Abstract: A fuel cell 12 has a liquid electrolyte 20, a cathode electrode 28, and an anode electrode 26. The fuel cell includes an electrolyte condensation zone 58 extending from an edge 56 of a first catalyst layer 36 on the cathode electrode to an outer edge 48 of an edge seals 52 and 49. An anode electrode has an anode catalyst layer 30 with an end substantially coinciding with an inner edge 53 of the edge seals. The acid condensation zone is located near the reactant exit, so that electrolyte that has evaporated into the reactant stream can condense out before leaving the fuel cell for re-absorption back into the fuel cell.

Abstract: An example fuel cell assembly includes a separator plate. Non-porous and hydrophobic flow field layers are associated with the separator plate. An electrolyte retaining matrix comprises silicon carbide powder and has a mean particle size of about 3 microns and a thickness of about 0.05 mm Hydrophilic substrates are associated with catalyst layers. The hydrophilic substrates are about 70% porous and have a void volume that is about 40% filled with transferable phosphoric acid in an initial condition. A condensation zone cools a vapor passing from the assembly to less than about 140° C.

Abstract: A liquid electrolyte fuel cell stack (13) includes a plurality of fuel cells (19) disposed in groups between a plurality of cooler plates (18-20), the cooler plates being connected by tubing (29) to a vertical coolant outlet manifold (27). The coolant outlet manifold has a coolant cross sectional flow area which increases from near the bottom to near the top, either by virtue of an increasing internal dimension (34-38) of the manifold or by virtue of an insert (41) which is larger at the bottom than at the top. The insert may be either a linear or rotund trianguloid, cone, conoid, pyramid or pyramoid. The internal dimension of the coolant outlet manifold or the dimension of the insert may be stepped or continuous, linear or non-linear.

Abstract: A fuel cell assembly (20) has a plurality of characteristics that extend the useful life of the assembly. In one example, flow field layers are non-porous and hydrophobic such that they have an acid absorption rate of less than about 0.10 mg/khr-cm2. An electrolyte retaining matrix has a reaction rate with phosphoric acid of less than about 0.010 mg/khr-cm2. Hydrophilic substrates associated with catalyst layers have an initial transferable phosphoric acid content of less than about 25 mg/cm2. A condensation zone provides an evaporative phosphoric acid loss rate that is less than about 0.17 mg/khr-cm2.

Abstract: An example fuel cell assembly includes a separator plate. Non-porous and hydrophobic flow field layers are associated with the separator plate. An electrolyte retaining matrix comprises silicon carbide powder and has a mean particle size of about 3 microns and a thickness of about 0.05 mm Hydrophilic substrates are associated with catalyst layers. The hydrophilic substrates are about 70% porous and have a void volume that is about 40% filled with transferable phosphoric acid in an initial condition. A condensation zone cools a vapor passing from the assembly to less than about 140° C.

Abstract: A fuel cell assembly (20) has a plurality of characteristics that extend the useful life of the assembly. In one example, flow field layers are non-porous and hydrophobic such that they have an acid absorption rate of less than about 0.10 mg/khr-cm2. An electrolyte retaining matrix has a reaction rate with phosphoric acid of less than about 0.010 mg/khr-cm2. Hydrophilic substrates associated with catalyst layers have an initial transferable phosphoric acid content of less than about 25 mg/cm2. A condensation zone provides an evaporative phosphoric acid loss rate that is less than about 0.17 mg/khr-cm2.

Abstract: A fuel cell system having a fuel cell stack (9) employing a phosphoric acid or other electrolyte, includes a non-reactive zone (11) in each of a group of fuel cells between corresponding coolant plates (55), the coolant entering the coolant plates in an area adjacent to the non-reactive zones (29–31). Each fuel cell has three-pass fuel flow fields, the first pass substantially adjacent to a third zone (13), remote from the first zone, the second pass substantially adjacent to a second zone contiguous with the first zone, the coolant flowing (33, 34) from a coolant inlet (29) through the first zone, to the far side of the second zone, and (37–41) from the near side of the second zone to the third zone and thence (45–50) to a coolant exit manifold (30), which assures temperatures above 150° C. (300° F.), to mitigate CO poisoning of the anode within the reactive zones, and assuring temperatures below 140° C. (280° F.

Abstract: A fuel cell system having a fuel cell stack (9) employs a group of fuel cells between corresponding cooler plates (55). The system utilizes single phase coolant, the outflow of the coolant plates (55) being divided into a flow (78) just sufficient to provide adequate steam (68, 79) to a fuel reformer (58), the remainder of the coolant outlet flowing (76) directly to heat recovery and utilization apparatus (77), which may include fuel cell power plant accessories (85), such as chillers or boilers.

Abstract: 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.

Abstract: The present invention discloses a corrosion resistant fuel cell in which an ion impermeable protective layer is positioned over at least a portion of the noncatalyzed carbon based components. This layer prevents reactant ions or molecules form reaching localized high potential areas of these components and corroding the carbon material.

Abstract: Ammonia which is found in fuel cell fuel gases is removed therefrom by passing the fuel gas stream through a scrubber bed of porous carbon pellets containing phosphoric acid. The ammonia reacts with the phosphoric acid in the scrubber bed to form ammonium phosphate compounds which remain in the scrubber bed. The ammonia content of the fuel gas stream is thus lowered to a concentration of about one ppm or less. By maintaining the temperature of the fuel gas stream passing through the scrubber bed in a range of about 400.degree. F. to about 450.degree. F. sufficient phosphoric acid will also be evaporated from the scrubber bed to replace acid electrolyte lost during operation of the power plant. Adjustments in the temperature of the fuel gas flowing through the scrubber may be made in order to match electrolyte losses which occur during different operating phases of the power plant.

Abstract: The cell stack assembly of a fuel cell power plant is provided with a cooling system which provides optimum cell operating temperatures across each cell in the stack and also produces an optimum amount of steam. The cooling system includes at least one bypass through which a fraction of the coolant is fed from the coolant inlet side of the stack to the coolant outlet side of the stack. The bypass ensures that a fraction of the coolant is not heated to its target operating temperatures as it passes through the stack. This results in a more uniform cell operating temperature profile from the coolant inlet to the coolant outlet side of each cell; and also results in a lessening of excess steam production in the power plant.