The present invention concerns the technical field of energy production based on a fuel cell battery and more particularly the architectures of fuel cell batteries.
Conventionally, a fuel cell battery comprises a succession of elementary cells, positioned beside each other in an assembly commonly called a “pack”. Each cell has an anode compartment where hydrogen oxidation takes place, as well as a cathode compartment in which oxygen from the air is reduced, with production of water. In addition, a proton exchange membrane (PEM) physically separates the anode and cathode compartments of a particular cell, which are also connected to an external electrical circuit.
The anode compartment is put into communication with a line introducing hydrogen, as well as a line for evacuating the hydrogen consumed. The latter is mixed with a water fraction that has been produced in the region of the cathode and has passed through the aforementioned separating membrane. Similarly, the cathode compartment is provided with a conduit introducing a gas mixture containing oxygen, typically air, and also a conduit for evacuating this oxygen-depleted mixture mixed with water.
In addition, several bipolar plates are generally provided, each of which separates two adjacent elementary cells. Such plates are capable of ensuring several functions, such as in particular the distribution of reactive gases.
The architecture of a fuel cell battery of the type described above exhibits certain disadvantages, in particular in terms of maintenance.
Indeed, when a cell of this battery of cells is damaged, it is necessary to dismantle the pack entirely and then to re-assemble the entire battery of cells. Moreover, it proves necessary to reject certain elements of the battery of cells, such as seals.
The present invention aims to remedy such disadvantages and proposes to produce a fuel cell battery with a simple and robust configuration, the maintenance of which is greatly facilitated.
To this end, the invention provides a fuel cell battery, more particularly comprising a series of elementary cells pressed against each other by compressive means, each of these cells having a central structure formed of a membrane and of two electrodes positioned either side of this membrane and, either side of the central structure, an outer separating structure, the cells being pressed with their separating structures in contact with each other, so that these two adjacent cells can be detached from each other by deactivating the compressive means, and means for introducing and evacuating fluids extending along the cells and that can be connected individually to the latter.
According to other features of the invention:
The invention also concerns an elementary cell, or a group of elementary cells, for a fuel cell battery such as defined above, the or each cell comprising at least one central structure formed of a membrane and of two electrodes, positioned either side of this membrane, as well as two separating devices provided at the two ends of the elementary cell or group of cells, each separating device being able to rest against another separating device belonging to an adjacent cell, in an arrangement making it possible in this way easily to detach the elementary cell or group of cells with respect to each adjacent cell without dismantling the entire battery of cells.
The invention also concerns a replacement kit for an elementary cell or a group of elementary cells such as defined above, comprising a central structure formed of a membrane and of two electrodes, positioned either side of this membrane, as well as a closed packaging in which the central structure is accommodated.
According to other features of the invention:
The invention finally concerns a process for manufacturing the replacement kit such as defined above, wherein the central structure is assembled by hot-pressing, and the packaging is added around this central structure.
According to another feature of the invention, before adding the packaging an electric preconditioning current is passed through the central structure.
The invention will be better understood on reading the following description of particular embodiments, given by way of non-limiting examples, made with reference to the accompanying drawings, in which:
In the embodiment shown in FIGS. 1 to 4, the fuel cell battery according to the invention comprises a base or supporting structure 2, typically in the form of a plate, above which there extends, parallel to the base, an intermediate platform or plate 4. Between these two elements, two gas distribution assemblies or manifolds are inserted, identified by references 6 and 7, which will be described below in greater detail.
The platform 4 is surmounted by two parallel vertical lateral walls 8, at the front end of which two parallel vertical insulating pieces 10 are positioned orthogonal to the walls 8. Conducting sheets 12, made for example of copper and linked to electrical terminals 14, are placed on the inner face of the insulating pieces 10.
A succession of elementary cells 161 to 16n is interposed between the two conducting sheets 12. The structure of each of these cells will be described subsequently in greater detail.
Two vertical holding plates 181 and 182, designed to hold the assembly of elementary cells mechanically, are positioned against the outer face of the insulating pieces 10. In addition, four bars or stays 20 extend horizontally along the lateral walls 8, outside these.
Each bar 20 traverses the first holding plate 181 at a first end. It is secured there via a stop formed by a head 22, while a Belleville washer 220, not shown in detail, is interposed between this stop 22 and the opposite face of the plate 181.
In service, these washers 220 make it possible to absorb variations in length due to possible thermal expansions and guarantee maintenance of the assembly pressure.
At their other end, the bars 20 traverse the other holding plate 182 and are engaged in an auxiliary vertical plate 24, provided at a distance, outside the holding plate 182 parallel to the latter. The bars 20 are provided at their ends with a threaded portion, cooperating with an end assembly nut 26.
In the embodiment shown, a jack 28, advantageously hydraulic, provided with its supply pipework 30, is inserted between the holding plate 182 and the auxiliary plate 24. It should be noted that, in the vicinity of the holding plate 182, each bar 20 is advantageously provided with an intermediate threaded portion that can cooperate with a nut 32 for maintaining tension cooperating by resting against the outer face of the plate 182.
Finally, the auxiliary plate 24 receives four axial screws, only two 34 of which are shown. The ends of the stems of these screws are able to press against the outer face of the holding plate 182 so that these screws are, where appropriate, able to substitute for the jack 28.
Referring from now on in particular to
In the embodiment shown, two intermediate plates 38 and 40, forming current collectors, are positioned either side of the central structure 36. As will be subsequently seen, the intermediate plate 38 is intended for the circulation of hydrogen, while the plate 40 is intended for the circulation of air. These plates 38, 40 are for example made of graphite or of a porous metallic material.
Finally, two separating plates 42 and 44 are placed either side of the plates 38 and 40. These end plates 42 and 44, that are dedicated to distributions of hydrogen and air respectively, are put into communication with an adjacent intermediate plate, as will subsequently be described. They are made for example of graphite, a graphite-polymer mixture or metal.
As shown in
As a variant, not shown, each plate 42 or 44 can be made in one piece with a corresponding intermediate plate 38 or 40, so as to form a single separating device. In this case, the overall thickness of the cell can be brought down to approximately 6 mm.
A loop or handle 46 is additionally provided, fixed at its ends onto the upper edges of the two separating plates 42 and 44 of the same elementary cell 16. Such a handle enables a user to grasp and handle this elementary cell, which makes demounting this cell particularly easy.
As shown in particular in
It should be noted that the pitch and width of the fins are calculated so as to prevent opposite fins from mutually interleaving, during mounting or demounting. The heat exchange function, described above, can also be provided by another device, such as a corrugated metal sheet, a mesh or furthermore a porous metallic material.
As shown more particularly in
As a variant, all the elementary cells of the fuel cell battery need not be individual, in this sense a subassembly of these cells is able to form an indissociable group, given the reference 116 in
Only the end separating plates 142 and 144 of this group of cells are then individual, that is to say they are for example similar to cells 42 and 44 of the figures. In this way, this group of cells 116 is detachable in a block in relation to the cells that are adjacent thereto, not shown in this
As a supplementary variant, it is advantageous to provide, in a separate manner, supplementary cells or groups of cells, that can be substituted for any cells which might be damaged. In this respect, it is more particularly advantageous to place and store these replacement cells or groups of cells in an individual package, for example in cellophane packaging.
In the example shown, the assembly 6 is composed of three aligned distribution elements 61 to 63, each drilled with an axial through-hole drilling 55, these drillholes communicating with each other. These elements are additionally linked two-by-two by intermediate annular connections 56 inserted in end zones of widened diameter of the drillholes 55. Each connection, which is provided with two peripheral O-ring seals, is capable of sliding with respect to the two elements that it connects. In this way, it provides a telescopic attachment between these two elements. This therefore makes it possible to absorb variations in the length of the battery of cells due to it being put under pressure, with a view to its assembly, or furthermore due to thermal expansions in operation.
One (61) of the distribution elements is additionally provided at its outer end with a connection 58, designed to be connected to an air inlet. This connection 58, provided with a peripheral seal, and accommodated in one end with a widened diameter of the drillhole 55 of the element 61, is also capable of sliding with respect to this element 61. Finally, the other end element 63 is equipped with a stopper 60, designed to prevent any premature loss of air.
Advantageously, at least one of the distribution assemblies 6, 7 is made of an electrically insulating material, for example polyamide or polypropylene. Accordingly, water which is evacuated by this distribution assembly is not in contact with the electrical components of the cells. This consequently provides excellent insulation to the power circuit. Advantageously, each fluid distribution assembly is made of a moldable material, which makes it possible to establish mass production, and thus to reduce the corresponding costs.
As shown in
Attention will now be given more particularly to
With reference to
More precisely, the peripheral seal 82 rests against a sealing zone 85, bordering the channel 84. This sealing zone 85 possesses a cylindrical shape of which the cross-section, circular in the example shown, may be of any type. In addition, the principal axis of the cylinder forming the zone 85 is parallel to the principal plane of the cell, namely it is vertical in
It should be noted that the two ends 74 and 80 of the finger 701 also enable it to absorb variations in length of the battery of cells while guaranteeing leakproofness by virtue of the two O-ring seals 76, 82. As an alternative, the two ends of the joining finger 70 can be made of a material allowing such a clearance. Reference will in particular be made, in a non-limiting manner, to an elastomeric material.
As shown in
Referring from now on to
This hydrogen network, which is provided in the intermediate plate 38, extends opposite, with respect to the central structure 36, to the air distribution network previously described. Such a distribution network is intended for carrying out the reaction of hydrogen oxidation in the anode compartment of the cell.
As shown in
As a variant, the addition may be envisaged of supplementary connections that would be linked to the fluid distribution assemblies 6 and 7. Such connections, dedicated for example to the circulation of a cooling fluid, are capable of supplying a circuit that would then be integrated into the separating plates 42 and 44. Such a cooling circuit would thus substitute for air cooling, guaranteed by the fins 47.
Putting the different elementary cells of the fuel cell battery under compression, described with reference to the preceding figures, is carried out as follows:
The necessary assembly pressure should first of all be ensured. This phase is carried out by means of the jack 28, that can where appropriate be associated with the screws 34 or be replaced by these.
The lock nuts 32 are then screwed, for example manually, against the holding plate 182, so as to hold the latter in position pressed flat against the pack of cells. This also helps to keep the compression exerted on the assembly of cells constant. It should moreover be noted that the plates 181 and 182 enable this compression to be made uniform.
Once this operation has been carried out, it is then possible to release the action exerted by the jack 28, and, where appropriate, by the screws 34. The fuel cell battery is then in a normal functioning configuration.
It should be noted that, in service, the compression exerted on the assembly of cells ensures electrical contact and therefore the passage of current between the various cells via the separating plates 44.
If it is desired to release the assembly pressure exerted on the various cells, a temporary pressure slightly greater than this assembly pressure is first of all applied by the jack 28 and where appropriate the screws 34. This makes it possible to free and unscrew the lock nuts 32. The action of the jack 28 and the screws 38 is then stopped. Once these operations have been carried out successfully, the different elementary cells 16 of the fuel cell battery are no longer subjected to any mechanical pressure. In this way, they are no longer secured to each other.
It can thus be imagined that it is then possible to withdraw one or other of these elementary cells transversely, for example with a view to their maintenance or replacement without dismantling the rest of the pack of cells. With this in mind, a supplementary substitution cell can easily be positioned in place of the cell that has been lifted out.
As a variant, provision can be made not to use a Belleville washer or other added elements forming a spring. With this in mind, the holding plate 181 is then formed in order to obtain a prestress, so that it ensures at the same time the functions of making the compression uniform and of holding this compression.
This kit comprises a central replacement sandwich structure 36R, similar to that previously described. This central structure 36R is provided in a known manner, with a flat peripheral seal 37 bordering the membrane and electrodes. Two orifices 37′ are provided in this seal 37, for example symmetrically with respect to the center of gravity of all the structure. Such orifices are able to receive the pins 49, 50 described with reference to
In addition, the replacement kit includes a packaging 36′ in which the structure 36R is received in a leakproof manner. Such a packaging is for example made of cellophane or polyurethane. Advantageously, this package encloses an inert gas such as nitrogen.
The process for manufacturing the replacement kit of
Advantageously, before confining the structure 36R by means of the packaging 36′, this central structure is validated by submitting the latter to a conditioning current, of which the value is for example between 0.4 and 0.6 A/cm2. Such a measure makes it possible to guarantee and optimize subsequent performances of the central replacement structure once the latter is installed in an elementary cell.
When one of the cells 161 to 16n of the fuel cell battery is damaged in the region of its central structure, for example in the case of tearing of its membrane, it is possible to withdraw this cell individually, as previously described. Then, instead of replacing all the cell, it is possible only to change the central structure, the intermediate plates and separating plates not then being rejected. This is most particularly advantageous since it is possible to provide, on site, a reserve of a certain number of replacement kits, such as that of
Although the invention has been described in relation to particular embodiments, it is not limited to these but is capable of adaptations and variants that will be apparent to a person skilled in the art within the framework of the following claims.
Number | Date | Country | Kind |
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02/02843 | Mar 2002 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR03/00672 | 3/3/2003 | WO |