Development and simulation of a hydrogen storage unit using metal hydrides

Abstract

This paper presents a hydrogen storage system using metal hydrides for a Combined Heat and Power CHP) system. Hydride storage technology has been chosen due to project specifications: high volumetric capacity, low pressures (<3.5 bar) and low temperatures (<75 °C: fuel cell temperature). During absorption, heat from hydride generation is dissipated by fluid circulation. An integrated plate-fin type heat exchanger has been designed to obtain good compacity and to reach high absorption/desorption rates. At first, the storage system has been tested in accordance with project specifications (absorption/desorption 3.5/1.5 bar). Then, the hydrogen charge/discharge times have been decreased to reach system limits. System design has been used to simulate thermal and mass comportment of the storage tank. The model is based on the software Fluent. We take in consideration heat and mass transfers in the porous media and a convective flow for cooling/heating the system during absorptions/desorptions. The hydride thermal and mass comportment has been integrated in the software. The heat and mass transfers experimentally obtained have been compared to results calculated by the model.