Abstract: An electrochemical fuel cell having reactant flow passages with a non-uniform design to increase reactant access to an adjacent fluid distribution layer at the outlet region as compared to the inlet region. In an embodiment, at least one reactant flow passage is narrower at the inlet than at the outlet, with a substantially constant cross-sectional area maintained along its length. Coolant channels may optionally be incorporated in the fluid flow plate to provide increased cooling at the reactant inlet. The plates may vary in thickness and run in counter-flow to improve efficient stacking of the fuel cells in a fuel cell stack with reactant passages of varying depth. In another embodiment, electrically conductive, masking foil covers a portion of at least one reactant flow passage in the inlet region, but does not extend the length of the passage.

Abstract: An electrochemical fuel cell having reactant flow passages with a non-uniform design to increase reactant access to an adjacent fluid distribution layer at the outlet region as compared to the inlet region. In an embodiment, at least one reactant flow passage is narrower at the inlet than at the outlet, with a substantially constant cross-sectional area maintained along its length. Coolant channels may optionally be incorporated in the fluid flow plate to provide increased cooling at the reactant inlet. The plates may vary in thickness and run in counter-flow to improve efficient stacking of the fuel cells in a fuel cell stack with reactant passages of varying depth. In another embodiment, electrically conductive, masking foil covers a portion of at least one reactant flow passage in the inlet region, but does not extend the length of the passage.

Abstract: An improved flow field design for a flow field plate comprises fluid distribution channels having an average width W and separated by landings in which the channels are configured such that unsupported rectangular surfaces of length L and width W on an adjacent fluid diffusion layer have a ratio L/W less than about 3. Improved support may be obtained for instance by using sinusoidally shaped channels. Certain fluid diffusion layer embodiments offer desirable characteristics (for example, low cost, thickness) for use in fuel cells but may also be undesirably weak mechanically and consequently will benefit from improved mechanical support from adjacent flow field plates comprising the present flow field design.

Abstract: An electrochemical fuel cell comprises at least one fluid distribution layer comprising a substantially fluid impermeable sheet material which is rendered fluid permeable at least in the active area through the non-uniform application of perforations. In some embodiments, the size of the perforations in the fluid distribution layer increases in the reactant flow direction. In other embodiments, the density of the perforations in the fluid distribution layer increases in the reactant flow direction. The fluid permeability of the fluid distribution layer may also increase from the inlet to a mid-point between the inlet and the outlet and then decrease thereafter to the outlet.

Abstract: A method is provided for adjusting the temperature of a solid polymer electrolyte fuel cell, such as a direct methanol fuel cell or PEM fuel cell. A method is also provided for starting a solid polymer electrolyte fuel cell. A solid polymer electrolyte fuel cell apparatus is further provided. In the present methods and apparatus, the temperature of a fuel cell is increased by providing a fuel stream containing methanol to the fuel cell anode and facilitating methanol crossover and combustion. The methanol concentration or methanol pressure can be adjusted in response to a measured parameter indicative of the fuel cell temperature.

Abstract: An improved flow field design for a flow field plate comprises fluid distribution channels having an average width W and separated by landings in which the channels are configured such that unsupported rectangular surfaces of length L and width W on an adjacent fluid diffusion layer have a ratio L/W less than about 3. Improved support may be obtained for instance by using sinusoidally shaped channels. Certain fluid diffusion layer embodiments offer desirable characteristics (for example, low cost, thickness) for use in fuel cells but may also be undesirably weak mechanically and consequently will benefit from improved mechanical support from adjacent flow field plates comprising the present flow field design.