摘要:
The invention is a hydrogen passivation shut down system for a fuel cell power plant (10, 200). During shut down of the plant (10, 200), hydrogen fuel is permitted to transfer between an anode flow path (24, 24′) and a cathode flow path (38, 38′). A controlled-oxidant flow device (209) near an oxygen source (58′) permits a minimal amount of atmospheric oxygen to enter the power plant (200) during shut down to equalize pressure between ambient atmosphere and the flow paths (24′, 28′) and to keep limited atmospheric oxygen entering the power plant (200) through the device (209) as far as possible from fuel cell flow fields (28′, 42′). A non-leaking hydrogen inlet valve (202), a non-leaking cathode exhaust valve (208), and a combined oxidant and fuel exhaust line (206) also minimize penetration of oxygen into the shut down power plant (200).
摘要:
A fuel cell includes an electrode assembly having an electrolyte between a cathode catalyst and an anode catalyst, and a flow field plate having a channel for delivering a reactant gas to the electrode assembly. The flow field plate includes a channel having a channel inlet. A porous diffusion layer is located between the electrode assembly and the flow field plate. The porous diffusion layer includes a first region near the channel inlet and a second region downstream from the first region relative to the channel inlet. The first region includes a filler material that partially blocks pores of the first region such that the first region has a first porosity and the second region has a second porosity that is greater than the first porosity.
摘要:
A fuel cell power plant (5) includes a stack (6) of fuel cells, each of which have an anode (9), a cathode (10), and a PEM (11) disposed between the anode and the cathode. A controller (17) recognizes an indication (67) of no load demand (68) by a load (59), to operate (45) an air recycle loop (44-46) utilizing the process air blower (35) and transfer the power output (57) of the stack from the load (59) to an auxiliary load (60), comprising a resistance which will consume a predetermined small amount of power in response to the current applied thereto, when the stack operates at a critical voltage above which fuel cell corrosion is unacceptable. Fuel and air will also be reduced (16, 40). The controller may cause increased cathode recycle when the critical voltage is reached and increased air when the voltage is a fraction of a volt below the critical voltage.
摘要:
A polymer electrolyte membrane (PEM) fuel cell power plant is cooled evaporatively by a non-circulating pressurized water coolant system. The coolant system utilizes a hydrophobic porous plug for bleeding air from the coolant water while maintaining coolant back pressure in a coolant flow field of the system. Furthermore, there is a first method for identifying appropriate parameters of the hydrophobic porous plug for use with a known particular coolant system; and a second method for determining proper operating conditions for a fuel cell water coolant system which can operate with a hydrophobic porous plug closure having known physical parameters.
摘要:
A fuel cell stack (31) includes a plurality of fuel cells (9) each having an electrolyte such as a PEM (10), anode and cathode catalyst layers (13, 14), anode and cathode gas diffusion layers (16, 17), and water transport plates (21, 28) adjacent the gas diffusion layers. The cathode diffusion layer of cells near the cathode end (36) of the stack have a high water permeability, such as greater than 3×10−4 g/(Pa s m) at about 80° C. and about 1 atmosphere, whereas the cathode gas diffusion layer in cells near the anode end (35) have water vapor permeance greater than 3×10−4 g/(Pa s m) at about 80° C. and about 1 atmosphere. In one embodiment, the anode gas diffusion layer of cells near the anode end (35) of the stack have a higher liquid water permeability than the anode gas diffusion layer in cells near the cathode end; a second embodiment reverses that relationship.
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:
The direction of flow of purged fuel reactant gas (20) is sensed (38, 39, 44, 53, 54) to ensure it flows outwardly from a fuel cell stack (9) towards the ambient (21). If the purged fuel reactant. gas is not flowing outwardly, a signal (39) causes a controller (26) to open the circuit (35) thereby disconnecting the electrical load (33) from the fuel cell stack.
摘要:
Recycle fuel gas is provided (36) to an impeller (34, 34a) for application to the input (24) of the anode flow fields of a fuel cell stack (25). The impeller may be an ejector (34) having its primary input (33) connected to a source (11) of hydrogen and its secondary input (35) connected to the outlet (27, 37) of the fuel cells anode flow fields. The ejector outlet provides the minimum fuel flow required at the lowest power rating. The impeller may be an electrochemical hydrogen pump (34a) with a constant current generator (50) providing for a substantially constant recycle flow (the highest not more than double the lowest), and one pressure regulator (20) providing minimum flow of fresh fuel to the fuel inlets of the first stack. Pressure regulators (20, 21) control the amount of fresh fuel to the anode flow fields for power in excess of minimum power.
摘要:
A membrane electrode assembly includes an anode; a cathode; a membrane disposed between the anode and the cathode; and a protective layer positioned between the membrane and the cathode, the protective layer having a first side and a second side and being adapted to restrict migration of oxygen at the first side and to restrict the migration of hydrogen at the second side and thereby maintain a plane of potential change between the anode and the cathode within the protective layer.
摘要:
Fuel cells (38) have water passageways (67; 78, 85; 78a, 85a) that provide water through reactant gas flow field plates (74, 81) to cool the fuel cell. The water passageways may be vented to atmosphere (99), by a porous plug (69), or pumped (89, 146) with or without removing any water from the passageways. A condenser (59, 124) receives reactant air exhaust, may have a contiguous reservoir (64, 128), may be vertical, (a vehicle radiator, FIG. 2), may be horizontal, contiguous with the top of the fuel cell stack (37, FIG. 5), or below (124) the fuel cell stack (120). The passageways may be grooves (76, 77; 83, 84) or may comprise a plane of porous hydrophilic material (78a, 85a) contiguous with substantially the entire surface of one or both of the reactant gas flow field plates. Air flow in the condenser may be controlled by shutters (155). The condenser may be a heat exchanger (59a) having freeze-proof liquid flowing through a coil (161) thereof, the amount being controlled by a valve (166). A deionizer (175) may be used.