A flow field plate for use in a fuel cell includes a porous, wettable plate body including a first reactant gas channel having an inlet portion, a second reactant gas channel having an outlet portion that is adjacent the inlet portion of the first reactant gas channel, and at least one moisture reservoir fluidly connected with pores of the porous, wettable plate body. The at least one moisture reservoir can selectively collect and release moisture received from a reactant gas in the outlet portion to thereby selectively move the moisture from the outlet portion toward the adjacent inlet portion.
A device for use in a fuel cell includes a bipolar plate having a reactant side that includes a reactant flow field with a plurality of ribs that are spaced apart to define a plurality of reactant channels extending between the plurality of ribs. The plurality of reactant channels open to the reactant side of the bipolar plate. At least one of the plurality of ribs includes a water channel that also opens to the reactant side of the bipolar plate.
A device for use in a fuel cell includes a bipolar plate having flow field channels, a manifold fluidly connected with the flow field channels for conveying a reactant gas, and a sump fluidly connected with the manifold.
An inductor (27) is connected by switches (30-33) across the DC link output (21, 22) of a fuel cell system (18) in alternatively-reversed fashion at a frequency which is high compared to ripple current on the DC link which is typically twice the fundamental frequency (e.g., 50 Hz or 60 Hz) of a DC/ AC inverter and power conditioner (13). This substantially eliminates ripple in the fuel cell output current without the use of a large bank of low frequency filter capacitors (20). The DC/AC inverter may have a small, high frequency filter capacitor (40) across its input.
The electrical output connections (155, 158) of a fuel cell stack (151 ) are short circuited (200; 211, 212) during start up from freezing temperatures. Before the stack is short circuited, fuel is provided in excess of stoichiometric amount for a limiting stack current, and oxidant is provided to assure stoichiometric amount for the limiting stack current.
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) or 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).
Fuel cell stack assemblies (15, 16) connected in parallel through related power control portions (39, 40; 60, 61 ) of a system power converter (41 ) supply power to a common grid (22) or non-grid load (58) on an equal or near-equal current basis. Power command to one portion is one-half the total power (P*) minus a function (46) of the difference (45) in current from the stack assemblies. The other portion power command (P1*) for a utility grid (22) is the difference between the total power and the power command (P2*) to the first stack assembly. For a non-grid load, one portion (61 ) controls the load voltage, the other portion command (P2*) causes substantially equal currents. Altering (33b) actual current signals results in the cell stack assemblies providing different currents. A failed stack assembly is disconnected from the load and reactant; the non-failed assembly having an appropriate power command.
An ammonia contact scrubber system (10) for removing ammonia from a fuel stream for a fuel cell (16) includes a contact scrubber (12) having a scrubber fuel inlet (14) and a scrubber fuel exhaust (20) for directing flow of the fuel stream through support material (24) within the scrubber (12) and into the fuel cell (16). An acid circulating loop (26) has an acid holding tank (28) holding a liquid acid solution (30), an acid feed line (32) secured in fluid communication between the holding tank (28) and a scrubber acid inlet (36) of the contact scrubber (12), an acid return (38) for returning the acid solution from the scrubber (12) to the acid holding tank (28), and an acid circulation pump (42) for pumping the acid solution (30) through the acid circulating loop (26) and through the support material (24) within the scrubber (12).
H01M 8/04 - Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
B01D 53/14 - Separation of gases or vapoursRecovering vapours of volatile solvents from gasesChemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases or aerosols by absorption
A device for managing fluid flow within a fuel cell assembly (24) includes a water transport plate (42) having a plurality of channels (44) and a rib (48) on each side of each channel (44). At least some of the ribs (48) have a hydrophobic layer (46) near an end of the ribs (48). The hydrophobic layer (46) in a disclosed example is adjacent a gas diffusion layer (38) associated with a cathode catalyst layer (34). One example use of the example hydrophobic layer (46) is to prevent water movement into pores of the cathode catalyst layer during cold temperature conditions.
A polymer electrolyte membrane (PEM) fuel ceil power plant is cooled evaporatively with a water coolant system which does not permit liquid water to exit or flow through the coolant system. The coolant system utilizes a hydrophobic porous member (28) for venting gases such as fuel and/or air from a coolant water flow field in the system. Coolant water (36) is prevented from continuosly contacting the porous member during operation of the power plant thus preventing blockage of the porous member by coolant water or contaminants disposed in the coolant water.
A polymer electrolyte membrane (PEM) fuel cell power plant is cooled evaporatively by a pressurized water coolant system. The coolant system utilizes a hydrophobic porous member (29) for venting gases such as fuel and/or air from a coolant water flow field in the system. Coolant water is prevented from clogging the porous member by vibrating (34) the member, either intermittently or continuously, during operation of the power plant .
A method for operating a fuel cell having a membrane electrode assembly including an anode, a cathode, and a membrane between the anode and the cathode, the method including the steps of : feeding fuel to the anode at a fuel pressure; feeding oxidant to the cathode at an oxidant pressure, wherein the feeding steps create a transition plane between the fuel and the oxidant; and selectively maintaining the fuel pressure higher than the oxidant pressure sufficient to position the transition plane in the cathode or within 5% thickness of the membrane of the cathode. A protective layer can be included in the assembly, and the pressure can be manipulated to position a transition jplane (Xo) within the protective layer.
A regenerable ammonia scrubber system (10) for removing ammonia from a fuel stream for a fuel cell (18) includes a first regenerable scrubber (12) and a second regenerable scrubber (22). Each scrubber (12, 22) is secured in fluid communication with a fuel distribution valve (28) configured to selectively direct the fuel stream to one of the first scrubber (12) or the second scrubber (22), and is also secured in fluid communication with an oxidant distribution valve (38) configured to selectively direct flow of the oxidant to the other of the first or the second scrubbers (12, 22). The first and second regenerable scrubbers (12, 22) contain an acid solution (60), a porous support material (62) within the acid solution (60), and a noble metal catalyst uniformly dispersed through the porous support material (62). The noble metal catalyst is preferably platinum.
A method of making an electrochemical cell electrode substrate includes creating an aqueous or dry mixture of chopped carbon fibers, chopped cross-linkable resin fibers that are still fuseable after being formed into a felt, such as novolac, a temporary binder, such as polyvinyl alcohol fiber or powder, and a resin curing agent, such as hexamethylene tetramine; forming a non-woven felt from either an aqueous suspension of the aqueous mixture or an air suspension of the dry mixture, by a non-woven, wet-lay or dry-lay, respectively, felt forming process; pressing one or more layers of the formed felt for 1-5 minutes to a controlled thickness and a controlled porosity at a temperature at which the resin melts, cross-links and then cures, such as 1500C - 2000C; and heat treating the pressed felt in a substantially inert atmosphere, first to 75O0C - 10000C and then to 1000°C - 3000°C.
D04H 1/12 - Felts made from mixtures of fibres and incorporating man-made organic fibres
D04H 1/14 - Felts made from mixtures of fibres and incorporating inorganic fibres
D04H 1/54 - Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
D04H 1/72 - Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
D04H 1/74 - Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being orientated, e.g. in parallel
15.
HYDROGEN SENSOR CELL FOR DETECTING FUEL STARVATION
A fuel cell stack includes at least one fuel cell having a fuel inlet for directing a hydrogen fuel to the fuel cell to generate electric current; a sensor cell having an anode flow field, a cathode flow field and an unitized electrode assembly between the anode flow field and the cathode flow field, the anode flow field being communicated with the fuel inlet to receive a portion of fuel from the fuel inlet, the sensor cell being connected in series with the stack to carry the electric current whereby hydrogen from the portion of fuel is evolved into the cathode flow field of the sensor cell; and a sensor communicated with the sensor cell to receive a signal corresponding to content of hydrogen in the sensor cell.
A reformer system (11) having a hydrodesulfurizer (12) provides desulfurized natural gas feedstock to a catalytic steam reformer (16), the outflow of which is treated by a water gas shift reactor (20) and optionally a preferential CO oxidizer (58) to provide reformate gas (28, 28a) having high hydrogen and moderate carbon dioxide content. To avoid damage to the hydrodesulfurizer from overheating, any olefins in the non-desulfurized natural gas feedstock (35) are reacted (38) with hydrogen (28, 28a; 71) to convert them to alkanes (e.g., ethylene and propylene to ethane and propane) in a hydrogenator (38) cooled (46), below a temperature which would damage the hydrogenator, by evaporative cooling with pressurized hot water (42). Hydrogen for the desulfurizer and the olefin reaction may be provided as recycle reformate (28, 28a) or from a mini-CPO (67), or from other sources.
A fuel cell (10) includes a PEM electrolyte (12) secured between a first catalyst (14) and a second catalyst (16) , and a sealed coolant plate (30) , At least one antifreeze saturator (42, 46) is secured in fluid communication with one of a first or a second reactant stream. The saturator (42, 46) contains a high molecular weight direct antifreeze solution and directs the reactant stream to pass through the liquid antifreeze and back into a reactant inlet (18, 24) of the fuel cell (10) . The high molecular weight direct antifreeze solution preferably includes as an antifreeze component a polyethylene glycol having a molecular weight ranging from 200 to 8,000 AMU. An preferred high molecular weight direct antifreeze is polyethylene glycol having a molecular weight of about 400. The antifreeze solution resists freezing and humidifies the reactant stream with only water.
H01M 8/12 - Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
18.
FUEL CELL SYSTEM WITH A POROUS HYDROPHOBIC PLUG FOR MAINTAINING SYSTEM BACK PRESSURE AND METHODS FOR DESIGNING THE PLUG AND FOR DESIGNING SYSTEMS FOR USING THE PLUG
A polymer electrolyte membrane (PEM) fuel cell (4) power plant is cooled evaporatively by a non-circulating pressurized water coolant system (2). The coolant system utilizes a hydrophobic porous plug (28) for bleeding air from the coolant water while maintaining coolant back pressure in a coolant flow field (12) 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.
Contaminants are removed from one or both electrodes of proton exchange membrane fuel cells (23, 25) in a stack (17), periodically, after the fuel cell stack is shut down, by flowing an ozone containing gas (12, 13) through the oxidant reactant gas flow fields (35, 23, 25, 38) of the fuel cells and/or by flowing a mixture of nitrogen (12) and ozone (13) through the fuel reactant gas flow fields (21, 23, 24, 25, 28) of the fuel cells. Shorting (55) the electrodes allows cleansing both electrodes at once.
An electrolysis stack (53) with oxygen-depolarized cathodes (31) employs solid-plate anodes (38) and porous-plate cathodes (42). The stack (53) of electrolysis cells (29) (e.g, hydrogen-chloride or chlor-allkali cells) each include an ion exchange membrane (32) sandwiched between an anode conductor (34) and a permeable cathode (35); an oxygen-consuming gas diffusion cathode (31) is adjacent the cathode conductor of each cell. Between the anode conductor of one cell and the gas diffusion cathode of an adjacent cell there is a composite bipolar plate (51) including a solid plate (38) having channels (39) for conducing salt solution and product of the process; the bipolar plates also include a porous plate (42) having channels (43) for conducting oxidant adjacent the gas diffusion cathode and channels (49) connected to a source of liquid (such as water or dilute sodium hydroxide).
C25B 1/46 - Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis in diaphragm cells
C25B 1/34 - Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
21.
EVAPORATIVE COOLING OF FUEL CELLS EMPLOYING ANTIFREEZE SOLUTION
A fuel cell power plant (19) has a stack of fuel cells (20) cooled by a mixture of water with a non-volatile, miscible fluid that sufficiently depresses the freezing point, such as polyethylene glycol (PEG). The water and fluid are mixed in a reservoir (21), a small pump (22, 60) flows the mixture through coolant channels (28) in or adjacent water transport plates (29); heat of the catalytic reaction warms the water transport plates causing water to evaporate therefrom thereby cooling the stack. The PEG is non-volatile at stack operating temperature and does not evaporate; concentrated PEG is returned (33) to the reservoir (21). Water in the process air flow channels (41), including evaporated process water, is recovered in a condensation-rate-controlled (53, 54)) condenser (46) in communication (48) with the reservoir (21) for remixture with the concentrated PEG solution. Hydrophobic gas diffusion layers (72) shield the proton exchange membrane (70) from the PEG.
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