摘要:
Methods and apparatus for improving water management in a PEM fuel cell power supply are disclosed. The fuel cell power supply includes a combustion unit that combusts anode exhaust, producing combusted exhaust that includes water. The combusted exhaust is recycled to the anode input and/or the cathode input. The recycling system can include additional devices, for example, a CO removal device for removing CO from the combusted exhaust prior to recycling to the anode. A fuel processor can be thermally coupled to the combustion unit that combusts the anode exhaust. One advantage of the invention is that the condenser typically employed for recovering water from combusted exhaust can be eliminated, of reduced capacity or operated less frequently, thereby reducing the cost and/or the complexity of the fuel cell power supply.
摘要:
A fuel cell includes a membrane electrode assembly (46) having a first reactant flow field (80) secured adjacent a first or second surface (48, 50) of the assembly (46) for directing flow of a first reactant adjacent the first or second surface of the assembly (46). The first reactant flow field (80) defines a plurality of two-pass circuits (82, 84, 86, 88), and each two-pass circuit (82) is in fluid communication with both a first reactant inlet (90) for directing the first reactant into the fuel cell (12), and with a first reactant outlet (92) for directing the first reactant out of the fuel cell (12). The plurality of two-pass circuits (82) facilitate water movement (112) toward the reactant inlet (90) to aid in passive maintenance of fuel cell (12) water balance.
摘要:
A fuel cell includes a plurality of power-producing electrode-electrolyte assemblies and heat-conducting elements. Cathode air supplied to the fuel cell is heated inside the fuel cell by fuel cell by-product heat via the heat-conducting elements.
摘要:
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. The procedure allows start-up of the fuel cell system without the use of an inert gas purge while minimizing dissolution of the catalyst and corrosion of the catalyst support during the start-up process.
摘要:
A PEM flow field system of coolant medium for preventing the formation and accumulation of gas bubbles, having a critical viscous pressure drop therein is provided. The water transport plate includes a coolant flow field channel therein having an input port and an exit port. The coolant flow field channel includes at least one upward flow channel portion, at least one downward flow channel portion. Coolant medium is fluidly routed through the coolant flow field channel of the water transport plate at a flow rate which results in a viscous pressure drop that is greater than the buoyancy of a gas bubble trapped within the coolant flow field channel to prevent the accumulation thereof within the coolant flow field channel.
摘要:
A PEM fuel cell system includes a PEM fuel cell that has an input and output port each for fuel or reformate, process air and coolant. A predetermined fraction of volume of moistened exhaust air leaving the air output port of the fuel cell is diverted back and combined with fresh, air at ambient temperature entering the air input port of the PEM fuel cell to maintain water balance in the fuel cell at high ambient operating temperatures. The recycle-to-air vent ratio is controlled by a processor which adjusts the recycle flow based on the ambient temperature and the power level of the fuel cell.
摘要:
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. The procedure allows start-up of the fuel cell system without the use of an inert gas purge while minimizing dissolution of the catalyst and corrosion of the catalyst support during the start-up process.
摘要:
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.
摘要:
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.
摘要:
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).