Water Removal
"In a conventional fuel cell that uses a polymer electrolyte membrane, a fuel chamber and an oxygen chamber sandwich the electrolyte membrane from opposite sides. A fuel gas in the fuel chamber is ionized through a fuel electrode, or an oxidizing gas (mainly oxygen in air) in the oxygen chamber is ionized through an oxygen electrode, and the ions are drawn through the electrolyte membrane to obtain electric power."
"After electric power is obtained, the oxidizing gas is discharged from the oxygen chamber to an exhaust chamber. Also, when the oxidizing gas flows into the oxygen chamber, coolant water is injected into the oxygen chamber from a water tank. Because the coolant water is injected into the oxygen chamber in this manner, the injected water arrives in the exhaust chamber through the oxygen chamber. The coolant water also functions to maintain the electrolyte membrane in a moist state. To maintain all of the electrolyte membranes that make up a fuel cell stack in a moist state, the oxygen and the water must be supplied uniformly to each of the stacked electrolyte membranes."
"However, when the coolant water that is supplied to the oxygen chamber drops from an air flow passage, a water droplet forms at an opening, then falls after growing to a size that can drip. There is concern that a water droplet that accumulates at the opening might obstruct air flow in the air flow passage 95, thereby reducing the cooling action."
Recent US Patents
11/2/2010
7,824,818
Fuel cell stack with water removal projections at air outlets
Kenichi, Toshihiko and Mogi of Kabushiki Kaisha Equos Research, Japan, have developed a “fuel cell stack that is made by stacking unit cells in alternation with separators, lower edges of collector members that are in contact with oxygen electrodes of the unit cells project downward, providing projecting portions that project below lower edges of frames. Water-repellent regions are provided on lower edges of the projecting portions, facilitating shedding of water from the projecting portions.” (RDC 3/2/2011)