Abstract: A fuel cell system includes a fuel cell stack and a flow control device that controls a supply of a first phase fluid flowing through the fuel cell stack. A controller monitors at least one parameter of the fuel cell stack and controls the supply to generate pulses of reactant when the at least one parameter crosses a threshold to flush a second phase fluid from said fuel cell stack.

Abstract: A fuel cell comprises an electrode plate having a flow field formed therein and a proton exchange membrane. A compressible permeable diffusion media is disposed adjacent the electrode plate. The diffusion media is compressed against the electrode plate so that a portion of the media intrudes into the flow field. A fuel cell stack can be made by compressing a plurality these fuel cells together. The fuel cell stack is compressed so that the diffusion media in each fuel cell is compressed against the adjacent electrode plate with a portion of the media intruding into the flow field in the adjacent electrode plate. The compression of the fuel cell stack can be adjusted so that a magnitude of intrusion of the diffusion media into the flow channels is adjusted and a pressure drop of a predetermined magnitude occurs across the fuel cell stack at a desired operational state.

Abstract: A fuel cell system that employs a purge valve, an accumulator and a bleed valve for selectively purging and bleeding anode exhaust gas. When the purge valve is opened, the anode exhaust gas purges to the accumulator where it is collected. The bleed valve provides a controlled release of the anode exhaust gas from the accumulator that allows the concentration of hydrogen bled from the accumulator to remain below its combustible limit. In one embodiment, the purged anode exhaust gas is combined with the cathode exhaust gas and released to atmosphere. In another embodiment, the purged anode exhaust gas is combined with a cathode input gas. In another embodiment, the purged anode exhaust gas is combined with an anode input gas.

Abstract: A fuel cell system includes fuel cell stacks electrically connected in parallel and supplying a gross current to a load. A controller determines the gross load current, and produces a desired current through the load by adjusting, based on the gross load current, at least one parameter affecting at least one of the inputs to and outputs from the system. This system allows a stack design and its voltage output to be kept constant while stacks are added for increased power.

Abstract: A fuel cell comprises an electrode plate having a flow field formed therein and a proton exchange membrane. A compressible permeable diffusion media is disposed adjacent the electrode plate. The diffusion media is compressed against the electrode plate so that a portion of the media intrudes into the flow field. A fuel cell stack can be made by compressing a plurality these fuel cells together. The fuel cell stack is compressed so that the diffusion media in each fuel cell is compressed against the adjacent electrode plate with a portion of the media intruding into the flow field in the adjacent electrode plate. The compression of the fuel cell stack can be adjusted so that a magnitude of intrusion of the diffusion media into the flow channels is adjusted and a pressure drop of a predetermined magnitude occurs across the fuel cell stack at a desired operational state.

Abstract: A fuel cell comprises an electrode plate having a flow field formed therein and a proton exchange membrane. A compressible permeable diffusion media is disposed adjacent the electrode plate. The diffusion media is compressed against the electrode plate so that a portion of the media intrudes into the flow field. A fuel cell stack can be made by compressing a plurality these fuel cells together. The fuel cell stack is compressed so that the diffusion media in each fuel cell is compressed against the adjacent electrode plate with a portion of the media intruding into the flow field in the adjacent electrode plate. The compression of the fuel cell stack can be adjusted so that a magnitude of intrusion of the diffusion media into the flow channels is adjusted and a pressure drop of a predetermined magnitude occurs across the fuel cell stack at a desired operational state.

Abstract: A fuel cell system having first and second fuel cells that each receive anode reactant flows and cathode reactant flows. Each of the fuel cells uses the reactant flows to produce electricity. The electricity production by the fuel cells produces respective first and second anode and cathode effluents that are exhausted from the respective fuel cells. The second fuel cell is connected to and downstream from the first fuel cell so that the anode reactant flow to the second fuel cell is formed from a portion of the anode effluent exhausted from the first fuel cell.

Abstract: A fuel cell system that employs a purge valve, an accumulator and a bleed valve for selectively purging and bleeding anode exhaust gas. When the purge valve is opened, the anode exhaust gas purges to the accumulator where it is collected. The bleed valve provides a controlled release of the anode exhaust gas from the accumulator that allows the concentration of hydrogen bled from the accumulator to remain below its combustible limit. In one embodiment, the purged anode exhaust gas is combined with the cathode exhaust gas and released to atmosphere. In another embodiment, the purged anode exhaust gas is combined with a cathode input gas. In another embodiment, the purged anode exhaust gas is combined with an anode input gas.

Abstract: A fuel cell stack having a plurality of fuel cells arranged adjacent one another and compressed together. At least one of the fuel cells has an electrode plate with a flow field formed therein, a proton exchange membrane and a compressible fluid-permeable diffusion media that is disposed adjacent the electrode plate. A compressing member is operable to vary a compression of the fuel cells during operation which varies an intrusion of the compressible diffusion media into the flow field in the adjacent electrode plate. The variation of the intrusion of the diffusion media into the flow fields allows the control of the pressure drop across the fuel cell stack and enables the fuel cell stack to be dynamically controlled so that a desired operational state is achieved.

Abstract: A fuel cell system includes fuel cell stacks electrically connected in parallel and supplying a gross current to a load. A controller determines the gross load current, and produces a desired current through the load by adjusting, based on the gross load current, at least one parameter affecting at least one of the inputs to and outputs from the system. This system allows a stack design and its voltage output to be kept constant while stacks are added for increased power.

Abstract: A fuel cell stack having a plurality of fuel cells arranged adjacent one another and compressed together. At least one of the fuel cells has an electrode plate with a flow field formed therein, a proton exchange membrane and a compressible fluid-permeable diffusion media that is disposed adjacent the electrode plate. A compressing member is operable to vary a compression of the fuel cells during operation which varies an intrusion of the compressible diffusion media into the flow field in the adjacent electrode plate. The variation of the intrusion of the diffusion media into the flow fields allows the control of the pressure drop across the fuel cell stack and enables the fuel cell stack to be dynamically controlled so that a desired operational state is achieved.

Abstract: A fuel cell comprises an electrode plate having a flow field formed therein and a proton exchange membrane. A compressible permeable diffusion media is disposed adjacent the electrode plate. The diffusion media is compressed against the electrode plate so that a portion of the media intrudes into the flow field. A fuel cell stack can be made by compressing a plurality these fuel cells together. The fuel cell stack is compressed so that the diffusion media in each fuel cell is compressed against the adjacent electrode plate with a portion of the media intruding into the flow field in the adjacent electrode plate. The compression of the fuel cell stack can be adjusted so that a magnitude of intrusion of the diffusion media into the flow channels is adjusted and a pressure drop of a predetermined magnitude occurs across the fuel cell stack at a desired operational state.