Method of using a water transport plate

Abstract

A water transport plate is provided with optimized physical characteristics to greatly improve fuel cell operation. In a preferred method of manufacturing, graphite powder, reinforcing fibers, cellulosic fibers, and a thermosetting resin are mixed with a liquid to form a slurry and showered onto a screen to form a planar sheet which is dried to form paper. The paper is cut into the desired size and is laid-up. The lay-up is laminated with pressure and heat, carbonized, and graphitized to form a water transport plate for later machining as desired. The finished water transport plate exhibits optimal physical characteristics for bubble pressure, water permeability, median pore size, porosity, thru-plane resistivity and compressive yield strength.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to water transport plates. More specifically, the present invention relates to water transport plates and a method of use thereof.[0002]Solid polymer electrolyte fuel cell power plants are known in the prior art, and prototypes are even available from commercial sources, such as Ballard Power Systems, Inc. of Vancouver, Canada. These systems are serviceable, but are relatively complex. An example of a Ballard Power Systems polymer membrane power plant is shown in U.S. Pat. No. 5,360,679, granted Nov. 1, 1994. One problem occurring in solid polymer fuel cells relates to the management of water, both coolant and product water, within the cells in the power plant. In a solid polymer membrane fuel cell power plant, product water is formed by an electro-chemical reaction on the cathode side of the cells, specifically by the combination there of hydrogen ions, electrons and oxygen molecules. The product water must be drawn awa...

AI Technical Summary

Benefits of technology

[0014]It is also an object of the present invention to provide a water transport plate which has a construction with an optimal balance of bubble pressure and water permeability.

[0015]It is further an object of the present invention to provide a water transport plate which has optimal pore size, open porosity, resistivity and yield strength.

Problems solved by technology

These systems are serviceable, but are relatively complex.

One problem occurring in solid polymer fuel cells relates to the management of water, both coolant and product water, within the cells in the power plant.

The aforesaid solution to water management and cell cooling in ion-exchange membrane fuel cell power plants is difficult to achieve due to the quality control requirements of the fine and finer pore plates, and is also expensive because the plate components are not uniformly produced.

Due to the constraints of the water transport plate formation process, these plates are costly to manufacture and possess limited strength.

Although this is a common water transport plate formation process, the forming speed is slow and it is difficult to incorporate relatively long fibers which are desirable for water transport plate structural integrity.

This fiber bundling, which corresponds to uneven fiber distribution, creates weak areas within the composite which are susceptible to structural failure.

Consequently, the tolerances in the specification for the water transport plate are small and the fabrication is difficult, resulting in many rejected parts.

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