Downsizing chemical processes for portable hydrogen production

Various exothermic and endothermic components of a portable hydrogen production system are explored through modeling and experiments. Gas phase combustion in a microburner to generate energy needed for hydrogen generationby endothermic reactions is first studied. An elliptic computational fluid dynamics model of a microburner is used to determine the effects of wall conductivity, external heat losses, choice of fuel, and operating conditions on the steady state, self-sustained gaseous flame stability of propane/air and methane/air mixtures. Experimental prototype catalytic microburners are subsequently evaluated to determine the range of operating conditions for stabilized catalytic combustion of propane/air mixtures. It appears that the dimensions of microburners have a strong effect on performance. Finally, catalytic, post microreactors for the production of hydrogen from ammonia decomposition over ruthenium catalyst are modeled using a hierarchy of models. Good agreement of simulation predictions with experimental data is observed. Important issues in the design of the above components are identified.