FR3065904A1 - PLATE FOR ASSEMBLY MEMBRANE / ELECTRODES - Google Patents

Abstract

The invention relates to a heating and cooling tray (26), comprising internally at least one heating cord (30) and a coolant circuit (28).

Description

@ Holder (s): COMMISSIONER FOR ATOMIC ENERGY AND ALTERNATIVE ENERGIES Public establishment.

® Agent (s): ERNEST GUTMANN - YVES PLASSERAUD SAS.

® TRAY FOR MEMBRANE / ELECTRODES ASSEMBLY.

@) The invention relates to a heating and cooling plate (26), internally comprising at least one heating cord (30) and a coolant circuit (28).

FR 3 065 904 - A1

TRAY FOR MEMBRANE / ELECTRODES ASSEMBLY

FIELD [001] The present invention relates to the field of membrane / electrode assembly devices for fuel cells.

BACKGROUND [002] Fuel cells with a proton exchange membrane, called PEMFC corresponding to the English acronym for "proton exchange membrane fuel cells" or "polymer electrolyte membrane fuel cells", have particularly interesting compactness properties. Each cell includes a polymer electrolyte membrane allowing only the passage of protons and not the passage of electrons. The membrane is brought into contact with an anode on a first face and with a cathode on a second face to form a membrane / electrode assembly called AME.

The above-mentioned assembly is generally carried out by successive superposition of the various membranes and electrodes with an interposition of reinforcing membranes making it possible to support the assembly. In order to secure the different thicknesses together, it is possible to carry out an assembly thermocompression operation. However, this operation is complicated to carry out. Indeed, a simple thermocompression with a steel plate brought to a desired temperature and then lowered in temperature when desired is difficult to use since the thermal regulation times of the plate prove to be long for industrial use.

SUMMARY OF THE INVENTION [004] Thus, the present invention relates to a heating and cooling plate, internally comprising at least one heating cord and a coolant circuit.

The use of such a tray allows rapid heating of the tray and rapid cooling due to the integration of a liquid circuit.

According to another characteristic of the invention, the heating cord and the coolant circuit are each arranged substantially in one plane, these planes being different from each other and parallel to each other and to first and second faces of the plate, so as to have successively a first face of the plate, the heating cord, the cooling circuit and then the second face of the plate.

Preferably, the plane of the heating cord will be arranged as close as possible to a surface of the plate so that it can be brought into contact with an element to be heated.

According to another characteristic of the invention, the first face comprises at least one groove housing said heating cord and in which the cooling circuit comprises at least one coolant circulation channel.

To allow a good distribution of cold and hot, each of the cooling channel (s) and the groove (s) are of the coil type.

The plate may comprise at least a first plate made of a thermally conductive material, this first plate comprising on a first face forming the first face of the plate said at least one groove and on a second opposite face at least one groove closed by a second plate so as to form a coolant circulation channel.

The first plate can be formed of two thicknesses assembled to one another with a thermally conductive cement to promote the heat flows from one to the other of the two thicknesses, a first thickness integrating the heating cord and a second thickness incorporating the cooling circuit.

[012] Preferably, at least one of said at least one groove and of said at least one channel opens onto a side of said first plate or of the plate.

According to another characteristic of the invention, the first plate is made of a material, for example metallic, having a coefficient of thermal conduction of at least 100 W / m / K and a Young's modulus of at least minus 100 GPa. Such a combination makes it possible to have an excellent compromise for a material having good thermal conduction properties (performance in heating and cooling), good mechanical properties allowing it to withstand the compression forces while allowing simple manufacture by machining the circuit. cooling.

A good example of a material is copper, which has a thermal conductivity coefficient of 390 W / m / K and a Young's modulus of 124 GPa. Brass would also be suitable since it has a thermal conductivity coefficient of 120 W / m / K and a Young's modulus of 100 to 130 GPa.

[015] Preferably, the heating cord is of the resistive type and comprises two free ends connected to means of electrical supply.

[016] The heating cords can be matted externally by a nickel wire.

According to another characteristic of the invention, the cooling circuit comprises at least two fluidly independent parts and arranged side by side and extending in the same plane.

[018] Also, each part of the circuit can be of the coil type comprising an input and an output, the distance along the circuit from the input of the circuit to the center of the plate being less than the distance from the output of the circuit to the center of the plate.

The invention also relates to an assembly comprising a plate and a compression plate produced from a thermally conductive material, this compression plate being applied to the first face of the plate and being dimensioned so that the masses of material of on either side of a median plane of the heating cord are substantially identical, in order to limit the bending effects of the first plate.

The invention also relates to a press for manufacturing a membrane / electrode assembly for a fuel cell comprising a piston comprising at a free end a plate of the type described above or an assembly as mentioned above.

[021] Also, the press may include a static support facing the piston, the support carrying a plate of the type described above or an assembly as mentioned above.

The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of nonlimiting example with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic illustration of an electrolyte-polymer-electrode-electrode assembly obtained with the method according to the invention;

Figure 2 is a schematic sectional view of a heating and cooling plate according to the invention;

Figure 3 is a schematic view of a first embodiment of a cooling circuit for a tray according to the invention;

Figures 4 and 5 are schematic views of a second embodiment of a cooling circuit for a tray according to the invention;

Figure 6 is a schematic sectional view of the heating means for a tray according to the invention;

Figure 7 to 10 show a first embodiment of the invention; Figures 11 to 13 show a second embodiment of the invention.

DETAILED DESCRIPTION [023] First of all, reference is made to FIG. 1 which represents an assembly 10 polymer electrolyte membrane / electrodes called AME comprising the successive elements from the bottom to the top:

a first electrode 12 or lower electrode capable of forming an anode in a fuel cell,

a first membrane 14 or lower reinforcement membrane comprising an internal edge 14b delimiting an opening 14a closed at the bottom by the first electrode 12, the external edge 12a of the first electrode 12 being in contact with the internal edge 14b of the first reinforcement membrane 14 ,

- a polymer electrolyte membrane 16 ensuring proton conduction,

a second membrane 18 or upper reinforcement membrane comprising an internal edge 18b delimiting an opening 18a,

a second electrode 20 or upper electrode capable of forming a cathode in a fuel cell and closing off the opening 18a of the upper reinforcement membrane 18, the external edge 20a of the second electrode 20 being in contact with the internal edge 18b of the second reinforcing membrane 18.

It is understood that in Figure 1, the various aforementioned layers are in contact with each other and that the spacings between said layers do not exist in an actual assembly. As is clearly visible in this figure, the polymer electrolyte membrane 16 has an external edge 16a which is applied:

- superiorly on the internal edge 14b of the first reinforcing membrane 14 so as to close off its opening 14a,

- lower on the internal edge 18b of the second reinforcing membrane 18 so as to close its opening 18a.

Thus, the polymer electrolyte membrane 16 is fully housed between the first 14 and second 18 reinforcement membranes and thus achieves isolation of the polymer electrolyte membrane from the coolant and pure gas passages. This type of assembly is known by the English name of "anti-wicking". More specifically, the assembly presented in FIG. 1 comprises a peripheral cut 22 with a closed contour forming an external contour of the assembly 10 electrolyte membrane - electrodes - reinforcement membranes. The assembly 10 also includes orifices 24 between said peripheral cutout 22 and the external edge 16a of the polymer electrolyte membrane 16, these orifices 24 being intended for the passage of coolant and pure gases (H ₂ and O ₂ ). In other words, these orifices 24 are formed in a peripheral zone surrounding the polymer electrolyte membrane 16 and the first 12 and second 20 electrodes.

[026] Figure 2 shows a tray 26 according to the invention comprising a circuit 28 for the flow of a cooling liquid and a heating cord 30 formed in the thickness of the tray 26. The term "tray" refers here to a substantially parallelepipedic element having at least a first and a second dimension perpendicular to each other which are larger than a third dimension perpendicular to the first and second dimensions.

[027] This plate 26 comprises a first plate 32 and a second plate 34 applied one on the other. The first plate 32 carries the cooling circuit 28 and the heating cord 30. This first plate 32 comprises a first face 36 comprising at least one groove 38 housing a heating cord 30, the groove 38 being formed so as to extend over said first face 36 and so as to include a first end opening onto a side 40 of the first plate 32. This first plate 32 also includes at least one groove 42 formed on a second face 44 opposite the first face 36. This groove 42 opens out , preferably on a side 40 of the first plate 32. The groove or grooves 42 are closed by the second plate 34. It is understood that the first face 36 of the first plate 32 forms a first face of the plate 26, the second face 46 opposite is formed by the face of the second plate 34 opposite to the first plate 32.

[028] As is clearly visible in FIG. 2, the heating cord 30 is arranged as close as possible to the first face 36 of the plate 26 so as to achieve optimal heat transmission to a compression plate intended to come apply to this first face 36. The heating cord 30 can be matted in the groove 38 by means of a nickel wire for example. In addition, the heating cord 30 extends in a first plane Ai and the cooling channel extends in a second plane A ₂ which are parallel to each other and to the first 36 and second face 46 of the plate 26. The channel 28 of cooling is interposed between the heating cord 30 formed in the first face 36 of the plate 26 and the second face 46 of the plate 26.

[029] In order to achieve good thermal conduction of heat from the heating cord 30 and from the cold of the cooling circuit, the first plate 32 is advantageously made of a material that is a good thermal conductor and capable of withstanding significant compression forces.

Thus, the first plate 32 is advantageously made of a material, for example metallic, having a coefficient of thermal conduction of at least 100 W / m / K and a Young's modulus of at least 100 GPa. A good example of a material is copper, which has a thermal conductivity coefficient of 390 W / m / K and a Young's modulus of 124 GPa. Brass would also be suitable since it has a thermal conductivity coefficient of 120 W / m / K and a Young's modulus of 100 to 130 GPa.

Each heating cord 30 is preferably of the resistive type, the ends of each cord 30 being connected to electrical supply means. Also, temperature sensors can be provided in the first plate 32 and extend into the first plate 32, from the entry of a groove 38 of the first plate.

[031] As shown in Figure 3, in a first embodiment of a plate 47 the first plate 32 may include a first groove 48 and a second groove 50 formed on the second face of 44 the first plate 32 and forming independent channels coolant circulation, each channel 48, 50 comprising an inlet 48a, 50a and an outlet inlet 48b, 50b of liquid in the tray. The first plate 32 could also include four fluidly independent channels. In order to allow a good distribution of cold and heat, each of the cooling channel (s) and the groove (s) are of the coil type. To obtain a good transfer of frigories in the first plate 32, it is desirable that the distance along a channel 48, 50 from the inlet 48a, 50a of each of the channels 48, 50 to the center of the first plate 32 is less than the distance along the channel from the outlet 48b, 50b of each of the channels 48, 50 to the center of the plate 26. Thus, a circulation of the liquid is favored towards the center then in the rest of the first plate 32, which allows better uniformity of the heat of the plate 32.

Note also that the first plate 32 could be formed by the association, that is to say the juxtaposition edge to edge of two half plates, each comprising a cooling circuit as described above.

[033] Figure 4 shows a possible form of a heating cord 30 for use with a cooling circuit described above, such as that shown in Figure 3 for example. The cord 30 is here arranged in the form of two spirals 30a, 30b nested one inside the other, the internal ends of the two spirals being connected to each other.

[034] Figures 5 and 6 show a second embodiment of a plate 52 comprising two parts 54, 56 in L defining therebetween a separate central portion 58. Each of the two parts 54, 56 in L comprises a cooling channel 59 as described above, the central portion being devoid of cooling channel and being made of a thermally insulating material. The channels 59 of the parts 54, 56 are configured so as to allow the coolant to flow around the central portion and then outwards.

In this embodiment, a single heating cord could be used (not shown), the latter surrounding itself around the central portion 58 in the manner of a spiral. The central portion 58 is also devoid of any heating means.

It is easily understood that the shape of the cooling channels is more critical than that of the heating cords because of the greater time required to reduce the temperature by a given number of degrees using the flow of a liquid as the time required to increase the temperature by the same number of degrees using a resistive type heating cord.

[037] Figures 7 to 10 show a first hydraulic press Pi allowing controlled pressing, heating and cooling of the assembly 10 of Figure 1. This first press Pi allows to provide heating and cooling of the area Zi of stacking lower electrode - polymer electrolyte membrane - upper electrode. This first press Pi is intended to be used with a plate 47 according to the first embodiment shown in Figures 3 and 4. This zone Zi includes all of the electrodes and preferably only these. [038] Figures 11 to 13 show a second hydraulic press P ₂ for heating and pressing the assembly of Figure 1 in a peripheral annular zone Z ₂ surrounding the lower electrode 12 and the upper electrode 20. This annular zone begins internally in the immediate vicinity of the external edges of the first electrode 12 and the second electrode 20. This second press P ₂ is intended to be used with a plate 52 according to the second embodiment shown in FIGS. 5 and 6.

With reference to FIGS. 7 to 10, the first press Pi comprises a piston 58 comprising a pressure distributor 60 which carries a layer 62 of thermal insulation in order to limit the thermal conduction. A plate 47 as described with reference to FIGS. 3 and 4 is applied to the insulating layer 62 the second face of the plate 47 coming into contact with the insulating layer 62. A plate 64 or compression sole is applied to the first face of the plate 47.

The first press Pi comprises a static support 66 arranged opposite the piston 58 which successively carries a layer of thermally insulating material 68, a plate 47 as described with reference to Figures 5 and 6 and a plate 70 or compression sole. The plate 47 is positioned so that its first face is in contact with the compression sole 68 and that its second face is in contact with the insulating layer 68.

[041] The plate 64, 70 or compression sole follows the same selection criteria as the material of the first plate 32 as described above.

[042] The second press P ₂ shown in Figures 11 to 13 has a completely identical assembly to what has been described with reference to the first pressure. This second press thus comprises a piston 58 comprising an insulating layer 62, a plate 52 and a compression plate 64 of annular shape and a static support 66 carrying an insulating layer 68, a plate 52 and a compression plate 70.

[043] The invention is obviously applicable to an assembly which does not perform an “anti-wicking” function, that is to say in which the polymer electrolyte membrane is not confined between the first and 10 second reinforcing membranes such as explained with reference to Figures 1 to but extends everywhere between the first reinforcing membrane and the second reinforcing membrane.

Claims (12)

1. Heating and cooling plate (26), internally comprising at least one heating cord (30) and a coolant circuit (28). 2. Tray according to claim 1, in which the heating cord (30) and the coolant circuit (28) are each arranged substantially in a plane (A1, A2), these planes being different from each other. and parallel to each other and to first (36) and second (46) faces of the plate (26), so as to have successively a first face (36) of the plate (26), the heating cord (30), the circuit of cooling (28) then the second (46) face of the plate (26). 3. Tray according to claim 1 or 2, wherein the first face (36) comprises at least one groove (38) housing said heating cord (30) and wherein the cooling circuit (28) comprises at least one channel ( 42) circulation of coolant. 4. Tray according to claim 3, in which it comprises at least a first plate (32) made of a thermally conductive material and comprising on a first face (36) forming the first face of the tray (26) said at least one groove ( 38) and on a second face (46) opposite at least one groove (42) closed by a second plate (34) so as to form a channel (43) for circulating coolant. 5. Tray according to claim 3 or 4, wherein at least one of said at least one groove (38) and said at least one channel (42) opens onto a side (40) of said first plate or of the tray (26 ). 6. Tray according to claim 4 or 5, wherein the first plate (32) is made of a material, for example metallic, having a coefficient of thermal conduction of at least 100 W / m / K and a Young's modulus at least 100 GPa. 7. Tray according to one of claims 1 to 6, wherein the heating cord (30) is of the resistive type and comprises two free ends connected to electrical supply means. 8. Tray according to one of claims 1 to 7, wherein the cooling circuit (28) comprises at least two parts (48, 50) fluidly independent and arranged side by side and extending in the same plane. 9. Tray according to claim 8, in which each circuit part is of the coil type comprising an inlet (48a, 50a) and an outlet (48b, 50b), the distance along the circuit from the inlet (48a, 50a ) of the circuit in the center of the plate (52) being less than the distance from the outlet (48b, 50b) of the circuit in the center of the plate. 10. An assembly comprising a plate according to one of claims 1 to 8 and claim 2 and a compression plate (64, 70) made of a thermally conductive material, this compression plate (64, 70) being applied to the first face of the plate (26) and being dimensioned so that the masses of material on either side of a median plane of the heating cord (30) are substantially identical. 11. Press (P1, P2) for manufacturing a membrane / electrode assembly for a fuel cell comprising a piston (58) comprising at a free end a plate (26) according to one of claims 1 to 9 or an assembly according to claim 10. 12. Press (P1, P2) according to claim 11, in which it comprises a static support (66) facing the piston, the support (66) carrying a plate according to one of claims 1 to 9 or an assembly according to claim 10. 2/5