Abstract: A method and apparatus for increasing the operational efficiency of a fuel cell power plant including a cell stack assembly having a plurality of fuel cells in electrical communication with one another, each of the fuel cells including an anode substrate in fluid communication with an anode flow field plate. The proposed method includes forming a fuel channel in the anode flow field plate, providing a fuel stream to a fuel channel and interrupting the fuel channel at a location along the fuel channel so that the fuel stream is directed to permeate the anode substrate before being exhausted from the fuel cells.

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: A fuel cell system is shut down by disconnecting the primary load, shutting off the air flow, and controlling the fuel flow into the system (including shutting off the fuel flow) and the gas flow out of the system in a manner that results in the fuel cell gases coming to equilibrium across the cells at a gas composition of at least 0.0001% hydrogen (by volume), and preferably between 1.0% and less than 4.0% hydrogen, by volume, with a balance of nitrogen and possibly other gases inert and harmless to the fuel cell, all the oxygen having been consumed by reacting with the hydrogen within the cell. That gas composition is maintained within the cells throughout shut-down, such as by adding hydrogen to replace any that is consumed by reaction with air leaking into the cells during the period of shut-down. This shut-down procedure causes virtually no cell performance losses.

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: The invention reduces free water volume in a fuel cell power plant so support systems of the plant are freeze tolerant. The fuel cell power plant includes a coolant system having a sealed cooler plate that circulates an antifreeze coolant in heat exchange with a fuel cell and that collects fuel cell water; a water vapor removal system that removes water vapor from the antifreeze coolant to regulate the antifreeze concentration; and a start-up system having a start-up heat exchanger and a start-up valve that selectively direct heated antifreeze coolant into the cooler plate for a start-up procedure. The plant may also include a fuel processing system that utilizes the removed water vapor, and that is in heat exchange with the start-up heat exchanger. The antifreeze coolant is a low vapor pressure solution, such as an alkanetriol or polyethylene glycol.

Abstract: A fuel cell power plant has a fuel cell (38) receiving hydrogen (37) from a fuel processing system (12) which employs a vaporizer (19) to vaporize clean gasoline from a source (13). A conventional start burner (22) and startup heat exchanger (28) are utilized to convert water (31) from the fuel processing system (12) and fuel cell (38) into steam (32); but during sub-zero startup, an aqueous antifreeze solution (46) is provided to the heat exchanger (28) to produce the steam (32) for starting the vaporization of gasoline in the vaporizer (19).

Abstract: The invention is a freeze tolerant fuel cell power plant that includes at least one fuel cell; a coolant loop having a coolant circulating device that directs a water coolant through a water transport plate within the fuel cell; and a water displacement system having a freeze tolerant accumulator that contains a water immiscible fluid and water coolant. The water displacement system also includes a water immiscible fluid pump, heater and displacement valves for directing the water immiscible fluid to flow from the accumulator into the coolant loop; for directing the water coolant in the coolant loop to flow into the accumulator; and, for directing heated water immiscible fluid to flow from the accumulator into the coolant loop and back into the accumulator.

Abstract: The invention is a freeze tolerant fuel cell power plant that includes at least one fuel cell; a coolant loop having a coolant circulating device that directs a water coolant through a water transport plate within the fuel cell; and a water displacement system having a freeze tolerant accumulator that contains a water immiscible fluid and water coolant. The water displacement system also includes a water immiscible fluid pump, heater and displacement valves for directing the water immiscible fluid to flow from the accumulator into the coolant loop; for directing the water coolant in the coolant loop to flow into the accumulator; and, for directing heated water immiscible fluid to flow from the accumulator into the coolant loop and back into the accumulator.

Abstract: A fuel cell system is shut down by disconnecting the primary load, shutting off the air flow, and controlling the fuel flow into the system (including shutting off the fuel flow) and the gas flow out of the system in a manner that results in the fuel cell gases coming to equilibrium across the cells at a gas composition of at least 0.0001% hydrogen (by volume), and preferably between 1.0% and less than 4.0% hydrogen, by volume, with a balance of nitrogen and possibly other gases inert and harmless to the fuel cell, all the oxygen having been consumed by reacting with the hydrogen within the cell. That gas composition is maintained within the cells throughout shut-down, such as by adding hydrogen to replace any that is consumed by reaction with air leaking into the cells during the period of shut-down. This shut-down procedure causes virtually no cell performance losses.

Abstract: A fuel cell power plant has a fuel cell (38) receiving hydrogen (37) from a fuel processing system (12) which employs a vaporizer (19) to vaporize clean gasoline from a source (13). A conventional start burner (22) and startup heat exchanger (28) are utilized to convert water (31) from the fuel processing system (12) and fuel cell (38) into steam (32); but during sub-zero startup, an aqueous antifreeze solution (46) is provided to the heat exchanger (28) to produce the steam (32) for starting the vaporization of gasoline in the vaporizer (19).

Abstract: A fuel cell with a direct antifreeze impermeable cooler plate is disclosed for producing electrical energy from reducing fluid and process oxidant reactant streams. The fuel cell includes an electrolyte secured between an anode catalyst and a cathode catalyst; an anode flow field secured adjacent the anode catalyst for directing the reducing fluid to pass adjacent the anode catalyst; a cathode flow field secured adjacent the cathode catalyst for directing the process oxidant stream to pass adjacent the cathode catalyst; a direct antifreeze impermeable cooler plate secured in heat exchange relationship with the cathode flow field; and a direct antifreeze solution passing through the cooler plate for controlling temperature within the fuel cell. The direct antifreeze solution is an organic antifreeze solution that is not volatile at cell operating temperatures.

Abstract: A method and apparatus for increasing the operational efficiency of a fuel cell power plant including a cell stack assembly comprised of a plurality of fuel cells in electrical communication with one another, each of the fuel cells including an anode substrate in fluid communication with an anode flow field plate. The proposed method includes forming a fuel channel in the anode flow field plate, providing a fuel stream to a fuel channel and interrupting the fuel channel at a location along the fuel channel so that the fuel stream is directed to permeate the anode substrate before being exhausted from the fuel cells.

Abstract: A direct antifreeze cooled fuel cell power plant is disclosed. The plant includes at least one fuel cell a thermal management system that directs flow of a cooling fluid for controlling heat within the plant, including a direct antifreeze solution passing through the water transport plate. The plant also integrates the direct antifreeze solution with a direct mass and heat transfer device, a water treatment system, and a steam injection system so that the direct antifreeze solution minimizes problems related to operation of the plant in sub-freezing conditions. A preferred antifreeze solution is an alkanetriol selected from the group consisting of glycerol, butanetriol, and pentanetriol. The direct antifreeze solutions minimize movement of the antifreeze as a vapor out of a water transport plate into contact with cathode or anode catalysts, and also minimize direct antifreeze solution loss from other power plant systems.

Abstract: A coolant treatment system for a direct antifreeze cooled fuel cell power plant including a degassifier for providing interaction between an oxidant and an antifreeze solution which has circulated throughout the fuel cell power plant so that dissolved gases within the antifreeze solution are removed. The fuel cell power plant is configured to allow the antifreeze solution to be in direct fluid communication with the fuel cell assemblies comprising the fuel cell power plant.

Abstract: A direct antifreeze cooled fuel cell is disclosed for producing electrical energy from reducing and process oxidant fluid streams that includes an electrolyte secured between an anode catalyst and a cathode catalyst; a porous anode substrate secured in direct fluid communication with and supporting the anode catalyst; a porous wetproofed cathode substrate secured in direct fluid communication with and supporting the cathode catalyst; a porous water transport plate secured in direct fluid communication with the porous cathode substrate; and, a direct antifreeze solution passing through the porous water transport plate.

Abstract: An interdigitated enthalpy exchange device is disclosed for a fuel cell power plant that includes at least one fuel cell and a direct mass and heat transfer device secured in fluid communication with both an oxidant stream entering the fuel cell and an exhaust stream leaving the fuel cell. The direct mass and heat transfer device secures the interdigitated enthalpy exchange device in mass transfer relationship between the oxidant and exhaust streams. The device includes discontinuous oxidant entry and oxidant exit channels and discontinuous exhaust entry and exhaust exit channels, thereby providing for direct transfer of mass and heat from the exhaust stream to the oxidant stream while also restricting loss of liquid from the plant in the exhaust stream, filtering of dust entering the plant in the oxidant stream, and dampening of noise of the plant.

Abstract: An operating system for a direct antifreeze cooled fuel cell power plant is disclosed for producing electrical energy from reducing and process oxidant fluid reactant streams. The system includes at least one fuel cell for producing electrical energy from the reducing and oxidant fluid streams; fuel processing components for processing a hydrocarbon fuel into the reducing fluid; a thermal management system that directs flow of a cooling fluid for controlling heat within the plant including a porous water transport plate adjacent and in fluid communication with a cathode catalyst of the fuel cell; a direct antifreeze solution passing through the water transport plate; and, a split oxidant passage that directs the process oxidant stream into and through the fuel cell.

Abstract: A direct antifreeze cooled fuel cell power plant system is disclosed for producing electrical energy from reducing and process oxidant fluid reactant streams. The system includes at least one fuel cell for producing electrical energy from the reducing and oxidant fluid streams; a thermal management system that directs flow of a cooling fluid for controlling temperature within the plant including a porous water transport plate adjacent and in direct fluid communication with a cathode catalyst of the fuel cell; a direct antifreeze solution passing through the water transport plate; and, fuel processing components secured in fluid communication with the thermal management system for processing a hydrocarbon fuel into the reducing fluid and for controlling a concentration of a direct antifreeze in the direct antifreeze solution.

Abstract: A direct antifreeze cooled fuel cell is disclosed for producing electrical energy from reducing and process oxidant fluid streams that includes an electrolyte secured between an anode catalyst and a cathode catalyst; a porous anode substrate secured in direct fluid communication with and supporting the anode catalyst; a porous wet proofed cathode substrate secured in direct fluid communication with and supporting the cathode catalyst; a porous water transport plate secured in direct fluid communication with the porous cathode substrate; and, a direct antifreeze solution passing through the porous water transport plate. In operation of the fuel cell, because product water generated electrochemically at the cathode catalyst flows away from the cathode catalyst into the cathode substrate and into the water transport plate and because the cathode substrate is wetproofed, the antifreeze solution passing through the water transport plate remains essentially within this plate.

Abstract: A fine pore enthalpy exchange barrier is disclosed for use with a fuel cell power plant. The barrier includes a support matrix that defines pores and a liquid transfer medium that fills the pores creating a gas barrier. An inlet surface of the fine pore enthalpy exchange barrier is positioned in contact with a process oxidant inlet stream entering a fuel cell power plant, and an opposed exhaust surface of the barrier is positioned in contact with an exhaust stream exiting the plant so that water and heat exchange from the exhaust stream directly into the process oxidant inlet stream to heat and humidify the stream as it enters the plant. The liquid transfer medium may include water, aqueous salt solutions, aqueous acid solutions, or organic antifreeze water solutions.