Abstract: A catalytic combustion unit for a fuel cell system is provided. The catalytic combustion unit includes a reactor having a porous medium with a catalyst deposited thereon. The reactor is disposed adjacent a heat exchanger and adapted to receive an air stream and a hydrogen stream. The reactor is further adapted to promote an exothermic reaction and modulate a temperature of a fuel cell stack. A fuel cell system and method employing the catalytic combustion unit are also provided.

Abstract: A fuel cell stack includes a plurality of solid oxide fuel cell tubes and a heat recuperator. The heat recuperator is formed from sheet metal. The plurality of walls define an exhaust gas channel having an exhaust gas flowing therethrough and an oxidant channel having an oxidant flowing therethrough. The exhaust gas channel is in thermal communication with the oxidant channel such that heat is transferred between the exhaust gas and the oxidant.

Abstract: Method and apparatus for cooling a fuel cell stack. The cooling system uses vaporization cooling of the fuel stack and supersonic vapor compression of the vaporized coolant to significantly increase the temperature and pressure of the liquid coolant flowing through a heat exchanger. By increasing the heat rejection temperature of the coolant delivered to the heat exchanger, the heat transfer area of the heat exchanger can be reduced and the mass flow rate of coolant can also be reduced. The increased fluid pressure is used to circulate the coolant through the cooling system, thereby eliminating the circulation pump associated with conventional systems.

Abstract: A method for operating a cooling system for a fuel cell stack in a vehicle is provided. The method includes the steps of: determining a fan request for a variable speed fan disposed in the cooling system; employing a noise-comfort function to select a fan comfort request; and adjusting a speed of the variable speed fan in response to the fan request; wherein a noise emission by the variable speed fan is militated against. A cooling system for a fuel cell stack in a vehicle that employs the noise-comfort function is also provided.

Abstract: The air-cooled thermal management of a fuel cell stack is disclosed. One disclosed embodiment comprises a cooling plate apparatus for an air-cooled fuel cell stack, where the cooling plate comprises a body configured to receive heat from one or more fuel cells in thermal communication with the body, and airflow channels formed in the body and configured to allow a flow of a cooling air to pass across the body. An insulating structure is disposed in the airflow channels, wherein the insulating structure has decreasing thickness from a cooling air inlet toward a cooling air outlet.

Abstract: A system and method for providing a fuel cell stack purge at fuel cell system shut-down. The method provides a two-stage purge process where the first stage purge uses humidified cathode air to get the fuel cell stack to a known stack hydration level from an unknown stack hydration level at system shut-down. As the stack is purged with the humidified air, the hydration level of the stack decreases asymptotically to the known stack hydration level where the duration of the first stage is set based on the asymptote as a safety margin. Once the known hydration level is achieved, then the second stage purge is performed with dry air to further reduce the stack hydration to a final desired hydration level.

Abstract: A modular fuel cell power system includes a coolant source, a reactant source and a plurality of fuel cell modules. Each of the fuel cell modules includes a fuel cell stack and a fluid distribution plant in fluid communication with the reactant source, coolant source and fuel cell stack. The fluid distribution plant controls the flow of reactant between the reactant source and fuel cell stack. The fuel cell stacks are configured to be selectively electrically connected.

Abstract: In at least one embodiment, a purge system for a fuel cell stack is provided. The system comprises a blower, a differential pressure sensor and a purge valve. The blower delivers a recirculated gas back to the stack at varying electrical power levels and blower speeds. The differential pressure sensor senses pressure of the recirculated gas across the blower. The purge valve purges the recirculated gas based on at least one of a blower power level, a blower speed, and the pressure of the recirculated gas.