Coolant fluid distribution in a pem fuel cell

Abstract

Aspects of methods, apparatuses, and systems for controlling coolant delivery in a fuel cell stack are disclosed herein. The cathode inlet on the bipolar plate disclosed herein has a variable water channel configured to deliver a uniform amount of water in the cathode flow field in each fuel cell forming the stack.

Description

[0001] Cross-reference of related applications This application is a PCT application that claims priority to UK Patent Application No. 2319823.7, filed on 21 December 2023, the entire contents of which are incorporated herein by reference as if fully set forth herein. Technical Field

[0002] This disclosure relates to the distribution of coolant in a fuel cell stack, and particularly to membrane fuel cells. Background Technology

[0003] A typical fuel cell system includes a fuel cell stack for generating electricity, a hydrogen supply to the fuel cell stack as fuel, an oxygen (air) supply system for supplying oxygen-containing air as an oxidant in the electrochemical reaction, and a thermal management system for removing reaction heat from the fuel cell stack and managing humidity and dehydration within the stack. The fuel cell system generates heat, water, and electricity.

[0004] Each fuel cell assembly has an anode, a cathode, and an electrolyte (electrolyte membrane). Hydrogen is supplied to the anode, and oxygen-containing air is supplied to the cathode. Through the membrane electrode assembly (MEA), hydrogen and oxygen generate electricity, heat, and water.

[0005] A fuel cell stack is formed from multiple such fuel cells, each with its own anode and cathode fluid flow paths. Such stacks are typically block-shaped, comprising multiple individual fuel cell plates held together by endplates at either end of the stack. Importantly, the polymer ion transfer membrane remains hydrated for efficient operation. Controlling the stack's temperature is also crucial. Therefore, a coolant can be supplied to the stack for cooling and / or hydration.

[0006] In a hydrogen fuel cell, hydrogen is supplied to the fuel cell from an external source. Such fuel cells typically include a proton exchange membrane (PEM) sandwiched between electrodes, which together form a membrane electrode assembly (MEA). Traditionally, the MEA itself is sandwiched between the cathode and anode sides.

[0007] A critical consideration in the operation of this type of fuel cell is water management within the system. During PEM fuel cell operation, product water from the reaction between hydrogen and oxygen forms at the catalytic sites of the MEA. This water is generated in one or more of the liquid, gas, and transition phases, depending on temperature and pressure, and must be expelled from the MEA via the cathode diffusion structure while oxygen is being delivered to the cathode surface of the MEA. However, it is equally important that the MEA be properly hydrated to ensure that the cell's internal resistance remains within tolerable limits. Failure to control MEA humidification can lead to hot spots and potential cell failure and / or poor cell performance. The anode and cathode fluid flow field plates may each comprise a rigid conductive material with fluid flow pathways in the surface adjacent to the respective diffusion structure for transporting reactant gases (e.g., hydrogen and oxygen) and removing exhaust gases (e.g., unused oxygen and water vapor).

[0008] A fuel cell stack comprises a series of individual fuel cells arranged in a stack-like configuration. Each fuel cell itself may include various layered components such as a polymer electrolyte membrane, a gas diffusion layer, fluid flow plates, and various sealing gaskets for maintaining fluid tightness and distributing fluid fuel and oxidant to the active surfaces of the membrane. Fluid input and output are guided through flow fields and plates at the fuel cell level and through connecting manifolds at the stack level. Common piping is typically used to supply oxidant and fuel to the fuel cells within the fuel cell assembly that forms the stack.

[0009] In a typical high-power fuel cell arrangement, cooling fluid is injected into and dispersed on the anode or cathode side of the fuel cell. Uneven cooling is suboptimal and affects the uniformity of operation and reduces efficiency.

[0010] High-efficiency PEM fuel cells (PEMFCs) generate heat during operation, and the removal or management of heat from the fuel cell stack is a factor affecting system efficiency. To maintain the temperature within the nominal range while current flows, heat must be reduced or removed. Therefore, there is an urgent need to: (1) reduce uneven heat removal within the fuel cell stack; and (2) reduce uneven cooling of the fuel cell within the stack. Summary of the Invention

[0011] The following description of the implemented embodiments is taken with reference to the accompanying drawings, which form a part thereof, and the drawings illustrate, by way of illustration, specific implementations of the present disclosure that can be utilized. Other implementations may be utilized, and structural changes may be made without departing from the scope of the present disclosure.

[0012] Exemplary implementations for reducing uneven heat removal in fuel cells forming fuel cell stacks are disclosed.

[0013] Exemplary implementations of providing uniform cooling within a fuel cell stack are disclosed.

[0014] Exemplary aspects of an apparatus and method for distributing coolant to cool a fuel cell are disclosed, comprising a cathode cap and a water distribution cap fixed to a bipolar plate, the bipolar plate having a plurality of fluid guides, each fluid guide having a diameter along the length of a first cathode fluid channel in fluid communication with a cathode flow field, and the water distribution cap having a fluid conduit in fluid communication with a plurality of thin streams. Each thin stream has a head connected to the fluid conduit and a tail end configured to align with at least a portion of the plurality of fluid guides fixed to the cathode cap. In some cases, each thin stream has a body between the head and the tail. In some cases, at least two thin stream bodies have different lengths between the head and the tail. In some cases, each thin stream body has a different length between the head and the tail.

[0015] Exemplary aspects of an apparatus and method for distributing coolant to cool a fuel cell are disclosed, comprising a cathode cap and a water distribution cap fixed to a bipolar plate. The bipolar plate has a plurality of fluid guides, each having a diameter along the length of a first cathode fluid channel in fluid communication with a cathode flow field. The water distribution cap has a fluid conduit in fluid communication with a plurality of thin streams. Each thin stream has a head connected to the fluid conduit and a tail end configured to align with at least a portion of the plurality of fluid guides fixed to the cathode cap. In some cases, each thin stream body has a width, and at least two thin streams have bodies of different widths. In some cases, the thin stream bodies have a depth, and at least two thin streams have different depths. In some cases, at least two fluid guides have different diameters.

[0016] Exemplary aspects of an apparatus and method for distributing coolant to cool a fuel cell are disclosed, comprising controlling the flow of water into discrete portions of a cathode flow field via fluid guides aligned with each discrete portion, and connecting multiple thin streams of fluid formed in a distribution cap to fluid conduits. Each thin stream is connected to a fluid guide, thereby allowing water to flow from the thin stream through the fluid guide and into the discrete portions of the cathode flow field. In some cases, each thin stream also includes a head connected to the fluid conduit and a tail connected to the fluid guide. In some cases, each thin stream has a body between the head and the tail. In some cases, at least two thin stream bodies have different lengths between the head and the tail. In some cases, each thin stream body has a different length between the head and the tail.

[0017] Exemplary aspects of an apparatus and method for distributing coolant to cool a fuel cell are disclosed, comprising controlling the flow of water into discrete portions of a cathode flow field via fluid guides aligned with each discrete portion, and connecting multiple thin streams of fluid formed in a distribution cap to fluid conduits. Each thin stream is connected to a fluid guide, thereby allowing water to flow from the thin stream through the fluid guide and into the discrete portions of the cathode flow field. In some cases, each thin stream further includes a head connected to the fluid conduit and a tail connected to the fluid guide. In some cases, each thin stream has a width, and at least two thin streams have bodies of different widths. Attached Figure Description

[0018] This application will be further understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the subject matter, exemplary aspects of the subject matter are shown in the drawings; however, the subject matter of this disclosure is not limited to the specific methods, apparatus, and systems disclosed.

[0019] The components in the accompanying drawings are not necessarily drawn to scale; rather, the focus is on illustrating the principles of the invention. In the drawings, the same reference numerals denote corresponding parts in different views.

[0020] Figure 1 A side exploded assembly view of a high-efficiency fuel cell assembly is depicted.

[0021] Figure 2 A perspective exploded assembly view of a high-efficiency fuel cell assembly, from the anode side to the cathode side, is depicted.

[0022] Figure 3 Depicting Figure 1 A top view of the anode side of a frame with an anode flow field in a high-efficiency fuel cell assembly.

[0023] Figure 4A Depicting Figure 1 A top view of the cathode side of a frame with a cathode flow field in a high-efficiency fuel cell assembly.

[0024] Figure 4B Depicting Figure 4A The image shows a top view of the cathode side of the frame of a high-efficiency fuel cell assembly, with the cathode components assembled on the frame.

[0025] Figure 5 A top view of the cathode side of a high-efficiency fuel cell assembly is depicted.

[0026] Figure 6 Aspects of a fuel cell stack, which consists of multiple high-efficiency fuel cell components, are described.

[0027] Figure 7A and 7BThe cathode inlet cover is shown, which is formed to fit with the water distribution cover.

[0028] Figure 8A It is a water distribution cover configured to be installed on the cathode inlet cover in Figure 7.

[0029] Figure 8B It is along Figure 8A A cross-sectional view of the line “A”-“A” within region “Z”.

[0030] Figure 8C This is a comparison diagram of two thin streams of different widths.

[0031] Figure 9A Showing Figure 7A The bottom of the cathode cover.

[0032] Figure 9B The assembly portion of the bipolar cathode inlet region is shown.

[0033] Figure 10 This is a graph showing aspects of variable stream length.

[0034] All descriptions and references in the accompanying drawings, and all contents thereof, are incorporated herein by reference as if fully set forth herein. Aspects of this disclosure will now be described in detail with reference to the accompanying drawings, wherein, unless otherwise stated, the same reference numerals always refer to the same elements. Detailed Implementation

[0035] This disclosure will be more readily understood by referring to the following detailed description, in conjunction with the accompanying drawings and embodiments, which form part of this disclosure. It should be understood that this disclosure is not limited to the specific apparatus, methods, applications, conditions, or parameters described and / or shown herein, and the terminology used herein is for illustrative purposes only and is not intended to limit the scope of the claimed disclosure.

[0036] This document discloses aspects of methods and systems to provide at least one of the following: improved cooling and consistent compression of at least one of a fluid flow plate, a flow assembly, a fuel cell, and a fuel cell stack, which improves power generation efficiency and reduces production costs.

[0037] By rationally designing the dimensions of the cathode inlet and outlet to maintain pressure across the flow field and entering the gas diffusion layer (GDL) from the inlet to the outlet on the cathode side of the fuel cell, fluid flow bottlenecks are eliminated and / or minimized. When the oxidant flows through the cathode side of the fuel cell assembly, the expansion of air and the addition of moisture cause the volume to expand by at least 5 times or more, in some cases by 50 times or more, in some cases by 100 times or more, and in some cases by 200 times or more. By minimizing bottlenecks, the example fuel cell assembly, the fuel cell formed from such assemblies, and the stack formed from multiple such fuel cells are more efficient fuel cell stacks. Greater efficiency refers to the power density during operation compared to conventional fuel cells or stacks utilizing the outlet and inlet of conventional fuel cell assemblies.

[0038] Figure 1 This is an overview of fuel cell components and fuel cell parts.

[0039] When two fuel cell components 10 and 10' (each component having bipolar plates that provide a fluid flow path) are stacked together and compressed into part of a fuel cell stack, they cooperate with each other and together serve as fuel cell 100 in that stack.

[0040] Figure 2 This shows aspects of the fuel cell assembly viewed from the cathode side upwards. Figures 3-6 The following aspects are shown: the anode side of the bipolar plate, the cathode side of the bipolar plate of this disclosure, and the cathode side of the bipolar plate of this disclosure.

[0041] A membrane electrode assembly (MEA) containing a proton exchange membrane (also known as a polymer electrolyte membrane) is typically a multilayer interface, through which protons from the anode side of the fuel cell pass through the MEA, and stripped electrons travel around the MEA to generate electricity. Oxygen is supplied on the cathode side, and hydrogen protons eventually combine with some of the supplied oxygen to form water.

[0042] Traditionally, the MEA 12 in a fuel cell assembly (or fuel cell) has several gas diffusion layers (or layers) between the MEA and the bipolar frame 13. A cathode gas diffusion layer (or layers) 15 is located on the first side of the cathode face 14 closest to the bipolar frame 13 in the MEA 12A. An anode gas diffusion layer 17 is located on the opposite second side of the anode face 16 closest to the bipolar frame 13 in the MEA 12B. The bipolar frame 13 has a first end 18 opposite a second end 19. A bipolar frame is disclosed herein configured such that the anode face 16 is formed as part of the bipolar frame. A novel bipolar plate 200 is disclosed herein, wherein the cathode face has a separate cathode outlet cap 20 attached to the bipolar frame and a separate cathode inlet cap 22 attached to the bipolar frame. Configuring the bipolar frame 13 to fix separate cathode inlet and outlet caps eliminates the waste material caused by using a single cathode frame, thereby reducing at least one of carbon footprint, cost, and manufacturing cost. A separate water distribution cover 30 may be attached, optionally fixed above at least a portion of the cathode inlet cover. During fuel cell formation within the fuel cell stack, one or more gaskets are added to seal the fuel cell assembly. At least a cathode gasket 40 and an anode gasket 42 are included.

[0043] Figure 3 The anode side of the bipolar plate is shown. At the first end 18 are an air inlet 300, a water inlet 310, and a hydrogen outlet 315. At the second end 19 are a cathode fluid outlet 320 and a hydrogen inlet 325. The hydrogen inlet is fluidly connected to the anode surface of the bipolar plate via a first anode fluid channel 330. The anode surface is fluidly connected to a second anode fluid channel 335, which is fluidly connected to the hydrogen outlet 315. The water inlet 310 and the air inlet 300 are fluidly connected to the cathode surface of the bipolar plate.

[0044] Figure 4AThe unassembled cathode side of the bipolar frame 13 is shown. A cathode outlet cap 20 is attached to the bipolar frame at its first end 18, aligned with the bipolar frame's water inlet, air inlet 300, and hydrogen outlet 315. A first cathode fluid channel 340 is formed at one edge of the cathode inlet cap 22. A separate cathode inlet cap 22 is attached to the bipolar frame at its second end 19, aligning the bipolar frame's cathode inlet 320 and hydrogen outlet. A second cathode fluid channel 345 is formed at one edge of the cathode outlet cap 20. Once the cathode caps are attached, the bipolar plate is formed. Those skilled in the art will recognize that conventional bipolar plates utilizing multiple frames fixed together and bipolar plates with a single frame and no cap are both within the scope of this disclosure. A separate water outlet cap is configured to be fixed above at least a portion of the cathode inlet cap. The air inlet 300 and water inlet 310 are fluidly connected to the cathode surface of the bipolar plate via the first cathode fluid channel 340. The cathode surface is fluidly connected to the second cathode fluid channel 345, and the second cathode fluid channel 345 is fluidly connected to the cathode fluid outlet 320.

[0045] Figure 4B The assembly of the cathode side of the bipolar plate 200B is shown, which includes an optional water distribution cover.

[0046] Figure 5 The assembled bipolar plate is shown with the cathode face upward and the cathode gas diffusion layer 15 visible. A fluid 500 containing air, water, and water vapor from the air inlet 300 and water inlet 310 fluidly passes along the line of arrow 500 through uniformly spaced fluid guides 700 (e.g., ...). Figure 7A and 7B (As shown) to the first cathode fluid channel 340, through the cathode surface 14 and the cathode gas diffusion layer 15 to the second cathode fluid channel 345, and then to the cathode fluid (or exhaust) outlet 320.

[0047] Figure 6 An assembly diagram of a fuel cell stack 600, consisting of multiple fuel cell components 10 (1-N), a cathode gas diffusion layer 14, a first end plate 602, and a second end plate 604, is shown. The outlet is also in fluid communication with the cathode fluid outlet.

[0048] Figures 7A to 9B Aspects of methods and systems for an exemplary implementation of controlled coolant distribution in a fuel cell are shown.

[0049] Figure 7A A top view of the cathode outlet cover 22, which includes a fluid guide 700, is shown. Figure 7B Showing Figure 7AEnlarged view of the mid-section “Y”. The cathode inlet cover has a top surface 701 and is configured to cooperate with the water distribution device to deliver water through an array of fluid guides 700A-700N. Welds or other connectors 702 can be added to secure the cathode inlet cover to the bipolar frame. A series of spacers 705 protrude from the bottom surface 703 of the cathode inlet cover to fluidly connect the water flow to the cathode flow field 14 and the cathode gas diffusion layer 15 of the bipolar plates. The diameters of the fluid guides 700A-700N can be different.

[0050] Figure 8A and 8B The image shows aspects of the fine streams 800A to 800N formed in the water distribution cover 30. The water distribution cover is provided with a fluid conduit 802 having a first end 803 and a second end 804. Figure 8B The water distribution cover is shown. Figure 8A The bottom surface 805 of the central "Z" portion has a depth "D" for each stream, which appears as height when viewed from the top side; therefore, for the purposes of this disclosure, it is an out-of-plane protrusion or recess through which fluid can flow. Each stream has a head 807 that is fluidly connected to a fluid conduit 802. Water flows from the head 807 through the recessed stream body 809 and to the tail 810 of the stream. The tail of each stream is configured to align with and fluidly connect to one of the fluid guides 700 on the cathode inlet cap. Figure 8C A portion of the main body of the duct 800B is shown. By increasing the width of the duct body 809 to the body 809', the width "W" forms a larger channel through which water passes through the duct body 809' and then through the duct body 809, thereby increasing the volume of water that can be transported.

[0051] Figure 9A Showing Figure 4B Part of the "X" in the middle. The cathode inlet cover is shown with its bottom surface 703 facing upwards. In this figure, the water distribution cover is fixed to the cathode inlet cover. The tail end 810 of the stream can be seen through the fluid guide 700, and the water 900 from the stream is guided from below the bottom surface 707 of the cathode inlet cover to the cathode flow field 14, as shown. Figure 9B As shown. Water or coolant 900 is guided via fluid guides to different discrete portions “CFFA”, “CFFB”, and “CFFN” of the cathode flow field 14. In some cases, to ensure uniform fluid flow into the cathode flow field 14 through the cathode inlet cover, the diameters of the fluid guides 700A-700N are varied, thereby restricting the fluid flow through their cross-sections.

[0052] Figure 10This illustrates how the flow body 809 can vary with distance from the first end 803 of the fluid conduit 802 to balance the general aspect of coolant (such as water) supply to the distribution cap. Variations in the flow body length can also be combined with variations in the fluid inlet size.

[0053] Figure 8A-10 Another water distribution method for a fuel cell is illustrated. Each of the streams 800(1) to 800(N) can be of different sizes. The streams are constructed in a wave-like pattern, so that if each stream has the same width, changing the frequency and / or amplitude of the stream body will change the length of the wave or stream. By changing the length while keeping the diameter of each stream body 809 the same, the actual length of the body is lengthened or shortened. Fluid traveling through the more meandering (longer) body of stream 800A will travel a longer distance. A more meandering path also slows the flow compared to fluid traveling through the less meandering path of stream 800N. Variations in body length maintain uniform water delivery to each stream. Typically, the stream closest to the first end 803 receives either a larger volume of water or water at higher pressure, while the stream closest to the end 804 receives either a smaller volume of water or water at lower pressure. Over time, maintaining the same water flow through each sluice will deliver the same amount of water to each tail end of the sluice 800A-N, which in turn will provide the same amount of water to each section of the flow field 14 passing through the leading edge 811 of the water distribution cover.

[0054] The depth “D” of the main body of the stream can be changed to further change the amount or flow rate of water passing through the stream, which is also within the scope of this disclosure and will be recognized by those of ordinary and skilled in the art.

[0055] In some cases, any one or all of the depth, width, amplitude, and frequency of the stream can be varied along the stream 800A to 800N along the distribution cover to deliver a uniform volume of water to all parts of the cathode flow field 14.

[0056] Returning to the cathode inlet cover 22, in Figure 8A In the model, the body of stream 800A is longer than that of stream 800B. The two streams exhibit similar frequencies, but stream 800A is configured with a larger amplitude in its body 809 compared to stream 800B. The larger amplitude in stream 800A corresponds to the greater length of its body 809 compared to the body of stream 800B. The contrast is even greater when comparing the bodies of stream 800A and stream 800N. Stream 800N can have a similar contrast to stream 800B, but it is even more pronounced compared to stream 800A.

[0057] The systems described throughout this disclosure can be used in a variety of applications to provide electricity generated by fuel cells. In some aspects, the systems disclosed throughout this application can be used in machine handling equipment (MHE), such as forklifts. In some aspects, the systems can be used in unmanned aerial vehicles (UAVs), such as fixed-wing or multi-rotor UAVs. In some aspects, the systems disclosed herein can be used in automotive, marine, or aerospace applications, such as cars, trucks, watercraft, aircraft, or stationary propulsion systems. It should be understood that these systems can be used in a variety of other applications, and certain functionalities and physical parameters, such as component size and quantity, can vary depending on the specific application and can be determined by the requirements of a particular purpose. Additional advantages of the foregoing include the ability to install the system and related components (such as fuel tank cylinders) in a small space and the ability to arrange the system and related components.

[0058] The components disclosed in this article can utilize known materials used in industry.

[0059] In this specification, terms should be used in their normal meaning as understood by those skilled in the art. However, to avoid misunderstanding, the meanings of certain terms will be specifically defined or clarified.

[0060] While this disclosure has been described with reference to various embodiments in conjunction with the accompanying drawings, those skilled in the art will understand that modifications may be made to the above embodiments without departing from its broad inventive concept. Therefore, it should be understood that this disclosure is not limited to the specific embodiments disclosed, and that it is intended to cover modifications within the spirit and scope of this disclosure as defined in the claims.

[0061] The features of this disclosure described above in the context of individual embodiments may be provided in combination in a single embodiment. Conversely, the various features of this disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, while an embodiment may be described as part of a series of steps or a more general structure, each of the steps may also be considered an independent embodiment that may be combined with other steps.

[0062] Unless otherwise stated herein, references to ranges of values ​​herein are intended only as a shorthand way of referring to each individual value within that range, and each individual value is incorporated into the specification as if it were stated separately herein. Unless otherwise stated herein or clearly contradicted by the context, all methods described herein may be performed in any suitable order.

Claims

1. A fuel cell cooling system, comprising: A cathode cover (22) is fixed to a bipolar plate having a plurality of fluid guides (700A-700N), each fluid guide (700A-700N) having a diameter along the length of a first cathode fluid channel (340) in fluid communication with the cathode flow field (14); and, A water distribution cover (30) has a fluid conduit (802) in fluid communication with a plurality of thin streams (800A-800N), each thin stream (800A-800N) having a head (807) connected to the fluid conduit (802) and a tail end (810) configured to align with at least a portion of the plurality of fluid guides fixed to the cathode cover.

2. The fuel cell cooling system according to claim 1, wherein each filament has a body (809) between the head and tail.

3. The fuel cell cooling system according to claim 1, wherein at least two thin stream bodies (809) have different lengths between the head and the tail.

4. The fuel cell cooling system according to claim 1, wherein at least three thin stream bodies (809) have different lengths between the head and tail.

5. The fuel cell cooling system according to claim 1, wherein each stream body (809) has a different length between the head and the tail.

6. The fuel cell cooling system according to claim 1, wherein: Each of the aforementioned thin streams has a width (W); and, There are at least two thin streams with different widths.

7. The fuel cell cooling system according to claim 1, wherein: The main body of the stream has a depth "D"; and, At least two of the streams have different depths.

8. The fuel cell system of claim 1, wherein at least two fluid guides have different diameters.

9. A method for cooling a fuel cell, the method comprising: The flow of water into the discrete parts (CFFA, CFFB, and CFFN) of the cathode flow field is controlled by fluid guides aligned with each discrete part. The multiple thin streams of fluid formed in the water distribution cover are connected to the fluid conduit; Connect a thin stream of fluid to a fluid guide; Thus, water flows from the thin stream through the fluid guide and into the discrete portion of the cathode flow field.

10. The method for cooling a fuel cell according to claim 9, wherein each stream further includes a head connected to the fluid conduit and a tail connected to the fluid guide.

11. The method for cooling a fuel cell according to claim 10, wherein each filament has a body (809) between the head and tail.

12. The method for cooling a fuel cell according to claim 11, wherein at least two thin stream bodies have different lengths between the head and the tail.

13. The method for cooling a fuel cell according to claim 11, wherein at least three thin stream bodies (809) have different lengths between the head and the tail.

14. The method for cooling a fuel cell according to claim 11, wherein each stream body has a different length between the head and the tail.

15. The method for cooling a fuel cell according to claim 11, wherein: Each of the aforementioned thin streams has a width (W); and, There are at least two thin streams with different widths.

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