On the effect of process temperature on the performance of activated carbon bed hydrogen storage tank

Abstract

A numerical model is used to investigate hydrogen charging in packed bed storage tank as function of the charging process temperature. The model is based on the solution of the 2D transport equations for mass, momentum and energy in porous media. The equation system is characterized by the existence of adsorption source terms in both mass and energy equations along with very low Mach number flow condition. It was solved using a pressure splitting technique. Results showed that heating effects due to mechanical energy dissipation and to the exothermal character of the adsorption reaction are enhanced at low temperature. They result in a significant tank capacity reduction. This reduction reaches 25% of the total storage capacity as predicted assuming isothermal charging process. Unlike what has been suggested in several previous studies the major part of the tank capacity decrease is mainly due to the decrease of the gas density. Using recently developed activated carbon monolith with a conductivity exceeding 10 W m −1 K −1 can help in limiting the heating effect and reducing this capacity limitation. It makes possible the development of packed bed storage tanks that fulfill the DOE recommendations.