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DE-102024133163-A1 - Bipolar plate and electrochemical unit

DE102024133163A1DE 102024133163 A1DE102024133163 A1DE 102024133163A1DE-102024133163-A1

Abstract

To provide a bipolar plate (100) for an electrochemical unit, through which an optimized supply and discharge of a fluid medium to and from a flow field of the bipolar plate (100) is achieved, it is proposed that the bipolar plate body (102) comprises at least one bipolar plate body (102) on which a plurality of flow channels are provided, forming at least one flow field (104) for a fluid medium, at least one media inlet (106) for supplying and/or at least one media outlet (108) for discharging the fluid medium, and at least one sealing rib (110) is provided, which at least partially delimits the flow field (104), the at least one media inlet (106) and/or the at least one media outlet (108) and forms a primary channel (118) through which a primary flow (P) of a fluid can flow, wherein at least one secondary channel (120) is provided, which provides a fluid connection between at least one branch (122) from the primary canal (118) and at least one introduction (124) into the primary canal (118).

Inventors

  • Juergen KRAFT

Assignees

  • EKPO FUEL CELL TECHNOLOGIES GMBH

Dates

Publication Date
20260513
Application Date
20241113

Claims (10)

  1. Bipolar plate (100) for an electrochemical unit, comprising at least one bipolar plate body (102) on which: - a plurality of flow channels are provided, forming at least one flow field (104) for a fluid medium, - at least one media inlet (106) for supplying and/or at least one media outlet (108) for discharging the fluid medium is formed, - at least one sealing rib (110) is provided, which at least partially delimits the flow field (104), the at least one media inlet (106) and/or the at least one media outlet (108) and forms a primary channel (118) through which a primary flow (P) of a fluid can flow, wherein - at least one secondary channel (120) is provided, which forms a fluid connection between at least one branch (122) from the primary channel (118) and at least one inlet (124) into the primary channel (118).
  2. Bipolar plate after Claim 1 , characterized in that a secondary flow (S) of the fluid can be branched off from the primary channel (118) through the at least one secondary channel (120) and can be introduced downstream and/or upstream back into the primary channel (118).
  3. Bipolar plate after Claim 1 or 2 , characterized in that the inlet (124) forms an inlet angle (E) for introducing the secondary flow (S) into the primary channel (118), in which at least one directional component (X, Y, Z) of the secondary flow (S) is directed against at least one directional component (X, Y, Z) of the primary flow (P) in the primary channel (118).
  4. Bipolar plate after Claim 3 , characterized in that the inlet angle (E) is formed by an acute angle between the at least one secondary channel (120) and the primary channel (118) against a flow direction of the primary flow (P) in the primary channel (118).
  5. Bipolar plate after Claim 3 or 4 , characterized in that the introduction angle (E) for introducing the secondary flow (S) into the primary channel (118) is at most 80°, preferably at most 70°, further preferably at most 60°, further preferably at most 50°, and/or at least 10°, preferably at least 20°, further preferably at least 30°, further preferably at least 40°, against the flow direction of the primary flow (P) in the primary channel (118).
  6. Bipolar plate according to one of the preceding claims, characterized in that the branch (122) forms a branch angle (A) for branching off the secondary flow (S) from the primary channel (118) into the at least one secondary channel (120) of at most 60°, preferably at most 50°, more preferably at most 40°, more preferably at most 30°, and/or at least 10°, preferably at least 20°, more preferably at least 30°, in the flow direction of the primary flow (P) in the primary channel (118).
  7. Bipolar plate according to one of the preceding claims, characterized in that a flow cross-section of the at least one secondary channel (120) is equal to or smaller than a flow cross-section of the primary channel (118), preferably a cross-sectional height (130) and/or a cross-sectional width (132) of the secondary channel (120) with respect to a principal extension plane of the bipolar plate body (102) is equal to or smaller than a cross-sectional height (134) and/or a cross-sectional width (136) of the sealing rib (110).
  8. Bipolar plate according to one of the preceding claims, characterized in that several secondary channels (120) are provided along an extension direction of the at least one sealing rib (110), through which a secondary flow (S) of the fluid can be branched off from the primary channel (118) and introduced back into the primary channel (118), and preferably the several secondary channels (120) are provided on both sides, in particular alternately, to the sealing rib (110).
  9. Bipolar plate according to one of the preceding claims, characterized in that the at least one sealing web (110) in the main extension plane of the bipolar plate body (102) has a wave-like profile and preferably at least one of the branches (122) from the primary channel (118) is provided substantially in the region of a vertex (138) of the wave-shaped sealing web (110) and/or at least one of the inlets (124) into the primary channel (118) is provided substantially in the region of a downstream and/or upstream vertex (138) of the wave-shaped sealing web (110).
  10. Electrochemical unit comprising at least one membrane electrode unit and at least one bipolar plate (100) according to one of the Claims 1 until 9 .

Description

The present invention relates to a bipolar plate for an electrochemical unit and an electrochemical unit. The core of a fuel cell consists of membrane electrode assemblies (MEAs), which are separated on the cathode and anode sides by bipolar plates. These bipolar plates have a channel structure that creates a flow field, through which reaction media are supplied to the MEAs and reaction products are removed. The reaction space formed between the bipolar plates is typically sealed by welding the cathode and anode bipolar plates together or by providing a gasket between them to prevent the escape of reaction media and products. Sealing between the bipolar plates can also be achieved using sealing ribs, known as sealing beads, formed from the plate bodies. Due to their design, these sealing ribs create a flow channel through which a bypass flow, such as the reaction medium or coolant, can occur, potentially impairing the fuel cell's performance. The present invention is based on the objective of providing a bipolar plate through which an optimized supply and discharge of a fluid medium to and from a flow field of the bipolar plate is achieved. Furthermore, it is an objective of the invention to provide an electrochemical unit that exhibits an optimized performance potential. This problem is solved by a bipolar plate for an electrochemical unit, comprising at least one bipolar plate body on which a plurality of flow channels are provided, forming at least one flow field for a fluid medium, at least one media inlet for supplying and/or at least one media outlet for removing the fluid medium is formed, at least one sealing rib is provided, which at least sectionally delimits the flow field, the at least one media inlet and/or the at least one media outlet and forms a primary channel through which a primary flow of a fluid can flow, wherein at least one secondary channel is provided, which forms a fluid connection between at least one branch from the primary channel and at least one inlet into the primary channel. The bipolar plate can preferably be formed from one layer of the bipolar plate body or from several layers of the bipolar plate body. In particular, at least one bipolar plate body can be made of metal. The at least one bipolar plate body can be provided with a coating, in particular with a conductive and/or corrosion-resistant coating, for example the at least one bipolar plate body can be coated with gold, titanium, titanium nitride, carbon, chromium nitride and/or a ceramic material. The flow channels forming the flow field for the fluid medium are preferably formed on the at least one bipolar plate body, in particular formed from it, molded onto it or introduced into it. At least one sealing rib is formed to limit the flow field, at least section by section, to an edge region of the bipolar plate, i.e., to an outer surface, and/or to the media supply and media discharge of the bipolar plate, which are also referred to as manifolds or headers. Advantageously, at least one sealing rib extends fully along the edge area of the bipolar plate and/or fully around the media supply and/or media discharge. The at least one sealing ridge can thereby form a seal or boundary for the flow field to the edge area of the bipolar plate and/or to the media supply and/or media discharge. In an assembled state of the fuel cell unit, the at least one sealing rib can thus form a seal of the flow field to the outside and/or to the media supply and/or media discharge by the at least one sealing rib abutting or being pressed against an adjacent bipolar plate in a sealing manner when several such bipolar plates are stacked on top of each other. The sealing rib could be an edge rib of the bipolar plate. Preferably, the at least one sealing rib is formed as a groove, in particular a sealing groove, on the bipolar plate body. Preferably, the at least one sealing rib can be formed from the at least one bipolar plate body, formed onto the at least one bipolar plate body, or incorporated into the at least one bipolar plate body. In particular, the at least one sealing rib is integrally formed from the at least one bipolar plate body. The at least one secondary channel can also be referred to as a bypass channel, which forms a bypass to the primary channel formed by the sealing bridge and through which a partial flow of the fluid flowing in the primary channel can be diverted from the primary channel as a bypass flow and reintroduced into it. The at least one branch comprises or forms a fluid outlet from the primary channel into the at least one secondary channel, through which a partial flow of the fluid flowing in the primary channel can be branched off or discharged into the at least one secondary channel. The at least one inlet comprises or forms a fluid inlet from the at least one secondary channel into the primary channel, through which the divertable or divertable partial flow of the fluid from the secondary channel can be int