摘要:
In one example, a fuel cell utilizes a non-carbonized, non-graphitized porous polymer water transport plate having a water permeability of less than 30×10−17 m2. The water transport plate is part of a fuel cell that employs an evaporative cooling loop. In one example, the water transport plate has a bubble pressure of less than 5 psig. The water transport plate is less costly and easier to manufacture.
摘要:
The air blower (18) of a fuel cell power plant (9) is used to force water out of the coolant flow fields (27) of a fuel cell stack (10), a coolant pump (35) and a heat exchanger (40) through a valve (46) which is closed during normal operation. The water removal occurs as part of a shutdown procedure in which the fuel cell stack continues to operate so that it provides the power for the air pump and to assist in water removal (such as retaining low vapor pressure). The water flow to an accumulator (33) is blocked by a valve (29) during the shutdown procedure.
摘要:
A vehicle (150) includes a fuel cell stack (151) started when the stack is below freezing, by connection (158) to the vehicle propulsion system (159) within a few seconds of starting the flow of fuel (179) and oxidant (173), or when open circuit voltage (155, 156) is detected. The fuel is in excess of stochiometry requirement and the oxidant is in excess of at least twice stochiometric requirement, either may be at about atmospheric pressure or at 4 kPa (0.6 psi) or more above the pressure of any water in said water passages, and either may be below freezing. Water transport plates (84, 86, 88, 89) have water passages connected to a water circulation loop (170) including a reservoir (164) having an auxiliary heater (161) connected (160) to the stack. Warming of cell stack materials and ice in the water transport plates, heat of fusion of melting ice, warming of melted water, and evaporative cooling of water melted in the water transport plates keep the fuel cell cool until liquid coolant can be circulated.
摘要:
An exemplary method of treating a material such as carbon or graphite to render at least some surfaces of the material hydrophilic includes coating at least a portion of the at least some surfaces with an oxygenated element and controlling a rate of a breakdown of the oxygenated element to leave a corresponding elemental oxide on the surfaces. In one example, the material is treated before being incorporated into an article comprising the material. Another example method includes treating an article comprising the material. Disclosed examples include precipitation or decomposition as the breakdown of the oxygenated element.
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:
The air blower (18) of a fuel cell power plant (9) is used to force water out of the coolant flow fields (27) of a fuel cell stack (10), a coolant pump (35) and a heat exchanger (40) through a valve (46) which is closed during normal operation. The water removal occurs as part of a shutdown procedure in which the fuel cell stack continues to operate so that it provides the power for the air pump and to assist in water removal (such as retaining low vapor pressure). The water flow to an accumulator (33) is blocked by a valve (29) during the shutdown procedure.
摘要:
A plurality of fuel cell stacks (8, 8a, 9, 9a) have their cathode ends (11, 12) contiguous with either a common current collector (15a–15d) or respective current collectors (15a, 15b) which may be separated by electrical isolation (27a, 27b). The cathode-to-cathode relationship protects the cathode of each of the stacks from cold ambient environments, thereby permitting improved cold starts and mitigation of performance loss as a result of cold starts as well as freeze/thaw cycles. Heaters (30, 30a–30d) may be provided in current collectors, or in or between electrical isolation. Four stacks may share one current collector, or each may have its own current collector.
摘要:
A plurality of fuel cell stacks (8, 8a, 9, 9a) have their cathode ends (11, 12) contiguous with either a common current collector (15a-15d) or respective current collectors (15a, 15b) which may be separated by electrical isolation (27a, 27b). The cathode-to-cathode relationship protects the cathode of each of the stacks from cold ambient environments, thereby permitting improved cold starts and mitigation of performance loss as a result of cold starts as well as freeze/thaw cycles. Heaters (30, 30a-30d) may be provided in current collectors, or in or between electrical isolation. Four stacks may share one current collector, or each may have its own current collector.
摘要:
A fuel cell includes a membrane electrode assembly comprised of a membrane sandwiched between anode and cathode catalyst structures. An anode separator plate and a cathode separator plate are arranged adjacent to the membrane electrode assembly opposite from one another. The anode and cathode separator plates include opposing sides in which one of the opposing sides of the anode and cathode respectively have fuel and oxidant flow fields in communication with the membrane. The anode separator plate is a structure having a first water permeability and is configured to permit passage of water between its opposing sides and with its flow field, and the cathode separator plate comprises a structure having a second water permeability less than the first water permeability of the anode separator plate. In one example, the anode is provided by a porous separator plate, and the cathode is provided by a non-porous, or solid, plate.
摘要:
An exemplary method of treating a material such as carbon or graphite to render at least some surfaces of the material hydrophilic includes coating at least a portion of the at least some surfaces with an oxygenated element and controlling a rate of a breakdown of the oxygenated element to leave a corresponding elemental oxide on the surfaces. In one example, the material is treated before being incorporated into an article comprising the material. Another example method includes treating an article comprising the material. Disclosed examples include precipitation or decomposition as the breakdown of the oxygenated element.