Cooling field for a stacked electrochemical system and electrolyzer

Abstract

Cooling field (1) for a stacked electrochemical system (10), with at least one coolant inlet (2) and at least one coolant outlet (3) larger than the coolant inlet (2), wherein an inlet region (4), a main flow field (7) and an outlet region (9) are formed between the coolant inlet (2) and the coolant outlet (3), wherein the main flow field (7) lying in a plane normal to the stacking direction of the electrochemical system (10) has a central constriction region (8) in which it is narrower than the inlet region (4) and the outlet region (4), while regions (11, 12) of greater width of the main flow field (7) are present at the transitions (14, 15) between the main flow field (7) and the inlet region (4) and the outlet region (9), and wherein channels (13) are formed in the central constriction region (8),which run parallel to each other and parallel to a reference line (G1, G2) in the relevant area, which is placed centrally through the coolant inlet (2) and the coolant outlet (3), whereas between the central constriction area (8) and the transitions (14, 15) to the inlet area (4) and outlet area (9) respectively, there are several channel sections (16, 17) that are at least simply bent, which are connected to the inlet area (4) and the outlet area (9) respectively in different ways, in that a rib structure (18) on the side of the coolant inlet (2) and a pin structure (25) on the side of the coolant outlet (3) of the respective inlet or outlet area (2, 3) are adjacent to the main flow field (7), in each case while maintaining a distance to the aforementioned channel sections (16, 17).

Description

[0001] The invention relates to a cooling field intended for use in a stacked electrochemical system. The invention further relates to an electrolyzer for water electrolysis.

[0002] An electrolyzer for water electrolysis, i.e., for the production of hydrogen from water, is known, for example, from DE 10 2023 109 185 A1. The known electrolyzer includes, among other things, a cooling field frame as a component of a cell stack. Bipolar plates of the electrolyzer according to DE 10 2023 109 185 A1 separate a half-cell of a first electrochemical cell from a half-cell of another electrochemical cell. A channel area is located between a port kept clear by the bipolar plate and an active area of ​​the electrochemical cells, i.e., electrolysis cells. Several groups of protrusions are formed in the channel area by the bipolar plate; these serve as support structures and simultaneously as flow-conducting structures.The port, which is separated from the active area of ​​the electrolyzer by the channel area, lies in an opening of a frame which is arranged in a cooling plane of the stacked electrolyzer, the cooling plane being located between two half-sheets from which the bipolar plate is constructed.

[0003] An electrolyzer described in US 2022 / 0243348 A1 is designed to convert CO and CO2 into other carbon-containing substances, such as chemicals and fuels. US 2022 / 0243348 A1 details the design of flow fields and gas diffusion layers.

[0004] Another electrochemical system is described in DE 10 2022 110 122 A1. In this case, it is an electrolysis stack that processes process water, with a separate coolant circuit for temperature control.

[0005] The invention is based on the objective of further developing the cooling of electrochemical systems, in particular electrolyzers, compared to the prior art, with particular emphasis on achieving the most uniform cooling possible.

[0006] This problem is solved according to the invention by a cooling field having the features of claim 1 for a stacked electrochemical system. According to claim 10, the electrochemical system can in particular be an electrolyzer for water electrolysis.

[0007] The cooling field comprises at least one coolant inlet and at least one larger coolant outlet. Water or a liquid containing water as its main component can be used as the coolant. Alternatively, oil, for example, can be used as a coolant.

[0008] Between the coolant inlet and outlet, regardless of the type of coolant, an inlet area, a main flow field, and an outlet area are formed. The main flow field is larger than the inlet area and larger than the outlet area, in particular larger than the sum of the areas of the inlet and outlet areas. The area of ​​the inlet area can be the same as the area of ​​the outlet area. For example, the inlet area, which excludes the area of ​​the coolant inlet, is slightly larger than the outlet area, for example by at least 1% but not more than 10%, where, analogous to the definition of the inlet area, the area of ​​the coolant outlet is also not included in the outlet area.

[0009] The main flow field, lying in a plane normal to the stacking direction of the electrochemical system comprising at least one cooling field according to claim 1, has a central constriction region in which the main flow field is narrower than the inlet and outlet regions, while regions of greater width of the main flow field are present at the transitions between the main flow field and the inlet and outlet regions. The width of the various regions and fields is to be measured in the plane of the main flow field, and thus also of the inlet and outlet regions, orthogonal to the main flow direction of the coolant.

[0010] In the aforementioned constriction region of the main flow field, channels are formed which run parallel to each other and parallel to a reference line that passes centrally through the coolant inlet and outlet. This reference line defines the main flow direction of the coolant.

[0011] Between the central constriction and the transitions to the inlet and outlet areas, several channel sections, each with at least a simple bend, are formed. These sections are connected to the inlet and outlet areas in different ways: on the coolant inlet side, a ribbed structure, and on the coolant outlet side, a pin structure, are adjacent to the main flow field, maintaining a distance from the aforementioned channel sections. The ribbed structure is part of the inlet area, and the pin structure is part of the outlet area. The pins forming the pin structure are approximately point-like in shape.Geometric elements that deviate from a perfectly circular shape, exhibiting a slightly elongated form, particularly with a length-to-width ratio of no more than five, are also considered pins. Larger length-to-width ratios, such as those found in the inlet area, are referred to as ribs. Ribs can be straight, simply curved, or multiply curved.

[0012] Overall, the ribs structuring the inlet area contribute significantly to a uniform distribution of the coolant across the individual channels of the main flow field. In contrast, such a distribution or collection function is not required in the outlet area to direct the coolant to the outlet. Instead, a static function within the cell stack, which forms the main component of the electrochemical system, takes precedence. This function is fulfilled by the pin-shaped structural elements of the outlet area.

[0013] Various possible configurations of the cooling field provide for the existence of edge channel fragments parallel to the reference line at the two transitions between the main flow field, the inlet area, and the outlet area. These edge channel fragments are attributable to one of the channel sections that are at least singly bent, and in these cases, multiply bent. In addition to the edge channel fragments, further channel fragments, each attributable to a multiply bent channel section, can be arranged. These fragments have a length that decreases with decreasing distance from the reference line, so that the edge channel fragment, together with the other, also doubly bent, channel fragments, forms a triangular sub-area of ​​the main flow field.

[0014] In addition to the doubly bent channel sections, which form, among other things, the aforementioned triangular section, several simply bent channel sections can be arranged, exhibiting an angle of inclination relative to the reference line that decreases with increasing distance from the triangular section. Optionally, several point-like structural elements are formed on the inlet side of the main flow field, within the inlet area, adjacent to the simply bent channel sections.

[0015] Regardless of the precise design of the main flow field, the rib structure of the inlet area can comprise continuous main ribs extending from the coolant inlet to the end of the rib structure on the main flow field side, as well as comparatively short auxiliary ribs. The auxiliary ribs are more prevalent in the section of the inlet area bordering the main flow field, whereas the rib structure in the section of the inlet area bordering the coolant inlet may consist predominantly or exclusively of main ribs. At the transition between the inlet area and the main flow field, the distance measured orthogonally to the reference line between two ribs—whether two main ribs, two auxiliary ribs, or a combination of one main and one auxiliary rib—can be greater than the distance measured between the adjacent channel sections in the main flow field.

[0016] The pin structure formed in the outlet area can consist exclusively of circular pins. Alternatively, configurations are possible in which the outlet pin structure comprises a matrix-like array of round pins adjacent to the main flow field, as well as several, particularly two, rows of oval pins aligned longitudinally with the reference line and adjacent to the coolant outlet. Regarding the distinction between oval pins and ribs, the previously mentioned length-to-width ratios are relevant.

[0017] The number of coolant inlets and outlets is not subject to any theoretical restrictions. For example, the cooling field comprises two coolant inlets and associated coolant outlets, being mirror-symmetrical about a median plane located midway between two reference lines that each intersect a coolant inlet and its associated outlet.

[0018] An electrolyzer according to the invention is designed for water electrolysis and comprises at least one cooling field according to the invention, which conducts cooling water that is separate from the process water of the electrolyzer, i.e., from highly purified water which is electrolytically decomposed into hydrogen and oxygen. The cooling field thus directs the cooling water for cooling an electrolysis cell in a separate plane from the process water through the electrolyzer.

[0019] The uniform cooling of the electrochemical cells via the cooling fields, which essentially cover the entire active area of ​​the cells, i.e., the area in which the desired electrochemical reactions take place, particularly benefits the service life of the proton-permeable membranes of the individual cells.

[0020] In short, a cooling field of an electrochemical system has at least one coolant inlet and at least one larger coolant outlet, in particular two such inlets and outlets each, wherein an inlet region, a main flow field and an outlet region are formed between the coolant inlet and the coolant outlet, wherein the main flow field has a central constriction region, and wherein channels are formed in the central constriction region which run parallel to each other in the region concerned, whereas between the constriction region and the transitions to the inlet region and outlet region there are several at least simply bent channel sections, and wherein on the side of the coolant inlet there is a rib structure and on the side of the coolant outlet there is a pin structure of the respective outlet region.each while maintaining a distance from the aforementioned canal sections, adjacent to the main flow field.

[0021] An embodiment of the invention is explained in more detail below with reference to a drawing. The drawing shows: Fig. 1. A cooling field of an electrochemical system, namely an electrolyzer for water electrolysis, in top view. Fig. 2 a detail from Fig. 1, Fig. 3. Sectional view of a plate element forming the cooling field of the electrolyzer in side view.

[0022] An electrochemical system, designated by reference numeral 10, is in this case configured as an electrolyzer for water electrolysis. The electrolyzer 10 is constructed in a stacked configuration, with the stacking direction, relative to the Fig. 1 and Fig. 2, is aligned perpendicular to the image plane. In the arrangement according Fig. 3. The stacking direction lies in the plane of the image. Where the present text contains terms such as "top", "bottom", "left", or "right", these refer only to the figures and do not imply any statement about the spatial arrangement of the components of the electrochemical system 10. Regarding the basic structure and function of the stacked electrochemical system 10, reference is made to the prior art cited at the beginning.

[0023] The electrolyzer 10 is temperature-controlled with cooling water or another coolant, which is separate from the process water. For this purpose, numerous cooling fields 1 are provided, which are arranged in parallel planes. The coolant to be distributed in the cooling field 1, in particular cooling water, is supplied via a coolant inlet 2 and discharged via a coolant outlet 3. In this case, a metallic plate element 32, which defines the structure of the cooling field 1, has mirror symmetry with respect to a median plane ME. The plate elements 32 are inserts that are installed above and below the individual cells of the electrochemical system 10.

[0024] The intermediate plane ME is located midway between two reference lines G1 and G2, each of which runs between the center of a coolant inlet 2 and the center of the corresponding coolant outlet 3. The main flow direction of the coolant in the cooling field 1 is determined by the orientation of the reference lines G1 and G2. As shown in Fig. As can be seen from Figure 1, the width of each coolant inlet 2 corresponds to the width of the associated coolant outlet 3. However, in the main flow direction of the coolant, the coolant outlet 3 is more extensive than the associated coolant inlet 2, so that the coolant outlet 3 has a larger area than the coolant inlet 2.

[0025] The coolant inlet 2 is located in an inlet area 4, which is divided into a narrow section 5 and a wide section 6. The main flow field of the cooling field 1, designated 7, borders the wide section 6 of the inlet area 4. A constriction area 8 is formed within the main flow field 7. On the outlet side, an outlet area, designated 9, borders the main flow field 7. Analogous to the inlet area 4, the outlet area 9 also has a wide section 30 adjoining the main flow field 7 and a narrow section 29. The coolant outlet 3 is located in the narrow section 29.

[0026] Within the main flow field 7, a wider region 11 exists above the constriction region 8, bordering the inlet region 4. Below the constriction region 8, a further region 12 of greater width exists, this region 12 of the main flow field 7 bordering the outlet region 9. The outer contours of the plate element 32 are mirror-symmetrical with respect to another mirror plane, which is to be placed midway between the lower and upper edges of the plate element 32 and intersects the median plane ME at a right angle.

[0027] In the main flow field 7, channels generally designated 13 are provided for the coolant. All sections of the channels 13 located in the constriction region 8 are parallel to each other, aligned in the main flow direction of the coolant. The inlet end of the channels 13 is located at the transition designated 14 between the inlet region 4 and the main flow field 7. On the outlet side, the channels 13 terminate at a transition 15 between the main flow field 7 and the outlet region 9. The channels 13 have a uniform depth along their entire length, as shown in the figure. Fig. 3 emerges. Likewise, the depth of all channels 13 is the same. As the Fig. As further illustrated in Figure 3, all channels 13 on the front and back of the plate element 32 are mirror images of each other.

[0028] The channels 13 are completely straight in two rectangular sub-areas, designated 31, bordering the central plane ME. Furthermore, there are doubly bent channel sections 16 and singly bent channel sections 17, which together describe a fan-like structure. The doubly bent channel sections 16 have edge channel fragments 19 at the left and right edges of the plate element 32, relative to the arrangement shown. Fig. 1. Parallel to each edge channel fragment 19, parallel channel fragments 20 are formed, also aligned along the reference lines G1, G2, the length of which decreases in the direction from the edge channel fragment 19 to the nearest reference lines G1, G2. The edge channel fragment 19 thus forms, together with the adjacent channel fragments 20, a triangular sub-area 21 of the main flow field 7. In total, there are four such triangular sub-areas 21. Two of these sub-areas 21 extend at the upper edge of the main flow field 7 to the transition 14 between the main flow field 7 and the inlet area 4.

[0029] In entrance area 4, as can be seen from Fig. As can be seen from 1, a rib structure 18 is formed. The rib structure 18 comprises main ribs 23 and, in comparison to these, shorter auxiliary ribs 24. Furthermore, several exist in the inlet area 4, consisting of Fig.2 emerging point-like structural elements 22 in the area bordering the main flow field 7.

[0030] In contrast to the inlet area 4, the outlet area 9 features a matrix-shaped pin structure 25, predominantly formed by round pins 26, which together define an array 27 of round pins 26. Additionally, the outlet area 9 contains several oval pins 28 arranged in two rows adjacent to the coolant outlet 3. The oval pins 28 are located in the narrow section 29 of the outlet area 9. The wide section 30 of the outlet area 9 borders, among other things, the sub-area 31 of the main flow field 7, which consists exclusively of straight channels 13. This same sub-area 31 also borders the wide section 6 of the inlet area 4. The rib structure 18, the pin structure 25, and the channels 13 can be produced, for example, by etching.

[0031] Within the inlet area 4, the ribs 23, 24 of different lengths, supplemented by the individual point structural elements 22, are shaped in such a way that the coolant is distributed almost evenly to the various channels 13, regardless of whether these have angled sections 16, 17.

[0032] Additionally, the rib structure 18 of the inlet area 4 within the electrolyzer 10 has a supporting function. In the outlet area 9, a flow-guiding function is primarily performed by the oval pins 28, which are part of the pin structure 25. Otherwise, the pin structure 25 mainly serves a static function. The flow velocity of the coolant in the coolant outlet 3 is lower than in the coolant inlet 2. Together with the described structuring of the inlet area 4, the main flow field 7, and the outlet area 9, this contributes to efficient cooling with low flow resistance and thus low pressure loss. Reference symbol list 1 cooling compartment 2 Coolant inlet 3 Coolant outlet 4 Entrance area 5 narrow section of the inlet area 6 wide section of the inlet area 7 Main flow field 8 Constriction area 9 Outlet area 10 Electrochemical system, electrolyzer 11 Area of ​​greater width of the main flow field, bordering the inlet area 12 Area of ​​greater width of the main flow field, bordering the outlet area Channel 13 14 Transition between the inlet area and the main flow field 15 Transition between the outlet area and the main flow field 16 double-bent canal section 17 simply bent channel section 18 rib structure 19 Edge canal fragment 20 Channel Fragment 21 triangular sub-area of ​​the main flow field 22 point-like structural element 23 Main rib 24 Additional rib 25-pin structure 26 round pin 27 field of round pins 28 Oval pin 29 narrow section of the outlet area 30 wide section of the outlet area 31 sub-area with straight channels 32 plate elements G1, G2 Reference line ME Middle Level QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2023 109 185 A1

[0002] US 2022 / 0243348 A1

[0003] DE 10 2022 110 122 A1

[0004]

Claims

[1] Cooling field (1) for a stacked electrochemical system (10), with at least one coolant inlet (2) and at least one coolant outlet (3) larger than the coolant inlet (2), wherein an inlet region (4), a main flow field (7) and an outlet region (9) are formed between the coolant inlet (2) and the coolant outlet (3), wherein the main flow field (7) lying in a plane normal to the stacking direction of the electrochemical system (10) has a central constriction region (8) in which it is narrower than the inlet region (4) and the outlet region (4), while regions (11, 12) of greater width of the main flow field (7) are present at the transitions (14, 15) between the main flow field (7) and the inlet region (4) and the outlet region (9), and wherein channels (13) are formed in the central constriction region (8),which run parallel to each other and parallel to a reference line (G1, G2) in the relevant area, which is placed centrally through the coolant inlet (2) and the coolant outlet (3), whereas between the central constriction area (8) and the transitions (14, 15) to the inlet area (4) and outlet area (9) respectively, there are several channel sections (16, 17) that are at least simply bent, which are connected to the inlet area (4) and the outlet area (9) respectively in different ways, in that a rib structure (18) on the side of the coolant inlet (2) and a pin structure (25) on the side of the coolant outlet (3) of the respective inlet or outlet area (2, 3) are adjacent to the main flow field (7), in each case while maintaining a distance to the aforementioned channel sections (16, 17). [2] Cooling field (1) according to claim 1, characterized by, that at transitions (14, 15) between the main flow field (7) and the inlet area (4) on the one hand and the outlet area (9) on the other hand parallel to the reference line (G1, G2) there exist edge channel fragments (19) which are to be attributed to one of the channel sections (16) that are at least simply bent, in these cases multiple times bent. [3] Cooling field (1) according to claim 2, characterized by , that in addition to the marginal channel fragments (19) further channel fragments (20) are arranged, each belonging to a multiply bent channel section (16), which have a length that decreases with decreasing distance from the reference line (G1, G2), so that the marginal channel fragment (19) together with the further channel fragments (20) forms a triangular partial area (21) of the main flow field (7). [4] Cooling field (1) according to claim 3, characterized by, that in addition to the doubly bent channel sections (16), which form among other things the aforementioned triangular partial surface (21), several simply bent channel sections (17) are arranged, which have an inclination angle relative to the reference line (G1, G2) that decreases with increasing distance from the triangular partial surface (21). [5] Cooling field (1) according to claim 4, characterized by , that on the inlet side of the main flow field (7) several point structural elements (22) attributable to the inlet area (4) are adjacent to the simply bent channel sections (17). [6] Cooling field (1) according to any one of claims 1 to 4, characterized by, that the rib structure (18) of the inlet area (4) comprises continuous main ribs (23) extending from the coolant inlet (2) to the main flow field side end of the rib structure (18) as well as comparatively short additional ribs (24), the additional ribs (24) being more frequently present in the section of the inlet area (4) bordering the main flow field (7). [7] Cooling field (1) according to claim 6, characterized by , that at the transition (14) between the inlet area (4) and the main flow field (7) the distance to be measured orthogonally to the reference line (G1, G2) between two ribs (23, 24), whether main or additional ribs, is greater than the distance to be measured between the adjacent channel sections (16, 17). [8] Cooling field (1) according to any one of claims 1 to 7, characterized by, that the pin structure (25) of the outlet area (9) comprises a matrix-shaped field (27) of round pins (26) adjacent to the main flow field (7) and several, in particular two, rows of oval pins (28) adjacent to the coolant outlet (3) and aligned in the longitudinal direction of the reference line (G1, G2). [9] Cooling field (1) according to any one of claims 1 to 8, characterized by , that this includes two coolant inlets (2) and associated coolant outlets (3) and is designed in a mirror-symmetrical manner with respect to a central plane (ME), which is placed midway between two reference lines (G1, G2) that each centrally intersect a coolant inlet (2) and the associated coolant outlet (3). [10] Electrolyzer (10) for water electrolysis, comprising at least one cooling field (1) designed according to one of claims 1 to 9, which is provided for conveying cooling water that is separated from process water to be electrolytically decomposed into hydrogen and oxygen in the electrolyzer (10).

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