Abstract: A battery system of an aircraft includes one or more battery packages. Each battery package includes a plurality of battery cells. A thermal management system is fluidly connected to the one or more battery packages. The cooling system has a flow of coolant flowing therethrough. Thermal energy is dissipated from the one or more battery packages via a phase change of the flow of coolant. A method of managing thermal energy of a battery package includes conducting thermal energy from a plurality of battery cells via a conductive inter-cell separator located between adjacent battery cells, and transferring the thermal energy from the inter-cell separator to a flow of coolant in thermal communication with the conductive inter-cell separator, thereby causing a phase change in the flow of coolant resulting in cooling of the plurality of battery cells. The thermal energy is then dissipated from the flow of coolant.

Abstract: Fuel cell reactant flow field plates (22, 32) are formed by extruding long sections (17, 25) of carbonaceous material, either with straight grooves (18, 28) formed by the extrusion die, or by end milling or arbor milling, and then cut to a proper size, including cuts in which the edges of the plates are at an angle with respect to the grooves. Cooler plates are formed of water-permeable material (39) in which hydrophobic material (40) is impregnated so as to define coolant channels (42-44) with inlets and outlets (47, 49). A two-layer cooler plate is formed by stamping voids in one layer (51) that define coolant flow channels (52) with inlets (54) and outlets (56) while a second layer (59) is stamped with voids (61, 62) that define coolant inlet and exit headers; juxtaposition of the layers, with or without bonding, form the cooler plate. A cooler plate (65) is made by corrugating thin metal sheet, providing coolant channels (68) for cathodes and coolant channels (73) for anodes when interposed therebetween.

Abstract: A gas detection device including a vessel, wherein the vessel contains an aqueous solution, and a sensing element operably coupled to the vessel, wherein the sensing element is not in direct contact with the aqueous solution.

Abstract: A fuel cell includes a water transport plate providing a water flow field. The water flow field permits a flow of water having an entrained gas. A vent is in fluid communication with the water flow field. At least some of the gas is released from fuel cell by opening a vent. In a disclosed example, a valve is opened in response to conditions indicative of an undesired amount of gas. For example, the valve is actuated in response to a signal from a water level sensor. In another example, the valve is opened based upon a schedule.

Abstract: The fuel flow channels (20a) of the end fuel cell (9a) at the anode end (34) of a fuel cell stack are significantly deeper than the fuel flow field channels (20) of the remaining fuel cells (9) in the stack, whereby fuel starvation caused by ice in the fuel flow channels is avoided during cold startup. The fuel flow field channels of the end cell (9) at the anode end of the stack is between about 0.15 mm and about 1.5 mm deeper than the fuel flow field channels in the remaining fuel cells of the stack, or between about 35% and about 65% deeper than the fuel flow field channels in the remaining fuel cells of the stack.

Abstract: A method of operating a fuel cell power plant (10) including a stack (11) of fuel cells having an anode catalyst layer and a cathode electrode (15) including a catalyst layer disposed on catalyst support material is characterized by, during normal operation of said power plant, adjusting the voltage of the stack to be substantially equal to or less than a predetermined maximum voltage for the temperature of the stack. Further, said step of adjusting comprises adjusting the stack voltage to the lesser of: a) a predetermined voltage above which corrosion of catalyst support material is significant and below which corrosion of catalyst support material is insignificant at the temperature of the stack; and b) a predetermined voltage above which dissolution of catalyst is significant and below which dissolution of the catalyst is insignificant at the temperature of the stack.

Abstract: Fuel cell systems and related methods involving accumulators with multiple regions of differing water fill rates are provided. At least one accumulator region with a relatively more-rapid fill rate than another accumulator region is drained of water at shutdown under freezing conditions to allow at least that region to be free of water and ice. That region is then available to receive water from and supply water to, a fuel cell nominally upon start-up. The region having the relatively more-rapid fill rate may typically be of relatively lesser volume, and may be positioned either relatively below or relatively above the other region(s).

Abstract: A gas detection device including a vessel, wherein the vessel contains an aqueous solution, and a sensing element operably coupled to the vessel, wherein the sensing element is not in direct contact with the aqueous solution.

Abstract: A fuel cell power plant (36) has vertical fuel cells (102) each sharing a half of a hybrid separator plate (100) which includes a solid fuel flow plate (105) having horizontal fuel flow channels (106) on one surface and coolant channels (108) on an upper portion of the opposite surface, bonded to a plain rear side of a porous, hydrophilic oxidant flow field plate (115) having vertical oxidant flow channels (118). Coolant permeates through the upper portion of the porous, hydrophilic oxidant flow field plates and enters the oxidant flow channels, where it evaporates as the water trickles downward through the oxidant flow field channels, thereby cooling the fuel cell.

Abstract: Fuel cells (38) have passageways (83, 84) that provide water through one or both reactant gas flow field plates (75, 81) of each fuel cell, whereby the fuel cell is cooled evaporatively. The water passageways may be vented by a porous plug (not shown), or by a microvacuum pump (89). A condenser (59) may have a reservoir (64); the condenser (59) may be a vehicle radiator. A highly water permeable wicking layer (90) is disposed adjacent to one or both water passageways (83, 84) which exist between individual fuel cells (38). The passageways may be flow-through passageways (83) (FIG. 5) or they may be interdigitated passageways (83a, 83b) (FIG. 6) in order to increase the flow of water-purging air through the wicking layer (90) utilized to clear the stack of water during shutdown in cold environments.

Abstract: A fuel cell includes a water transport plate providing a water flow field. The water flow field permits a flow of water having an entrained gas. A vent is in fluid communication with the water flow field. At least some of the gas is released from fuel cell by opening a vent. In a disclosed example, a valve is opened in response to conditions indicative of an undesired amount of gas. For example, the valve is actuated in response to a signal from a water level sensor. In another example, the valve is opened based upon a schedule.

Abstract: Fuel cell reactant flow field plates (22, 32) are formed by extruding long sections (17, 25) of carbonaceous material, either with straight grooves (18, 28) formed by the extrusion die, or by end milling or arbor milling, and then cut to a proper size, including cuts in which the edges of the plates are at an angle with respect to the grooves. Cooler plates are formed of water-permeable material (39) in which hydrophobic material (40) is impregnated so as to define coolant channels (42-44) with inlets and outlets (47, 49). A two-layer cooler plate is formed by stamping voids in one layer (51) that define coolant flow channels (52) with inlets (54) and outlets (56) while a second layer (59) is stamped with voids (61, 62) that define coolant inlet and exit headers; juxtaposition of the layers, with or without bonding, form the cooler plate. A cooler plate (65) is made by corrugating thin metal sheet, providing coolant channels (68) for cathodes and coolant channels (73) for anodes when interposed therebetween.

Abstract: The system (10) controls at least one of a pressure of the reactant streams (16A, 16B) within at least one of an anode flow field (28) and a cathode flow field (36), a flow rate of the reactant streams (16A, 16B) flowing through the anode and/or cathode flow fields (26, 28), a temperature of a coolant fluid passing through a sealed coolant flow field (44), and a flow rate of the coolant fluid; so that water (14) moves from a water reservoir (18A, 18B) into the reactant stream (16A, 16B) whenever power generated by the fuel cell (20) is between about 80% and about 100% of a maximum fuel cell power output, and so that water (14) moves from the reactant stream (16A, 16B) into the water reservoir (18A, 18B) whenever fuel cell power is less than about 75% of the maximum power output.

Abstract: A fuel cell stack (10) is operated with a low air utilization which is very low when the stack is providing low current density, and is operated with air utilization increasing as a function of current density above a predetermined current density.

Abstract: Fuel cell systems and related methods involving accumulators with multiple regions of differing water fill rates are provided. At least one accumulator region with a relatively more-rapid fill rate than another accumulator region is drained of water at shutdown under freezing conditions to allow at least that region to be free of water and ice. That region is then available to receive water from and supply water to, a fuel cell nominally upon start-up. The region having the relatively more-rapid fill rate may typically be of relatively lesser volume, and may be positioned either relatively below or relatively above the other region(s).

Abstract: A fuel cell system includes a fuel cell, a controller, a resistance sensor, and a regulator. The fuel cell has a cathode plate, an anode plate, and an ion-exchange membrane interposed between the cathode plate and the anode plate. The controller is for controlling a gas flow rate to the anode plate. The resistance sensor is coupled to the fuel cell for measuring a resistance of the fuel cell. The regulator is coupled to the controller and coupled to the anode plate for regulating the gas flow to the anode plate. The controller receives a signal from the resistance sensor and is configured to control the regulator to adjust the gas flow to the anode plate based on the signal from the resistance sensor.

Abstract: The fuel flow channels (20a) of the end fuel cell (9a) at the anode end (34) of a fuel cell stack are significantly deeper than the fuel flow field channels (20) of the remaining fuel cells (9) in the stack, whereby fuel starvation caused by ice in the fuel flow channels is avoided during cold startup. The fuel flow field channels of the end cell (9) at the anode end of the stack is between about 0.15 mm and about 1.5 mm deeper than the fuel flow field channels in the remaining fuel cells of the stack, or between about 35% and about 65% deeper than the fuel flow field channels in the remaining fuel cells of the stack.

Abstract: In a proton exchange membrane fuel cell power plant (9) in which each of the fuel cells (11) employ reactant gas flow field channels (51) extending inwardly from a first surface of a conductive, water permeable reactant gas flow field plate (50), for at least one of the reactants of the fuel cell, a region (63) of the reactant gas flow field channels is substantially shallower than the remaining portion (60) of the flow field channels (51) thereby decreasing resistance to gas phase mass transfer from the wetted walls of the flow field plate to the gas in the region (63), the resulting increase in thickness of the web (58) adjacent the region (63) reduces the resistance to liquid water transport from the first coolant channel (52) to the inlet edge (55) of the plate (50) so that the plate supports a higher evaporation rate into the reactant gas in the shallow region (63).

Abstract: Coolant velocity greater than zero everywhere within the coolant channels (78, 85) of fuel cells (38) in a fuel cell stack (37) is assured by providing a flow of biphase fluid in the coolant channels, the flow being created by the outflow of a condenser (59). Positive pressure is applied to the coolant inlet (66) of the coolant channels. Biphase flow from an oxidant exhaust condenser, which may be a vehicle radiator (120), renders the coolant return flow more freeze tolerant. Using biphase flow within the coolant channels eliminates the need for a bubble-clearing liquid pump and reduces liquid inventory and other plumbing; this makes the fuel cell power plant more freeze tolerant.

Abstract: The system (10) controls at least one of a pressure of the reactant streams (16A, 16B) within at least one of an anode flow field (28) and a cathode flow field (36), a flow rate of the reactant streams (16A, 16B) flowing through the anode and/or cathode flow fields (26, 28), a temperature of a coolant fluid passing through a sealed coolant flow field (44), and a flow rate of the coolant fluid; so that water (14) moves from a water reservoir (18A, 18B) into the reactant stream (16A, 16B) whenever power generated by the fuel cell (20) is between about 80% and about 100% of a maximum fuel cell power output, and so that water (14) moves from the reactant stream (16A, 16B) into the water reservoir (18A, 18B) whenever fuel cell power is less than about 75% of the maximum power output.