kWe sodium borohydride hydrogen generation system Part II: Reactor modeling

Sodium borohydride (NaBH4) hydrogen storage systems offer many advantages for hydrogen storage applications. The physical processes nside a NaBH4 packed bed reactor involve multi-component and multi-phase flow and multi-mode heat and mass transfer. These processes are lso coupled with reaction kinetics. To guide reactor design and optimization, a reactor model involving all of these processes is desired. A oneimensional numerical model in conjunction with the assumption of homogeneous catalysis is developed in this study. Two submodels have been reated to simulate non-isothermal water evaporation processes and pressure drop of two-phase flow through the porous medium. The diffusion oefficient of liquid inside the porous catalyst pellets and the mass transfer coefficient of water vapor are estimated by fitting experimental data t one specified condition and have been verified at other conditions. The predicted temperature profiles, fuel conversion, relative humidity and ressure drops match experimental data reasonably well. 2007 Elsevier B.V. All rights reserved.