Ammonia Borane (H₃B NH₃) is a promising chemical hydride with close to 20% hydrogen content by weight, and is currently being investigated as a potential hydrogen storage alternative, particularly for portable applications. One of the possible dehydrogenation routes for ammonia borane (AB) is pyrolysis, in which AB releases 2 moles of H₂ at temperatures around 150ºC, and the last mole of H₂ contained in AB at temperatures around 450ºC. The pyrolysis reactions are exothermic; therefore it is possible to design self-sustaining AB systems that could generate H₂ without continuous external heat addition.

A mathematical model is developed to describe the chemical kinetics of AB pyrolysis and heat and mass transport in a fuel element that contains thermal management components in addition to the AB. Based on computational fluid dynamics (CFD) techniques, the governing equations are discretized and solved with a commercial CFD software. The predictions are in general agreement with the experimental results albeit limited material properties. Sensitivity analyses for several design parameters are performed to improve the performance of AB pyrolysis. The results show that the thermal design of the fuel element has a strong impact on self-sustainability of AB pyrolysis.