Flow plate
The flow plate design with alternating serpentine and interleaved channels addresses manufacturing and efficiency issues by simplifying production and improving reactant distribution, enhancing fuel cell performance.
Patent Information
- Application Number
- JP2024218668
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-12-13
- Filing Date
- 2024-12-13
- Publication Date
- 2025-06-25
AI Technical Summary
Existing fuel cell flow plates, such as interdigitated and serpentine designs, face manufacturing complexity and efficiency issues due to complex channel structures, excessive cross-flow, and liquid water accumulation, leading to pressure drops and reduced performance.
A flow plate design featuring alternating serpentine and interleaved channels with controlled flow direction changes and shorter lengths, minimizing pressure drops and ensuring uniform reactant distribution.
The new design enhances manufacturing simplicity, reduces pressure losses, and improves reactant distribution, thereby increasing the efficiency and performance of fuel cells.
Smart Images
Figure 2025094942000001_ABST
Abstract
Description
Technical Field
[0001] A flow plate for a fuel cell and its operating method will be described.
Background Art
[0002] A fuel cell is an electrochemical device that directly converts the chemical energy of a fuel such as hydrogen into electrical energy through a chemical reaction with an oxidant, usually oxygen from air. A Proton Exchange Membrane (PEM) fuel cell is a type of fuel cell that uses a polymer membrane as its electrolyte. It operates at a relatively low temperature (60 - 80°C) and enables rapid startup. In a PEM fuel cell, hydrogen is supplied to the anode, where it is separated into protons and electrons. The protons pass through the electrolyte membrane to the cathode, while the electrons flow through an external circuit to generate an electric current. The only by-products are water and heat.
[0003] Briefly, the flow field plate in a fuel cell helps control the flow of reactants such as hydrogen and oxygen to the electrodes where the chemical reaction occurs. This is an important component for ensuring a uniform distribution of these gases across the surface of the electrodes and an efficient and uniform reaction. In a PEMFC, these plates are often made of a conductive material such as graphite or metal coated with a protective coating and are used to distribute hydrogen gas (fuel) and oxygen (from air) to the membrane electrode assembly (MEA), where the electrochemical reaction takes place and electricity is generated. The design of the flow field is important because it affects the gas distribution, the removal of water generated during the reaction, and the overall fuel cell performance.
[0004] One design of a fuel cell flow plate is known as an interdigitated flow plate. The term "interdigitated" typically refers to the design of channels within a flow plate that has a comb-like structure with an array of interdigitated channels extending from first and second ends of the flow plate. The purpose of these plates is to improve the distribution and flow of reactant gases across the electrodes. By providing a pattern of interlocking alternating channels between an inlet and an outlet, the interdigitated design improves gas distribution and the efficiency of the fuel cell reaction by passing reactants through a porous gas diffusion layer.
[0005] However, the interdigitated design can be relatively complex to manufacture due to the complex nature of the interdigitated channels and, in relation to that, the need to manufacture the channels with high tolerances. Excessive cross-flow between the interdigitated channels due to wide spacing can negatively affect the fuel cell by passing reactants through the porous electrode support medium, resulting in a higher pressure drop.
[0006] Another design of a fuel cell flow field plate is the serpentine design. According to this design, one or more channels having a meandering repeating S-shaped pattern including at least one or more turns are provided on the flow plate. Similar to the interdigitated design, this design can also provide a relatively large surface area. Furthermore, the phenomenon of cross-flow is less common in the serpentine design, thereby providing an advantage over the interdigitated design.
[0007] However, due to the length of the individual serpentine channels, liquid water (generated from the electrochemical reaction) can accumulate significantly, which, when combined with the turns or meanders of one or more channels, can significantly drop the pressure between the inlet and outlet of one or more channels of the serpentine design. This can potentially negatively affect the efficiency of a fuel cell using a serpentine flow plate.
[0008] Therefore, a flow plate is needed to solve the above problems.
Summary of the Invention
[0009] According to the present disclosure, a first aspect relates to a flow plate for a fuel cell. The flow plate includes a substrate including a flow inlet and a flow outlet, and a flow field in fluid communication with both the flow inlet and the flow outlet and including a plurality of flow channels. The plurality of flow channels includes at least two serpentine channels, each of the at least two serpentine channels defining a channel inlet and a channel outlet and including at least one curved section that causes a change in the flow direction within each serpentine channel, and the plurality of flow channels includes alternating arrangement channels extending between the at least two serpentine channels and defining a channel inlet and a closed channel end (e.g., straight alternating arrangement channels).
[0010] In some examples, the flow plate may include a first side where the flow inlet is disposed and a second side where the flow outlet is disposed. In some examples, each first half of each of the plurality of serpentine channels may define an inlet portion, and each second half of each of the plurality of serpentine channels may define an outlet portion. The alternating arrangement channels are disposed adjacent to the outlet portions of at least two serpentine channels (e.g., two of the at least two channels).
[0011] In some examples, each of the at least two serpentine channels may include at least two straight sections fluidly connected by at least one curved section, and the alternating arrangement section may include a straight section.
[0012] In some examples, each of the at least two serpentine channels may include three straight sections connected by two curved sections, and the alternating arrangement channels may include a single straight section.
[0013] According to some examples, the straight sections of at least two meandering channels can be parallel to the straight sections of the alternating array channels. According to some examples, each of the two curved sections can cause a 180-degree change in the flow direction.
[0014] According to some examples, the flow plate can include an inlet channel that fluidly connects the flow field to the flow inlet, and an outlet channel that fluidly connects the flow field to the flow outlet.
[0015] According to some examples, the flow plate can include a plurality of inlet channels that define an inlet manifold, and a plurality of outlet channels that define an outlet manifold. According to some examples, the flow plate can include a plurality of alternating array channels and at least four meandering channels. Each of the plurality of alternating array channels can be disposed between two of the at least four meandering channels.
[0016] Each of the plurality of alternating array channels can be, for example, in contrast to the meandering channels, a straight channel, e.g., a single straight section of a channel having no arbitrary curved section or bend.
[0017] Each of the plurality of alternating array channels can be parallel to at least one (e.g., one or two) straight sections (e.g., at least one straight section of two adjacent meandering channels) of at least two of the meandering channels. For example, each of the plurality of alternating array channels can be parallel to one or two outlet portions of at least two of the meandering channels.
[0018] At least two serpentine channels may be dividable into a main section and a secondary section. The main section is substantially longer in length than the secondary section. Optionally, the main section is a straight section and the secondary section is a curved section. Optionally, the main section extends in a direction from the side including the inlet of the flow plate to the side including the outlet of the flow plate. A part of the secondary section may extend perpendicular to the main section. Each of the plurality of alternately arranged channels may extend parallel to at least one (e.g., one or two) main sections of at least two serpentine channels (e.g., adjacent, directly adjacent serpentine flow channels).
[0019] According to some examples, the number of serpentine channels may be twice the number of alternately arranged channels. According to some examples, the channel inlet of the alternately arranged channels may be disposed closer to the inlet than the outlet.
[0020] According to some examples, the channel inlet of the alternately arranged channels may be disposed closer to the outlet than the inlet. The channel inlet of each of the plurality of alternately arranged channels may be disposed closer to the inlet of one (e.g., directly adjacent) of the adjacent ones of the at least two serpentine channels than the outlet of the adjacent serpentine channel. The closed channel end of each of the plurality of alternately arranged channels may be closer to the outlet of one (e.g., directly adjacent) of the adjacent ones of the at least two serpentine channels than the outlet of the adjacent serpentine channel.
[0021] According to some examples, the alternately arranged channels may extend in the flow direction, and the flow inlet and the flow inlet may be separated along the flow direction. A second aspect is a method of operating a fuel cell, including providing a fuel cell having a flow plate according to the first aspect, flowing fuel into the flow inlet of the flow plate and the flow field of the fuel cell, and flowing fuel into at least two serpentine channels and alternately arranged channels of the fuel cell simultaneously.
Brief Description of the Drawings
[0022]
Figure 1
Figure 2
Figure 3
Figure 4A
Figure 4B
Mode for Carrying Out the Invention
[0023] FIG. 1 is a schematic diagram of a fuel cell 2 shown in cross section. Here, it can be seen that the fuel cell 2 is substantially composed of several layers. The flow plate 10 is shown as the outermost layer in FIG. 1. The flow field plates 10, 10' are pressed against each other by current collector plates and end plates (not shown). Adjacent to the flow plate, a diffusion layer 4 (for example, a porous diffusion layer) is disposed, where (in this example) a gas (for example, hydrogen gas) from a fuel source diffuses through the fuel cell and combines with oxygen or air to generate, for example, water and heat. Adjacent to the diffusion layer 4, a catalyst layer (as shown in the figure, the anode-side electrode 6) is disposed on the opposite side of the flow plate 10, and adjacent to the diffusion layer 4, a catalyst layer (as shown in the figure, the cathode-side electrode 8) is disposed on the opposite side of the flow plate 10', and these are electrically connected in this example. Electrons move between the electrodes to form an electrical circuit. An electrolyte membrane 5 is disposed between the anode-side electrode 6 and the cathode-side electrode 8, which, in this example, enables the flow of hydrogen ions from the anode-side electrode 6 to the cathode-side electrode 8 and combines with oxygen in the diffusion layer 4 to form water.
[0024] As shown by arrows 1 and 3, the flow of hydrogen enters the flow plate 10 (indicated by arrow 1), and the residual gas and water flow out of the flow plate at 3. On the other side of the fuel cell 2, fuel (here oxygen) enters the flow plate 10' at arrow 7 and flows out of the flow plate at arrow 9. Here, the structures of the flow plates 10, 10' may be slightly different, and thus each is indicated by a different reference number.
[0025] When the flow of hydrogen is provided at 1, hydrogen flows through the flow plate 10. Then, the flow plate 10 distributes hydrogen through the diffusion layer 4 towards the anode-side electrode 6. When reaching the anode-side electrode 6, the electrons of the diatomic hydrogen accumulate in the anode-side electrode 6, generating positively charged hydrogen ions. The positively charged hydrogen ions are attracted from the anode-side electrode 6 through the electrolyte membrane 5 to the cathode-side electrode 8. When the hydrogen ions reach the cathode-side electrode 8, they can enter the flow plate 10 at 7 and combine with oxygen passing through the diffusion layer 4 to form water. Then, the water can flow out of the flow plate at 9.
[0026] Note that the above description is applicable to a fuel cell having hydrogen gas as fuel. However, those skilled in the art will recognize that there are other types of fuel cells, such as those that function with hydrocarbons.
[0027] Figure 2 shows a flow plate 10 for a fuel cell. The flow plate 10 includes a substrate 12, a flow field 14, and a flow inlet 16 and a flow outlet 18. The flow inlet 16 and the flow outlet 18 are in fluid communication with the flow field 14 via respective inlet manifolds 20 and outlet manifolds 22 in this case. In use, a flow of fluid (e.g., fuel such as hydrogen) is introduced into the flow inlet 16 and, in this example, flows into the flow field 14 through the inlet manifold 20. The fluid then flows into the outlet manifold 22 through the flow field 14 and can ultimately flow into the fluid outlet 18. As the fluid (e.g., fuel) flows through the flow field 14, the fuel is supplied to the fuel cell, enabling the generation of energy.
[0028] In the example of FIG. 2, the flow field 14 comprises a number of channels 24, 26 that are in fluid communication with the inlet manifold 20 and the outlet manifold 22. The channels 24, 26 are in the form of either serpentine channels 24 or interleaved channels 26. One of each of the serpentine channels 24 and the interleaved channels 26 is filled with a thick line to emphasize the shape of the channels within the flow field 14. In this example, the flow field does not have simply one serpentine channel spanning the entire flow field, but instead comprises a plurality of serpentine channels 24 (here, eight serpentine channels). Thus, by having shorter serpentine channel lengths, large pressure drops occurring within each serpentine channel 24 are avoided. This is further achieved by limiting the number of turns within each serpentine channel 24. In this example, each serpentine channel 24 has two 180-degree turns, although serpentine channels with different numbers of turns are possible, for example, four 90- or 180-degree turns may also be useful, but it should be understood that they may result in a higher pressure drop than desired due to the additional number of turns. For example, other options exist such as two 90-degree turns, and it should be noted that the serpentine channels are not limited to a strict S-shaped curve, but may simply be channels that include a change in the flow direction therein. Each of the serpentine channels 24 is shown here as having the same form, but it should also be noted that it is further possible to have one or more serpentine channels 24 having different forms.
[0029] The flow field 14 of this example is generally rectangular in shape and extends in a first flow direction indicated by arrow 28 and in a transverse direction perpendicular to the flow direction 28. Each of the serpentine channels 24 mainly extends in the flow direction 28. Also, each serpentine channel 24 extends generally transversely to the flow direction 28 and has two short curved sections that change the flow direction of the channel 24 by 180 degrees. Thus, each serpentine channel 24 starts at the end of the flow field 14 adjacent to the flow inlet 16 and ends at the end of the flow field 14 adjacent to the flow outlet 18. In this example, one, some, or each serpentine channel 24 may include an inlet portion that extends in the flow direction 28 and includes an inlet to the serpentine channel 24, an intermediate section that is fluidly connected to the inlet portion by a curved section and extends in a direction opposite to the flow direction 28, and an outlet portion that extends in the flow direction and includes an outlet to the serpentine channel 24.
[0030] Interleaved channels 26 are disposed between the serpentine channels 24. The interleaved channels 26 are positioned such that the serpentine channels 24 are on both sides of each interleaved channel 26 and extend in the flow direction 28 along the flow field 14 of the flow plate 10. Each of the interleaved channels 26 includes an inlet that is disposed adjacent to the flow inlet 16 and / or the inlet manifold 20 in this example, although it is also conceivable that the inlet is disposed adjacent to the flow outlet 18 and / or the outlet manifold 22. Each interleaved channel 26 also includes a flow channel portion that extends in the flow direction 28 in this example and a closed end at the end of the channel 26 opposite the inlet.
[0031] Here, each of the serpentine channels 24 is oriented such that the outlet portion is disposed adjacent to the alternating array channel 26 and the inlet portion is disposed adjacent to the inlet portion of the adjacent serpentine channel 24. As fuel flows along each of the serpentine channels 24, the fuel depletes as it approaches the outlet of the serpentine channel 24. Thus, by positioning the alternating array channel 26 adjacent to the outlet portion, in the region of the flow plate 10 where the fuel in the adjacent serpentine channels 24 depletes, flow of fluid through the alternating array channel 26 (which is generally shorter in length than the serpentine channel 24) is enabled, and thus a more uniform distribution of fuel across the flow plate 10 is provided.
[0032] FIG. 3 shows another example of a flow plate 110 that is mostly similar to that shown in FIG. 2, and thus, similar reference numerals incremented by 100 are used to describe each of the illustrated components. Similar to the previous example, the flow plate 110 includes a flow field 114 that includes a plurality of serpentine channels 124 and alternating array channels 126. In this example, the manifold extends perpendicular to the flow direction 28 and has a more compact design compared to that of FIG. 2. Further, only four serpentine channels 124 and two alternating array channels 126 are shown here, which further enables the flow plate 100 of FIG. 3 to have a more compact design.
[0033] Figures 4A and 4B show a flow plate similar to that shown in FIG. 2, but FIGS. 4A and 4B show contrasting inlet manifold 20 and outlet manifold 22. In FIG. 4B, the inlet manifold 20 and the outlet manifold 22 distribute the flow from the flow inlet 16 to different positions of the flow field 14 in a direction perpendicular to the flow direction 28, thereby providing, for example, a more uniform distribution of fuel to each of the plurality of serpentine channels 24 and the interleaved channels 26. In contrast, the inlet manifold 20 and the outlet manifold 22 of FIG. 4A supply and receive fuel along a much shorter length compared to FIG. 4B. In the example of FIG. 4A, fuel may be supplied to / from the flow field at the corners of the flow field and then propagate throughout the remainder of the flow field.
Claims
1. a substrate (12) including a flow inlet (16) and a flow outlet (18); a flow field (14) in fluid communication with both the flow inlet (16) and the flow outlet (18), the flow field (14) including a plurality of flow channels; the plurality of flow channels includes at least two serpentine channels, each of the at least two serpentine channels defining a channel inlet and a channel outlet and including at least one curved section causing a change in flow direction within the respective serpentine channel; A flow plate (10) for a fuel cell, wherein the plurality of flow channels includes alternating channels extending between the at least two serpentine channels, the alternating channels defining channel inlets and closed channel ends.
2. 2. The flow plate of claim 1, wherein a first half of each of the plurality of serpentine channels defines an inlet portion and a second half of each of the plurality of serpentine channels defines an outlet portion, the alternating channel being disposed adjacent the outlet portions of two of the at least two serpentine channels.
3. 3. The flow plate of claim 1 or 2, wherein each of the at least two serpentine channels comprises at least two straight sections fluidly connected by the at least one curved section, and the alternating sections comprise straight sections.
4. The flow plate of claim 3 , wherein each of the at least two serpentine channels includes three straight sections connected by two curved sections, and the alternating channel includes a single straight section.
5. 5. The flow plate of claim 3 or 4, wherein the straight sections of the at least two serpentine channels are parallel to the straight sections of the alternating channels.
6. 6. The flow plate of claim 4 or 5, wherein each of the two curved sections causes a change in the flow direction of 180 degrees.
7. A flow plate according to any preceding claim, comprising an inlet channel fluidly connecting the flow field to the flow inlet, and an outlet channel fluidly connecting the flow field to the flow outlet.
8. The flow plate of claim 7 comprising a plurality of inlet channels defining an inlet manifold and a plurality of outlet channels defining an outlet manifold.
9. 9. The flow plate of claim 1, comprising a plurality of alternating channels and at least four serpentine channels, each of the plurality of alternating channels being disposed between two of the at least four serpentine channels.
10. A flow plate according to any preceding claim, wherein the number of serpentine channels is twice the number of alternating channels.
11. A flow plate according to any preceding claim, wherein the channel inlets of the alternating channels are located closer to the inlets than to the outlets.
12. A flow plate according to any preceding claim, wherein the channel inlets of the alternating channels are located closer to the outlets than the inlets.
13. The flow plate of any preceding claim, wherein the alternating channels extend in a flow direction, and the flow inlets and flow inlets are separated along the flow direction.
14. Providing a fuel cell comprising a flow plate according to claim 1; flowing fuel into the flow inlets of the flow plate and into the flow fields of the fuel cells; flowing fuel simultaneously into the at least two serpentine channels and the alternating channels of the fuel cell; A method of operating a fuel cell comprising: