A Study on Hydrogen Generation Reactor using NaBH₄ and Load Following Ability for Fuel Cell Application

Abstract

NaBH₄-Fuel Cell system, which can respond to increasing demands for power in a mobile device, has attracted much attention as an alternative power source for lithium batteries due to the advantages. However, before the system can be of practical use, hydrogen must be efficiently generated from the NaBH₄. We have conducted optimization of the hydrogen generation reactor as function of several factors, which we present in this paper. An optimized aspect ratio between diameter and length of catalyst layer in a reactor exists, and the value can be conducted as a function of hydrogen generation rates and the catalyst mass. The reactor which supplies hydrogen to a 1.2kW class fuel cell system has only 53.1ml of the internal volume, and it can generate 21L/min of hydrogen with 100% efficiency. For the purpose of adding a pressure buffer to the reactor, it has been recognized that pressurized conditions bring no influence in H₂ generation up to 0.4MPa. Moreover, we have developed and validated a NaBH₄-Fuel Cell system that uses a pressure-buffer to supply hydrogen stably under variable loads.