Abstract: A fuel processing system (FPS) (110) is provided for a fuel cell power plant (115) having a fuel cell stack assembly (CSA) (56). A water gas shift (WGS) reaction section (12, 120) of the FPS (110) reduces the concentration of carbon monoxide (CO) in the supplied hydrocarbon reformate, and a preferred oxidation (PROX) section (40) further reduces the CO concentration to an acceptable level. The WGS section (12, 120) includes a reactor (124) with a high activity catalyst for reducing the reformate Co concentration to a relatively low level, e.g., 2,000 ppmv or less, thereby relatively reducing the structural volume of the FPS (110). The high activity catalyst is active at temperatures as low as 250° C., and may be a noble-metal-on-ceria catalyst of Pt and Re on a nanocrystaline, cerium oxide-based support. Then only a low temperature PROX reactor (46) is required for preferential oxidation in the FPS (110).

Abstract: Fuel is provided to an inlet (14) of a cascade region (15) which has a plurality of stages (17-23), each of which divides fuel flow evenly into a pair of corresponding slots (24-26). The flow is then spread across a floor surface (41) of a cascade exit header (40), the flow spreading into areas between the slots. The flow is then directed into an open cavity which is in fluid communication with the inlets of the fuel flow fields (12) of the fuel cells, reaching the fuel flow field inlets uniformly and simultaneously.

Abstract: Water flow field inlet manifolds (33, 37) are disposed at the fuel cell stack (11) base. Water flow field outlet manifolds (34, 38) are located at the fuel cell stack top. Outlet and inlet manifolds are interconnected (41-43, 47, 49, 50) so gas bubbles leaking through the porous water transport plate cause flow by natural convection, with no mechanical water pump. Variation in water level within a standpipe (58) controls (56, 60, 62, 63) the temperature or flow of coolant. In another embodiment, the water is not circulated, but gas and excess water are vented from the water outlet manifolds. Water channels (70) may be vertical. A hydrophobic region (80) provides gas leakage to ensure bubble pumping of water. An external heat exchanger (77) maximizes water density differential for convective flow.

Abstract: Each cell of a fuel cell stack is provided, between the anode 37 and cathodes 38, with either (a) a permanent shunt (20) which may be a discrete resistor (42-44), a diode (95), a strip of compliant carbon cloth (65), or a small amount of conductive carbon black (22) in the ionomer polymer mixture of which the proton exchange membrane (39) is formed, or (b) a removeable shunt such as a conductor (69) which may be rotated into and out of contact with the fuel cell anodes and cathodes, or a conductor (85) which may be urged into contact by means of a shape memory alloy actuator spring (90, 91), which may be heated.

Abstract: A high molecular weight direct antifreeze cooled fuel cell 10 includes an electrolyte 52 secured between an anode catalyst 54 and a cathode catalyst 56; a porous anode substrate 58 secured in direct fluid communication with and supporting the anode catalyst 54; a porous wetproofed cathode substrate 62 secured in direct fluid communication with and supporting the cathode catalyst 56; a porous water transport plate 64 secured in direct fluid communication with the porous cathode substrate 62; and, a high molecular weight direct antifreeze solution passing through the porous water transport plate 64 to cool and remove product water from the fuel cell 10. The high molecular weight direct antifreeze solution preferably includes polyethylene glycol having a molecular weight ranging from 200 to 8,000 AMU. The direct antifreeze solution does not leave the water transport plate 64 in significant quantities to poison the catalysts.

Abstract: Either (a) the exhaust (20) of an engine (9) and/or (b) inlet air (11) is sent to a hydrogen generator (22) along with diesel fuel (18) to produce hydrogen and carbon monoxide (26) for either (c) mixing with the mainstream of exhaust fed to a catalytic converter (28) or (d) regenerating a pair of NOx adsorption traps (35, 36), thereby reducing oxides of nitrogen (NOx) to provide system exhaust (29) which may have less than 0.20 grams/bhp/hr of NOx and 0.14 grams/bhp/hr of non-methane hydrocarbons. A water recovery unit (52, 63) may extract water from either the exhaust or the effluent of the NOx traps to humidify inlet air (11) for mixture with fuel. Inlet air (11) may be humidified in an air bubbling humidifier (72) that receives water from a condenser (76) that uses inlet air to cool NOx trap effluent.

Abstract: Fuel mixing control arrangements are provided for fuel cell power plants (10) operating on multiple fuels (22, 24, 26). A fuel delivery system (16) supplies hydrogen-rich fuel (20) to the cell stack assembly (CSA) (12) after controlled mixing of a primary fuel (22) and at least a secondary fuel (24), each having a respective “equivalent hydrogen (H2) content”. The relative amounts of the primary fuel (22) and secondary fuel (24) mixed are regulated (18, 34, 36) to provide at least a minimum level (LL) of hydrogen-rich fuel having an equivalent hydrogen content sufficient for normal operation of the CSA (12). The primary fuel (22) is a bio-gas or the like having a limited, possibly variable, equivalent H2 content, and the secondary fuel (22) has a greater and relatively constant equivalent H2 content and is mixed with the primary fuel in an economic, constant relationship that assures adequate performance of the CSA (12). One or more parameters (IDC, P, V, E. C.

Abstract: A procedure for starting up a fuel cell system that is disconnected from its primary load and has both its cathode and anode flow fields filled with air includes initiating a flow of air through the cathode flow field and rapidly displacing the air in the anode flow field by delivering a flow of fresh hydrogen containing fuel into the anode flow field, and thereafter connecting the primary load across the cell. Sufficiently fast purging of the anode flow field with hydrogen prior to connecting the cells to the load eliminates the need for purging the anode flow field with an inert gas, such as nitrogen, upon start-up.

Abstract: A method for operating a fuel cell power plant. The fuel cell can include a reactant passage (22) with an upstream portion and a downstream portion for providing reactant to an electrode (16, 18), at least one liquid passage (24), and a plate (20) made from a porous material that is liquid permeable and conductive. The porous material separates the reactant passage and the liquid passage. A pressure profile is controlled to provide a positive pressure difference in the upstream portion and a negative pressure difference in the downstream portion. A positive pressure difference is one where the liquid pressure is higher than that of the reactant. A negative pressure difference is one where the liquid pressure is less than that of the reactant. The pressure profile can be used to provide enhanced humidification of the reactant in the upstream portion and effective liquid water removal in the downstream portion to maximize both the performance and the life of the fuel cell.

Abstract: In a hydrocarbon fueled reformed gas fuel cell system having a rated power, a process for cooling reformed gas from a fuel processor prior to feeding the reformed gas to a shift converter includes the steps of providing a cooling zone having a hot gas inlet, a cooled gas outlet and a water inlet, feeding the reformed gas at a temperature of between 600 to 900° F. to the hot gas inlet, redirecting the reformed gas in the cooling zone so as to provide a swirling recirculating flow of the reformed gas in the cooling zone, atomizing water into droplets and contacting the droplets with the redirected reformed gas so as to cool the reformed gas and vaporize the water, and removing a stream of cooled reformed gas from the cooling zone wherein the reformed gas is at a temperature between 400 to 500° F. and the stream is substantially free of water droplets.

Abstract: A method for shutting down a fuel cell system including a plurality of fuel cells arranged in a stack, includes cooling the fuel cells to a shutdown temperature while maintaining a substantially uniform water vapor pressure through the fuel cells whereby migration of water within the fuel cells during cooling is reduced.

Abstract: The invention is a reversible fuel cell power plant (10). A reactant switch-over assembly (48) is secured between a reducing fluid fuel source (30), an oxygen containing oxidant source (24), and first and second flow fields (20) (22) of a fuel cell (12). The switch-over assembly (48) first directs a reducing fluid fuel stream to flow into the first flow field (20) while it simultaneously directs the oxygen containing oxidant stream to flow into the second flow field (22). Then, after a first half of a useful life span of the fuel cell (12) but before a final one quarter of the useful life span, the switch-over assembly (48) directs the reducing fluid fuel stream to flow into the second flow field (22) while it simultaneously directs the oxygen containing oxidant stream to flow into the first flow field (20).

Abstract: A procedure for shutting down an operating fuel cell system includes disconnecting the primary electricity using device and stopping the flow of hydrogen containing fuel to the anode, followed by quickly displacing the residual hydrogen with air by blowing air through the anode fuel flow field. A sufficiently fast purging of the anode flow field with air eliminates the need for purging with an inert gas such as nitrogen.

Abstract: The invention is a fuel cell (20) having a corrosion resistant and protected cathode catalyst layer (24). The cathode catalyst layer (24) includes a platinum oxygen reduction catalyst and an oxygen evolution catalyst selected from the group consisting of catalysts that are more active than platinum for oxygen evolution. The oxygen evolution catalyst may be uniformly applied within the cathode catalyst layer, or non-uniformly applied to identified high corrosion areas (82) (84) of the cathode catalyst layer (24). The cathode catalyst layer (24) may include heat-treated carbon support material, and/or a heat-treated carbon black within a diffusion layer (40) supporting the cathode catalyst layer (24). The fuel cell (20) may also include an anode catalyst layer (22) having a poor oxygen reduction catalyst having a greater oxygen reduction over potential than platinum.

Abstract: Performance of a fuel cell stack (12) is recovered following long term decay by connecting (51) an auxiliary load (50) to the fuel cell while shutting off one or more of oxidant inlet valve (27a), oxidant pressure regulating valve (28a) or oxidant pump (26), which all may be achieved with a controller (46), to cyclically starve the cathode of oxidant so that it achieves hydrogen potential, e.g., less than 0.1 volts, for on the order of tens of seconds, repetitively, such as at every 10 or 20 seconds, while the auxiliary load remains connected, initially drawing 10 to 100 mASC, for example. Complete rejuvenation is obtained following 1800 or more cycles over a period of five or more hours.

Abstract: A high water permeability proton exchange membrane (12) is disclosed for use in an electrochemical cell, such as a fuel cell (10) or an electrolysis cell. The membrane (12) includes: a. between about 20 volume percent (“vol. %”) and about 40 vol. % of a structural insulating phase (40); between about 50 vol. % and about 70 vol. % of a hydrated nanoporous ionomer phase (42); and, about 10 vol. % of a microporous water-filled phase (44). The structural insulating material (40) defines an overall membrane volume, and the ionomer phase (42) fills all but 10% of the overall volume so that the microporous water-filled phase (44) is defined within the ionomer phase (42) and consists of open pores having a diameter of between 0.3 microns and 1.0 microns. Water transport is enhanced between opposed catalytic surfaces (14), (16) of the membrane (12).

Abstract: The invention is a start up system and method for a fuel cell power plant (10) using a purging of the cathode flow field (38) with a hydrogen rich reducing fluid fuel to minimize corrosion of the cathode electrode (16). The method for starting up the shut down fuel cell power plant (10) includes the steps of: a. purging the cathode flow field (38) with the reducing fluid fuel; b. then, directing the reducing fluid fuel to flow through an anode flow field (28); c. next, terminating flow of the fuel through the cathode flow field (38) and directing an oxygen containing oxidant to flow through the cathode flow field (38); and, d. finally, connecting a primary load (70) to the fuel cell (12) so that electrical current flows from the fuel cell (12) to the primary load (70).

Abstract: The invention is a method of using a temporary dilute surfactant water solution to enhance mass transport in a fuel cell (10) that generates electrical current from hydrogen containing reducing fluid and oxygen containing oxidant reactant streams. The method includes the steps of: a. directing the dilute surfactant water solution to flow through a cathode flow field (20) of a fuel cell (10); b. then removing the solution from the fuel cell (10); and, c. then directing flow of the reactant streams through the flow fields (12) (20). The temporary dilute surfactant water solution has a surface tension of not less than 50 dynes/cm. Flowing the temporary dilute surfactant water solution through the fuel cell (10) for a temporary, short duration improves mass transport of the cell (10) even after the solution is removed from the cell (10).

Abstract: The invention is a system and method for shutting down a fuel cell power plant having at least one fuel cell, a primary load, and an auxiliary load that receive electrical current from electrodes of the fuel cell through an external circuit. Shutting down the plant includes disconnecting the primary load; terminating flow of the oxidant through a cathode flow field; connecting the auxiliary load to consume oxygen within the fuel cell; disconnecting the auxiliary load; connecting a power supply to the fuel cell electrodes to increase a concentration of hydrogen within the cathode flow field; and, then, decreasing or eliminating flow of hydrogen into an anode flow field after an equilibrium gas concentration of at least 0.0001% hydrogen, balance fuel cell inert gases, is achieved in both the anode and cathode flow fields.

Abstract: A precooler for use in a fuel cell system between a thermal reformer and a shift converter includes an atomizing water inlet in combination with a swirling inducing reformed gas inlet which act to increase the resistance time of the reformed gas in the precooler so as to effectively cool same.