Abstract: An extruded seal material which is stable in phosphoric acid is composed of fibrillating polytetrafluoroethylene, a halogenated oil, and a filler. Preferably the oil is a fluorocarbon oil and the filler is either non-fibrillating polytetrafluoroethylene, silicon carbide or graphite, all of which are stable in phosphoric acid at temperatures up to at least 400.degree. F. This seal material is particularly suited for use in the environment of a phosphoric acid fuel cell.

Abstract: A novel electrode for use in an electrochemical cell is provided by a pyrolytic carbon coated, hydrophobic polymer impregnated carbon paper having a catalyst-hydrophobic polymer layer applied thereon.

Abstract: In a fuel cell utilizing an acid electrolyte, such as H.sub.3 PO.sub.4, the electrolyte retaining matrix is made from silicon carbide. The silicon carbide has been found to be virtually inert to H.sub.3 PO.sub.4 at fuel cell operating temperatures and provides all the other necessary and desirable matrix properties. This matrix is expected to have a life of at least 40,000 hours under normal fuel cell operating conditions.

Abstract: A fuel cell power plant for producing electricity uses pressurized reactants in the cells. In one embodiment air is the oxidant and is compressed in a compressor driven by a turbine. The turbine is powered by waste energy produced in the power plant in the form of a hot pressurized gaseous medium. For example, effluent gases from both the anode and cathode sides of the cells is delivered into the turbine which in turn drives the compressor. In a preferred embodiment the effluent gases from the anode side of the cells is first delivered into a burner for providing heat to a steam reforming reactor, and the effluent gases from the burner are delivered into the turbine. In another embodiment, in addition to effluent gases delivered from the anode side of the cells into the burner, a portion of the effluent gases from the anode side of the cells is also delivered into the steam reforming reactor to provide steam for the fuel processing.

Abstract: A fuel cell system includes an ejector for pumping steam and fuel into a steam reformer. Steam is the primary flow through the ejector and fuel is the secondary flow. The rate of steam flow is metered by a variable area orifice in the ejector. The fuel passes through a fuel control valve before reaching the ejector. A pressure regulator maintains a constant pressure drop across a variable area orifice in the valve. The fuel flow is thus metered by the valve orifice area and not by the ejector pumping characteristics. Ejector back pressure is also eliminated as a factor affecting the amount of fuel pumped by the ejector. Means are provided to simultaneously control the orifice areas of the ejector and the fuel valve in order to maintain a desired ratio of steam to fuel for the steam reformer for each operational mode of the fuel cell. In a preferred embodiment this means is a mechanical linkage connecting the ejector and fuel valve to a common actuator.

Abstract: A matrix for retaining the electrolyte in a fuel cell is applied to the surface of one or both of the electrodes by screen printing using an inking vehicle which is an aqueous solution of polyethylene oxide. This method produces a very thin, continuous and uniform matrix layer and is well suited to production operations.

Abstract: A fuel cell power plant for producing electricity uses pressurized reactants in the cells. In one embodiment air for the fuel cells is compressed in a compressor driven by a turbine which is powered by waste energy produced in the power plant in the form of a hot pressurized gaseous medium. The power plant includes fuel conditioning apparatus comprising a steam reforming reactor and a reactor burner to provide heat for the steam reforming reactor. Effluent gases from the anode side of the cells are delivered into the reactor burner and from the reactor burner are combined with effluent gases from the cathode side of the cells. The combined gases are used to drive the turbine. Water to produce steam for the steam reforming reactor is recovered from the effluent gases from the anode side of the cells before they are delivered into the reactor burner and from the effluent gases from the cathode side of the cells.

Abstract: A matrix for retaining the electrolyte in a fuel cell is applied to the surface of one or both of the electrodes by screen printing. In a preferred embodiment an aqueous solution of glycol is used as the inking vehicle to screen print a very thin, continuous and uniform matrix layer on the surface of an electrode.

Abstract: A flow scheme for feeding a reactant gas to the cells of a fuel cell stack wherein the cells are connected electrically in series. For example, the fuel gas is passed in parallel over a portion of each fuel electrode and thereupon into a mixing manifold which directs the exhausted gases in parallel over a different portion of each fuel electrode and thereupon into another manifold. This is continued, depending upon the stack configuration, with the exhausted gases passing back and forth in parallel over different portions of the fuel electrodes and exhausting into a manifold until the fuel gas has covered the entire fuel electrode of each cell in the stack. This reduces the harmful effect of a blockage within the reactant gas chamber of a cell and also reduces the harmful effect caused by a maldistribution of current in one of the cells in the stack.

Abstract: In a fuel cell stack utilizing an alkali metal electrolyte, the electrolyte is distributed in parallel between the electrodes of a plurality of fuel cells and is then fed to regenerator cell which converts carbonate ions to molecular CO.sub.2 gas which is discharged from the cell. Regeneration is effected through the establishment of a hydroxyl ion gradient within a regenerator cell. The regenerated electrolyte is then returned to the fuel cells. In this manner a carbonate buildup in the cells is prevented.

Abstract: A grease-like material, suitable for use with phosphoric acid fuel cells, is comprised of a phosphoric acid base with a filler which is stable in phosphoric acid at the temperatures to which the grease will be subjected and is preferably thermally conductive. Three fillers which are particularly suited for fuel cell applications are carbon, graphite, and silicon carbide.

Abstract: A stack of fuel cells operating on gaseous reactants includes an ejector in integral heat exchange relationship with the stack for recirculating one of the reactant gases through the cells of the stack. The recirculating reactant is continuously heated by waste heat from the cells as it recirculates thereby preventing condensation of water from the recirculating reactant gas and thereby maintaining the dew point constant from the time the reactant gas leaves the cells until it is mixed with fresh reactant in the ejector. The fresh reactant gas is preheated prior to being introduced to the ejector so that there is no condensation throughout the entire loop. The recirculation rate relative to the amount of fresh reactant can be controlled to regulate the dew point at the entrance to the cells to best advantage. By this invention flooding of the electrodes or drying of the electrodes does not occur.

Abstract: A fuel cell power plant for producing electricity uses pressurized air and fuel in the cells. A compressor is driven by a turbine operably connected thereto and provides compressed air to the cells. The turbine is driven by a working fluid in a hot, pressurized, vapor state. Energy to convert the working fluid into this state is waste energy produced by the power plant, such as stack waste heat. In one embodiment the power plant includes a steam reforming reactor and a reactor burner. Effluent gases from the anode side of the cell are used in the reactor burner. The working fluid is water and the turbine is driven by steam which is condensed to the liquid state after passing through the turbine. The liquid water is reconverted to steam by passing it into heat exchange relationship with the stack and it is then delivered again into the turbine. Part of the steam may be used in the steam reforming reactor.

Abstract: A regenerative fuel cell assembly is provided in which a fuel cell is integrated with an electrolysis cell. In a preferred embodiment the fuel cell assembly and electrolysis cell assembly are spaced apart and have their hydrogen electrodes in facing relationship; a water transport matrix is disposed in the space between the hydrogen electrodes, and a water storage matrix is disposed adjacent the oxygen electrode of the fuel cell. During operation of the fuel cell the water storage matrix holds the water produced by the fuel cell; during electrolysis cell operation the water in the water storage matrix passes to the water transport matrix which carries it to the electrolysis cell where it is consumed.

Abstract: A power plant for producing electricity uses fuel cells run on pressurized air and pressurized fuel. The air is compressed by compressor apparatus which is driven by waste energy in the form of hot pressurized gases produced in the power plant. In one embodiment the compressor apparatus includes a turbine operably connected to a compressor for driving the same. At part power, in order to maintain the pressure of the air being fed to the cells while reducing the amount of air fed to the cells, a portion of the compressed air is bypassed around the fuel cells, is increased in temperature using an auxiliary burner, and is delivered into the turbine to help drive the compressor. By doing this the mass flow of air through the cells may be reduced without reducing the mass flow of gases into the turbine thereby maintaining the speed of the compressor at part power.

Abstract: A fuel cell power plant for producing electricity uses pressurized air and fuel in the cells. The power plant includes an autothermal reactor for processing the fuel and a compressor driven by a turbine for compressing the air used by the fuel cells. Pressurized effluent gases from the cathode side of the cell and pressurized fuel is delivered into the autothermal reactor and from the reactor passes into the anode side of the cells. Effluent gases from the anode side of the cells is delivered into the turbine thereby driving the compressor. A burner is used to increase the temperature of the gases entering the turbine. The burner is run on air and unburned fuel in the effluent gases from the anode side of the cells.

Abstract: A fuel cell power plant for producing electricity uses pressurized air and fuel in the cells. The air is compressed by compressor apparatus powered by waste energy in the form of hot pressurized gases including hot pressurized steam produced by the power plant. In one embodiment the compressor apparatus includes a turbine operably connected to a compressor, and hot pressurized gases produced by the power plant flow into the turbine thereby driving the compressor. The steam is generated by heat from the fuel cells, passes through the fuel cells adjacent the cathode electrode thereof, and is delivered into the turbine along with the other gases.

Abstract: A fuel cell power plant for producing electricity uses pressurized reactants in the cells. The air is compressed by compressor apparatus which is powered by waste energy produced by the power plant in the form of a hot pressurized gaseous medium, such as the exhaust gases from the cathode side of the cells. For example, the compressor apparatus may comprise a compressor and a turbine which are operably connected. The exhaust gases from the cathode side of the cell are delivered into the turbine which drives the compressor for compressing the air delivered to the cells.

Abstract: A novel method for making an electrode for use in an electrochemical cell comprises forming a substrate by coating the fibers of a fibrous carbon paper with pyrolytic carbon, wet proofing the coated paper with a hydrophobic polymer, sintering the wet proofed paper, and applying a catalyst/hydrophobic polymer layer thereon.

Abstract: A cooler for removing waste heat from a stack of fuel cells uses a non-dielectric coolant which is carried in a plurality of tubes passing through one or more separator plates in the stack. Preferably the coolant is water so that heat removal is by evaporation of the water within the tubes by boiling. The tubes are electrically insulated from the cells by a coating of dielectric material such as polytetrafluoroethylene. In one embodiment of the present invention the cooler tubes are connected to the stack coolant supply conduits by dielectric hoses having a high length to diameter ratio to provide a several hundred thousand ohm impedance path in case of a flaw in the protective dielectric coating, in order that a short circuit of the stack does not occur.