PLATE, SYSTEM AND FUEL CELL STACK

Abstract

Plate (12, 20, 22) comprising: a work surface (36, 36a, 36b) which defines a plurality of reactant channels (24b, 26b) on it; a manifold section (40, 40a, 40b) which is arranged in a circumferential area of ​​the plate (12, 20, 22), wherein the manifold section (40, 40a, 40b) comprises: a plurality of flanges arranged thereon (50), where the plurality of flanges (50) defines a plurality of openings (44) through the plate (12, 20, 22), wherein each of the plurality of flanges (50) defines a respective plurality of openings (44), wherein at least one of the plurality of openings (44) is fluidically connected to the plurality of reactant channels (24b 26b); and a plurality of ridges (42) arranged on the work surface (36, 36a, 36b), wherein each of the plurality of ridges (42) is arranged around a respective plurality of openings (44), thereby defining a respective one of the multiple flanges (50), wherein each of the plurality of ridges (42) defines a shape consisting of ridge corners (108) and ridge sides (106), wherein each ridge corner (108) defines an angle (α), wherein each of the plurality of beads (42) has a sealing surface (46) on it, wherein the sealing surface (46) is configured to flex when subjected to contact pressure in order to provide a substantially fluid-tight seal, characterized by the fact that Each respective angle (α) lies between 50° and 70°.

Description

[0001] The disclosure relates to the field of fuel cells and, in particular, to manifold sections using regular shapes.

[0002] Fuel cell systems can be used as an energy source in a wide variety of applications to provide electrical energy. The generated electrical energy can be used immediately to power a device, such as an electric motor. Additionally or alternatively, the generated electrical energy can be stored for later use, for example, using batteries.

[0003] In some applications, fuel cells are integrated into stationary systems to supply electrical power to buildings, homes, and the like. In some applications, fuel cells are incorporated into devices such as smartphones, video cameras, computers, and the like. In some applications, fuel cells are incorporated into vehicles to provide or supplement motive power.

[0004] Fuel cell systems generally comprise fuel cells arranged in a fuel cell stack. The fuel cell stack, which may contain more than one hundred plates, is compressed to exert contact pressure on seals between adjacent components of the fuel cell stack to prevent leakage of fluids flowing through it. For example, coolant mixing of the reactants or reactants mixing away from the active areas of the fuel cells reduces the effectiveness of the fuel cell stack. Due to the number of components, even slight differences in the contact pressure distribution along the seals are amplified across the stack, which can prevent the formation of fluid-tight seals.

[0005] The document DE 10 2009 012 730 A1 discloses a plate according to the preamble of claim 1, a system according to the preamble of claim 4 and a fuel cell stack according to the preamble of claim 8.

[0006] It is an object of the invention to distribute the contact pressure evenly across seals of the fuel cell stack.

[0007] The problem is solved by the features of the independent claims. Advantageous further developments are defined in the subclaims. SUMMARY

[0008] According to aspects of the present disclosure, a plate includes a working surface and a manifold portion. The working surface defines a plurality of reactant channels thereon. The manifold portion is disposed in a peripheral region of the plate and includes a plurality of flanges and a plurality of beads. The plurality of flanges are disposed on the manifold portion. The plurality of flanges define a plurality of openings through the plate. Each of the plurality of flanges defines a respective one of the plurality of openings. At least one of the plurality of openings is fluidly connected to the plurality of reactant channels. The plurality of beads is disposed on the working surface. Each of the plurality of beads is disposed about a respective one of the plurality of openings, thereby defining a respective one of the plurality of flanges. Each of the plurality of beads defines a shape comprised of bead corners and bead sides.Each of the plurality of beads has a sealing surface thereon. The sealing surface is configured to flex when subjected to contact pressure, thereby providing a substantially fluid-tight seal.

[0009] According to further aspects of the present disclosure, the shape is generally hexagonal.

[0010] Each bead corner defines an angle, with each respective angle being between approximately 50° and approximately 70°.

[0011] According to further aspects of the present disclosure, each bead corner defines an angle measuring approximately 60°.

[0012] According to further aspects of the present disclosure, each bead corner defines a respective angle, and each respective angle is within about 10° of each other respective angle.

[0013] According to further aspects of the present disclosure, the bead corners are configured to produce a contact pressure variation of less than about 50% along the sealing surface.

[0014] According to further aspects of the present disclosure, the bead corners are configured to produce a contact pressure variation of less than about 30% along the sealing surface.

[0015] According to further aspects of the present disclosure, each of the bead corners is generally rounded.

[0016] According to further aspects of the present disclosure, each of the bead sides follows a serpentine path.

[0017] According to aspects of the present disclosure, a system comprises a plate, a component, and a compression member. The plate includes a working surface and a manifold portion. The working surface defines a plurality of reactant channels thereon. The manifold portion is disposed in a peripheral region of the plate. The manifold portion includes a plurality of flanges and a plurality of beads. The plurality of flanges are disposed on the working surface. The plurality of flanges define a plurality of first openings through the plate. Each of the plurality of flanges defines a respective one of the plurality of first openings. At least one of the plurality of first openings is fluidly connected to the plurality of reactant channels. The plurality of beads is disposed on the working surface.Each of the plurality of beads is disposed around a respective one of the plurality of first openings to thereby define a respective one of the plurality of flanges. Each of the plurality of beads defines a shape. The shape consists of bead corners and bead sides. Each of the plurality of beads has a sealing surface thereon. The sealing surface is configured to flex when subjected to a contact pressure to thereby provide a substantially fluid-tight seal. The component abuts the plate. The component includes a plurality of second openings therethrough. Each of the plurality of second openings is aligned with a respective one of the plurality of first openings. The compression member is configured to apply a compressive force to the plate to thereby create the contact pressure.

[0018] According to further aspects of the present disclosure, the component further comprises a second working surface. The second working surface has a plurality of second beads disposed thereon. Each of the plurality of second beads is disposed around a respective one of the plurality of second openings. Each of the plurality of second beads defines the shape.

[0019] According to further aspects of the present disclosure, the second working surface is disposed proximate the working surface, each of the plurality of second beads having a second sealing surface thereon, and the component abuts the plate when the second sealing surface contacts the sealing surface to create the contact pressure therebetween.

[0020] According to further aspects of the present disclosure, the plate further comprises a first rear surface opposite the working surface, and the component further comprises a second rear surface. The second rear surface is attached to the first rear surface. The first rear surface and the second rear surface define a plurality of coolant channels between the plate and the component. The plurality of coolant channels are fluidly connected to at least one other of the plurality of first openings.

[0021] Each bead corner defines an angle, with each respective angle being between approximately 50° and approximately 70°.

[0022] According to further aspects of the present disclosure, the bead corners are configured to produce a contact pressure variation of less than about 30% along the sealing surface.

[0023] According to further aspects of the present disclosure, the component is a combined electrode assembly.

[0024] According to aspects of the present disclosure, a fuel cell stack includes a first plate, a second plate, a combined electrode assembly, and a compression member. The first plate includes a first working surface and a first manifold portion. The first working surface defines a plurality of first reactant channels thereon. The first manifold portion is disposed in a peripheral region of the first plate. The first manifold portion includes a plurality of first flanges and a plurality of first beads. The plurality of first flanges are disposed on the manifold portion. The plurality of first flanges define a plurality of first openings through the first plate. Each of the plurality of first flanges defines a respective one of the plurality of first openings. At least one of the plurality of first openings is fluidly connected to the plurality of first reactant channels.The plurality of first beads are disposed on the first working surface. Each of the plurality of first beads is disposed around a respective one of the plurality of first openings to thereby define a respective one of the plurality of first flanges. Each of the plurality of first beads defines a shape. The shape consists of bead corners and bead sides. Each of the plurality of first beads has a first sealing surface thereon. The first sealing surface is configured to flex when subjected to contact pressure to thereby provide a substantially fluid-tight seal. The second plate includes a second working surface and a second manifold portion. The second working surface defines a plurality of second reactant channels thereon. The second manifold portion is disposed in a peripheral region of the second plate.The second manifold section includes a plurality of second flanges and a plurality of second beads. The plurality of second flanges are disposed on the second manifold section. The plurality of second flanges define a plurality of second openings through the second plate. Each of the plurality of second flanges defines a respective one of the plurality of second openings. At least one of the plurality of second openings is fluidly connected to the plurality of second reactant channels. The plurality of second beads are disposed on the second working surface. Each of the plurality of second beads is disposed around a respective one of the plurality of second openings to thereby define a respective one of the plurality of second flanges. Each of the plurality of second beads defines the shape. The shape consists of bead corners and bead sides. Each of the plurality of second beads has a second sealing surface thereon.The second sealing surface is configured to flex when subjected to the contact pressure, thereby providing a substantially fluid-tight seal. The unified electrode assembly is disposed between the first plate and the second plate. The unified electrode assembly includes a first side contacting the plurality of first reactant channels and a second side contacting the plurality of second reactant channels. The compression member is configured to apply a compressive force to the first plate, the second plate, and the unified electrode assembly. The compressive force is configured to apply the contact pressure to the plurality of first beads and the plurality of second beads.

[0025] Each bead corner defines an angle, with each respective angle being between approximately 50° and approximately 70°.

[0026] According to further aspects of the present disclosure, each bead corner defines an angle measuring approximately 60°.

[0027] According to further aspects of the present disclosure, the shape is a hexagon.

[0028] The above features and advantages and other features and advantages of the present disclosure will become readily apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are for illustrative purposes. Exemplary aspects are discussed in the following detailed description and shown in the accompanying drawings, in which: Fig. 1 is a schematic exploded view of a fuel cell stack according to aspects of the present disclosure; Fig. 2 a schematic plan view of a monopolar plate of the fuel cell stack of Fig. 1 according to aspects of the present disclosure; Fig. 3 a schematic cross-sectional view of the plate of Fig. 2 is; Fig. 4 is a schematic isometric view of a bipolar plate shown in partial cross-section according to aspects of the present disclosure; Fig. 5 is a schematic plan view of an exemplary manifold section employing generally regular shapes in accordance with aspects of the present disclosure; Fig. 6 is a schematic plan view of another exemplary manifold section utilizing generally regular shapes in accordance with aspects of the present disclosure; Fig. Figure 7 is a graph comparing contact pressure probability distributions for manifold sections using generally regular shapes and manifold sections using non-regular shapes. DETAILED DESCRIPTION

[0030] Fig. 1 is an exploded view of a fuel cell stack 10. The fuel cell stack 10 includes a plurality of plates 12, at least one combined electrode assembly 14, and a compression member 16. The plurality of plates 12 may include any suitable combination of plates 12. For example, the plurality of plates 12 may include end plates 18, monopolar plates 20 (in Fig. 2 shown in more detail) and / or bipolar plates 22 (shown in more detail in Fig. 4). According to aspects of the present disclosure, some or all of the seals between the plurality of plates 12, the at least one combined electrode assembly 14, and the compression member 16 may be configured to evenly distribute contact pressure across the seals by utilizing regular manifold shapes as described herein.

[0031] End plates 18 are disposed on the top and bottom of fuel cell stack 10. End plates 18 include fuel inlets 24a, fuel outlets 24c, oxidant inlets 26a, oxidant outlets 26c, coolant inlets 28a, and coolant outlets 28c disposed thereon. As used herein, "fluids" may refer to fuels, oxidants, coolants, or any combination thereof, as the context dictates, and "reactants" may refer to fuels, oxidants, or both, depending on the context. For example, “fluid inlets 24a, 26a, 28a” may refer to any or all of the fuel inlets 24a, the oxidizer inlets 26a, or the coolant inlets 28a, as the context dictates, and “reactant channels 24b, 26b” may refer to one or both of the fuel channels 24b and the oxidizer channels 26b, as the context dictates.It is contemplated that certain of the fluid inlets 24a, 26a, 28a and fluid outlets 24c, 26c, 28c may be located on one end plate 18, with the remaining fluid inlets 24a, 26a, 28a and fluid outlets 24c, 26c, 28c being located on the opposite end plate 18.

[0032] The combined electrode assembly 14 includes a fuel cell 30 disposed between diffusion media 32. The fuel cell 30 may, for example, be a membrane electrode assembly comprising a membrane disposed between a cathode and an anode. The membrane may, for example, be a proton exchange membrane. The cathode and anode may, for example, contain a finely divided catalyst supported on carbon particles and mixed with an ionomer. In some aspects, the catalyst is platinum.

[0033] The diffusion media 32 are porous layers that facilitate the delivery of reactants to the fuel cell 30. The reactants may include any suitable combination of fuel and oxidant. For example, the fuel may be hydrogen and the oxidant may be oxygen. In a hydrogen fuel cell 30, hydrogen and oxygen react to produce electricity, with heat and water as byproducts. For example, other fuels may be used, such as natural gas, methanol, gasoline, and coal-derived synthetic fuels. In some aspects, the diffusion media 32 is attached to a surface of the fuel cell 30 using lamination, adhesion, or any other suitable method. In some aspects, the diffusion media 32 is adjacent to, but not adhered to, the surface of the fuel cell.For example, the diffusion medium 32 can be arranged on the surface of the fuel cell 30 and held in place by a retaining element 34. The retaining element 34 can be a gasket, for example.

[0034] The compression element 16 exerts a compressive force on the fuel cell stack 10 along the stacking direction. The compressive force secures the plates 12 and the fuel cells 30 in position through contact pressure between adjacent components. In some aspects, the compression element 16 includes a plurality of threaded rods that engage structures on the end plates 18. By tightening the threaded rods, a compressive force is increased to a desired level along the stacking direction, resulting in contact pressure being distributed along seals between adjacent components. In some aspects, the compression elements 16 engage less than the entire fuel cell stack 10.For example, compression elements 16 may engage two adjacent plates 12 to exert a compressive force on the two plates 12, or may engage a number of adjacent plates 12 to exert a compressive force on the number of adjacent plates 12.

[0035] Fig. 2 is a plan view of an exemplary monopolar plate 20 of the fuel cell stack 10. The monopolar plate 20 is a generally flat sheet having a working surface 36, a rear surface 38 opposite the working surface, manifold portions 40, and ridges 42. The illustrated monopolar plate 20 is a metal sheet defining structures thereon. The structures are formed by stamping the metal sheet. It is contemplated that other materials, such as carbon fiber, and other forming methods, such as molding and additive manufacturing, may be used to form the monopolar plate 20.

[0036] The reactant channels 24b, 26b are defined on the working surface 36 of the monopolar plate 20. The reactant channels 24b, 26b of a particular monopolar plate 20 are either fuel channels 24b or oxidant channels 26b. The reactant channels 24b, 26b distribute the fluid flowing therethrough over the surface of an adjacent combined electrode assembly 14 or fuel cell 30. For example, the fuel channels 24b distribute hydrogen to the anode of the fuel cell 30, and the oxidant channels 26b distribute oxygen to the cathode of the fuel cell 30.

[0037] The manifold section 40 is disposed in a peripheral region of the monopolar plate 20 and defines a plurality of openings 44 extending through the monopolar plate 20. The openings 44 allow fluid to flow from one side of the monopolar plate 20 to the other side of the monopolar plate 20.

[0038] The ridges 42 extend from the working surface 36 of the monopolar plate 20. At least one ridge 42 is disposed along a perimeter of the working surface 36 of the monopolar plate 20 to prevent fluid from, for example, the reactant channels 24b, 26b from leaking to the exterior of the monopolar plate 20 (e.g., leaking into the environment or into the fuel cell stack 10). Additional ridges 42 are disposed adjacent to and surrounding each opening 44. The ridges 42 surrounding each opening prevent fluid from leaking from the opening to the fluid channels 24b, 26b, 28b of the monopolar plate 20. For example, the ridge 42 surrounding an opening 44 through which coolant flows inhibits the coolant from entering the reactant channels 24b, 26b of the monopolar plate 20 and mixing with the reactant flowing therethrough. It is contemplated that a ridge 42 may surround more than one opening 44.

[0039] Optionally, coolant channels 28b may be defined on the rear surface 38 of the monopolar plate 20. The coolant channels 28b distribute the flowing coolant across the rear surface 38 of the monopolar plate 20 to remove heat generated during the chemical reaction. Additionally, the coolant channels 28b may be used to supply heat to the fuel cells 30 to facilitate the chemical reaction, for example, in cold operating conditions. It is contemplated that the beads 42 and other features may extend from the rear surface 38 of the monopolar plate 20.

[0040] Fig. Figure 3 is a cross-sectional view of the bead 42 of the monopolar plate 20 taken along line 3-3. The bead 42 defines a generally arcuate shape. The bead 42 defines a sealing surface 46 at the working surface 36. The sealing surface 46 is configured to contact a component adjacent to the working surface 36 of the monopolar plate 20. The sealing surface 46 forms a fluid-tight seal with the adjacent component when the contact pressure at all points on the bead 42 exceeds a certain threshold.

[0041] The beads 42 form a resilient structure that deflects when pressure is applied. The deflection increases the portion of the sealing surface 46 in contact with the adjacent component. While the illustrated bead 42 is generally curved in cross-section, it is contemplated that other shapes may be used. In some non-limiting examples, the cross-sectional profile of the bead 42 is generally rectangular, generally trapezoidal, generally linear sidewalls with an arcuate portion splayed therebetween, combinations thereof, or the like. Further, while the illustrated bead 42 is generally symmetrical, it is contemplated that asymmetrical beads 42 may be used.

[0042] Fig. Figure 4 is an isometric view of the bipolar plate 22 in partial cross-section. Bipolar plates 22 can be formed in various ways. For example, the rear surfaces 38 of two monopolar plates 20 can be placed together, and the monopolar plates 20 can be joined to form the bipolar plate 22. The joint can be formed, for example, by welding or using an adhesive.

[0043] The bipolar plate 22 includes a first working surface 36a opposite a second working surface 36b. Each working surface 36 defines reactant channels 24b, 26b thereon. For example, the first working surface 36a defines the fuel channels 24b, while the second working surface 36b defines the oxidant channels 26b. The co-arrangement of the back surfaces 38 of the two monopolar plates 20 results in the coolant channels 28b being defined by the space between the two monopolar plates 20, as shown in Fig. 4 is shown.

[0044] Bipolar plates 22 can also be formed using a variety of methods, such as 3D printing. In some aspects, bipolar plate 22 is formed by embossing reactant channels 24b, 26b on opposite sides of a single sheet without the presence of cooling channels 28b therebetween.

[0045] When the fuel cell stack 10 is assembled, the openings 44 in the manifold sections 40 of each plate 12 are substantially aligned with respective openings 44 of adjacent plates 12 or combined electrode assemblies 14 to form a plurality of inlet manifolds (not shown) and a plurality of outlet manifolds (not shown). The beads 42 of each component are compressed against the beads 42 of adjacent components to form fluid-tight seals to define a plurality of fluid flow paths 24, 26, 28. The fuel flow path 24 is defined by the fuel inlet 24a, a fuel inlet manifold (not shown), fuel channels 24b of respective plates 12, a fuel outlet manifold (not shown), and fuel outlet 24c.Similarly, an oxidant flow path 26 is defined by the oxidant inlet 26a, an oxidant inlet manifold (not shown), the oxidant channels 26b, the oxidant outlet manifold (not shown), and the oxidant outlet 26c. The coolant flow path 28 includes the coolant inlet 28a, a coolant inlet manifold (not shown), the coolant channels 28b, a coolant outlet manifold (not shown), and a coolant outlet 28c.

[0046] During operation, at least two fluids flow through the fuel cell stack 10 in separate fluid flow paths 24, 26, 28. In some example fuel cell stacks 10, the fluids enter the fluid inlets 24a, 26a, 28a, flow through a respective manifold along one circumferential side of the fuel cell stack 10, traverse the components in a lateral direction via the fluid channels 24b, 26b, 28b, flow through a respective manifold on an opposite circumferential side of the fuel cell stack 10, and exit the fuel cell stack 10 via the fluid outlets 24c, 26c, 28c. In some examples, at least two of the fluids flow in a countercurrent configuration.

[0047] A substantially fluid-tight seal is formed between components of the fuel cell stack 10 to prevent undesirable mixing of the fluids flowing through the fuel cell stack 10. These substantially fluid-tight seals are formed by applying contact pressure to the sealing surfaces 46. Differences in the contact pressure along the sealing surfaces 46 of the beads 42 are believed to contribute to leaks. It is also believed that a uniform distribution of the contact pressure along the sealing surfaces 46 of the beads 42 may beneficially affect the properties of the fuel cell stack 10. For example, systems, components, and methods according to the present disclosure may increase sealing effectiveness by evenly distributing the contact pressure across the manifold portions 40 of the plates 12.Furthermore, systems, components, and methods consistent with the present disclosure may also reduce component manufacturing costs by reducing the amount of compression force required to maintain adequate contact pressure throughout the stack. Furthermore, systems, components, and methods consistent with the present disclosure may also positively impact fuel cell stack longevity by reducing the maximum contact pressure exerted on the components.

[0048] The contact pressure applied to the sealing surfaces 46 results from the compressive force applied to the fuel cell stack 10 and should be maintained above a threshold level to maintain substantially fluid-tight seals. Because the fuel cell stack 10 may include a significant number of components, even slight variations in the distribution of contact pressure along the beads 42 can be greatly amplified when the components are assembled into the fuel cell stack 10.

[0049] Advantageously, the contact pressure distribution along the sealing surface 46 of a bead 42 can be uniformly distributed by using generally regular shapes in the manifold sections 40. It is believed that the use of regular shapes results in a uniformly distributed contact pressure along the sealing surface 46 by providing geometric features (e.g., corner angles) that are substantially uniform throughout the manifold section 40.

[0050] Fig. Figure 5 is a schematic plan view of a plate 12 having a manifold section 40a employing generally regular shapes. The plate 12 includes a working surface 36, a plurality of reactant channels 24b, 26b, manifold sections 40a, and a bead 42 disposed generally around the perimeter of the plate 12.

[0051] The manifold sections 40a are disposed at ends of the plate 12. The manifold sections 40a include a plurality of ridges 42 and a plurality of flanges 50 defining a plurality of openings 44 through the plate 12. Each flange 50 is defined between a ridge 42 and a corresponding opening 44 with a flange edge 104 defining the opening 44 through the plate. Each of the openings 44 is configured to allow fluid to flow therethrough, and at least one of the openings 44 in each manifold section 40a is fluidly connected to the plurality of reactant channels 24b, 26b.In use, fluids flow through each of the openings 44 such that a reactant flowing through the connected opening 44 or openings 44 at one end of the plate 12 can enter the reactant channels 24b, 26b, traverse the flow field defined by the reactant channels 24b, 26b, and exit the plate through the connected opening 44 or openings 44 at the opposite end of the plate 12. The bead 42 disposed around the periphery of the plate 12 may also be referred to as an outer bead 42, while the beads 42 disposed around the flanges 50 may be referred to as inner beads 42.

[0052] The beads 42 are configured to provide a substantially fluid-tight seal between the plate 12 and adjacent components of the fuel cell stack 10. Each inner bead 42 is disposed around a respective one of the openings 44 to define the respective flange 50.

[0053] Each of the beads 42 defines a respective shape. The shape may, for example, be a polygon consisting of the bead sides 106 and the bead corners 108. The polygon may have any number of bead sides 106 and bead corners 108, such as generally hexagonal, as represented by the regular hexagons of Fig. 5. The bead corners 108 define an angle α. The angle α is defined by a first line extending perpendicular to a first of the bead sides 106 and a second line extending perpendicular to a second of the bead sides 106. The first line begins at a transition between the bead corner 108 and the first of the bead sides 106, and the second line begins at a transition between the bead corner 108 and the second of the bead sides 106. In some aspects, each bead corner defines an angle α measuring from about 50° to about 70°. In some aspects, each bead corner defines an angle α measuring about 60°. While the illustrated polygon is generally hexagonal, it is contemplated that other polygonal shapes may be used. In some aspects, the shape includes more than six bead corners 108 and each bead corner 108 measures an angle α within about 10° of any other angle α.

[0054] It is contemplated that the manifold section 40 may include any number of flanges 50. For example, a plate 12 configured for operation with two reactants and one coolant may include one coolant flange 50, one first reactant flange 50, and one second reactant flange 50. Alternatively, another plate 12 configured for operation with two reactants and one coolant may include one coolant flange 50, two first reactant flanges 50, and one second reactant flange 50.

[0055] In some aspects, the bead side 106 is generally linear and the bead corner 108 is generally rounded. While the bead corner 108 is generally rounded, one of ordinary skill in the art will readily recognize that the rounded bead corner 108 would still define an angle. In some aspects, the bead sides 106 include reinforcing structures or "snakeways" that follow a generally serpentine path. These reinforcing structures are configured to prevent weak points from appearing along straight paths of the bead 42 by preventing excessive deformation of the bead 42 when the plate 12 is compressed within the fuel cell stack 10. The bead side 106 is generally linear throughout the serpentine path.Notably, the “turns” along the serpentine path share a certain radius, with first sections being rounded inward toward the flange 50 and second sections, located between the first sections, being rounded outward from the flange 50.

[0056] Fig. Figure 6 is a schematic plan view of a plate 12 having a manifold section 40b employing generally regular shapes. Similar to Fig. 5, the plate 12 includes a working surface 36, a plurality of reactant channels 24b, 26b, manifold sections 40b, and a bead 42 disposed generally around the periphery of the plate 12.

[0057] Similar to Fig. 5 are the manifold sections 40b, which in Fig. 6 are arranged at ends of the plate 12, and each of the beads 42 defines a respective shape, such as a polygon consisting of bead sides 106 and bead corners 108. The polygons shown in Fig. 6 are irregular hexagons. These irregular polygons can provide a closer grouping of the flanges 50, such as the five flanges 50 shown in Fig. 6 and occupy the same general space as the three in Fig. 5. In addition, the flanges 50 may be offset to allow for closer grouping of the flanges 50.

[0058] Surprisingly, the manifold sections 40 employing regular shapes equalize contact pressures exerted on all beads 42 of the manifold section 40, including the inner beads 42 around the flange 50 and the outer beads 42 adjacent to the inner beads 42. In some aspects, the regular shapes include corner angles of approximately 60° to accommodate the various radii of corners exerted by the contact pressure.

[0059] Different bead configurations can be modeled to compare different configurations of manifold sections 40, for example, manifold sections 40 with various bead corner angles, various bead corner radii, and various features between bead 42 and opening 44 to compare and optimize spring constants for different configurations. It is assumed that the spring constant generally decreases as the bead corner angle decreases. For example, the spring constant for a bead 42 with a bead corner angle of 60° is generally lower than the spring constant for the bead 42 with a bead corner angle of 120°. It is further assumed that the spring constant generally decreases as the bead corner radius increases. For example, the spring constant for a bead 42 with a bead corner radius of 15 mm is generally lower than for the bead 42 with a bead corner radius of 6 mm.It is additionally assumed that the spring constant for a bead 42 that has features (such as additional beads 42) between the bead 42 and the opening 44 is generally lower than the spring constant for the bead 42 that has no features between the bead 42 and the opening 44. For example, the spring constant for an outer double bead 42 (i.e., the outermost bead 42 of two beads 42 near the modeled flange 50) is generally lower than the spring constant for a single bead with a similar bead corner radius and bead corner angle.

[0060] By way of non-limiting example, modeling the spring constant of a single inner bead 42 with a radius of 6 mm produces a spring constant of about 200 N / mm 2 when the bead angle is about 120° and a spring constant of about 135 N / mm 2when the bead angle is about 60°. As a non-limiting example, modeling the spring constant of a double outer bead 42 with a radius of 6 mm produces a spring constant of about 180 N / mm 2 when the bead angle is about 120° and a spring constant of about 95 N / mm 2 when the bead angle is about 60°. As a non-limiting example, modeling the spring constant of a single inner bead 42 with a radius of 10 mm produces a spring constant of about 120 N / mm 2 when the bead angle is about 120° and a spring constant of about 90 N / mm 2 when the bead angle is about 60°. As a non-limiting example, modeling the spring constant of a double outer bead 42 with a radius of 10 mm produces a spring constant of about 160 N / mm 2 when the bead angle is about 120° and a spring constant of about 90 N / mm 2when the bead angle is about 60°. As a non-limiting example, modeling the spring constant of a single inner bead 42 with a radius of 15 mm produces a spring constant of about 90 N / mm 2 when the bead angle is about 120° and a spring constant of about 80 N / mm 2 when the bead angle is about 60°. As a non-limiting example, modeling the spring constant of a double outer bead 42 with a radius of 15 mm produces a spring constant of about 130 N / mm 2 when the bead angle is about 120° and a spring constant of about 90° N / mm 2 when the bead angle is approximately 60°.

[0061] As can be seen, the modeled examples show that the spring constants for beads 42 of different radii and bead types begin to converge as the bead corner angles approach 60° from larger bead corner angles. In particular, the variation of the spring constants for the beads 42 of different radii and configurations at 60° is much narrower than the variation of the spring constants for the beads 42 at 120°. For example, the spring constants for the beads 42 modeled and described above vary between approximately 200 N / mm 2 and about 90 N / mm 2 at 120°, while the spring constants for the beads 42 modeled and described above are between about 135 N / mm 2 and about 80 N / mm 2at 60°. In particular, the spring constants for a subset of the beads 42 modeled and described above, namely a single bead with a radius of 6 mm, a double bead with a radius of 6 mm, a double bead with a radius of 10 mm, and a double bead with a radius of 15 mm, are within about 10 N / mm 2 This generally narrow range of spring constants contributes to a contact pressure distribution along the sealing surfaces 46 of the beads 42. Advantageously, flanges 50 with beads 42 having bead corners between 50° and 70° allow for more tunnels to be formed connecting the flange 50 to the reactant channels 24b, 26b than flanges with beads that generally have curved boundaries.

[0062] As can also be seen, the trend lines have different slopes, and therefore, the spring constant spread may not be smaller than a non-zero minimum value as the lines begin to diverge from each other. Furthermore, since the angles of the bead corners are narrow, design constraints such as the circumferential distance for the tunnels supplying the reactant channels 24b, 26b from the respective flanges 50, as well as the positioning of the flanges 50, become less favorable than bead corners with larger angles, such as angles between 50° and 70°.

[0063] Fig.Figure 7 is a graph comparing contact pressure probability distributions for header sections using non-regular shapes, represented by line 802, and header sections using generally regular shapes, represented by line 804. The contact pressure boxes are in MPa, and the percentage of bulges occupying each box is illustrated by the height of the respective bar. Line 806 represents the contact pressure distribution of headers using irregular shapes, while line 808 represents the contact pressure distribution of headers using regular shapes. As can be seen, the contact pressure distribution 808 of headers using regular shapes is significantly narrower than the contact pressure distribution 806 of headers using non-regular shapes.As can also be seen, the probability that points along the sealing surface 46 are subjected to contact pressures deviating from the median (e.g., those below 2.8 MPa and those above 5.2 MPa) is significantly reduced. This narrowed distribution and reduced probability provides fewer leaks along the sealing surfaces 46 for a given compression force for the fuel cell stack 10 because fewer portions of the beads 42 are subjected to contact pressures below the sealing threshold.

[0064] In some aspects, bead corners are configured to produce a contact pressure variation of less than about 50% along the sealing surface. In some aspects, the bead corners are configured to produce a contact pressure variation of less than about 30% along the sealing surface. In some aspects, the bead corners are configured to produce a contact pressure variation of less than about 15% along the sealing surface.

[0065] It is contemplated that the bead 42, generally disposed around the perimeter of the plate (also referred to as the outer bead), may define a path that inserts the outer bead between the beads 42 of the plurality of flanges 50 in the manifold section 40. For example, the outer bead may surround portions of the flanges 50 in a serpentine manner such that the outer bead is disposed in a space between a first flange 50 and an outer flange of the plate 12, a space between the first flange 50 and a second flange 50, a space between the second flange and the reactant channels 24b, 26b, a space between the second flange 50 and a third flange 50, a space between the third flange 50 and the outer edge of the plate 12.It is contemplated that this serpentine path may also be configured to help evenly distribute the contact pressure along the sealing surfaces 46 of the beads.

Claims

[1] Plate (12, 20, 22) comprising: a working surface (36, 36a, 36b) defining a plurality of reactant channels (24b, 26b) thereon; a manifold section (40, 40a, 40b) arranged in a peripheral region of the plate (12, 20, 22), the manifold section (40, 40a, 40b) comprising: a plurality of flanges (50) arranged thereon, wherein the plurality of flanges (50) define a plurality of openings (44) through the plate (12, 20, 22), wherein each of the plurality of flanges (50) defines a respective one of the plurality of openings (44), wherein at least one of the plurality of openings (44) is fluidly connected to the plurality of reactant channels (24b 26b); and a plurality of beads (42) arranged on the working surface (36, 36a, 36b), wherein each of the plurality of beads (42) is disposed around a respective one of the plurality of openings (44), thereby defining a respective one of the plurality of flanges (50), wherein each of the plurality of beads (42) defines a shape consisting of bead corners (108) and bead sides (106), each bead corner (108) defining an angle (α), wherein each of the plurality of beads (42) has a sealing surface (46) thereon, the sealing surface (46) being configured to flex when subjected to a contact pressure to thereby provide a substantially fluid-tight seal, characterized by , that each respective angle (α) lies between 50° and 70°. [2] Plate (12, 20, 22) according to claim 1, wherein: each respective angle (α) lies within 10º of every other corresponding angle (α). [3] The plate (12, 20, 22) of claim 1, wherein the bead corners (108) are configured to produce a contact pressure variation of less than 30% along the sealing surface (46). [4] System comprising: a plate (12, 20, 22) with: a working surface (36, 36a, 36b) defining a plurality of reactant channels (24b, 26b) thereon; and a manifold section (40, 40a, 40b) arranged in a peripheral region of the plate (12, 20, 22), the manifold section (40, 40a, 40b) comprising: a plurality of flanges (50) disposed thereon, the plurality of flanges (50) defining a plurality of first openings (44) through the plate (12, 20, 22), each of the plurality of flanges (50) defining a respective one of the plurality of first openings (44), wherein at least one of the plurality of first openings (44) is in fluid communication with the plurality of reactant channels (24b, 26b); and a plurality of beads (42) disposed on the working surface (36, 36a, 36b), each of the plurality of beads (42) disposed around a respective one of the plurality of first openings (44), thereby defining a respective one of the plurality of flanges (50), each of the plurality of beads (42) defining a shape comprised of bead corners (108) and bead sides (106), each bead corner (108) defining an angle (α), each of the plurality of beads (42) having a sealing surface (46) thereon, the sealing surface (46) being configured to flex when subjected to contact pressure to thereby provide a substantially fluid-tight seal; a component abutting the plate (12, 20, 22), the component including a plurality of second openings (44) therethrough, each of the plurality of second openings (44) being aligned with a respective one of the plurality of first openings (44); and a compression element (16) configured to exert a compression force on the plate to thereby generate the contact pressure, characterized by , that each respective angle (α) lies between 50° and 70°. [5] The system of claim 4, wherein the component further comprises: a second working surface (36b) having a plurality of second beads (42) arranged thereon, each of the plurality of second beads (42) being arranged around a respective one of the plurality of second openings (44), wherein each of the plurality of second beads (42) defines the shape. [6] The system of claim 5, wherein the second work surface (36b) is disposed proximate the work surface (36, 36a, 36b); wherein each of the plurality of second beads (42) includes a second sealing surface (46) thereon; and wherein the component abuts the plate (12, 20, 22) when the second sealing surface (46) contacts the sealing surface (46) to create the contact pressure therebetween. [7] The system of claim 4, wherein the bead corners (108) are configured to produce a contact pressure variation of less than 30% along the sealing surface (46). [8] Fuel cell stack (10) comprising: a first plate (12, 20, 22) with: a first working surface (36, 36a, 36b) defining a plurality of first reactant channels (24b, 26b) thereon; and a first manifold section (40, 40a, 40b) arranged in a peripheral region of the first plate (12, 20, 22), the first manifold section (40, 40a, 40b) comprising: a plurality of first flanges (50) disposed thereon, the plurality of first flanges (50) defining a plurality of first openings (44) through the first plate (12, 20, 22), each of the plurality of first flanges (50) defining a respective one of the plurality of first openings (44), at least one of the plurality of first openings (44) being in fluid communication with the plurality of first reactant channels (24b, 26b); and a plurality of first beads (42) disposed on the first working surface (36, 36a, 36b), each of the plurality of first beads (42) disposed around a respective one of the plurality of first openings (50), thereby defining a respective one of the plurality of first flanges (50), each of the plurality of first beads (42) defining a shape comprised of bead corners (108) and bead sides (106), each bead edge (108) defining an angle (α), each of the plurality of first beads (42) having a first sealing surface (46) thereon, the first sealing surface (46) being configured to flex, when subjected to a contact pressure to thereby provide a substantially fluid-tight seal; a second plate (12, 20, 22) with: a second working surface (36, 36a, 36b) defining a plurality of second reactant channels (24b, 26b) thereon; and a second manifold section (40, 40a, 40b) arranged in a peripheral region of the second plate (12, 20, 22), the second manifold section (40, 40a, 40b) comprising: a plurality of second flanges (50) disposed thereon, the plurality of second flanges (50) defining a plurality of second openings (44) through the second plate (12, 20, 22), each of the plurality of second flanges (50) defining a respective one of the plurality of second openings (44), at least one of the plurality of second openings (44) being in fluid communication with the plurality of second reactant channels (24b, 26b); and a plurality of second beads (42) disposed on the second working surface (36, 36a, 36b), each of the plurality of second beads (42) disposed around a respective one of the plurality of second openings (44), thereby defining a respective one of the plurality of second flanges (50), each of the plurality of second beads (42) defining the shape consisting of bead corners (108) and bead sides (106), each bead edge (108) defining an angle (α), each of the plurality of second beads (42) having a second sealing surface (46) thereon, wherein the second sealing surface (46) is configured to flex when subjected to contact pressure to thereby provide a substantially fluid-tight seal; a combined electrode assembly (14) disposed between the first plate (12, 20, 22) and the second plate (12, 20, 22), the combined electrode assembly (14) having a first side contacting the plurality of first reactant channels (24b, 26b) and a second side contacting the plurality of second reactant channels (24b, 26b); and a compression element (16) configured to exert a compression force on the first plate (12, 20, 22), the second plate (12, 20, 22) and the combined electrode assembly (14), wherein the compression force is configured to exert the contact pressure on the plurality of first beads (42) and the plurality of second beads (42), characterized by , that each respective angle (α) lies between 50° and 70°.

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