Fuel cell assembly with an external manifold for parallel flow

Abstract

A fuel cell single cell is provided, which includes an anode configured to receive an anode process gas and allow the anode process gas to pass through, a cathode configured to receive a cathode process gas and allow the cathode process gas to pass through, and an electrolyte matrix layer separating the anode and the cathode. One of the anode and the cathode has a protruding edge sealing chamber, and the fuel cell single cell is configured to receive the anode process gas and the cathode process gas in directions substantially perpendicular to each other, and the protruding edge sealing chamber is configured to allow the anode process gas and the cathode process gas to pass through the anode and the cathode in substantially parallel flow paths.

Description

Field of the Invention

[0001] The present application generally relates to the field of fuel cell assemblies, and more particularly to a fuel cell assembly having an external manifold that provides anode and cathode feed gases flowing in a parallel direction. Background Art

[0002] Conventional fuel cell stack assemblies may be formed from a plurality of fuel cell monoliths, each fuel cell monolith having an anode layer and a cathode layer separated by an electrolyte layer. The plurality of fuel cell monoliths may be arranged to form a fuel cell stack. Each anode layer includes an anode inlet (i.e., one end face of the fuel cell stack) and an opposite anode outlet (i.e., the opposite end face of the fuel cell stack), and the anode feed gas passes through the anode layer from the anode inlet to the anode outlet in a first direction. Similarly, each cathode layer includes a cathode inlet (i.e., the other end face of the stack) and an opposite cathode outlet (i.e., the opposite end face of the stack), and the cathode feed gas passes through the cathode layer from the cathode inlet to the cathode outlet in a second direction perpendicular to the first direction. The perpendicular flow of the anode feed gas and the cathode feed gas creates a two-dimensional distribution of current within the fuel cell monolith. For example, the current may be highest at the corners near both the anode inlet and the cathode inlet (due to increased gas concentration) and lowest at the corners near the anode outlet and the cathode outlet (due to reduced electrochemical activity). Then, the two-dimensional distribution of current changes in both the first and second directions, making it difficult to optimize the flow of the anode and cathode feed gases to reduce the variation in the current flowing through each fuel cell monolith.

[0003] Standard vertical flow or cross-flow configurations create two-dimensional current across the cell monolith surface, which in turn induces two-dimensional thermal gradients. Due to different thermal expansions, this thermal gradient - where one corner is cooler than the average temperature of the flow field and the other corner is warmer than the average temperature of the flow field - is problematic when many cell monoliths are stacked. The hot corners / sides grow more than the cold corners / sides, resulting in stack deformation, tilting, and bending because the cell monoliths are no longer planar. This deformation also introduces contact losses and changes the local compression of the cell monoliths in different regions. The taller the stack, the more pronounced this effect becomes. It would be advantageous to provide a fuel cell assembly that provides anode and cathode feed gases flowing in a parallel direction in order to provide a one-dimensional distribution of current and thus a one-dimensional thermal gradient. If achieved, the cell monoliths within the stack would remain substantially flat, enabling better contact, more predictable movement, and reducing the challenge of maintaining uniform stack compression. Summary of the Invention

[0004] According to the present invention, a fuel cell stack is provided, which includes a plurality of fuel cell monomers. The fuel cell monomers have an anode and a cathode separated by an electrolyte matrix layer, and one of the anode and the cathode has a protruding edge sealing chamber. The protruding edge sealing chamber is configured such that during operation, when the anode process gas and the cathode process gas are supplied to the fuel cell stack in directions substantially perpendicular to each other, these process gases can flow through the fuel cell monomers substantially in parallel.

[0005] According to an embodiment of the present invention, a fuel cell monomer for a fuel cell stack is provided. The fuel cell monomer has: a first layer having an active area configured to receive and output a first process gas; a second layer configured to receive and output a second process gas; and an electrolyte matrix layer separating the first layer and the second layer. The first layer includes an edge sealing chamber (a protruding edge sealing chamber) that extends outwardly from the stack end face in a cantilever manner beyond the active areas located on opposite sides of the fuel cell monomer. The protruding edge sealing chamber is configured to receive the first process gas supplied to the fuel cell stack in a first direction relative to the fuel cell stack and output the first process gas to the active area in a second direction substantially perpendicular to the first direction and substantially parallel to the second process gas. The active area is configured to allow the first process gas to react with the second process gas. The two gases in the active area flow substantially parallel to each other.

[0006] On the other hand, the second layer is configured to receive and output the second process gas in a direction substantially parallel to the second direction.

[0007] On the other hand, the first layer includes a turning surface configured to receive the first process gas and turn the first process gas into the protruding edge sealing chamber.

[0008] According to another embodiment of the present invention, a fuel cell monomer for a fuel cell stack is provided. The fuel cell monomer has: an anode layer having an anode active area configured to receive and output an anode process gas; a cathode layer configured to receive and output a cathode process gas; and an electrolyte matrix layer separating the anode layer and the cathode layer. The anode layer includes a first protruding edge sealing chamber extending away from the anode active area on a first side of the fuel cell monomer. The first protruding edge sealing chamber is configured to receive the anode process gas supplied to the fuel cell stack in a first direction relative to the fuel cell stack and output the anode process gas to the anode active area in a second direction substantially perpendicular to the first direction. The anode active area is configured to allow the anode process gas to react with the cathode process gas.

[0009] On the other hand, the fuel cell unit includes a second protruding edge seal chamber extending away from the anode active area on a side of the fuel cell unit opposite to the first side, wherein the second protruding edge seal chamber is configured to receive the anode process gas in the second direction and redirect the anode process gas in a first direction with respect to the fuel cell stack.

[0010] On the other hand, the cathode layer is configured to receive the cathode process gas in a direction substantially parallel to the second direction.

[0011] On the other hand, the cathode layer is configured to output the cathode process gas in a direction substantially parallel to the second direction.

[0012] On the other hand, the anode layer includes a first redirecting surface configured to receive the anode process gas in the first direction and redirect the anode process gas towards the first protruding edge seal chamber.

[0013] On the other hand, the anode layer includes a second redirecting surface configured to receive the anode process gas from the second protruding edge seal chamber and redirect the anode process gas in the first direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram of a fuel cell unit.

[0015] Figure 2 is a perspective view of a conventional fuel cell stack.

[0016] Figure 3 is a perspective view of a fuel cell stack according to an exemplary embodiment.

[0017] Figure 4A is a top plan view of a fuel cell assembly according to an exemplary embodiment.

[0018] Figure 4B is a top plan view of a fuel cell assembly according to another exemplary embodiment.

[0019] Figure 4C is Figure 4A a top plan view of the cathode layer of the fuel cell assembly shown in

[0020] Figure 4D is Figure 4A a top plan view of the anode layer of the fuel cell assembly shown in

[0021] Figure 5 shows the current distribution in a conventional fuel cell assembly with bipolar plates that provide an anode feed gas flow perpendicular to the cathode feed gas flow.

[0022] Figure 6 Shows the current distribution in a fuel cell assembly having a bipolar plate that provides an anode feed gas flow parallel to the cathode feed gas flow. Detailed Description

[0023] Figure 1 Shows a schematic view of a fuel cell single cell 1. The fuel cell single cell 1 includes an electrolyte matrix 2, an anode 3, and a cathode 4. The anode 3 and the cathode 4 are separated from each other by the matrix 2. An oxidant (e.g., air or exhaust gas from a combustion exhaust supply unit) is supplied to the cathode 4. A fuel gas (e.g., a hydrocarbon gas) is supplied to the anode 3. In the fuel cell single cell 1, in the cathode, CO2 and O2 in the form of CO3= ions are transferred from the cathode to the anode, and an electrochemical reaction occurs between the fuel gas and the oxidant gas under the action of an electrolyte (e.g., a carbonate electrolyte) present in the pores of the electrolyte matrix 2.

[0024] Referring to Figure 2 , a conventional fuel cell stack 10 includes a plurality of fuel cell single cells 11, each fuel cell single cell having an anode layer 12 (including an anode electrode and an anode flow chamber / collector not shown) and a cathode layer 14 (including a cathode electrode and a cathode flow chamber / collector not shown), wherein the fuel cell single cells are stacked on top of each other. The fuel cell stack 10 includes an anode inlet side (or stack end face) 16 configured to receive an anode feed gas and an opposing anode outlet side (or stack end face) 18 configured to output the anode exhaust after the anode exhaust has passed through the anode layer 12. The anode feed gas can be provided via an external manifold (anode inlet manifold) 116 that seals against the anode inlet stack end face 16. For reference purposes, Figure 2 the external manifold shown in has been removed from the fuel cell stack 10. More specifically, during operation, the external manifold (e.g., the anode inlet manifold 116) will seal against the corresponding fuel cell stack end face. The anode exhaust can be received by another external manifold (anode outlet manifold 118) that seals against the anode outlet stack end face 18. The fuel cell stack 10 also includes a cathode inlet side (or stack end face) 20 configured to receive a cathode feed gas and an opposing cathode outlet side (or stack end face) 22 configured to output the cathode exhaust after the cathode exhaust has passed through the cathode layer 14. The cathode feed gas can be provided via an external manifold (cathode inlet manifold 120) that seals against the cathode inlet stack end face 20. The cathode exhaust can be received by another external manifold (cathode outlet manifold 122) that seals against the cathode outlet stack end face 22. In some embodiments, at least three of the four stack end faces can have an external manifold that seals against each stack end face. For example, the fuel cell stack can be housed in a sealed housing (e.g., a module), and the anode inlet side, the anode outlet side, and the cathode inlet side can be sealed with external manifolds. The cathode outlet side in this example can lead to the sealed housing.

[0025] In Figure 2 the fuel cell stack 10 shown, the anode feed gas flows in a generally linear direction from the anode inlet stack end face 16 through each anode layer 12 to the anode outlet stack end face 18. (As used herein, "generally linear" means that most of the volume of the gas flows in a particular direction.) Similarly, the cathode feed gas flows in a generally linear direction from the cathode inlet stack end face 20 through the cathode layer 14 to the cathode outlet stack end face 22. The anode and cathode feed gases flow generally perpendicular to each other when they are within the stack (i.e., most of the volume of the anode feed gas flows in a first direction and most of the volume of the cathode feed gas flows in a second direction generally perpendicular to the first direction) (also referred to as "cross flow"). Because of this, the current density may be highest at the corners at the intersection (region I) of the anode inlet side 16 and the cathode inlet side 20 of the fuel cell stack 10 and varies non-linearly in the direction in which each of the anode feed gas stream and the cathode feed gas stream passes through the fuel cell assembly 11. Therefore, it would be advantageous to reorient the anode feed gas and the cathode feed gas relative to each other within the stack such that the anode and cathode flows pass through the fuel cell stack 10 in a generally parallel configuration (also referred to as "parallel flow", "cocurrent flow" or "countercurrent flow").

[0026] The present invention allows two process gas mixtures to flow generally parallel within a four-sided fuel cell stack, where the two process gas mixtures are supplied and removed from the stack in directions generally perpendicular to each other. In other words, the present invention allows generally parallel flow within the fuel cell stack without significantly altering the process gas delivery to and from the fuel cell stack (i.e., having external manifolds) as described with respect to Figure 2 the fuel cell stack.

[0027] Now referring to Figure 3, the fuel cell stack 200 shows how the anode feed gas passes through the corners of the fuel cell stack 200 to be redirected to be generally parallel to the cathode feed gas, and the anode exhaust is again redirected to be generally perpendicular to the cathode exhaust output. (For ease of reference, the arrows labeled "A" represent the flow path of the anode process gas, and the arrows labeled "C" represent the flow path of the cathode process gas). The fuel cell stack 200 includes a plurality of fuel cell assemblies 211, each fuel cell assembly having an anode layer 208 and a cathode layer 210, wherein the fuel cell cells are stacked on top of each other and separated from each other by a steel separator sheet (e.g., bipolar plate). Note that the top surface of the topmost fuel cell assembly 211 has been removed to show the flow path within this fuel cell assembly. It should be understood that, in addition to the porous active region (anode active region) 213 of the anode electrode, the anode layer 208 of each fuel cell assembly 211 is additionally a sealed chamber having a single inlet (partial anode inlet 216 discussed below) and a single outlet (partial anode outlet 218 discussed below). As used herein, an "active region" is a region on a fuel cell layer (anode, cathode) that is configured to allow selective diffusion of molecules in the process gas to diffuse therethrough, i.e., the feed gas undergoes an electrochemical reaction in the active region. In other words, both the leading and trailing edges of both the anode and cathode of the fuel cell cell have narrow non-active regions that correspond to the wet seals between adjacent cell cells above and below the fuel cell cell. The feed gas passes through the wet seal without undergoing an electrochemical reaction. The remaining regions of the fuel cell cell - which overlap and are common to both the anode and cathode layers - are affected by electrochemical activity and are referred to as the "active region". Similarly, in addition to the porous active cathode electrode (not shown), the cathode layer 210 of each fuel cell assembly 211 is additionally a sealed chamber having a cathode inlet 226 and a cathode outlet 228. It should be further noted that the side wall portions of the fuel cell assembly 211 have been removed to show the flow path through the cathode layer of the topmost fuel cell assembly 211 (as well as the flow paths of the anode and cathode layers of the fuel cell assembly 211 directly below the topmost fuel cell assembly 211). It should be further noted that the enumerated features corresponding to the topmost fuel cell assembly 211 may be referenced, but such enumerated features may apply to other fuel cell assemblies 211 included in the fuel cell stack 200.

[0028] It should be noted that the fuel cell assembly 211 described herein includes an anode layer 208 and a cathode layer 210 separated by an electrolyte matrix layer, and the steel separator forms the upper and lower surfaces of the fuel cell assembly. However, in other embodiments, the first fuel cell assembly may include an anode layer 208 and a cathode layer 210 separated by a steel separator, and the anode forms the first surface (e.g., the upper surface), while the cathode forms the second surface (e.g., the lower surface). When a second fuel cell assembly (having the same components as the first fuel cell assembly) is stacked on top of or below the first fuel cell assembly and the two fuel cell assemblies are separated by an electrolyte matrix layer, a single functional fuel cell unit is formed. In other words, a single fuel cell unit is formed when the cathode of the first fuel cell assembly communicates with the electrolyte matrix, and the electrolyte matrix communicates with the anode of the second fuel cell assembly.

[0029] Although Figure 3 three fuel cell assemblies 211 are shown, the present invention is not limited thereto, and the fuel cell stack may include more or fewer fuel cell assemblies. Each fuel cell assembly 211 includes two protruding edge seal chambers 236, 246, namely a first protruding edge seal chamber 236 (e.g., the upstream protruding edge seal chamber) located on the first side of the fuel cell assembly and a second protruding edge seal chamber 246 (e.g., the downstream protruding edge seal chamber) located on the opposite side of the fuel cell assembly. As Figure 3 shown, the protruding edge seal chambers extend outwardly from the stack end face in a cantilever manner beyond the active regions on opposite sides of the fuel cell element.

[0030] Similar to Figure 2 the fuel cell stack 10 depicted in Figure 3 the fuel cell stack 200 (in Figure 3 ) includes an anode inlet side (or stack end face) 212 and an opposite anode outlet side (or stack end face) 214 that is substantially parallel to the anode inlet side 212. However, unlike the anode inlet stack end face 16 of the fuel cell stack 10 that includes a substantially open end face / inlet for the anode feed gas to enter each fuel cell element, the anode inlet stack end face 212 is not so open, and each fuel cell assembly 211 includes a first partial seal 212a and a partial anode inlet 216. In one exemplary embodiment, an external manifold seals against the anode inlet stack end face 212 (not shown), and the anode feed gas provided in the external manifold (not shown) enters the anode section of the fuel cell via the partial anode inlet 216. Similarly, unlike the anode outlet stack end face 18 of the fuel cell stack 10 that includes a substantially open end face / exit (not shown) for the anode exhaust gas to leave each fuel cell element, the anode outlet stack end face 214 is not so open, and each fuel cell assembly 211 includes a second partial seal 214a and a partial anode outlet 218.

[0031] During operation of the fuel cell stack 200, each anode layer 208 is configured to receive anode feed gas at the anode inlet side 212 of the fuel cell stack 200, e.g., via an external manifold (not shown), from an anode feed gas supply source (i.e., source), and to output anode exhaust gas at the anode outlet side 214 of the fuel cell stack 200, e.g., via another external manifold (not shown), after the anode feed gas has reacted with the cathode feed gas in the fuel cell stack 200. Specifically, each anode layer 208 includes a partial anode inlet 216 (i.e., anode inlet opening) formed only in a portion of the anode inlet side 212 at an upstream portion of the anode layer 208. Each anode layer 208 further includes a partial anode outlet 218 (i.e., anode outlet opening) formed only in a portion of the anode outlet side 214 at a downstream portion of the anode layer 208.

[0032] The fuel cell stack 200 further includes a cathode inlet side (or stack end face) 222 and an opposing cathode outlet side (or stack end face) 224 that is generally parallel to the cathode inlet side 222. In some embodiments, the cathode layer 210 is structurally similar to Figure 2 the cathode layer 14 of the fuel cell stack 10 depicted in and operates similarly thereto. In other words, in some embodiments, the cathode feed gas may flow from the cathode inlet stack end face 222 through the cathode layer 210 in a generally linear direction to the cathode outlet stack end face 224. As Figure 3 shown, it should be appreciated that the first protruding edge seal chamber 236 (at the anode layer 208) overhangs the cathode inlet 226. Additionally, a plurality of the first protruding edge seal chambers 236 form a series of cantilevered protrusions along the cathode inlet stack end face 22. Similarly, a plurality of second protruding edge seal chambers 246 form a series of cantilevered protrusions along the cathode outlet stack end face 224.

[0033] During operation of the fuel cell stack 200, each cathode layer 210 is configured to receive cathode feed gas at the cathode inlet side 222 of the fuel cell stack 200, e.g., via an external manifold (not shown), from a cathode feed gas supply source (i.e., a source), and to output cathode exhaust gas at the cathode outlet side 224 of the fuel cell stack 200, e.g., via an external manifold (not shown), after the cathode feed gas has reacted with the anode feed gas in the fuel cell stack 200. Specifically, each cathode layer 210 includes a cathode inlet 226 (i.e., a cathode inlet opening) formed in the cathode inlet side 222 at an upstream portion of the cathode layer 210. Each cathode layer 210 further includes a cathode outlet 228 (i.e., a cathode outlet opening) formed in the cathode outlet side 224 at a downstream portion of the cathode layer 210. According to one exemplary embodiment, the cathode inlet 226 and the cathode outlet 228 may extend substantially along the entire width of the cathode layer 210, although according to other exemplary embodiments, the cathode inlet 226 and / or the cathode outlet 228 may extend only along a portion of the width of the cathode layer 210.

[0034] As Figure 3 shown, along a generally parallel flow path through the fuel cell unit and the fuel cell stack, the anode feed gas is supplied to the anode layer 208 and the anode exhaust gas is output from the anode layer 208. For example, the anode feed gas is supplied from an anode inlet manifold (not shown) to the anode layer 208 along a streamline generally perpendicular to the anode inlet stack end face 212. The anode feed gas supplied through the partial anode inlet 216 is redirected by an anode inlet diverter (diverting surface) 252 to pass through the first protruding edge seal chamber 236 and return to the anode active region 213 of the fuel cell assembly 211, becoming a flow generally parallel to the cathode feed gas flow, then entering the second protruding edge seal chamber 246, and then being output through the partial anode outlet 218. It should be understood that a first side of the anode outlet diverter (another diverting surface) 266 redirects a portion of the anode gas traveling through the active anode section to enter the second protruding edge seal chamber 246 and a second side of the anode outlet diverter 266 may redirect the anode gas traveling through the second protruding edge seal chamber 246 to pass through the partial anode outlet 218.

[0035] In the above configuration, the anode exhaust gas is diverted into a streamline flowing generally perpendicular to the anode outlet stack end face 214 of the fuel cell stack 200. As Figure 3Further shown, the cathode inlet stack end face 222 and the cathode outlet stack end face 224 are substantially perpendicular to the anode inlet stack end face 212 and the anode outlet stack end face 214 of the fuel cell stack 200. In this configuration, along flow paths that are substantially parallel to each other, cathode feed gas is supplied to the cathode layer 210 and cathode exhaust is output from the cathode layer 210. For example, the cathode feed gas flows along streamlines that are substantially perpendicular to the cathode inlet stack end face 222 and the cathode exhaust flows along streamlines that are substantially perpendicular to the cathode outlet stack end face 224. According to one exemplary embodiment, the cathode feed gas flow through the cathode layer 210 flows between the cathode inlet 226 and the cathode outlet 228 along substantially linear streamlines as it reacts and is converted to cathode exhaust.

[0036] Although Figure 3 the first and second protruding edge seal chambers 236, 246 illustrated in have trapezoidal cover regions that extend away from the anode active region and are defined by one long side wall, two shorter side walls, one top surface, and one bottom surface, it should be understood that the present invention is not limited thereto. The first protruding edge seal chamber 236 can have any size or any shape that encloses a chamber that can receive anode process gas supplied via the partial anode inlet 216 and redirected by the anode inlet diverter 252 and supply the anode process gas to the anode active region 213 via the anode active region inlet 272. Similarly, the second protruding edge seal chamber 246 can have any size or any shape that encloses a chamber that can receive anode process gas supplied via the anode active region outlet 274 and supply the anode process gas via the partial anode outlet 218 (redirected via the anode outlet diverter 266).

[0037] As Figure 3 shown, the anode inlet diverter 252 extends at a non - perpendicular angle with respect to each of the anode inlet side 212 and the cathode inlet side 222 of the fuel cell stack 200. Moreover, as Figure 3 shown, the anode inlet diverter 252 extends in a straight line from the anode inlet side 212 toward the cathode inlet side 222. However, the anode inlet diverter 252 can be curved (concave or convex) or any other shape as long as it redirects the anode process gas supplied via the partial anode inlet 216 into the first protruding edge seal chamber 236. The anode inlet diverter 252 extends vertically along substantially the entire height of the anode layer 208 such that anode feed gas does not enter the remainder of the anode layer 208 above or below the anode inlet diverter 252.

[0038] Similarly, the anode outlet diverter 266 extends at a non - perpendicular angle with respect to each of the anode outlet side 214 and the cathode outlet side 224 of the fuel cell stack 200. Although Figure 3The anode inlet diverter 252 depicted in [Figure] extends in a straight line from the anode outlet side 214 towards the cathode outlet side 224, but the anode inlet diverter 252 can be curved (concave or convex) or any other shape as long as it redirects the anode process gas fed through the second protruding edge seal chamber 236 through the partial anode outlet 218. The anode outlet diverter 266 extends vertically along substantially the entire height of the anode layer 208 such that the anode process gas does not pass above or below the anode outlet diverter 252.

[0039] Returning to Figure 2 , it should be understood that as the process gas flows through the fuel cell unit, the composition of the gas will change as it travels through the fuel cell unit and reacts with another process gas in the fuel cell unit. Thus, the composition of the anode process gas flowing through the ( Figure 2 ) fuel cell stack 10 of [Figure] changes as it travels from the anode inlet side 16 of the stack to the anode outlet side 18. However, the composition of the cathode process gas entering the fuel cell stack 10 is uniformly distributed along the width of the cathode layer 14 (measured from the anode inlet side 16 to the anode outlet side 18 of the fuel cell stack 10). In contrast, during the operation of the embodiment shown in Figure 3 , the anode process gas enters the anode active region 213 through the active anode inlet 272 rather than through an opening across the anode inlet side 212 of the fuel cell stack 200 (as shown in Figure 2 ). Similar to the ( Figure 2 ) fuel cell stack 10, the cathode process gas enters the fuel cell stack 200 with a substantially uniform flow distribution (at the cathode inlet side 222) along the entire width of the cathode layer 210 (measured from the anode inlet side 212 to the anode outlet side 214 of the fuel cell stack 200). Thus, the composition of the anode process gas entering the anode active region 213 and the composition of the cathode process gas entering the cathode layer 210 are substantially uniform across the entire width of the fuel cell stack 200 (measured from the anode inlet side 212 to the anode outlet side 214 of the fuel cell stack 200). As will be discussed below, the uniform composition distribution of the process gas entering the stack in a substantially parallel manner (along the width of the cathode inlet) results in a more uniform distribution of the current density across the cathode inlet span, rather than a higher current density near the anode inlet side 16 and the cathode inlet side 20 ( Figure 2 Region I) of the stack 10 and a lower current density away from the inlet.

[0040] Figure 4Ais a top plan view of a fuel cell stack 200, in which the top surface of the anode layer 208 (of the topmost fuel cell assembly 211) is removed to show (a) anode feed gas entering the anode active area 213 from a first protruding edge seal chamber 236, and (b) anode exhaust exiting the anode active area 213 and entering a second protruding edge seal chamber 246. The anode process gas (which enters as anode feed gas and exits as anode exhaust) flows through the anode active area in a generally linear fashion parallel to the cathode process gas flow through the cathode layer 210 of the fuel cell assembly 211. As described above, this flow arrangement can be described as co-current flow.

[0041] Figure 4B Depicts the anode process gas flow through the fuel cell assembly in a counter-current direction. Figure 4B is a top plan view of a fuel cell stack 300, in which the top surface of the anode layer 308 (of the topmost fuel cell assembly 311) is removed. Similar to the fuel cell stack 200 and the fuel cell assembly 211, the anode process gas enters the fuel cell stack 300 / fuel cell assembly 311 from the anode inlet side, which is perpendicular to the side where the cathode process gas enters. The anode process gas exits the side opposite the anode inlet side and the cathode process gas exits the side opposite the cathode inlet side. The anode process gas enters the anode inlet side of the fuel cell assembly 311 via a partial anode inlet 316, which is similar to the partial anode inlet 216 (for the fuel cell assembly 211). However, the partial anode inlet 316 is close to the stack corner between the anode inlet side and the cathode outlet side of the fuel cell stack 300. While the partial anode inlet 216 (for the fuel cell assembly 211) is close to the stack corner between the anode inlet side and the cathode inlet side of the fuel cell stack 200. After entering the fuel cell assembly 311, the anode process gas is redirected (by an anode inlet diverter 352) to a first protruding edge seal chamber 326 (located on the cathode outlet side of the fuel cell assembly 311) and further redirected into the anode active area 313. The reacted anode process gas exits the anode active area 313 and enters a second protruding edge seal chamber 346, and is redirected towards an anode outlet diverter 366 and an anode partial outlet 318. In this configuration, the anode process gas flows through the anode active area 313 in a direction generally parallel but opposite to the cathode process gas through the cathode layer of the fuel cell assembly 311.

[0042] In either flow configuration (co-current or counter-current), each of the anode feed gas and the cathode feed gas is distributed generally uniformly across the fuel cell stack in a lateral direction from the anode inlet side to the anode outlet side, thereby providing a one-dimensional distribution of current density across the fuel cell stack (measured from the cathode inlet to the cathode outlet).

[0043] It should be understood thatFigure 4A the co - flow configuration depicted in Figure 4B and the counter - flow configuration depicted in Figure 2 can employ the same external manifold arrangement as described in the text with respect to the fuel cell stack 10 (shown in Figure 4A . Alternatively, a counter - flow configuration can be achieved by rearranging the direction of the anode process gas through the fuel cell stack (e.g., switching the anode inlet manifold with the anode outlet manifold) or by rearranging the direction of the cathode process gas through the fuel cell stack (e.g., switching the cathode inlet manifold with the cathode outlet manifold) using the embodiments of

[0044] Figure 4C is a top - plan view of the cathode layer 210 (of the fuel cell assembly 211) where the cathode electrode has been removed to show the cathode active area 2113. During operation, the cathode process gas travels through the cathode active area 2113 in a generally linear path from the cathode inlet side to the cathode outlet side. The first cathode edge seal 2115 prevents the cathode process gas from entering the anode inlet side of the fuel cell assembly 211, e.g., the anode inlet manifold (not shown). The second cathode edge seal 2117 prevents the cathode process gas from entering the anode outlet side of the fuel cell assembly 211, e.g., the anode outlet manifold (not shown).

[0045] Figure 4D is a top - plan view of the anode layer 208 (of the fuel cell assembly 211) where a major portion of the top surface covers the anode active area 313 and the protruding edge seal chambers 236, 246. During operation, as described in detail above, the anode process gas enters the first protruding edge seal chamber 236 and travels through the anode active area 313 in a generally linear path from the cathode inlet side to the cathode outlet side of (the fuel cell assembly 211). When the anode process gas travels from the partial anode inlet 216 to the first protruding edge seal chamber 236 and the anode active area 313, the first anode edge seal 3115 prevents the anode process gas from entering the cathode inlet side of the fuel cell assembly 211, e.g., the cathode inlet manifold (not shown). When the anode process gas travels from the anode active area 313 to the second protruding edge seal chamber 246 and the anode partial outlet 218, the second anode edge seal 3117 prevents the anode process gas from entering the cathode outlet side of the fuel cell assembly 211, e.g., the cathode outlet manifold (not shown).

[0046] According to yet another exemplary embodiment, it should be understood that the cathode layer 210 may be constructed in substantially the same manner as and in place of the anode layer 208 such that a protruding edge seal chamber associated with the cathode inlet (e.g., a "cathode inlet chamber" or a first protruding edge seal chamber 236) is provided on the stack side adjacent (and perpendicular) to the cathode inlet side 222 and is configured to cooperate with an inlet diverter in the cathode layer 210 to redirect the cathode feed gas therein to be substantially parallel to the anode feed gas received directly at the anode inlet side 212 of the stack. Similarly, a protruding edge seal chamber associated with the cathode outlet (e.g., a "cathode outlet chamber" or a second protruding edge seal chamber 246) may be provided on the stack side opposite the cathode inlet chamber and is configured to cooperate with an outlet diverter in the cathode layer to redirect the cathode exhaust gas from the fuel cell stack 200.

[0047] Now referring to Figure 5 , a representative distribution of current density on a conventional fuel cell stack 10 is shown, where the contour lines represent the contour lines of the current density of the same value. The contour line 501 represents the highest current density value, and the contour line 502 represents the lowest current density value. It should be understood that the intermediate contour lines between 501 and 502 represent the intermediate current density values at regular intervals. In this configuration, the current has the highest density along the anode inlet side 16 at the corner where the anode inlet side 16 contacts the cathode inlet side 20 (region I). The current density decreases non-linearly in the direction from the anode inlet side 16 to the anode outlet side 18. The current density also decreases non-linearly in the direction from the cathode inlet side 20 to the cathode outlet side 22. The distribution of the current density in each of these two directions provides a two-dimensional current distribution, which makes it difficult to optimize the fuel cell stack 10. It is worth noting that even if most of the fuel cell stack 10 can be optimized to linearize the current distribution, the corner where the anode inlet side 16 contacts the cathode outlet side 22 will experience a significant and sudden current drop, which may damage the performance of the fuel cell stack 10.

[0048] Now referring to Figure 6 , a current density distribution in a fuel cell stack 200 according to an exemplary embodiment is shown, where the contour lines show the contour lines of the current density of the same value. Similar to Figure 5, the isocontour 501 represents the highest current density value, and the isocontour 502 represents the lowest current density value. It should be understood that the intermediate isocontours between 501 and 502 represent intermediate current density values at regular intervals. This configuration can show the current density when both the anode feed gas and the cathode feed gas flow from the cathode inlet side 222 to the cathode outlet side 224 in the fuel cell stack 200. The substantially parallel flow of the anode feed gas and the cathode feed gas provides a substantially constant current density measured in the lateral direction perpendicular to the flow direction. For example, the current density at any given point in the fuel cell stack 200 can move in a direction directly from the anode inlet side 212 towards the anode outlet side 214 substantially identically.

[0049] Figure 5 and 6 The CFD models depicted in represent the current density curves of a conventional fuel cell stack 10 and a typical fuel cell unit within a fuel cell stack 200 according to an exemplary embodiment, where both stacks are operating under a similar total thermal gradient across the cell units. From the illustration, it should be understood that the fuel cell stack 200 has a more uniform and predictable current gradient across the cell units. Additionally, the fuel cell stack 200 is predicted to be able to generate a generally higher total current than the conventional fuel cell stack 10 when operating under a similar total thermal gradient across the fuel cell units. This is possible because the fuel cell stack 200 provides the longest leading-edge interface shared by the highest concentration of cathode gas and anode gas, creating a larger high-current density region (near the cathode inlet side 222, see Figure 5 the 501 in) compared to the single corner location (Region I, see Figure 6 the 501 in) in the conventional fuel cell stack 10 where both reactants are at their highest concentration. Specifically, the highest current density can be established at the location where the anode feed gas and the cathode feed gas are first introduced to opposite sides of the electrolyte matrix and the current density decreases as the feed gases react and are converted to exhaust gases. The substantially parallel flow paths of the anode feed gas and the cathode feed gas that form a one-dimensional distribution of the current density increase the surface area of the initial reaction of the anode feed gas and the cathode feed gas in the fuel cell stack 200 because, in the fuel cell stack 200, the feed gases react along substantially the entire length of the cathode inlet side 222 of the fuel cell stack 200 rather than only at the corners.

[0050] Additional embodiments

[0051] Example 1. A fuel cell single cell, comprising: an anode configured to receive an anode process gas and allow the anode process gas to pass therethrough, a cathode configured to receive a cathode process gas and allow the cathode process gas to pass therethrough, and an electrolyte matrix layer separating the anode and the cathode, wherein one of the anode and the cathode has a protruding edge seal chamber, wherein the fuel cell single cell is configured to receive the anode process gas and the cathode process gas in directions substantially perpendicular to each other, and wherein the protruding edge seal chamber is configured to allow the anode process gas and the cathode process gas to pass through the anode and the cathode in substantially parallel flow paths.

[0052] Example 2. A fuel cell stack, comprising fuel cell single cells, the fuel cell single cells comprising: a first layer having an active region configured to receive and output a first process gas; a second layer configured to receive and output a second process gas; and an electrolyte matrix layer separating the first layer and the second layer, wherein the first layer includes a protruding edge seal chamber extending away from the active region on a first side of the fuel cell single cell, wherein the protruding edge seal chamber is configured to receive a first process gas supplied to the fuel cell stack in a first direction with respect to the fuel cell stack and output the first process gas to the active region in a second direction substantially perpendicular to the first direction, and wherein the active region is configured to allow the first process gas to react with the second process gas.

[0053] Example 3. The fuel cell stack according to Example 2, wherein the second layer is configured to receive and output the second process gas in a direction substantially parallel to the second direction.

[0054] Example 4. The fuel cell stack according to Example 2 or 3, wherein the first layer includes a turning surface configured to receive the first process gas and turn the first process gas to the protruding edge seal chamber.

[0055] Example 5. A fuel cell unit for use in a fuel cell stack, the fuel cell unit including an anode layer having an anode active region configured to receive and output an anode process gas, a cathode layer configured to receive and output a cathode process gas, and an electrolyte matrix layer separating the anode layer and the cathode layer, wherein the anode layer includes a first protruding edge seal chamber extending away from the anode active region on a first side of the fuel cell unit, wherein the first protruding edge seal chamber is configured to receive the anode process gas supplied to the fuel cell stack in a first direction with respect to the fuel cell stack and output the anode process gas to the anode active region in a second direction substantially perpendicular to the first direction, and wherein the anode active region is configured to allow the anode process gas to react with the cathode process gas.

[0056] Example 6. The fuel cell unit according to Example 5, wherein the fuel cell unit further includes: a second protruding edge seal chamber extending away from the anode active region on a side of the fuel cell unit opposite to the first side, wherein the second protruding edge seal chamber is configured to receive the anode process gas in the second direction and redirect the anode process gas to the first direction with respect to the fuel cell stack.

[0057] Example 7. The fuel cell unit according to Example 5 or 6, wherein the cathode layer is configured to receive the cathode process gas in a direction substantially parallel to the second direction.

[0058] Example 8. The fuel cell unit according to any one of Examples 5-7, wherein the cathode layer is configured to output the cathode process gas in a direction substantially parallel to the second direction.

[0059] Example 9. The fuel cell unit according to any one of Examples 5-8, wherein the anode layer includes a first turning surface configured to receive the anode process gas in the first direction and redirect the anode process gas towards the first protruding edge seal chamber.

[0060] Example 10. The fuel cell unit according to any one of Examples 5-9, wherein the anode layer includes a second turning surface configured to receive the anode process gas from the second protruding edge seal chamber and redirect the anode process gas along the first direction.

[0061] As used herein, the terms "about," "approximately," "substantially," and similar terms are intended to have a broad meaning consistent with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Those of ordinary skill in the art who review this disclosure should understand that these terms are intended to allow the description of certain features being described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted to indicate that non-substantive or immaterial modifications or variations of the subject matter being described and claimed are considered to be within the scope of this disclosure as set forth in the appended claims.

[0062] It should be noted that the term "exemplary" as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and / or illustrations of possible embodiments (and such term is not intended to imply that such embodiments are necessarily superior or the best examples).

[0063] The terms "coupled," "connected," etc. as used herein mean that two components are joined to each other directly or indirectly. Such joining can be stationary (e.g., permanent) or movable (e.g., removable or releasable). Such joining can be achieved by the two components or the two components and any additional intermediate component or components that are integrally formed as a single unit with each other or attached to the two components.

[0064] References herein to the position of elements (e.g., "top," "bottom," "above," "below," etc.) are for purposes of describing the orientation of the various elements in the drawings only. It should be noted that, in accordance with other exemplary embodiments, the orientation of the various elements can be different, and such variations are intended to be covered by this disclosure.

[0065] It should be understood that although the invention has been described in terms of its preferred embodiments, those skilled in the art can conceive of various other embodiments and variations that are within the scope and spirit of the invention, and such other embodiments and variations are intended to be covered by the corresponding claims. Those skilled in the art will readily appreciate that many modifications are possible (e.g., the size, dimensions, structure, shape and proportions of various elements, the values of parameters, the mounting arrangements, the use of materials, colors, orientations, manufacturing processes, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. For example, the order or sequence of any process or method steps can be changed or re-ordered according to alternative embodiments. Other substitutions, modifications, changes, and omissions can also be made in the design, operation, adjustment, and arrangement of the various exemplary embodiments without departing from the scope of the invention.

Claims

1. A fuel cell single cell, comprising: An anode (208), the anode including a partial anode inlet (216) located on the anode inlet side (212) of the fuel cell single cell, a first protruding edge seal chamber (236), a second protruding edge seal chamber (246), and an anode active area (213), wherein the anode inlet side (212) is perpendicular to the cathode inlet side (222) and the cathode outlet side (224), wherein the first protruding edge seal chamber is located outside the anode active area (213) and on the cathode inlet side, the second protruding edge seal chamber (246) is located outside the anode active area and on the cathode outlet side (224), and wherein the first protruding edge seal chamber is in fluid communication with the anode inlet (216) and the anode active area inlet (272), wherein the anode active area inlet (272) is located on the cathode inlet side (222), and the anode active area outlet (274) is located on the cathode outlet side (224); A cathode (210), the cathode including a cathode inlet (226) located on the cathode inlet side (222) of the fuel cell single cell, a cathode active area, and a cathode outlet (228) located on the cathode outlet side of the fuel cell single cell, wherein the cathode outlet side (224) and the cathode inlet side (222) are opposite sides of the fuel cell single cell; and An electrolyte matrix layer (2) separating the anode and the cathode, wherein the first protruding edge seal chamber (236) is configured to allow anode process gas and cathode process gas to pass through the anode active area inlet (272) and the cathode inlet (226) in substantially parallel flow paths, wherein the anode active area inlet (272) and the cathode inlet (226) are substantially parallel.

2. A fuel cell stack, which comprises: A cathode input manifold (120) near the cathode inlet side (20) of the fuel cell stack; An anode input manifold (116) near the anode inlet side (16) of the fuel cell stack, the anode inlet side being perpendicular to the cathode inlet side; A cathode output manifold (122) near the cathode outlet side (22) of the fuel cell stack, the cathode outlet side being opposite to the cathode inlet side and perpendicular to the anode inlet side; Fuel cell single cells, the fuel cell single cells comprising: A partial anode inlet, a first protruding edge seal chamber, and an anode active region located on the anode inlet side (16) of the fuel cell stack, the partial anode inlet being in fluid communication with the anode manifold and the first protruding edge seal chamber, the first protruding edge seal chamber being located outside the anode active region and on the cathode inlet side, a second protruding edge seal chamber being located outside the anode active region and on the cathode outlet side, the first protruding edge seal chamber being in fluid communication with the partial anode inlet and the anode active region through an anode active region inlet, wherein the anode active region inlet is located on the cathode inlet side, the anode active region outlet is located on the cathode outlet side, and wherein the anode active region inlet and the cathode inlet are substantially parallel; A cathode including a cathode inlet and a cathode active region; and An electrolyte matrix layer separating the anode and the cathode.

3. The fuel cell stack according to claim 2, wherein, The first protruding edge seal chamber is configured to allow anode process gas and cathode process gas to enter the cathode and the anode along substantially parallel flow paths.

4. The fuel cell stack according to claim 3, wherein, The anode includes a turning surface (252) configured to receive the anode process gas and turn the anode process gas to the first protruding edge seal chamber.

5. A fuel cell single cell for a fuel cell stack, the fuel cell single cell comprising: An anode layer (208) having an anode active region (213) configured to receive anode process gas through an anode active region inlet (272) and output anode process gas through an anode outlet (218); A cathode layer (210) configured to receive cathode process gas from a cathode inlet (226) located on the cathode inlet side (222) of the fuel cell single cell and output the cathode process gas to a cathode outlet (228) located on the cathode outlet side (224) of the fuel cell single cell, wherein the cathode outlet side and the cathode inlet side are opposite; and An electrolyte matrix layer separating the anode layer and the cathode layer, wherein the anode layer includes a first protruding edge seal chamber (236), the first protruding edge seal chamber being a cantilevered protrusion located outside the anode active region and extending away from the anode active region from the cathode inlet side of the fuel cell single cell, wherein the first protruding edge seal chamber is configured to receive anode process gas provided to the fuel cell stack from an external anode manifold located on the anode inlet side of the fuel cell single cell and output the anode process gas through an anode active region inlet (272) located on the cathode inlet side or the cathode outlet side, wherein the anode active region inlet and the cathode inlet (226) are substantially parallel, wherein the anode inlet side is perpendicular to the cathode inlet side and the cathode outlet side, and The anodic active area is configured to allow the anodic process gas to react with the cathodic process gas.

6. The fuel cell single cell according to claim 5, wherein, the fuel cell single cell further comprises: a second protruding edge seal chamber extending away from the anodic active area on a side opposite to the first protruding edge seal chamber, wherein the second protruding edge seal chamber is configured to receive the anodic process gas from the anodic active area.

7. The fuel cell single cell according to claim 6, wherein, the cathode layer is configured to receive the cathodic process gas in a direction substantially parallel to the direction in which the anodic gas enters the anodic active area through the anodic active area inlet.

8. The fuel cell single cell according to claim 7, wherein, the cathode layer is configured to output the cathodic process gas in a direction substantially parallel to the direction in which the anodic gas flows through the anodic active area.

9. The fuel cell single cell according to claim 5, wherein, the anode layer includes a first turning surface configured to receive the anodic process gas from the anodic inlet side and redirect the anodic process gas towards the first protruding edge seal chamber.

10. The fuel cell single cell according to claim 9, wherein, the anode layer includes a second turning surface configured to receive the anodic process gas from the second protruding edge seal chamber and redirect the anodic process gas towards the anode outlet side of the fuel cell single cell, where the anode outlet side is opposite to the anode inlet side.

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