Fluid flow plate for a fuel cell
The invention relates to bipolar plates for electrochemical fuel cell assemblies, and in particular to configurations of bipolar plates allowing for multiple fluid flow channels for the passage of anode, cathode and coolant fluids. Embodiments disclosed include a bipolar plate ( 10 ) for an electrochemical fuel cell assembly, comprising: a first plurality of fluid flow channels ( 13 ) extending across a first face of the bipolar plate between first inlet and outlet ports ( 18 a, 18 b ) at opposing ends of the bipolar plate; a second plurality of fluid flow channels ( 22 ) extending across a second opposing face of the bipolar plate between second inlet and outlet ports ( 21 a, 21 b ) at opposing ends of the bipolar plate; and a third plurality of fluid flow channels ( 14 ) extending between third inlet and outlet ports ( 19 a, 19 b ) at opposing ends of the bipolar plate, the third plurality of fluid flow channels provided between first and second corrugated plates ( 11, 12 ) forming the first and second opposing faces of the bipolar plate, wherein the first, second and third fluid flow channels are coplanar.
1. A bipolar plate for an electrochemical fuel cell assembly, comprising:
a first plurality of fluid flow channels extending across a first face of the bipolar plate between first inlet and outlet ports at opposing ends of the bipolar plate;
a second plurality of fluid flow channels extending across a second opposing face of the bipolar plate between second inlet and outlet ports at opposing ends of the bipolar plate;
a third plurality of fluid flow channels extending between third inlet and outlet ports at opposing ends of the bipolar plate, the third plurality of fluid flow channels provided between first and second corrugated plates forming the first and second opposing faces of the bipolar plate, respectively;
first inlet and outlet manifolds across the first face of the bipolar plate providing respective fluid connections between the first inlet and outlet ports and the first plurality of fluid flow channels; and
a first gasket forming a fluid seal around a periphery of the first face of the bipolar plate and the first inlet and outlet ports and forming the first inlet and outlet manifolds,
the first inlet and outlet manifolds each comprising an open array of raised features formed in the first gasket configured to provide a defined separation between the bipolar plate and an adjacent layer while allowing flow of fluid between the first inlet and outlet ports and the first plurality of fluid flow channels; and
the first inlet and outlet manifolds minimize a pressure difference across the flow of fluid and maximize areas of the inlet and outlet ports which are non-nested;
wherein the first, second and third channels are coplanar;
wherein adjacent pairs of the first plurality of fluid flow channels are connected at opposing ends of the bipolar plate to form a single serpentine fluid flow path extending across the first face of the bipolar plate between the first inlet and outlet ports;
wherein each adjacent pair of the first plurality of fluid flow channels are connected by one of a plurality of transverse connecting regions extending between adjacent corrugations in the first corrugated plate, with each of the transverse connection regions having a depth less than the depth of the adjacent pair of first plurality of fluid flow channels.
2. The bipolar plate of claim 1 wherein the first and second corrugated plates are engaged with each other such that selected corrugations in the first plate lie within corresponding corrugations in the second plate.
3. The bipolar plate of claim 2 wherein the third plurality of fluid flow channels are formed between the first and second corrugated plates by omission of selected corrugations in the first or second plate.
4. The bipolar plate of claim 2 wherein the third plurality of fluid flow channels are formed between the first and second corrugated plates by narrowing of selected corrugations in the first or second plate.
5. The bipolar plate of claim 2 wherein the third plurality of fluid flow channels are formed between the first and second corrugated plates by a height reduction of selected corrugations in the first or second plate.
6. The bipolar plate of claim 1 wherein the second fluid flow channels form an array of interdigitated fluid flow channels.
7. The bipolar plate of claim 6 wherein the second face comprises barriers formed in the second corrugated plate at opposing ends of the interdigitated fluid flow channels, each barrier configured to form a fluid seal between an adjacent longitudinal fluid flow channel and an adjacent one of the second inlet and outlet ports.
8. A method of manufacturing a bipolar plate for an electrochemical fuel cell assembly, the method comprising:
press-forming a first metallic plate to form first second and third inlet and outlet ports at opposing ends and a plurality of corrugations to provide a first plurality of fluid flow channels extending across the first metallic plate between the first inlet and outlet ports;
press-forming a second metallic plate to form first second and third inlet and outlet ports at opposing ends and a plurality of corrugations to provide a second plurality of fluid flow channels extending across the second metallic plate between the second inlet and outlet ports;
joining the first and second metallic plates to form a bipolar plate having a third plurality of fluid flow channels between adjoining faces of the first and second metallic plates extending between the third inlet and outlet ports at opposing ends of the bipolar plate;
forming first inlet and outlet manifolds across the first face of the bipolar plate providing respective fluid connections between the first inlet and outlet ports and the first plurality of fluid flow channels using a first gasket to form a fluid seal around a periphery of the first face of the bipolar plate and the first inlet and outlet ports and to form the first inlet and outlet manifolds,
the first inlet and outlet manifolds each comprising an open array of raised features formed in the first gasket configured to provide a defined separation between the bipolar plate and an adjacent layer while allowing flow of fluid between the first inlet and outlet ports and the first plurality of fluid flow channels;
the first inlet and outlet manifolds minimize a pressure difference across the flow of fluid and maximize areas of the non-nested inlet and outlet ports;
wherein the first, second and third fluid flow channels are coplanar;
wherein the press-forming of the first metallic plate forms the first plurality of fluid flow channels such that adjacent pairs of the first plurality of fluid flow channels are connected at opposing ends of the bipolar plate to form a single serpentine fluid flow path extending across the first face of the bipolar plate between the first inlet and outlet ports;
wherein the press-forming of the first metallic plate further comprises press-forming a plurality of transverse connecting regions, wherein each adjacent pair of the first plurality of fluid flow channels are connected by one of the plurality of transverse connecting regions extending between adjacent corrugations in the first metallic plate, with each of the transverse connection regions having a depth less than the depth of the adjacent flow channels in the first plurality of fluid flow channels.
9. The method of claim 8 wherein the steps of press-forming the first and second metallic plates are performed simultaneously on a common metallic plate.
10. The method of claim 9 comprising forming a fold line between the first and second metallic plates, and wherein the step of joining the first and second metallic plates comprises folding the common metallic plate along the fold line.
11. The bipolar plate of claim 7 , wherein each of the barriers in the second corrugated plate is bonded to a corresponding transverse connecting region in the first corrugated plate.