Abstract: A catalytic hydrogen combustor is disclosed that is adapted to combust substantially all the hydrogen in the fuel cell exhaust gas during both steady state operation and for short duration higher hydrogen concentration pulses. Hydrogen combustion is catalyzed in two zones, a first zone in which a lower level of catalyst activity is used to catalyze combustion of a higher concentration hydrogen pulse as it moves through the zone and a second zone in which a higher level of catalyst activity is used to catalyze combustion of a lower concentration of hydrogen that is characteristic of steady state fuel cell operation.

Abstract: The present technology provides systems for monitoring particulate matter buildup on a filter installed in the engine exhaust stream of a vehicle. A filter differential pressure sensor monitors a pressure differential across the filter. A downstream differential pressure sensor monitors a pressure differential across an exhaust stream outlet. A processor monitors a particulate buildup value based at least in part on the pressure differential across the filter and the pressure differential across the exhaust stream outlet. A method for monitoring particulate buildup is also provided. The method monitors a pressure differential across the filter, and determines a downstream exhaust flow rate based on a pressure differential between a filter outlet housing and an exit pipe, where the diameter of the filter outlet housing is greater than the diameter of the exhaust exit pipe.