Separator plate for electrochemical systems
阅读说明:本技术 用于电化学系统的分离器板 (Separator plate for electrochemical systems ) 是由 T·斯托尔 C·昆茨 于 2018-05-30 设计创作,主要内容包括:本发明涉及一种用于电化学系统(1)、具体是用于电化学系统(1)的双极板(2)的分离器板(2a、2b)。分离器板(2a、2b)包括:第一通道(11c),用于引导冷却剂通过分离器板(2a、2b);活性区域(8),具有用于沿分离器板(2a、2b)的第一平坦表面引导反应介质的结构和用于沿分离器板(2a、2b)的第二平坦表面上的活性区域(8)的后表面引导冷却剂的结构;与分离器板(2a、2b)形成为一体的珠缘(7),用于至少密封活性区域(8);以及与分离器板(2a、2b)形成为一体的阻隔元件(18、18’、18"),这些元件设计成使得它们减少或防止反应介质沿珠缘(7)在分离器板(2a、2b)的第一平坦表面上流动并越过活性区域(8)。分离器板(2a、2b)的特征在于,珠缘(7)将第一通道(11c)和活性区域(8)完全封围在一起,并且至少一个阻隔元件(18、18’、18")至少部分地凹陷,特别是为了减少或防止冷却剂在所述阻挡元件的区域中在分离器板(2a、2b)的第二平坦表面上流动。本发明还涉及包括分离器板的双极板,并且涉及具有多个指定类型的双极板的电化学系统。(The invention relates to a separator plate (2a, 2b) for an electrochemical system (1), in particular for a bipolar plate (2) of an electrochemical system (1). The separator plates (2a, 2b) comprise: a first channel (11c) for leading coolant through the separator plate (2a, 2 b); an active region (8) having a structure for guiding a reaction medium along a first planar surface of the separator plate (2a, 2b) and a structure for guiding a coolant along a rear surface of the active region (8) on a second planar surface of the separator plate (2a, 2 b); a bead (7) integral with the separator plate (2a, 2b) for sealing at least the active area (8); and barrier elements (18, 18') formed integrally with the separator plates (2a, 2b), which elements are designed such that they reduce or prevent the flow of the reaction medium along the beads (7) over the first planar surface of the separator plates (2a, 2b) and over the active area (8). The separator plate (2a, 2b) is characterized in that the bead (7) completely encloses the first channel (11c) and the active region (8) together, and that at least one barrier element (18, 18') is at least partially recessed, in particular in order to reduce or prevent the flow of coolant on the second planar surface of the separator plate (2a, 2b) in the region of said barrier element. The invention also relates to a bipolar plate comprising a separator plate, and to an electrochemical system with a plurality of bipolar plates of the specified type.)
1. Separator plate (2a, 2b) for an electrochemical system (1), in particular for a bipolar plate (2) of an electrochemical system (1), comprising:
a first through opening (11c), the first through opening (11c) being for guiding coolant through the separator plate (2a, 2 b);
an active region (8), the active region (8) having structure for guiding a reaction medium along a first planar side of the separator plate (2a, 2b) and structure for guiding a coolant along a backside of the active region (8) on a second planar side of the separator plate (2a, 2 b);
a bead (7), said bead (7) being integral with said separator plate (2a, 2b) for sealing at least said active area (8); and
a barrier element (18, 18', 18"), said barrier element (18, 18', 18") being integral with said separator plate (2a, 2 b);
wherein the barrier element (18, 18')
a. Is arranged between the active region (8) and the bead (7)
And/or
b. Arranged between a distribution region (20) of the separator plate (2a, 2b) and the bead (7), wherein the distribution region (20) is configured for guiding the coolant from the through-openings (11c) to the rear side of the active region (8) or from the rear side of the active region (8) to through-openings (11c) on the second flat side of the separator plate (2a, 2 b); and is
And wherein the barrier elements (18, 18') are formed such that they reduce or prevent a flow of reaction medium along the beads (7) on the first flat side of the separator plate (2a, 2b) and past the active region (8);
it is characterized in that the preparation method is characterized in that,
the bead (7) completely encloses both the first through opening (11c) and the active zone (8) together, and at least one of the barrier elements (18, 18', 18") is at least partially recessed, in particular for reducing or preventing the flow of coolant on the second flat side of the separator plate (2a, 2b) in the region of this barrier element between the rear side of the active zone (8) and the interior (21) of the bead (7) and/or between the rear side of the distribution zone and the interior (21) of the bead (7).
2. The separator plate (2a, 2b) according to claim 1, having a second through-opening for leading coolant through the separator plate (2a, 2b), wherein the bead (7) also completely surrounds the second through-opening.
3. The separator plate (2a, 2b) according to claim 2, wherein the first through opening (11c) and the second through opening are arranged on opposite sides of the active area (8) from each other.
4. Separator plate (2a, 2b) according to one of the preceding claims, characterized in that, at least for one or more of the barrier elements (18, 18', 18"), a recess (23, 23', 23") extends in at least one direction over the entire barrier element.
5. Separator plate (2a, 2b) according to one of the preceding claims, wherein, at least for one or more of the barrier elements (18, 18', 18"), a recess (23, 23', 23") is spaced from an edge of the barrier element.
6. Separator plate (2a, 2b) according to one of the preceding claims, characterized in that, at least for one or more of the barrier elements (18, 18', 18"), the recesses (23, 23', 23") have an elongated shape and are aligned parallel or substantially parallel to the main extension direction of the beads (7).
7. The separator plate (2a, 2b) according to one of the preceding claims, characterized in that, at least for one or more of the barrier elements (18, 18', 18"), the recess (23, 23', 23") is designed such that it reduces by at least 50 percent, preferably by at least 70 percent, more preferably by at least 90 percent, the cross section defined perpendicular to the surface plane of the separator plate (2a, 2b), the location of the connection between the rear side of the active area (8) and the inner portion (21) of the bead (7) on the second flat side of the separator plate (2a, 2b), which connection is formed by the barrier element.
8. The separator plate (2a, 2b) according to one of the preceding claims, wherein at least one or more of the barrier elements (18, 18', 18") reach or reach the active region (8) and up to the bead (7).
9. The separator plate (2a, 2b) according to one of the preceding claims, wherein at least one or more of the barrier elements (18, 18', 18") are aligned at least partially transversely to the main extension direction of the bead (7).
10. The separator plate (2a, 2b) according to one of the preceding claims, wherein at least one or more of the barrier elements (18, 18', 18") are formed such that a cross section of a surface plane of the respective barrier element perpendicular to the plane of the separator plate (2a, 2b) tapers towards the bead (7), and particularly preferably tapers at least 50 percent, particularly preferably at least 70 percent.
11. The separator plate (2a, 2b) according to claim 10, wherein the cross-section is tapered (24) along a direction parallel to a surface plane of the separator plate (2a, 2b), preferably parallel to the main extension direction of the bead (7).
12. The separator plate (2a, 2b) according to one of claims 10 or 11, wherein the taper (24) is realized in a stepped manner at least with respect to one or several of the barrier elements (18, 18 ").
13. Separator plate (2a, 2b) according to one of the preceding claims, characterized in that at least some of the barrier elements (18, 18', 18") adjacent to each other are connected to each other, preferably by means of connections aligned parallel to the main extension direction of the beads (7).
14. The separator plate (2a, 2b) according to one of the preceding claims, having a distribution structure for distributing coolant on the rear side of the active region (8), wherein the distribution structure reaches the end of the active region (8) facing the bead (7) transversely to the flow direction of the coolant along the rear side of the active region (8).
15. The separator plate (2a, 2b) according to one of the preceding claims, characterized by at least one recess (23, 23', 23 "), which at least one recess (23, 23', 23") extends in a continuous manner from the active region (8) to the bead (7) transversely to the flow direction along the rear side of the active region (8).
16. The separator plate (2a, 2b) according to one of claims 14 and 15, wherein the barrier elements (18, 18', 18") are arranged in a row parallel to the main extension direction of the bead (7), and wherein the recesses (23, 23', 23") extending continuously from the active region (8) to the bead (7) are arranged at the end of the row facing the dispensing structure.
17. Separator plate (2a, 2b) according to one of the preceding claims, characterized in that there is at least one barrier element of the aforementioned type without recesses (23, 23', 23 ").
18. The separator plate (2a, 2b) according to one of the preceding claims, having a first port bead (12c), the first port bead (12c) completely surrounding the first through opening (11 c).
19. The separator plate (2a, 2b) according to any one of claims 2 or 3 or according to one of claims 4 to 18, when referring back to claim 2, having a second port bead which completely surrounds the second through opening.
20. The separator plate (2a, 2b) according to one of the preceding claims, wherein the separator plate (2a, 2b) is formed from a sheet of metal, preferably stainless steel, wherein at least one, more or all of the following elements are pressed into the separator plate (2a, 2 b):
the bead (7) or beads (7);
the structure of the active region (8);
-a distribution structure of said distribution area (20);
a barrier element (18, 18', 18 "); and/or
The recess (23, 23', 23 ").
21. Bipolar plate (2) for an electrochemical system (1), having a first separator plate (2a, 2b) according to one of the preceding claims and having a second separator plate (2a, 2b) according to one of the preceding claims, characterized in that two separator plates (2a, 2b) are connected to each other, wherein the first through openings (11c) of the two separator plates (2a, 2b) are arranged in an aligned manner for forming the first through openings (11c) of the bipolar plate (2), wherein the two separator plates (2a, 2b) enclose a chamber (22) for guiding a coolant through the bipolar plate (2), and wherein the first through openings (11c) of the bipolar plate (2) are in fluid connection with the chamber (22).
22. The bipolar plate (2) according to claim 21, with two separator plates (2a, 2b) according to one of claims 2 or 3 or one of claims 4 to 20, when referring back to claim 2, characterized in that the second through openings of the two separator plates (2a, 2b) are arranged in an aligned manner to form a second through opening of the bipolar plate (2), and wherein the second through opening of the bipolar plate (2) is in fluid connection with the chamber (22).
23. Bipolar plate (2) according to one of claims 21 or 22, characterised in that the barrier elements (18, 18', 18") of the first separator plate (2a, 2b) and the barrier elements (18, 18', 18") of the second separator plate (2a, 2b) are arranged in an at least partially overlapping manner, and wherein the recesses (23, 23', 23 ") of the barrier elements (18, 18', 18") of the first separator plate (2a, 2b) and the recesses (23, 23', 23 ") of the barrier elements (18, 18', 18") of the second separator plate (2a, 2b) are arranged at least partially offset parallel to a surface plane of the bipolar plate (2).
24. Bipolar plate (2) according to one of claims 21 to 23, wherein the barrier elements (18, 18', 18") of the first separator plate (2a, 2b) and the barrier elements (18, 18', 18") of the second separator plate (2a, 2b) are arranged in an at least partially overlapping manner, and wherein the recesses (23, 23', 23 ") of the barrier elements (18, 18', 18") of the first separator plate (2a, 2b) and the recesses (23, 23', 23 ") of the barrier elements (18, 18', 18") of the second separator plate (2a, 2b) are arranged in an at least partially overlapping manner.
25. The bipolar plate (2) according to one of claims 22 to 24, wherein the chamber (22) enclosed between the two separator plates (2a, 2b) comprises a first partial space and a second partial space, wherein the first partial space is enclosed between the active region (8) of the first separator plate (2a, 2b) and the active region (8) of the second separator plate (2a, 2b), wherein the second partial space is enclosed between the bead (7) of the first separator plate (2a, 2b) and the bead (7) of the second separator plate (2a, 2b), wherein the first through opening (11c) of the bipolar plate (2) and the second through opening of the bipolar plate (2) are connected via a first fluid connection comprising the first partial space, and wherein the first through-opening (11c) of the bipolar plate (2) and the second through-opening of the bipolar plate (2) are connected via a second fluid connection comprising the second partial space, wherein the smallest cross section A of the first fluid connection1,minGreater than the smallest cross-section A of the second fluid connection2,minWherein, the preferable condition is: a. the1,min≥10·A2,minParticularly preferably, A1,min≥25·A2,min。
26. Electrochemical system (1) with a plurality of bipolar plates (2) according to one of claims 21 to 25 arranged in a stack, characterized in that respective Membrane Electrode Assemblies (MEA) are arranged between adjacent bipolar plates (2) of the stack, wherein the MEAs in the active areas (8) of the adjacent bipolar plates (2) each comprise an ionomer (140) and preferably at least one gas diffusion layer (15).
27. Electrochemical system (1) according to claim 26, characterized in that each of the MEAs comprises a reinforced edge area which at least partially overlaps the barrier elements (18, 18', 18") of the bipolar plate (2) adjacent to the MEA.
Technical Field
The present invention relates to a separator plate for an electrochemical system, a bipolar plate comprising the separator plate, and an electrochemical system having a plurality of bipolar plates. The electrochemical system may be, for example, a fuel cell system, an electrochemical compressor, a redox flow battery, or an electrolysis cell.
Background
Known electrochemical systems generally comprise a stack of electrochemical cells, which are each separated from one another by bipolar plates. Such bipolar plates can be used, for example, for the electrical contacting of the electrodes of individual electrochemical cells (for example fuel cells) and/or for the electrical connection of adjacent cells (series connection of cells). Typically, the bipolar plate is formed from two separate separator plates that are bonded together. The separator plates of the bipolar plate can be joined together, for example, by means of one or more welded connections, in particular by means of one or more laser welded connections.
The bipolar plates or separator plates may each comprise or form a structure configured, for example, for supplying one or more media to electrochemical cells arranged between adjacent bipolar plates and/or for removing reaction products. The medium may be a fuel (e.g., hydrogen or methanol) or a reactant gas (e.g., air or oxygen). Furthermore, the bipolar plate or the separator plate can be used for conducting the coolant through the bipolar plate, in particular through a chamber enclosed by the separator plate of the bipolar plate. Typically, the fuel or reactant gas is directed on a first side of the separator plate, which is also often referred to as a first flat side due to the structure of the first side, while the coolant is directed on a second flat side of the separator plate. A cavity is then formed between the second flat sides of the two separator plates. In addition, the bipolar plates can be configured for the transfer of waste heat generated in the conversion of electrical or chemical energy in electrochemical cells and for sealing the various media or cooling channels with respect to one another and/or externally.
Barrier elements may be provided between the active region and the bead, which delimit the active region to the outside, and which are arranged and shaped such that they reduce or prevent the flow of the reaction medium through the active region. Such a barrier element may be formed, for example, by providing protrusions in the separator plate that are raised above the area of the separator plate adjacent thereto on the side of the reaction medium.
Furthermore, the bipolar plates typically each comprise at least one or more through openings. The medium and/or the reaction products can be conducted through the through-openings to the electrochemical cells arranged between adjacent bipolar plates of the stack or into the chambers formed by the separator plates of the bipolar plates, or out of the cells or chambers. The electrochemical cells typically additionally each comprise one or more Membrane Electrode Assemblies (MEAs). The MEA may include one or more gas diffusion layers that are generally oriented toward the bipolar plates and formed, for example, as a metallic or carbon nonwoven.
It has been found that in individual cases, for example, the coolant is guided to some extent in undesired paths on the side of the separator plate facing away from the electrochemically active side, for example in a chamber enclosed by two separator plates of a bipolar plate, which is problematic. Thus, it may happen, for example, that the coolant which is primarily used for cooling the electrochemically active region of the separator plate or bipolar plate is conducted at least partially through the active region or even through parts of the distribution region and thus does not or does not contribute to a sufficient extent to the cooling of the active region. In particular, given a pressed-in separator plate, the above-mentioned blocking element is formed by means of a press-in portion which is joined in the direction of the first flat side. However, these result in a cavity on the second flat side of the respective separator plate and may form an additional flow path for the coolant. By means of this, the risk of coolant flowing (bypassing) the active area on undesired paths is increased.
As a result of such an undesired coolant bypass, undesired temperature peaks in the region of the electrochemical cells and/or undesired pressure losses on the conducted coolant can occur. In addition, increased pumping power is required to deliver the coolant directed through the active region. All of these adverse effects may negatively impact the efficiency of the electrochemical system.
In order to prevent such an undesired coolant bypass completely or at least partially, it is proposed in document DE202014008157U1 to provide a filler, for example, in the edge region of the active region between the individual plates of the bipolar plate, in order to prevent the coolant from flowing past the rear side of the electrochemically active region. Nevertheless, there is a continuing need for separator plates or bipolar plates for electrochemical systems, which plates allow the system to be operated with as high an efficiency as possible.
Disclosure of Invention
It is therefore an object of the present invention to provide a separator plate and a bipolar plate for an electrochemical system which allows to operate the system with as high an efficiency as possible.
This object is achieved by a separator plate according to claim 1, by a bipolar plate comprising such a separator plate and by an electrochemical system having a plurality of bipolar plates of the above-mentioned type.
Accordingly, a separator plate for an electrochemical system, in particular for a bipolar plate of an electrochemical system, is proposed, which separator plate comprises:
a first through opening for guiding the coolant through the separator plate;
an active region having structure for directing a reaction medium along a first planar side of the separator plate and structure for directing a coolant along a backside of the active region on a second planar side of the separator plate.
A possible first distribution system for guiding the coolant between the first through opening and the active zone;
a bead formed integrally with the separator plate for sealing at least the active area; and
barrier elements, which are formed in one piece with the separator plate and are arranged between the active region and the bead or between the first distribution region and the bead, if present, and are formed such that they reduce or prevent the flow of the reaction medium along the bead on the first flat side of the separator plate and past the active region.
In order to completely or at least partially prevent coolant from the first through-opening from flowing into the interior of the bead on the second flat side of the separator plate, the bead runs such that it completely surrounds the active region and possibly the first distribution region, as well as completely surrounds the through-opening. In particular, the bead preferably does not traverse the flow path of the coolant from the first through opening to the rear side of the active region. In general, the barrier elements on the second flat side of the separator plate form an undesired fluid connection between the rear side of the active zone and the inside of the bead or between the rear side of the possibly present first distribution zone and the inside of the bead, since the projection on the first flat side increases the volume on the second flat side. To this end, in the region of the blocking elements on the second flat side of the separator plate, at least one of the blocking elements or at least some of the blocking elements is furthermore recessed in at least some regions for reducing or preventing the coolant from flowing between the rear side of the active region and the interior of the bead and/or between the rear side of the distribution region and the interior of the bead. By means of this, at least partial recesses on at least one of the blocking elements or on at least some of the blocking elements can reduce the cross section of the undesired fluid connection and can reduce the undesired coolant flow from the rear side of the active region into the bead interior or from the rear side of the possibly present first distribution region into the bead interior. It is particularly preferred that the barrier elements are recessed only in some areas, in order to minimize the risk of fuel or reaction gas flowing on undesired paths on the first flat side of the separator plate on the one hand, and coolant flowing on undesired paths on the second flat side of the separator plate on the other hand.
As already briefly mentioned, the separator plate may comprise on its rear side a distribution structure for distributing coolant on the rear side of the active region or for collecting coolant flowing through the rear side of the active region. The structure preferably extends from at least one port bead to an edge of the rear side of the active region, said edge facing the respective port bead. The distribution region formed by the distribution structure can, for example, run transversely to the flow direction of the coolant along the rear side of the active region up to the end facing the bead, or up to the side edge of the active region facing the bead.
The separator plate may comprise a second through opening for guiding the coolant through the separator plate. Between the second through opening and the active region, a distribution region or a collection region for conducting coolant to or from the rear side of the active region can in turn be arranged, and this region is referred to below as the second distribution region. The bead may then completely surround the second through opening and thus the active area, the first and/or second distribution areas, if present, and the first and second through openings. Then, the first through opening and the second through opening are preferably arranged on opposite sides of the rear side of the active region.
At least for one or more of the barrier elements, the recess may extend over the entire barrier element in at least one direction. This usually requires a transition region in which the material of the separator plate is reshaped from the plane of the blocking element onto the plane of the recess, so that excessively small bending angles can be avoided.
At least for one or more of the barrier elements, the recess may be spaced from an edge of the barrier element.
At least for one or more of the barrier elements, the recess may have an elongated shape. Furthermore, the recess may be aligned parallel or substantially parallel to the bead or with the main extension direction of the bead. The main extension direction of the bead is understood here to mean the main extension direction of the bead or of the bead section located closest to the blocking element.
At least for one or more of the blocking elements, the recess may be formed such that it is reduced by at least 50 percent, preferably by at least 70 percent, more preferably by at least 90 percent, at least in cross section, the cross section being defined perpendicular to the surface plane of the separator plate, the connection between the rear side of the active area and the inside of the bead on the rear side of the separator plate, said connection being formed by the blocking element.
At least one or more of the barrier elements may extend to the active or dispensing region and the bead. If the blocking element reaches the bead, the blocking element may be formed as a direct extension of the bead, so that in the region of the blocking element in a direction transverse to the main direction of extension of the bead, the bead feet facing the active area or the dispensing area or the blocking element do not rest on top of each other. On the other hand, it is preferred to arrange an area between two barrier elements along the main extension direction of the beads, with the bead feet facing one of the active area or the dispensing area resting on top of each other.
At least one or several of the blocking elements may be aligned, at least in cross section, transversely to the main extension direction of the bead.
At least one or more of the blocking elements may be formed such that a cross section of a surface plane of the respective blocking element perpendicular to the plane of the separator plate tapers towards the bead, and particularly preferably tapers at least 50 percent, particularly preferably at least 70 percent. For example, the cross section may taper in a direction along a surface plane parallel to the plane of the separator plate, preferably parallel to the bead or main extension direction. For example, the tapering may be realized in a stepped manner at least for one or several barrier elements.
At least some of the blocking elements adjacent to each other may be connected to each other, preferably by means of connections aligned parallel to the beads or to the main extension direction of the beads.
The separator plate may further comprise a first port bead completely surrounding the first through opening.
If the separator plate comprises the above-mentioned second through opening, it may further comprise a second port bead completely surrounding the second through opening.
At least one port bead may here comprise feed-through structures which allow a targeted transverse passage of the coolant through the port bead. Such structures are known, for example, from DE 10248531B 4, DE 202015104972U 1 and DE 202015104973U 1 of the applicant.
The separator plate may comprise at least one depression of the above-mentioned type, which extends in a continuous manner transversely to the flow direction of the coolant along the rear side of the active region, from the active region or from a distribution region, if present, up to the bead.
The barrier elements of the separator plate may be arranged in rows parallel to the beads or to the main extension direction of the beads. The abovementioned recesses, which extend continuously from the active area or the distribution area possibly present to the bead, can then be arranged in particular at the end of the row facing the distribution structure.
The separator plate may comprise at least one barrier element of the above-described type without recesses.
The separator plate may for example be formed from a metal sheet, preferably a stainless steel sheet. The beads and/or port beads, the structure of the active region, the structure of one or more dispensing regions that may be present, the barrier element and the recess may for example be pressed into the separator plate.
Further proposed is a bipolar plate for an electrochemical system having a first and a second separator plate of the above-mentioned type, wherein the two separator plates are connected to each other, wherein the first through openings of the two separator plates are arranged in an aligned manner to form the first through openings of the bipolar plate, wherein the two separator plates enclose a chamber for guiding a coolant through the bipolar plate, and wherein the first through openings of the bipolar plate are in fluid connection with the chamber.
The two separator plates of the bipolar plate may each additionally comprise the second through opening described above. The second through openings of the two separator plates may then be arranged in an aligned manner to form the second through openings of the bipolar plate. Typically, the second through opening of the bipolar plate is then also in fluid connection with the chamber enclosed by the two separator plates. In particular, one of the first and second through openings serves as an inlet and the other as an outlet for the same medium.
The barrier elements of the first separator plate and the barrier elements of the second separator plate may be arranged to overlap at least in areas. The indentations of the barrier elements of the first separator plate and the indentations of the barrier elements of the second separator plate may then be arranged offset at least partly parallel to the planar surface plane of the bipolar plate, thus not coinciding with a given parallel projection in the planar surface plane of the bipolar plate. Alternatively or additionally, the indentations of the barrier elements of the first separator plate and the indentations of the barrier elements of the second separator plate are also arranged in an at least partially overlapping manner, thus at least partially coinciding with a given parallel projection in the surface plane of the bipolar plate.
The chamber enclosed between the two separator plates may comprise a first partial space and a second partial space, wherein the first partial space is enclosed between the rear side of the second active area of the first separator plate and the rear side of the active area of the second separator plate, and wherein the second partial space is enclosed between the bead of the first separator plate and the bead of the second separator plate. The second partial space may thus comprise two bead sections in each separator plate running on two sides of the active area lying opposite one another. The first through-opening of the bipolar plate and the second through-opening of the bipolar plate can then be connected via a first fluid connection comprising a first partial space, and the first through-opening of the bipolar plate and the second through-opening of the bipolar plate can be connected via a second fluid connection comprising a second partial space. The first fluid connection is therefore generally used to guide or direct the main coolant flow for the desired cooling of the active region. The second fluid connection leads a practically undesirable flow into the interior of the bead, wherein the coolant is not available for cooling the active region. Minimum cross section A of the first fluid connection1,minAnd is then preferably larger than the smallest cross-section a of the second fluid connection2,min. Here, it is preferable that A is, for example1,min≥5·A2,minPreferably A1,min≥10·A2,minParticularly preferably A1,min≥15·A2,min. Here, for an efficient cooling of the electrochemical system, it is advantageous that, although the bead interior can be at least partially filled with coolant, no significant coolant flow takes place therein, and that the coolant in the bead interior is thus quasi stationary, so that the coolant fed from the first through-opening can be guided exclusively or almost exclusively via the distribution region to the rear side of the active region and via the rear side of the active region to the second through-opening.
Finally, an electrochemical system with a plurality of bipolar plates of the above-mentioned type is proposed, wherein the bipolar plates of the system are arranged in a stack. Typically, a Membrane Electrode Assembly (MEA) is disposed between adjacent bipolar plates of the stack. The MEAs may each include an ionomer and preferably at least one gas diffusion layer in the active area of the adjacent bipolar plates. The MEAs may also each include a reinforced edge region that at least partially overlaps the barrier elements and recesses of the bipolar plates adjacent the MEA. Therefore, no changes in MEA design are required over the prior art. The sealing elements of the bipolar plates are located on the MEA and the barrier elements are slightly spaced from the bipolar plates in a direction perpendicular to their surfaces.
Drawings
An example of embodiment of the invention is presented in the drawings and explained in more detail with the help of the following description. In which a number of features are presented that are combined together. However, each of the subsequently described features may also form part of the invention, independently of the other features exemplified. Hereinafter, more identical or similar elements will be continuously given identical or similar reference numerals, and thus, preferably, their description will not be repeated. Shown in the attached drawings:
figure 1 shows schematically in a perspective view an electrochemical system according to the invention with a plurality of stacked bipolar plates;
fig. 2 shows schematically a bipolar plate known from the prior art in a plan view;
fig. 3 schematically shows the system 1 of fig. 1 in a cross-sectional view;
figure 4A schematically shows a detail of a bipolar plate according to the invention in a plan view;
FIG. 4B is a detail from detail A of FIG. 4A;
figure 4C schematically shows a detail of another bipolar plate according to the invention in plan view;
figure 5A schematically shows a bipolar plate according to the invention in plan view, wherein the details shown in figures 4A and 4B are not shown for the sake of clarity;
figure 5B is a detail of a plan view of a bipolar plate according to the present invention; and
figures 6A-C schematically illustrate details of the bipolar plate of figures 4A and 4B in cross-sectional views.
Detailed Description
Fig. 1 shows an electrochemical system 1 according to the invention with a stack 32, the stack 32 having a plurality of
The z-axis 70, along with the x-axis 80 and the y-axis 90, spans a right-hand cartesian coordinate system. The end plate 4 comprises a plurality of media connections 5 via which media can be fed to the system 1 and via which media can be guided out of the system 1. These media, which may be fed to the system 1 and led out from the system 1, may comprise, for example, fuel such as molecular hydrogen or methanol, reaction gases such as air or oxygen, reaction products such as water vapor or coolants such as water and/or glycol.
Fig. 2 shows a detail of a
In order to seal the through
In the electrochemically
The distribution or
The through
Finally, the
In order to prevent that media directed from the through opening 11b into the
Fig. 3 schematically shows a detail of the internal construction of the inventive system 1 of fig. 1, in particular a cross-section through a fuel cell stack along the x-z plane. In this case, at least one cell (fuel cell) 14 is provided, which comprises an ion-conducting polymer membrane 140 which is provided on both sides with catalyst layers 141, 142 at least in the electrochemically
Furthermore, a gas diffusion layer 15 is arranged in the region between each
Corresponding to the
Fig. 4A shows one of the
The
The
A plurality of
The blocking
At the end facing the
An undesired side effect of the aforementioned design of the
In order to prevent or at least partially reduce the undesired outflow of coolant from the rear side of the
As can be seen from the illustration of fig. 4A, the
In fig. 4A, most of the
For example, the blocking element, labelled 18' and not reaching the
In addition, the blocking element, labelled 18", comprises a
Preferably, the
Fig. 4B shows a detail of the
The
Fig. 4C shows a plan view of a further
Fig. 5A only schematically shows a complete plan view of the
On the contrary, a functionally equivalent structure is shown in fig. 5B, which shows a detail of a plan view of a bipolar plate according to the invention, and in particular a detail corresponding to the detail of fig. 2. Here, in each blocking
Fig. 6A-C show a
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