Abstract: A phosphoric acid fuel cell (PAFC) system includes a cell stack assembly having an anode, a cathode and a coolant portion. At least one heat exchanger is fluidly interconnected with at least one of the anode, the cathode and the coolant portion and provides a fluid path for receiving a fluid from the anode, the cathode and/or the coolant portion. An absorption cycle refrigerant system includes an absorber having a solution of refrigerant and absorbent, and an absorbent loop and a refrigerant loop communicating with the absorber and respectively carrying absorbent and refrigerant. The at least one heat exchanger is arranged in the absorbent loop and is configured to transfer heat from the fuel cell system to the absorption chiller.

Abstract: An inlet fuel distributor (10-10d) has a permeable baffle (39, 54, 54a, 60) between a fuel supply pipe (11, 83) and a fuel inlet manifold (12, 53, 53a, 63) causing fuel to be uniformly distributed along the length of the fuel inlet manifold. A surface (53, 68) may cause impinging fuel to turn and flow substantially omnidirectionally improving its uniformity. Recycle fuel may be provided (25, 71) into the flow downstream of the fuel inlet distributor. During startup, fuel or inert gas within the inlet fuel distributor and the fuel inlet manifold may be vented through an exhaust valve (57, 86) in response to a controller (58, 79) so as to present a uniform fuel front to the inlets of the fuel flow fields (58).

Abstract: Fuel exhaust (109) of a primary fuel cell stack (11) flows into an auxiliary fuel cell stack (12) which powers a DC storage (82) feeding a bi-directional DC/AC converter (86) that is switchable (89) to auxiliary equipment (90, 91) (such as pumps) to a main power bus (54) feeding a main load (55). Fresh fuel (97) is provided (98, 105) to the primary stack for 90% fuel utilization, with over 99% overall power plant fuel utilization. The auxiliary equipment (90, 91) may be powered by the bus (54).

Abstract: A fuel cell system includes a fuel cell stack having a first plurality of fuel cells each having an anode, a cathode and an electrolyte disposed therebetween, the first plurality of fuel cells being communicated with a source of hydrogen-containing fuel and oxidant so as to generate an electric current, an oxidant exhaust stream and a hydrogen-containing exhaust stream; the stack further having a second plurality of fuel cells each having an anode, a counter electrode and an electrolyte disposed therebetween, the second plurality of fuel cells being communicated with the electric current and the hydrogen-containing exhaust stream so as to produce a hydrogen rich stream, the first plurality of fuel cells being communicated with the second plurality of fuel cells to receive the hydrogen rich stream as at least a portion of the source of hydrogen-containing fuel.

Abstract: A PEM fuel cell power plant system (10) has a process air pump (26), which may be a fan, a blower or a compressor, with an adiabatic efficiency of between 40% and 70%. The process air at the inlet 27 of the cathode reactant gas flow field 16 is between 1.07 atmospheres and 1.85 atmospheres, and may be at an optimal pressure for maximum overall system efficiency P={0.45+2.6E?1.8E2} atms±0.2 atms where P is the air inlet pressure and E is the adiabatic efficiency of the process air pump.

Abstract: A procedure for starting up a fuel cell system that is disconnected from its primary load and that has air in both its cathode and anode flow fields includes a) connecting an auxiliary resistive load across the cell to reduce the cell voltage; b) initiating a recirculation of the anode flow field exhaust through a recycle loop and providing a limited flow of hydrogen fuel into that recirculating exhaust; c) catalytically reacting the added fuel with oxygen present in the recirculating gases until substantially no oxygen remains within the recycle loop; disconnecting the auxiliary load; and then d) providing normal operating flow rates of fuel and air into respective anode and cathode flow fields and connecting the primary load across the cell. The catalytic reaction may take place on the anode or within a catalytic burner disposed within the recycle loop.

Abstract: A fuel cell power plant system includes the ability to operate an enthalpy recovery device even under cold conditions. A bypass arrangement allows for selectively bypassing one or more portions of the enthalpy recovery device under selected conditions. In one example, the enthalpy recovery device is completely bypassed under selected temperature conditions to allow the device to freeze and then later to be used under more favorable temperature conditions. In another example, the enthalpy recovery device is selectively bypassed during a system startup operation. One example includes a heater associated with the enthalpy recovery device. Another example includes preheating oxidant supplied to one portion of the enthalpy recovery device.

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: 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: 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: A PEM fuel cell power plant system (10) has a process air pump (26), which may be a fan, a blower or a compressor, with an adiabatic efficiency of between 40% and 70%. The process air at the inlet 27 of the cathode reactant gas flow field 16 is between 1.07 atmospheres and 1.

Abstract: A fuel cell power plant with enhanced water recovery includes a fuel cell power plant adapted to receive a reducing fluid and an oxidant and to generate therefrom electricity and an at least partially saturated exhaust stream; a mass and energy transfer device defining a first flow passage for the wet exhaust stream and a second flow passage for an oxidant stream, the first flow passage being in mass transfer relationship with the second flow passage; and an apparatus for cooling at least one of the oxidant stream, the exhaust stream and the mass and energy transfer device, whereby water is transferred from the exhaust stream to the oxidant stream so as to produce an at least partially saturated oxidant stream. A method is also disclosed.

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: A fuel cell system includes a fuel cell for reacting a hydrogen rich gas; a fuel processor system for converting a hydrocarbon fuel-steam mixture into said hydrogen rich gas; and a system for preparing the hydrocarbon fuel-steam mixture which includes (a) structure for superheating a hydrocarbon fuel so as to provide a superheated fuel, and (b) structure for mixing water with the superheated fuel so as to provide the hydrocarbon fuel-steam mixture.

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: 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 PEM fuel cell power plant system (10) has a process air pump (26), which may be a fan, a blower or a compressor, with an adiabatic efficiency of between 40% and 70%. The process air at the inlet 27 of the cathode reactant gas flow field 16 is between 1.07 atmospheres and 1.

Abstract: A fuel cell power plant with enhanced water recovery includes a fuel cell power plant adapted to receive a reducing fluid and an oxidant and to generate therefrom electricity and an at least partially saturated exhaust stream; a mass and energy transfer device defining a first flow passage for the wet exhaust stream and a second flow passage for an oxidant stream, the first flow passage being in mass transfer relationship with the second flow passage; and an apparatus for cooling at least one of the oxidant stream, the exhaust stream and the mass and energy transfer device, whereby water is transferred from the exhaust stream to the oxidant stream so as to produce an at least partially saturated oxidant stream. A method is also disclosed.

Abstract: A fuel cell power plant 10 having a fuel cell assembly 20 that may be operable at a high hydrogen utilization. The fuel cell assembly is provided with an inlet fuel stream 207, an inlet oxidant stream 210, and an inlet coolant stream 208, and further has an exhaust oxidant 75 stream and an exhaust coolant stream 205. A housing chamber 110 accepts the exhaust coolant stream and exposes it to a first gaseous stream. A mass and heat recovery device 95 accepts the first gaseous stream after the first gaseous stream is exposed to the exhaust coolant stream, and it promotes a transfer of thermal energy and moisture from the first gaseous stream to a second gaseous stream. The first gaseous stream includes the exhaust oxidant stream.

Abstract: A procedure for starting up a fuel cell system that is disconnected from its primary load and that has air in both its cathode and anode flow fields includes a) connecting an auxiliary resistive load across the cell to reduce the cell voltage; b) initiating a recirculation of the anode flow field exhaust through a recycle loop and providing a limited flow of hydrogen fuel into that recirculating exhaust; c) catalytically reacting the added fuel with oxygen present in the recirculating gases until substantially no oxygen remains within the recycle loop; disconnecting the auxiliary load; and then d) providing normal operating flow rates of fuel and air into respective anode and cathode flow fields and connecting the primary load across the cell. The catalytic reaction may take place on the anode or within a catalytic burner disposed within the recycle loop.