Abstract: A fuel cell system includes a primary fuel line to the fuel cell assembly, a jet pump in the primary fuel line and adapted to be driven by the flow of primary fuel, the jet pump having a nozzle, an entrainment chamber downstream of the nozzle and a mixing tube downstream of the entrainment chamber, a fuel exhaust recycle line from the fuel cell assembly opening to the entrainment chamber for supply of fuel exhaust thereto, and a mass flow control device in the primary fuel line upstream of the jet pump for controlling the primary fuel flow rate to the jet pump. The nozzle of the jet pump has an adjustable cross-sectional area to provide a variable area flow of the primary fuel so that the ratio of fuel exhaust entrained by the primary fuel in the entrainment chamber can be varied.

Abstract: A method of operating a fuel cell (1) in which a gaseous supply stream (5) comprising a reactive species is delivered to an electrode (2) where the reactive species is consumed in an electrochemical reaction to produce an exhaust stream (7, 8) which is depleted in reactive species, which method comprises: a) assessing the concentration of reactive species in the exhaust stream (7, 8); b) relating the concentration of reactive species in the exhaust stream (7, 9) to a maximum current that may be drawn from the fuel cell (1) without redox damage of the electrode; and c) adjusting the way in which the fuel cell (1) is operated in order to optimise efficiency without redox damage of the electrode (2).

Abstract: A method for the thermal management of a fuel cell, which method comprises: processing a fuel supply stream comprising hydrogen, steam, at least one carbon oxide and optionally methane using a methanator to produce a fuel cell supply stream comprising a controlled concentration of methane; and reforming within the fuel cell methane present in the fuel cell supply stream, wherein the way in which the methanator is operated is adjusted in response to fluctuations in the temperature of the fuel cell such that the concentration of methane in the fuel cell supply stream is controlled in order to achieve a desired level of reforming of methane within the fuel cell.