Separator plate for an electrochemical cell and fuel cell
Patent Information
- Application Number
- EP2023776384
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-09-26
- Filing Date
- 2023-09-25
- Publication Date
- 2025-08-06
AI Technical Summary
In fuel cells, the uneven pressure loss and gas distribution across different channels in separation plates lead to suboptimal operation, and the risk of channel misalignment during assembly due to varying orientations of corrugated and oblique channels.
The separation plate design features corrugated channels with uniform end orientations and regularly spaced junction points with oblique channels, ensuring consistent pressure drop and preventing channel nesting during assembly, by having all corrugated channel ends connect at identical angles to oblique channels.
This design ensures uniform gas distribution to the catalytic layers, improving fuel cell operation and preventing channel misalignment during assembly, resulting in enhanced performance and reliability.
Smart Images
Figure 1.1
Abstract
Description
[0001] TITLE: Separator plate for an electrochemical cell and fuel cell
[0002] The present invention relates generally to a fuel cell.
[0003] Such a fuel cell comprises a stack of electrochemical cells, each of which typically comprises:
[0004] An electrolytic membrane having first and second large faces opposite each other;
[0005] First and second catalytic layers, disposed against the first and second major faces of the electrolytic membrane;
[0006] Two separation plates, the first and second catalytic layers being arranged respectively between one of the separation plates and the electrolytic membrane.
[0007] Reactive gas circulation channels are provided on the separation plates. In particular, each separation plate may comprise corrugated channels extending in the same first direction, connecting to straight oblique channels.
[0008] The oblique channels may connect to portions of the corrugated channels which have different orientations from each other with respect to the first direction.
[0009] In this case, the pressure drop for the reactive gas flowing in the channels is not the same, depending on the orientation at the junction point.
[0010] As a result, the flow rate of reactant gas is not the same in all channels, and the operation of the fuel cell is not optimal.
[0011] The gas is in fact poorly distributed in contact with the catalytic layer next to the separation plate.
[0012] It is also possible to provide that the end parts of the corrugated channels connecting to the oblique channels are rectilinear and parallel to each other.
[0013] However, in this case there is a risk that the end parts of the corrugated channels of the individual plates will interlock with each other when the stack is assembled, when the plates are pressed against each other.
[0014] In this context, the invention aims to provide a separation plate for an electrochemical cell of a fuel cell contributing to solving the above problems. To this end, the invention relates to a separation plate for an electrochemical cell of a fuel cell, the separation plate comprising, in a first face:
[0015] * a plurality of corrugated channels for circulating a first reactive gas, the corrugated channels having respective end portions all extending in the same first direction and forming corrugations having the same determined period;
[0016] * a plurality of oblique channels, each extending in a second direction intersecting with the first direction, the end portion of each undulating channel connecting to one of the oblique channels at a junction point; the junction points defining projection points in projection onto a straight line parallel to the first direction, the projection being in a third direction perpendicular to the first direction, said projection points being regularly spaced from each other in the first direction and separated from each other by a constant gap equal to a multiple of said determined period.
[0017] Because the projection points are regularly spaced from each other in the first direction, and are separated from each other by a constant gap equal to a multiple of said determined period, the end of the corrugated channel at the junction point always has the same orientation, for all the corrugated channels.
[0018] Therefore, the connection between the oblique channels and the corrugated channels is essentially identical for all corrugated channels.
[0019] The pressure drop for the reactive gas flowing in the channels is practically the same, so the distribution of the reactive gas in the different corrugated channels is uniform.
[0020] As a result, the first catalytic layer is supplied with reactive gas homogeneously, and the operation of the fuel cell is improved.
[0021] Furthermore, the end portions of the corrugated channels have corrugations, which helps prevent the channels of the different plates from nesting inside each other when assembling the fuel cell.
[0022] The separation plate may also have one or more of the following characteristics, considered individually or in all technically possible combinations:
[0023] - the projection points are separated from each other by a constant gap equal to the said determined period;
[0024] - each corrugated channel comprises a main part extending in the first direction and forming large corrugations having a determined elongated period, greater than the determined period of the corrugations of the end part, the end part of a corrugated channel extending between the main part and the junction point of said corrugated channel;
[0025] - the number of oblique canals is less than the number of wavy canals, several wavy canals opening into the same oblique canal;
[0026] - the junction points of the wavy channels opening into the same oblique channel define the same projection point on the line;
[0027] - the junction points of the wavy channels opening into the same oblique channel define at least two distinct projection points on the line;
[0028] - the junction points are placed on a straight line intersecting the first direction;
[0029] - the end parts of the corrugated channels have, at their junction points, respective tangents all parallel to each other;
[0030] - the oblique channels have oblique end parts connected to the junction points, these oblique end parts being rectilinear and parallel to each other;
[0031] - the oblique end parts extend in the third direction, perpendicular to the first direction.
[0032] According to a second aspect, the invention relates to a fuel cell comprising a plurality of electrochemical cells, each electrochemical cell comprising:
[0033] - an electrolytic membrane, having first and second large faces opposite each other;
[0034] - first and second catalytic layers, arranged against the first and second large faces of the electrolytic membrane;
[0035] - a separation plate having the characteristics, the first catalytic layer being arranged between a first face of the separation plate and the electrolytic membrane.
[0036] Other characteristics and advantages of the invention will emerge from the detailed description given below, for information purposes only and in no way limiting, with reference to the appended figures, among which:
[0037] Figure 1 is a simplified, exploded schematic representation of a cell of a fuel cell according to the invention;
[0038] Figure 2 is a schematic, partial sectional view of the fuel cell of Figure 1;
[0039] Figure 3 is a schematic representation, in top view, of the channels of the first separation plate of Figures 1 and 2; and
[0040] Figure 4 is an enlarged top view of a zone IV of the first separation plate of Figure 1, for an alternative embodiment; and
[0041] Figure 5 is a schematic representation similar to that of Figure 3, for another alternative embodiment. The fuel cell 1 comprises a stack of electrochemical cells, each of which comprises, as illustrated in Figures 1 and 2, an electrolytic membrane 3, having first and second large faces 5 and 7.
[0042] The electrochemical cell of the fuel cell also comprises first and second catalytic layers 9 and 11, arranged against the first and second large faces 5 and 7 of the electrolyte membrane 3, for example by being formed on the first and second large faces 5 and 7 of the electrolyte membrane 3, or at least one or both of these catalytic layers being formed on a gas diffusion layer which is arranged against the corresponding large face 5 or 7 of the electrolyte membrane 3.
[0043] The membrane is for example a proton exchange polymer membrane.
[0044] Typically, a gas diffusion layer 13 is arranged against the first catalytic layer 9, opposite the electrolytic membrane 3. In the same way, another gas diffusion layer 15 is arranged against the second catalytic layer 11, opposite the membrane 3.
[0045] For example, the first catalytic layer 9, possibly with layer 13, constitutes an anode. The second catalytic layer 11, possibly with layer 15, constitutes a cathode.
[0046] The electrolytic membrane 3, the first and second catalytic layers 9 and 11 and the gas diffusion layers 13 and 15 together belong to a membrane-electrode assembly 17 (MEA).
[0047] The membrane-electrode assembly 17 of the fuel cell 1 typically also comprises a frame 19, internally delimiting a window in which the electrolytic membrane 3 is fixed. The frame 19 is for example formed mainly of one or two layers of a polymer film, for example polyethylene naphthalate or terephthalate (PEN or PET), with a total thickness which may be less than 200 micrometers, or even less than 100 micrometers.
[0048] Each electrochemical cell of the fuel cell 1 further comprises a first separation plate 21, having a first face 22a and a second face 22b opposite the first face 22a. The first catalytic layer 9 is arranged between the first face 22a and the electrolytic membrane 3.
[0049] In the example shown, the gas diffusion layer 13 and the first catalytic layer 9 are interposed between the first face 22a of the first separation plate 21 and the electrolytic membrane 3.
[0050] Symmetrically, each electrochemical cell of the fuel cell 1 comprises a second separation plate 23, having a first face 24a and a second face 24b opposite the first face 24a. The second catalytic layer 11 is arranged between the first face 24a and the electrolytic membrane 3.
[0051] More specifically, the gas diffusion layer 15 and the second catalytic layer 11 are interposed between the first face 24a of the second separation plate 23 and the electrolytic membrane 3.
[0052] The first separation plate 21 carries a set 25 of channels for the circulation of a first reactive gas.
[0053] The set of channels 25 is formed on the first face 22a of the first separation plate 21 which faces the first catalytic layer 9 of the electrochemical cell considered, therefore facing the electrolytic membrane 3 of the electrochemical cell considered.
[0054] The first reactant gas is typically hydrogen.
[0055] A set 27 of channels is formed on the first face 24a of the second separation plate 23 which faces the second catalytic layer 11 of the electrochemical cell considered, therefore facing the electrolytic membrane 3 of the electrochemical cell considered. These channels 27 are provided for the circulation of a second reactive gas.
[0056] The second reactant gas is typically air, or oxygen gas, or any other suitable gas.
[0057] The separation plate 21, the MEA 17 and the second separation plate 23 are stacked in a stacking direction E, one on top of the other.
[0058] The stacking direction E is shown in Figure 1.
[0059] Together, they define a cell of the fuel cell stack 1. Seals (not shown) are generally provided between each separation plate and the MEA. The fuel cell stack 1 comprises a large number of cells, stacked on top of each other in the stacking direction E.
[0060] Only one of the cells is shown in Figures 1 and 2.
[0061] The first separation plate 21 of one of the cells is therefore superimposed and in electrical contact with the second separation plate 23 of the neighboring cell in the stack.
[0062] In certain fuel cell architectures, channels 29 for circulating a heat transfer fluid are formed between said first separation plate 21 of a cell and said second separation plate 23 of the neighboring cell, therefore between two neighboring cells. The second faces 22b / 24b of these two plates can be welded together or glued to each other, or simply clamped against each other in the stack of cells, with, in particular in the latter case, the possibility of providing a sealing joint system between the two plates. The heat transfer fluid makes it possible to cool the cells of the fuel cell during its operation.
[0063] In Figure 1, the circulation channels 29 of the heat transfer fluid are not shown on the second separation plate 23.
[0064] In the example shown, the first and second separation plates 21, 23 and the frame 19 are rectangular and have respective shapes and sizes that are substantially identical to each other.
[0065] The first and second separation plates 21, 23 and the frame 19 have a general elongated shape in a longitudinal direction L, shown in FIG. 1.
[0066] Orifices 31a, 31b and 31c are provided respectively in the first separation plate 21, in the frame 19 and in the second separation plate 23. The orifices 31a, 31b and 31c are placed in coincidence with each other and constitute a distribution manifold for the first reactive gas.
[0067] The orifices 31 a, 31 b and 31 c are preferably placed at an angle respectively to the first separation plate 21, the frame 19 and the second separation plate 23.
[0068] The first separation plate 21, the frame 19 and the second separation plate 23 also comprise orifices 32a, 32b and 32c placed in coincidence with each other. The orifices 32a, 32b and 32c define a collector for discharging the first reactive gas. They are preferably placed in the corners opposite the orifices 31a, 31b and 31c.
[0069] The first separation plate 21, the frame 19 and the second separation plate 23 further comprise orifices 33a, 33b and 33c respectively, placed in coincidence with each other. They define a distribution manifold of the second reactive gas. They are preferably located at another angle of the first separation plate 21, the frame 19 and the second separation plate 23 respectively.
[0070] The first separation plate 21, the frame 19 and the second separation plate 23 also have orifices 34a, 34b and 34c respectively, placed in coincidence with each other. They are preferably located at angles opposite the orifices 33a, 33b and 33c. They define a collector for discharging the second reactive gas.
[0071] The first separating plate 21, the frame 19 and the second separating plate 23 also have orifices 35a, 35b and 35c respectively, placed in coincidence with each other. The orifices 35a, 35b and 35c together define a heat transfer fluid supply manifold. They are located for example respectively between the orifices 34a and 31a, between the orifices 34b and 31b, and between the orifices 34c and 31c. Finally, the first separating plate 21, the frame 19 and the second separating plate 23 respectively define orifices 36a, 36b and 36c, placed in coincidence with each other. They together define a heat transfer fluid discharge manifold. They are placed respectively, for example, between the orifices 32a and 33a, between the orifices 32b and 33b, and between the orifices 32c and 33c.
[0072] By way of example, the orifices 34a, 35a and 31a are placed at one longitudinal end of the first separation plate 21, and are juxtaposed in a transverse direction across the width of the plate. Still by way of example, the orifices 32a, 36a and 33a are placed at the other longitudinal end of the first separation plate 21, and are juxtaposed transversely across the width of the plate.
[0073] The holes 34b, 35b and 31b are placed at one longitudinal end of the frame 19, and are juxtaposed in a transverse direction across the width of the frame. The holes 32b, 36b and 33b are placed at the other longitudinal end of the frame 19, and are juxtaposed transversely across the width of the frame.
[0074] The holes 34c, 35c and 31c are placed at one longitudinal end of the second separating plate 23, and are juxtaposed in a transverse direction across the width of the plate. The holes 32c, 36c and 33c are placed at the other longitudinal end of the second separating plate 23, and are juxtaposed transversely across the width of the plate.
[0075] The set of channels 25 formed on the first separation plate 21 ensures the circulation of the first reactive gas, on the first face 22a of the first separation plate facing the electrolytic membrane 3, from the orifice 31a to the orifice 32a.
[0076] In the same way, the set of channels 27 formed on the second separation plate 23 ensures the circulation of the second reactive gas, on the first face 24a of the second separation plate facing the electrolytic membrane 3, from the orifice 33c to the orifice 34c.
[0077] The direction of flow described above in channel set 25 and / or in channel set 27 is an example and could be reversed, for either set, or for both.
[0078] As visible in Figure 1, the first separation plate 21 has a central zone 38, in which the channels of the assembly 25 extend in a general direction parallel to the longitudinal direction L.
[0079] The first separation plate 21 also comprises a distribution zone 40 interposed, in the longitudinal direction L, between the central zone 38 and the end of the first distribution plate 21 in which the orifices 31a, 35a and 34a are formed.
[0080] Among the channels of the set of channels 25, those which are formed in the distribution zone 40 comprise oblique channels 56 which extend in a general direction obliquely relative to the longitudinal direction L and fluidically connect the channels of the central zone 38 to the orifice 31 a. At least one section of the oblique channels 56 may be perpendicular to the longitudinal direction L, as will be seen with reference to FIG. 4.
[0081] The first separation plate 21 also comprises a second distribution zone 42. The second distribution zone 42 is interposed, in the longitudinal direction L, between the central zone 38 and the other longitudinal end of the first separation plate 21, in which the orifices 32a, 36a and 33a are formed.
[0082] Among the channels of the set of channels 25, those which are formed in the second distribution zone 42 comprise oblique channels 56 which extend in a general direction obliquely relative to the longitudinal direction L and fluidically connect the channels of the central zone 38 to the orifice 32a. At least one section of these oblique channels 56 may be perpendicular to the longitudinal direction L.
[0083] The second partition plate 23 is formed like the first partition plate.
[0084] It also has a central zone 44 in which the channels of the assembly 27 extend in a general direction parallel to the longitudinal direction L. It comprises a distribution zone 46 in which the channels of the assembly 27 extend in a general direction oblique to the longitudinal direction L. These channels make it possible to fluidically connect the channels of the central zone 44 to the orifice 33c. It also comprises a second distribution zone 48, in which the channels of the assembly 27 extend in a general direction oblique to the longitudinal direction L. These channels make it possible to fluidically connect the channels of the central zone 44 to the orifice 34c.
[0085] The distribution zone 46 is interposed in the longitudinal direction between the central zone 44 and the end of the second separation plate 23 in which the orifices 32c, 36c and 33c are formed. The other distribution zone 48 is interposed in the longitudinal direction L between the central zone 44 and the end of the second separation plate 23 in which the orifices 31c, 35c and 34c are formed.
[0086] The zones 44, 46 and 48 are delimited by broken lines in FIG. 1, because the channels 27 for circulation of the second reactive gas are arranged on the first face 24a of the separation plate 23 not visible in FIG. 1. According to the invention, and as shown in FIG. 3, the first separation plate 21 comprises a plurality of corrugated channels 49, for the circulation of the first reactive gas. These corrugated channels 49 have end portions 50 all extending in the same first direction D1 and forming corrugations having the same first determined period T1.
[0087] The corrugated channels 49 are part of the set 25 of channels ensuring the circulation of the first reactive gas.
[0088] Each end portion 50 extends along the first direction D1 in the sense that it extends along a general direction parallel to the first direction D1.
[0089] The undulations of the end portion 50 form bumps 52 alternately on both sides of a center line C, parallel to the first direction D1. All the bumps 52, taken perpendicular to the center line C, have the same transverse offset relative to the center line C in the plane of Figure 3, which is the extension plane of the first plate.
[0090] The transverse offset corresponds to the distance, perpendicular to the first direction D1, between the central line C and the top of the bump 52.
[0091] The period T 1 corresponds to the spacing between the peaks 54 of two consecutive bumps located on the same side of the central line C, this spacing being taken according to the first direction D1, along the central line C.
[0092] The undulations of the end portions 50 are in phase along the first direction D1.
[0093] This means that the bosses 52 of the different end portions 50 are located, along the first direction D1, at the same positions. In other words, all the bosses 52 located on a first side of the central line C for a given end portion 50 are located, along the direction D1, at the same positions as the bosses of the other end portions 50 located on the same side.
[0094] In the example shown, the bosses 52 of all the end portions 50 have the same transverse offset.
[0095] The spacing between the respective central lines C of the end portions 50 of the different corrugated channels is substantially constant. This spacing is taken perpendicular to the first direction D1.
[0096] In Figures 3 and 5, the spacing between the corrugated channels 49 is greatly exaggerated compared to the width of these corrugated channels 49, for reasons of clarity of the drawing. The first separation plate 21 also comprises a plurality of oblique channels 56, each extending in a second direction D2 intersecting with the first direction D1.
[0097] The oblique channels 56 are part of the set 25 of channels ensuring the circulation of the first reactive gas.
[0098] In the example shown, the oblique channels 56 are parallel to each other, and therefore all extend in the same second direction D2 intersecting with the first direction D1.
[0099] Alternatively, the oblique channels 56 extend in respective second directions slightly different from each other, and forming at most an angle of 30° with each other, preferably at most 15° with each other.
[0100] The spacing between the oblique channels 56 is substantially constant. This spacing is taken perpendicular to the second direction D2.
[0101] The corrugated channels 49 are typically formed on the central zone 38. The first direction D1 then corresponds to the longitudinal direction L. The oblique channels 56 are typically formed in the distribution zone 40 or 42.
[0102] As illustrated in Figure 3, the end portion 50 of each corrugated channel 49 connects to one of the oblique channels 56 at a junction point 58.
[0103] The end portion 50 connects directly to the corresponding oblique channel 56. This means that the oblique channel 56 directly extends the end portion 50, the first reactive gas flowing between the oblique channel 56 and the end portion 50 of the corrugated channel.
[0104] The oblique channels 56 have oblique end portions 60 connected to the junction points 58.
[0105] These oblique end portions 60 are preferably rectilinear and parallel to each other. These oblique end portions 60 extend along the second direction D2.
[0106] The second direction D2 forms with the first direction D1 an angle typically between 30° and 90°. For example, the second direction D2 is perpendicular to the first direction D1.
[0107] The junction points 58 define projection points p in projection onto a line D parallel to the first direction D1 (figure 3). The projection is taken along a third direction D3 perpendicular to the first direction D1.
[0108] Said projection points p are regularly spaced from each other along the first direction D1 and separated from each other by a constant gap equal to a multiple of said determined period T1. A gap equal to a multiple of the determined period T1 means here that the gap is equal to the determined period T1 multiplied by an integer greater than or equal to one.
[0109] In other words, the junction points 58 are regularly spaced from each other along the first direction D1. They are separated from each other by a constant gap, equal to a multiple of the determined period T1.
[0110] In the example shown, the gap between the projection points p is equal to the period T 1 .
[0111] Alternatively, this gap is twice T1 , or three times T1 , or any other multiple.
[0112] As a result, and as illustrated in Figure 3, the end portions 50 of the corrugated channels have respective tangents T at their junction points 58, all parallel to each other.
[0113] Here we consider the tangents to the end parts 50 of the corrugated channels, taken at the level of the junction points 58.
[0114] As a result, the inclination between the end of the oblique channel 56, taken at the level of the junction point 58, and the end of the part 50, also taken at the level of the junction point 58, is substantially the same regardless of the corrugated channel 25 considered.
[0115] This inclination is strictly the same if the oblique end portions 60 of all the oblique channels 56 are oriented in the same second direction.
[0116] This inclination may be slightly different from one channel to another, if the oblique end portions 60 do not all extend in the same second direction.
[0117] However, because the oblique end portions 60 extend in directions close to each other, the inclinations at the different junction points 58 are close to each other, so that the pressure drops for the first reactant gas flowing in the different channels are not significantly different.
[0118] Figure 4 shows in more detail an example of a first separation plate 21. It shows only one area of the separation plate. The view in Figure 4 is a zoom of area IV delineated in Figure 1.
[0119] It appears in Figure 4 that each corrugated channel 49 comprises a main part 62 extending in the first direction D1 and forming large corrugations.
[0120] Typically, the main portion 62 extends over most of the length of the central zone 38. The first direction D1 here corresponds to the longitudinal direction L.
[0121] The end portion 50 extends the main portion 62 of a given corrugated channel 49.
[0122] The large undulations have a determined elongated period T2, greater than the determined period T1 of the undulations of the end part 50. The main part 62 extends along the same central line C as the end part 50. The large undulations form bumps 64 on either side of the central line C. The elongated period T2 corresponds to the spacing, taken along the first direction D1, between the peaks of two successive bumps 64, located on the same side of the central line C.
[0123] Typically, the extended period T2 is between 1.5 times and 20 times the period T1, more preferably between 5 and 15 times the period T1.
[0124] The bosses 64 have, perpendicular to the central line C, a transverse offset greater than that of the bosses 52.
[0125] The large undulations of the main parts 62 of the different channels are in phase, that is to say that the bumps 64 of the different channels are located at the same level along the first direction D1.
[0126] The end portion 50 and the main portion 62 of the same corrugated channel 49 meet at a limit point 65.
[0127] This limit point 65 corresponds to the limit between small undulations and large undulations. The limit points 65 of the different undulating channels are aligned along the third direction D3, perpendicular to the first direction D1.
[0128] In the embodiment of Figure 3, the number of oblique channels 56 is equal to the number of corrugated channels 49. The corrugated channels 49 each open into a different oblique channel 56.
[0129] In the example of Figure 3, the junction points 58 are placed on a straight line. This straight line C' is illustrated by a dashed line in Figure 3. It intersects the first direction D1.
[0130] It also intersects the second direction(s) D2.
[0131] The corrugated channels 49 each comprise, as indicated above, a main portion with large corrugations, in addition to the end portion 50. This main portion is not shown in FIG. 3.
[0132] Because the end points 65 of the different corrugated channels 49 are aligned along the direction D3, the end portions 50 of the corrugated channels 25 are all of different lengths, the lengths being taken along the first direction D1.
[0133] More precisely, the end portions 50 of the corrugated channels 49 are juxtaposed along the third direction D3, perpendicular to the first direction D1. The end portion 50 located on a first edge of this juxtaposition, the upper edge in the representation of FIG. 3, is the shortest. The length of the end portion 50 increases when going from the first edge to the second edge. In the example of FIG. 3, the length increases by T1 when going from one corrugated channel 49 to another. In other words, in the example of FIG. 3, the end portions 50 of two neighboring corrugated channels 49 have a difference in length of T1.
[0134] In the embodiment of Figure 4, the number of oblique channels 56 is less than the number of corrugated channels 49, several corrugated channels 49 opening into the same oblique channel 56.
[0135] In this example of figure 4, the junction points 58 of the undulating channels 49 opening into the same oblique channel 56 define the same projection point p on the line D.
[0136] Thus, in this example of figure 4, the end parts 50 of the corrugated channels 49 opening into the same oblique channel 56 have the same length in the first direction D1.
[0137] The corrugated channels 49 opening into the same oblique channel 56 are juxtaposed next to each other in the third direction D3.
[0138] In the example shown in Figure 4, the first separation plate 21 comprises seven neighboring corrugated channels 49 opening into each oblique channel 56.
[0139] In other embodiments, the number of oblique channels 56 is less than the number of wavy channels 49, several wavy channels 49 opening into the same oblique channel 56, but the junction points 58 of the wavy channels 49 opening into the same oblique channel 56 define at least two different projection points p on the line D.
[0140] In such a case, they all define different projection points p on the line D. Alternatively, the junction points 58 of some wavy channels 49 define different projection points p on the line D, and the junction points 58 of other wavy channels 49 define the same projection point p on the line D.
[0141] In such cases, the end portions 50 of the corrugated channels 49 whose projection points p are different have different lengths along the first direction D1.
[0142] The undulating channels 49 opening into the same oblique channel 56 are juxtaposed next to each other along the third direction D3, and the projection points p are consecutive on the line D.
[0143] For example, two neighboring 49 corrugated channels opening into each oblique channel.
[0144] As illustrated in Figure 4, the walls 70 separating the oblique channels 56 have interruptions 72, through which the oblique channels 56 communicate with each other. This makes it possible to balance the pressures between the oblique channels 56. The second separation plate 23 also carries a network of channels. It may also comprise a plurality of corrugated channels for the circulation of the second reactive gas, and a plurality of oblique channels.
[0145] The corrugated channels of the second separating plate may in this case be similar to the corrugated channels of the first separating plate. They will therefore not be described in detail here.
[0146] The oblique channels of the second separation plate may be similar to the oblique channels of the first separation plate. They will therefore not be described here in detail.
[0147] The junction points between the oblique channels and the wavy channels can also define projection points on a straight line D parallel to the first direction, the projection being in the third direction, the projection points being regularly spaced from each other in the first direction and separated from each other by a constant gap equal to a multiple of the period of the undulations formed in the end parts of the wavy channels.
[0148] This period is for example the same as that of the undulations of the end parts of the channels of the first separation plate. Alternatively, this period is different.
[0149] Similarly, the elongated period of the large undulations of the corrugated channels of the second separating plate is for example equal to the elongated period of the corrugated channels of the first separating plate. Alternatively, it is not equal to the elongated period of the corrugated channels of the first separating plate.
[0150] The fuel cell described above has multiple advantages.
[0151] When the projection points are separated from each other by a constant distance, equal to the determined period of the undulations, the projection points are as close as possible along the first direction. It is thus possible to draw a very tight network of oblique channels.
[0152] When each corrugated channel comprises a main portion extending in the first direction and forming large corrugations each having a determined elongated period, greater than the determined period of the corrugations of the end portion, the risks of deformation of the channels of the first separation plate are reduced. The corrugated channels have more pronounced variations in shape at the large corrugations, the main portion of the corrugated channel therefore offering better mechanical resistance when the separation plates are clamped against each other.
[0153] Providing a smaller number of oblique channels than the number of corrugated channels, with several corrugated channels opening into the same oblique channel, makes it easier to manufacture the first separation plate and limits pressure losses in the oblique channels. This also makes it possible to form a large number of corrugated channels, and therefore guarantees a very homogeneous distribution of the first reactive gas in the central part of the plate.
[0154] Providing that the junction points of the corrugated channels opening into the same oblique channel define the same projection point on the line makes it possible to give the oblique channels an orientation substantially perpendicular to the first direction. This is advantageous for the organization of the channels on the first separation plate.
[0155] Because the end parts of the corrugated channels have respective tangents at their junction points which are all parallel to each other, the pressure drop of the first reactive gas passing through the junction point is substantially the same, regardless of the corrugated channel used.
[0156] The fuel cell described above has multiple variations.
[0157] In the embodiment described above, the corrugated channels extend in a first direction D1 corresponding to the longitudinal direction L, i.e. the direction of the large edges of the plate. Alternatively, the first direction D1 is not coincident with the longitudinal direction L, but forms an angle with the longitudinal direction L.
[0158] The oblique channels are not necessarily the channels belonging to the distribution zone 40 or to the distribution zone 42. They can be formed on the central part 38 of the plate.
[0159] The first separation plate 21 is not necessarily in contact with the catalytic layer forming the anode. It may be in contact with the catalytic layer forming the cathode.
[0160] The second separating plate is not necessarily of the same type as the first separating plate. Only one of the two separating plates can carry the corrugated channels and the oblique channels whose junction points are regularly spaced in the first direction, as described above.
[0161] Corrugated channels do not necessarily have straight centerlines. The centerlines can have sections of different orientations.
Claims
CLAIMS 1. Separator plate for an electrochemical cell of a fuel cell (1), the separator plate (21) comprising, in a first face: * a plurality of corrugated channels (49) for circulating a first reactive gas, the corrugated channels (49) having respective end portions (50) all extending in the same first direction (D1) and forming corrugations having the same determined period (T1); * a plurality of oblique channels (56), each extending in a second direction (D2) intersecting with the first direction (D1), the end portion (50) of each corrugated channel (49) connecting to one of the oblique channels (56) at a junction point (58); the junction points (58) defining projection points (p) in projection onto a straight line (D) parallel to the first direction (D1), the projection being in a third direction (D3) perpendicular to the first direction (D1), said projection points (p) being regularly spaced from each other in the first direction (D1) and separated from each other by a constant gap equal to a multiple of said determined period (T1).
2. Separator plate according to claim 1, in which the projection points (p) are separated from each other by a constant gap equal to said determined period (T1).
3. Separator plate according to any one of the preceding claims, in which each corrugated channel (49) comprises a main part (62) extending in the first direction (D1) and forming large corrugations having a determined elongated period (T2), greater than the determined period (T1) of the corrugations of the end part (50), the end part (50) of a corrugated channel (49) extending between the main part (62) and the junction point (58) of said corrugated channel (49).
4. Separator plate according to any one of the preceding claims, in which the number of oblique channels (56) is less than the number of corrugated channels (49), several corrugated channels (49) opening into the same oblique channel (56).
5. Separator plate according to claim 4, in which the junction points (58) of the corrugated channels (49) opening into the same oblique channel (56) define the same projection point (p) on the straight line (D).
6. Separator plate according to claim 4, in which the junction points (58) of the corrugated channels (49) opening into the same oblique channel (56) define at least two distinct projection points (p) on the straight line (D).
7. Separator plate according to any one of claims 1 to 4 and 6, in which the junction points (58) are placed on a straight line (C') intersecting the first direction (D1).
8. Separator plate according to any one of the preceding claims, in which the end portions (50) of the corrugated channels (49) have, at their junction points (58), respective tangents (T) all parallel to each other.
9. Separator plate according to any one of the preceding claims, in which the oblique channels (56) have oblique end portions (60) connected to the junction points (58), these oblique end portions (60) being rectilinear and parallel to each other.
10. Separator plate according to claim 9, wherein the oblique end portions (60) extend in the third direction (D3), perpendicular to the first direction (D1).
11. Fuel cell (1) comprising a plurality of electrochemical cells, each electrochemical cell comprising: - an electrolytic membrane (3), having first and second large faces (5, 7) opposite each other; - first and second catalytic layers (9, 11), arranged against the first and second large faces (5, 7) of the electrolytic membrane (3); - a separation plate (21) according to any one of the preceding claims, the first catalytic layer (9) being arranged between the first face of the separation plate (21) and the electrolytic membrane (3).