Abstract: We disclose a system that includes a fuel cell which during operation exhausts a fluid composition that includes an acid or a derivative of the acid, and an acid trap arranged to receive the fluid composition and configured to reduce a concentration of the acid or the derivative of the acid in the fluid composition.

Abstract: A technique that is usable with a fuel cell stack includes combining a fuel flow with an oxidant in a mixer to create a substantially funnel-shaped flow, which is ignited.

Abstract: Fuel cell system reformers for converting an input fluid to a reformate for a fuel cell is disclosed, where the reformers include: (a) a first heat exchanger configured to heat input fluid from a first input fluid temperature Ti1 to a second input fluid temperature Ti2, and to cool reformate from a first reformate temperature Tr1 to a second reformate temperature Tr2; (b) a second heat exchanger configured to heat input fluid from a third input fluid temperature Ti3 to a fourth input fluid temperature Ti4, and to cool an intermediate fluid from a first fluid temperature Tf1 to a second fluid temperature Tf2; and (c) a reactor configured to receive intermediate fluid from the second heat exchanger, to form reformate from intermediate fluid, and to direct reformate to the first heat exchanger.

Abstract: The invention provides integrated fuel cell systems and associated operating methods wherein oxidant flow is controlled in response to an oxygen sensor in an exhaust stream of a fuel cell exhaust gas oxidizer, and fuel flow is controlled in response to a temperature measurement associated with the oxidizer.

Abstract: A fuel cell system includes a fuel cell stack, which during operation generates electrical energy by reacting a first stream of reactant gas and a second stream of reactant gas. The fuel cell stack also produces a fuel cell exhaust stream. An oxidizer unit is positioned to receive the fuel cell exhaust stream and oxidize at least a part of the fuel cell exhaust stream during operation, to produce an oxidizer exhaust stream. A heat recovery system is positioned to receive the oxidizer exhaust stream. The heat recovery system transfers at least some heat from the oxidizer exhaust stream to an input stream to generate a heated stream of water. In some embodiments, a temperature sensor is positioned to sense the temperature of the heated input stream. A control system maintains the heated stream of water at a target temperature based on the sensed temperature by controlling the amount of the heat from the oxidizer exhaust stream that is transferred to the input stream.