摘要:
A cell stack assembly (102) coolant system comprises a coolant exhaust conduit (110) in fluid communication with a coolant exhaust manifold (108) and a coolant pump (112). A coolant inlet conduit (120) enables transportation of the coolant to the coolant inlet manifold. The coolant system further includes a bypass conduit (132) in fluid communication with the coolant exhaust manifold and the coolant inlet manifold, while a bleed valve (130) is in fluid communication with the coolant exhaust conduit and a source of gas. Operation of the bleed valve enables venting of the coolant from the coolant channels, and through a shut down conduit (124). An increased pressure differential between the coolant and reactant gases forces water out of the pores in the electrode substrates (107,109). An ejector (250) prevents air form inhibiting the pump. Pulsed air is blown (238,239,243,245) through the coolant channels to remove more water.
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 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 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).
摘要:
A procedure for shutting down an operating fuel cell system includes disconnecting the primary electricity using device and stopping the flow of hydrogen containing fuel to the anode, followed by quickly displacing the residual hydrogen with air by blowing air through the anode fuel flow field. A sufficiently fast purging of the anode flow field with air eliminates the need for purging with an inert gas such as nitrogen.
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:
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.
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.