Differential pressure fluid flow fields for fuel cells
AssigneeBallard Power Systems Inc.
InventorsMark C. Johnson, David P. Wilkinson, John Kenna, Olen R. Vanderleeden, Joerg Zimmerman, Mehrzad Tabatabaian
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Abstract
Flow fields comprising a set of fluid distribution channels may be employed in fuel cells for purposes of distributing fluid reactants to an electrochemically active area of the fuel cell. Water management and reactant distribution may be improved by increasing pressure gradients between adjacent channels. Such pressure gradients may be increased by engineering the channels such that the resistance to reactant flow differs along the length of adjacent channels.
Claims27
A flow field for supplying a fluid reactant to an electrochemically active area in a fuel cell, said flow field comprising at least two adjacent fluid distribution channels, and each of said two adjacent channels connected at an inlet end to an inlet manifold and connected at an exhaust end to an outlet manifold, said flow field characterized in that
- (a) the cross section of one of said two adjacent channels varies from inlet to outlet whereby the resistance to flow of said fluid reactant along at least one of said two adjacent channels varies from inlet to outlet;
- and
- (b) the cross sections of each of said two adjacent channels differ over at least about half of the channel length whereby the resistance to flow of said fluid reactant differs between each of said two adjacent channels over at least about half of the channel length.
A method of improving water management in a fuel cell using a flow field in which said flow field comprises at least two adjacent fluid distribution channels through which a fluid reactant flows and each of said two adjacent channels is connected at an inlet end to an inlet manifold and connected at an exhaust end to an outlet manifold, said method comprising:
- (a) varying the cross section of one of said two adjacent channels from inlet to outlet whereby the resistance to flow of said fluid reactant along each of said two adjacent channels from inlet to outlet;
- and
- (b) varying the cross sections of each of said two adjacent channels so that said channels differ along at least about half of said channel length whereby the resistance to flow of said fluid reactant in each of said two adjacent channels such that said resistance to flow differs in each of said two adjacent channels over a portion of channel length, thereby increasing pressure differences between said two adjacent channels in at least about half of said channel length.
A method of improving the distribution of a fluid reactant to an electrochemically active area in fuel cell using a flow field in which said flow field comprises at least two adjacent fluid distribution channels through which a fluid reactant flows and each of said two adjacent channels is connected at an inlet end to an inlet manifold and connected at an exhaust end to an outlet manifold, said method comprising:
- (a) varying a characteristic of the cross section of one of said two adjacent channels from inlet to outlet whereby the resistance to flow of said fluid reactant along each of said two adjacent channels from inlet to outlet;
- and
- (b) varying a characteristic of the cross sections of each of said two adjacent channels so that said channels differ along at least about half of said channel length whereby the resistance to flow of said fluid reactant in each of said two adjacent channels such that said resistance to flow differs in each of said two adjacent channels over a portion of channel length;
- thereby increasing pressure differences between said two adjacent channels in at least about half of said channel length.
Dependencies are inferred from the claim text.