Abstract: Water flow field inlet manifolds (33, 37) are disposed at the fuel cell stack (11) base. Water flow field outlet manifolds (34, 38) are located at the fuel cell stack top. Outlet and inlet manifolds are interconnected (41-43, 47, 49, 50) so gas bubbles leaking through the porous water transport plate cause flow by natural convection, with no mechanical water pump. Variation in water level within a standpipe (58) controls (56, 60, 62, 63) the temperature or flow of coolant. In another embodiment, the water is not circulated, but gas and excess water are vented from the water outlet manifolds. Water channels (70) may be vertical. A hydrophobic region (80) provides gas leakage to ensure bubble pumping of water. An external heat exchanger (77) maximizes water density differential for convective flow.

Abstract: Water flow field inlet manifolds (33, 37) are disposed at the fuel cell stack (11) base. Water flow field outlet manifolds (34, 38) are located at the fuel cell stack top. Outlet and inlet manifolds are interconnected (41-43, 47, 49, 50) so gas bubbles leaking through the porous water transport plate cause flow by natural convection, with no mechanical water pump. Variation in water level within a standpipe (58) controls (56, 60, 62, 63) the temperature or flow of coolant. In another embodiment, the water is not circulated, but gas and excess water are vented from the water outlet manifolds. Water channels (70) may be vertical. A hydrophobic region (80) provides gas leakage to ensure bubble pumping of water. An external heat exchanger (77) maximizes water density differential for convective flow.

Abstract: The invention is a bi-zone water transport plate for a fuel cell wherein the plate includes a water permeability zone and a bubble barrier zone. The bubble barrier zone extends between all reactive perimeters of the plate, has a pore size of less than 20 microns, and has a thickness of less than 25 percent of a shortest distance between opposed contact surfaces of the plate. The water permeability zone has a pore size of at least 100 percent greater than the pore size of the bubble barrier zone, and has a thickness of greater than 75 percent of the shortest distance between the opposed contact surfaces of the plate. By having a separate bubble barrier zone, the plate affords enhanced water permeability while the bubble barrier maintains a gas seal.

Abstract: The invention is a bi-zone water transport plate for a fuel cell wherein the plate includes a water permeability zone and a bubble barrier zone. The bubble barrier zone extends between all reactive perimeters of the plate, has a pore size of less than 20 microns, and has a thickness of less than 25 percent of a shortest distance between opposed contact surfaces of the plate. The water permeability zone has a pore size of at least 100 percent greater than the pore size of the bubble barrier zone, and has a thickness of greater than 75 percent of the shortest distance between the opposed contact surfaces of the plate. By having a separate bubble barrier zone, the plate affords enhanced water permeability while the bubble barrier maintains a gas seal.