CFD simulations of coupled, countercurrent combustor/reformer microdevices for hydrogen production

Two-dimensional computational fluid dynamics (CFD) simulations are used to study spatially segregated, multifunctional, microchemical devices for hydrogen production. In particular, coupling between homogeneous propane combustion and catalytic ammonia decomposition on a Ru catalyst is studied in a microdevice consisting of alternating combustion and decomposition channels as a function of flow rate and materials conductivity in the countercurrent flow configuration. It is found that the high temperatures generated via homogeneous combustion lead to high conversions in short contact times and thus to compact devices. Different performance measures are evaluated to assess the operability of the device. Sufficiently high ammonia flow rates serve a dual purpose by lowering device temperatures and enabling the production of larger flow rates of hydrogen. Finally, it is shown that device operation is limited only to high-conductivity materials and fast ammonia flows.