance of the H2 storage in the tank.