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: 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: A terminus (8) for a bungee cord (15) has a hook (9) with a transverse axis (17) which is within a given distance of the longitudinal axis (16) of a bore (13) within the stem (10) of the terminus. A cleat (24) opens into a cord passage (20) leading to the bore (13) to permit pulling a cord (15) into the cleat (24) thereby locking the terminus in position on the cord (15). The relative axial alignment of the load in the cord (15) with the transverse axis (17) of the hook (9) prevents the load (15) from rotating the hook substantially. A land (27) adjusts the thickness of the cleat.

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 fuel cell stack has a cascaded fuel flow field in which groups (10-12) of fuel cells (13, 13a) are arranged in flow-series, there being a fuel purge inlet valve (33) to provide fuel flow directly to two of the groups (11-12) downstream in the series, and a fuel purge outlet valve (36) to vent fuel flow directly from the first and second groups (10, 11) of fuel cells (13), whereby to avoid large pressure drop in the lowest group (12) of the series, to thereby facilitate quick purging of the fuel flow field. In other embodiments, rotary gates (40, 41) or sliding gates (56, 57) within manifolds cause fuel to flow into and out of all three groups directly during a purge.

Abstract: A single core 35, 50 or a plurality of cores arranged in rings 21, 28, 29 around a central core 20, 27, or in an array 42, are provided with either or both of (a) a modal discrimination characteristic, including gain, index of refraction and cross sectional area, which is greatest in the center of the core or the array, and lowers outwardly therefrom, and (b) an oblong cross section, thereby to provide either or both of (c) a bright laser beam of the fundamental in-phase supermode, and/or (d) a linearly polarized output beam.

Abstract: A proton exchange membrane (PEM) fuel cell includes fuel and oxidant flow field plates (26, 40) having fuel and oxidant channels (27, 28; 41, 44), and water channels, the ends (29, 48) of which that are adjacent to the corresponding reactant gas inlet manifold (34, 42) are dead ended, the other ends (31, 50) draining excess water into the corresponding reactant gas exhaust manifold (36, 45). Flow restrictors (39, 47) maintain reactant gas pressure above exit manifold pressure, and may comprise interdigitated channels (65, 66; 76, 78). Solid reactant gas flow field plates have small holes (85, 88) between reactant gas channels (27, 28; 41) and water drain channels (29, 30; 49, 50). In one embodiment, the fuel cells of a stack may be separated by either coolant plates (51) or solid plates (55) or both.

Abstract: A fuel cell power plant includes a fuel cell having a membrane electrode assembly (MEA), which is disposed between anode and cathode support plates. Porous water transport plates or the support plates have interdigitated flow channels for the reactant gas streams to pass through and conventional flow channels for coolant streams to pass through. The pressure of the reactant gas streams is greater than the coolant stream which, within the porous water transport plates allows the coolant water to saturate the water transport plates thereby forcing the reactant gases into the anode and cathode support plates. This, in turn, increases the mass transfer of such gases into the support plates, thereby increasing the electrical performance of the fuel cell. Current densities of about 1.6 amps per square centimeter are achieved with air stochiometries of not over 2.50.

Abstract: A fuel cell stack (7) has an auxiliary load (30) in series with a battery (29) which can selectively (25) be connected across the fuel cell stack in place of a main load (24). A method includes connecting the battery and auxiliary load across the fuel cell stack while providing fuel (13) to the anode flow fields (8, 10); in one embodiment, oxidant (17) is provided to the cathode flow fields (16) initially; in a second embodiment, oxidant is withheld from the cathode flow for a predetermined time or until a threshold voltage is reached.

Abstract: Oxides of nitrogen are adsorbed onto the surfaces of gas passages (68) in a bed (57, 100) that has relative rotation with respect to a gas inlet distributor (76, 101). The manifold has a baffle (85) or ribs (121, 122) that causes constantly flowing engine exhaust (53) to enter the gas passages over a large portion of a revolution of the adsorption bed or the distributor, and causes constantly flowing regeneration gas (54) to thereafter pass through those passages during a small portion of each revolution. The passages may be formed by planar (66a) or helical (66b) radial walls (66), a serpentine wall (70), a monolith (126), or a honeycomb (127). Either the distributor (101) or the bed (57) may be rotated to distribute the gases.

Abstract: Efficient delivery of large amounts of pump laser power distributed along the cladding (11, 54) of a single core (6) or multiple core (7, 51) laser fiber, without degrading the fiber integrity or compromising the fiber's waveguiding property, is accomplished by injecting the power into the cladding via delivery fibers (18, 30, 42, 62) permanently affixed to a peripheral wall (20, 56) at an angle that satisfies the condition for total internal reflection of the pump radiation so that it is confined within the inner cladding of the laser fiber. In one embodiment, the laser fiber (51) is wrapped around a drum (53). Each delivery fiber has a numerical aperture (NA) less than half the NA of the laser fiber, and a core 21 having a refractive index substantially the same as that of the inner cladding (11) of the laser fiber.

Abstract: A stack of plates (121) (such as fuel cells, electrochemical cells, or enthalpy exchange plates) is surrounded by a sleeve manifold (119) which is shaped to provide manifold chambers (34-39; 146-149; 151-153; 156-158; 161-163; 180-187), and including surfaces (142) for seals (143) to isolate the manifold chambers from each other. Sleeve manifolds (119a, 119b, 119c) may be formed of material of varying thickness, by machining, casting, or extrusion, or may be formed of material (119d) of uniform thickness by bending, casting or extrusion. Sleeve manifolds may be formed of metal, graphite, plastic or reinforced plastic.

Abstract: An improved water management system for PEM fuel cells is provided. Catalyst layers are disposed on both sides of a proton exchange membrane. Porous plates are positioned adjacent the catalyst layers. Water transport plates are positioned adjacent the porous plates and the reactant gas are humidified at their inlets, in one embodiment by fins, while moisture is removed in the fuel flow path and at the oxidant outlet, in one embodiment by other fins.

Abstract: Recovery of PEM fuel cell performance is achieved by evacuating (61, 62) or by flowing water absorbing gas (46) through, or both, the fuel flow field (12, 13, 19, 20), the air flow field (25, 26, 30, 31), and the water flow field (36, 39), while resistance of the individual cells, or of the fuel cell stack, is measured; the dry out process is continued until the resistance of the cells (or the resistance per cell, measured across the fuel cell stack as a whole), has increased by at least 5 to 1 (preferably 10 to 1) over the normal resistance of the cells. The water absorbing gas may be air (23) or nitrogen (47); it may be at ambient temperature or heated (50).

Abstract: A tie-down (9, 38) includes two straps (12, 21) with hooks (17, 24) secured to their ends, the other end (29) of a first strap (21) being workable with a buckle (15, 39) to provide tension. The buckle is captured in a loop (13) formed in the second strap (12), along with a soft loop (10), into which the hook (17) can be engaged so as to avoid damaging an article being restrained by the tie-down. The soft loop (10) is fashioned by stitching (33) of three contiguous layers of strap in a region (32) between the two loops, adjacent to the buckle; the stitching being perpendicular to the direction of tension (35) in the strap.

Abstract: A vehicle (150) includes a fuel cell stack (151) started when the stack is below freezing, by connection (158) to the vehicle propulsion system (159) within a few seconds of starting the flow of fuel (179) and oxidant (173), or when open circuit voltage (155, 156) is detected. The fuel is in excess of stochiometry requirement and the oxidant is in excess of at least twice stochiometric requirement, either may be at about atmospheric pressure or at 4 kPa (0.6 psi) or more above the pressure of any water in said water passages, and either may be below freezing. Water transport plates (84, 86, 88, 89) have water passages connected to a water circulation loop (170) including a reservoir (164) having an auxiliary heater (161) connected (160) to the stack. Warming of cell stack materials and ice in the water transport plates, heat of fusion of melting ice, warming of melted water, and evaporative cooling of water melted in the water transport plates keep the fuel cell cool until liquid coolant can be circulated.

Abstract: A fuel cell (40) has a proton exchange membrane (41) having a rectangular central portion (42) and flaps (43-46) extending from the central portion. The flaps are wrapped around the cathode and anode substrates (14, 26) to provide respective edge seals therefor. A liquified adhesive adheres the flaps to the substrates and intervening filler material (33) so as to form a unitized electrode assembly.

Abstract: A sealant system 13 for a manifold 10 of a proton exchange membrane fuel cell includes low temperature cured or heat cured silicone rubber bridges 14, 14a, 14c between the end plates 9 to compensate for the uneven edges of various fuel cell component layers, and a layer 15 of silicone rubber foam or sponge, or a molded silicone rubber gasket 15a, extending across the bridges and along the end plates, around the entire contact perimeter surfaces of the manifold, to seal the manifold to the fuel cell. The cured silicone rubber may extend along the end plates between the bridges. A rubber strip 20 may be adhered to the silicone rubber bridges and end plates. The bridges may comprise a first layer 22 of low shrinkage self-leveling RTV liquid rubber with viscosity in the range of 10,000-20,000 cps and a second layer 14 of RTV liquid rubber.

Abstract: A coolant system is proposed for addressing temperature concerns during start-up and shut-down of a cell stack assembly. The coolant system comprises a coolant exhaust conduit in fluid communication with a coolant exhaust manifold and a coolant pump, the coolant exhaust conduit enabling transportation of exhausted coolant away from a coolant exhaust manifold. A coolant return conduit is provided to be in fluid communication with a coolant inlet manifold and a coolant pump, the coolant return conduit enabling transportation of the coolant to the coolant inlet manifold. The coolant system further includes a bypass conduit in fluid communication with the coolant exhaust conduit and the coolant return conduit, while a bleed valve is in fluid communication with the coolant exhaust conduit and a gaseous stream. Operation of the bleed valve enables venting of the coolant from the coolant channels, and through said bypass conduit.