WO2018091727A1 - Device for heating a tank containing a corrosive liquid - Google Patents

Device for heating a tank containing a corrosive liquid Download PDF

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Publication number
WO2018091727A1
WO2018091727A1 PCT/EP2017/079881 EP2017079881W WO2018091727A1 WO 2018091727 A1 WO2018091727 A1 WO 2018091727A1 EP 2017079881 W EP2017079881 W EP 2017079881W WO 2018091727 A1 WO2018091727 A1 WO 2018091727A1
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WO
WIPO (PCT)
Prior art keywords
heating element
oxide layer
layer
element according
conductor
Prior art date
Application number
PCT/EP2017/079881
Other languages
French (fr)
Inventor
Mamadou Saliou BALDE
Julien GONTIER
Alexis GAUTIER
Original Assignee
Plastic Omnium Advanced Innovation And Research
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Publication date
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Priority to EP17816469.5A priority Critical patent/EP3542593B1/en
Publication of WO2018091727A1 publication Critical patent/WO2018091727A1/en

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/78—Heating arrangements specially adapted for immersion heating
    • H05B3/82—Fixedly-mounted immersion heaters
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/16—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor the conductor being mounted on an insulating base
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
    • H05B3/34—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/002—Heaters using a particular layout for the resistive material or resistive elements
    • H05B2203/003—Heaters using a particular layout for the resistive material or resistive elements using serpentine layout
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/002—Heaters using a particular layout for the resistive material or resistive elements
    • H05B2203/007—Heaters using a particular layout for the resistive material or resistive elements using multiple electrically connected resistive elements or resistive zones
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/013—Heaters using resistive films or coatings
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/014—Heaters using resistive wires or cables not provided for in H05B3/54

Definitions

  • the present invention relates to heaters mounted in tanks containing urea or ammonia, and often used in the exhaust air pollution control systems of motor vehicles "SCR".
  • SCR system is meant a system for catalytic reduction of NOx contained in the exhaust gas of an internal combustion engine, preferably a vehicle, and using urea as a precursor of liquid ammonia .
  • the tank is equipped with heating elements arranged on the bottom or on the sides of the tank.
  • These heating elements may be in the form of flexible sheets matching the shape of the walls of the tank. They are generally formed of a conductive element of stainless steel, acting as a heating resistor, sandwiched between two sheets of protective material, for example two thin sheets of silicone.
  • the object of the invention is to propose a more robust alternative solution.
  • the heating element which is intended to be placed in a tank containing a corrosive liquid, comprises an electrical resistance formed by an aluminum or titanium conductor on the surface of which is deposited respectively a layer of oxide of aluminum or a layer of titanium oxide composed of:
  • the heating element according to the invention has the same anticorrosive properties for other liquids than urea such as acid solutions and alkaline containing by way of example hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, boric acid, tartaric acid, etc.
  • Corrosion refers here to all the phenomena by which a metal or a metal alloy tends to oxidize under the influence of gaseous reactants or in solution.
  • This oxide layer is a protective layer that has the effect of preserving the metal against natural aggressions.
  • it is proposed to increase the thickness of the oxide layer by means of an electrochemical anodizing process.
  • This layer of increased thickness is then in the form of a dense oxide layer, without porosity, surmounted by a porous oxide layer.
  • the effect of the pores is to prevent, under the effect of surface tension mechanisms, the penetration of the corrosive element to the dense oxide layer disposed directly on the surface of the conductor.
  • the aluminum oxide or titanium oxide forms a corrosion resistant layer particularly resistant to the urea solution, and is an effective barrier to the permeation of ammonia molecules likely to alter the properties of aluminum or titanium is presented in metallic form.
  • the aluminum oxide or titanium oxide layer has a total thickness of less than 2000 nm, and preferably between 100 nm and 1500 nm.
  • the dense oxide layer has a thickness of between 10 nm and 10 nm.
  • the porous oxide layer has a thickness of between 100 nm and 1400 nm.
  • the porous oxide layer comprises pores in the form of hollow channels, one end of which is open to the outside.
  • the pores have an inner diameter which is between 10nm and 400nm.
  • the porous oxide layer has a pore density of between 10 9 and 10 11 pores / cm 2 .
  • the conductor is a layer of aluminum or titanium, of thickness between 10 ⁇ and 100 ⁇ .
  • the aluminum oxide or titanium oxide layer is deposited on at least one of the faces of the metal layer forming the conductor.
  • the electrical resistance is placed between two protective sheets made of plastic material.
  • the bending stiffness of the heating element is less than or equal to 4000 Nm, preferably less than or equal to 100 Nm, more preferably less than or equal to 10 Nm, and even more preferably less than or equal to 1 Nm.
  • the invention also relates to a tank, in which is installed a heating device comprising a heating element according to any one of the preceding characteristics.
  • This reservoir may contain water, urea, a mixture of water and urea or a mixture of water, urea and alcohol such as methanol, ethanol, water, ethylene glycol or isopropanol.
  • Figure 1 shows a perspective view of a heating element, comprising a conductor formed of a thin layer.
  • FIG. 2 represents a sectional view along A-A of the driver illustrated in FIG.
  • Figure 2a shows a sectional view of a conductor shaped cylindrical wire.
  • Figure 3 shows a schematic perspective view of the oxide layer.
  • Figures 4 and 5 are photographs taken under an electron microscope of an aluminum oxide layer in top view and in side view.
  • FIG. 1 illustrates a cutaway view of a heating element 1 in which the electrical resistance 10 is sandwiched between two protective sheets 11.
  • the material forming the protective sheets is chosen for its flexibility and for its chemical resistance to ammonia or its derivatives.
  • the electrical resistance 10 illustrated in FIG. 2 is formed by a thin layer of an electrically conductive metal 101, made of aluminum or titanium forming a continuous track, sandwiched between two oxide layers 102, of width I given, of total thickness e 2 , and traveling along a path defined on the surface of the heating element 1.
  • the thickness ei of the conductor layer 101 can usefully be between 10 ⁇ and 100 ⁇ . This thickness ei, is adjusted according to the type of metal forming the conductor and the width I, so as to obtain an ohmic resistance of the desired value, to provide the amount of heat necessary for thawing the liquid contained in the reservoir in a time compatible with the use of the vehicle.
  • the heating power is generally between 100W and 500W.
  • the heating element can then usefully have properties of flexibility and flexibility allowing it to match the shapes of the walls or the bottom of the tank, or be easily arranged on a technical module or a component such as a baffle fixed in the tank.
  • the term “flexible” we mean actually “easily deformable” and this usually reversibly. Generally, this corresponds to a bending stiffness (defined as being equal to (Eh 3/12 (lv 2)) where E is the Young's modulus of the flexible portion measured according to ASTM D790-03, h is its thickness, and v is the fish coefficient of its constituent material) preferably lower than 4000 Nm, the rigidity of the flexible part is less than or equal to 1000 Nm, or even 100 Nm or even 10 Nm and very particularly preferably, lower or equal to 1 Nm
  • the heating element may also comprise one or more resistive track (s) affixed to a sheet, or disposed between two sheets, ie two substantially flat supports, the material of which and the thickness are such that they are flexible.
  • Electrical conductors 12 are connected to both ends of the path traveled by the resistor 10, so as to bring the electric power to raise the temperature of the heating element by Joule effect.
  • the heating element comprises several tracks
  • these tracks are connected in parallel, so that, if one of the tracks is damaged, it does not jeopardize the operation of the other tracks
  • the protective sheets are preferably made of plastic (although any other insulating material may be suitable) and in particular, based on elastomer.
  • the flexible sheets may be silicone resin, polyolefin (polyethylene or polypropylene), thermoplastic elastomer (or TPE), polyester, polyimide (such as KAPTON® resin).
  • TPE thermoplastic elastomer
  • polyester polyimide
  • KAPTON® resin a polyimide
  • they are based on silicone, polyolefin or TPE, given that the polyester and the polyimide have a lower resistance to urea, especially at high temperature.
  • the oxide layer 102 may be disposed on both sides of the layer formed by the conductive metal 101 as proposed in Figure 2 or, in some arrangements, on only one side of the conductor.
  • the upper and lower oxide layers 102 have an identical thickness equal to e 2 . This feature is not limiting, and the two layers may, depending on the needs, have different thicknesses.
  • the oxide layer 102 is deposited over the entire surface of the wire, as shown in FIG. 2a.
  • the conductor 101 may also have a cylindrical shape and form a wire of given diameter as illustrated in Figure 2a, or be in the form of a thin layer as shown in Figure 2.
  • Electrical conductors 101 made of aluminum or titanium are known for their conductive properties, for their ability to transmit heat, for their ductility.
  • the modulus of elasticity of aluminum or titanium is relatively low which allows to obtain a heating resistance more robust to the geometric variations of the reservoir during freezing or thawing cycles of urea.
  • the conductivity of aluminum or titanium is excellent, which allows to design a heating resistance of the same efficiency as a steel resistance, having a mass and a much lower cost.
  • the oxide layer 102 is obtained, according to a known method, by anodizing a layer of aluminum or titanium forming the actual conductor.
  • the conductor is then immersed in an electrolytic bath and connected to the negative pole of a generator to form the anode.
  • the electrolytic bath is based on sulfuric acid, but may also be formed by boric acid or phosphoric acid.
  • the cathode is formed by an inert metal such as platinum connected to the positive pole of the generator.
  • the growth of the oxide layer is then controlled as a function of the density of the generated electric current, so as to obtain a structure of the alumina layer as illustrated in FIG.
  • the reaction at the anode is of the type: 2AI + 3H 2 0> AI 2 O 3 + 3H 2.
  • the reaction at the cathode is of the type: 6 H + + 6 e ⁇ > 3 H 2 .
  • the reaction at the anode is of the Ti + 2H 2 O> TiO 2 + 2H 2 type , and the reaction at the anode is of the type: 4H + 4e ⁇ > 2H 2 .
  • the oxide layer comprises a first layer 103, of thickness e 3 , resting directly on the metal 101 of the conductor.
  • the thickness e 3 of the layer 103 is advantageously between 10 nm and 100 nm.
  • This layer is considered to be dense in that it is formed of oxide aluminum or pure titanium oxide, and that it does not include porosities.
  • the layer 104 is disposed above the layer 103.
  • This layer 104 is formed of pores, in the form of hollow channels, whose inner diameter ⁇ is between 10 nm and 400 nm.
  • the ends of the channels, located opposite the dense oxide layer, are open to the outside.
  • the walls 105 of the pores are formed of pure oxide.
  • the pores have a depth ⁇ of between 100 nm and 1400 nm.
  • the pores make it possible to reinforce the anticorrosive effect of the oxide by reducing the access of the corrosive liquid to the dense oxide protective layer 102 which constitutes the ultimate barrier of protection.
  • This configuration also increases the flexibility of the oxide layer by preventing it from breaking in the event of bending of the conductor.
  • the total thickness e 2 of the oxide layer is therefore less than 2000 nm and preferably between 100 nm and 1500 nm.
  • FIG. 4 is a photograph in plan view of an aluminum oxide layer 102 taken with the aid of an electron microscope on which the pores of diameter ⁇ opening towards the outer surface are clearly distinguished.
  • the pore density is advantageously between 10 9 and 10 11 pores / cm 2 .
  • FIG. 5 is a side view photograph of the alumina layer 102 on which is distinguished the dense portion 103 and the porous portion 104 of said alumina layer 102.
  • the titanium oxide layer formed on the surface of a titanium conductor has the same characteristics as those illustrated in FIGS. 4 and 5.
  • the invention finally relates to a reservoir for containing a corrosive liquid, in which a heating device is arranged comprising a heating element according to the preceding characteristics.
  • This corrosive liquid may be basic in nature with a pH greater than 8, or an acid with a pH below 1.
  • the corrosive liquid is urea.
  • urea any solution, generally aqueous, containing urea.
  • the invention gives good results with eutectic solutions water / urea for which there is a quality standard:
  • AdBlue® also known under the name English Saxon DEF (Diesel Ehaust Fluid)
  • the urea content is between 31.8% and 33.2% (by weight) (ie 32.5 +/- 0.7% by weight) from which a quantity of available ammonia between 18.0% e 18.8%.
  • Adblue solution freezes from a temperature of -11 ° C.
  • the invention can also apply also urea mixtures / ammonium formate in aqueous solution and sold under the trade name Denoxium TM and one of the compositions (Denoxium-30) contains an equivalent amount of ammonia to that of the Adblue® solution.
  • Denoxium TM one of the compositions (Denoxium-30) contains an equivalent amount of ammonia to that of the Adblue® solution.
  • the present invention is also particularly advantageous in the context of water / urea eutectic solutions, or alternatively ternary solutions composed of water, urea and an alcohol such as methanol, ethanol, ethylene- glycol or isopropanol.
  • the invention can also be used for tanks containing water.
  • This assembly has resistance to aggression of the liquid contained in the tank much higher than that of steel or stainless steel used until today, and also has the advantage of being inexpensive because of the low cost of the heating element as described above, particularly when selecting an aluminum conductor.

Abstract

The invention relates to a heating element (1) to be placed in a tank containing a corrosive liquid, characterised in that the heating element (1) comprises an electrical resistor (10) formed by an aluminium or titanium conductor having a layer of aluminium oxide or a layer of titanium oxide respectively deposited on the surface thereof, formed by a dense oxide layer disposed between the surface of the conductor and a porous oxide layer.

Description

Dispositif de chauffage d'un réservoir contenant un liquide corrosif  Device for heating a tank containing a corrosive liquid
La présente invention concerne les dispositifs de chauffage montés dans les réservoirs contenant de l'urée ou de l'ammoniac, et souvent utilisés dans les systèmes de dépollution des gaz d'échappement des véhicules automobiles « SCR ». The present invention relates to heaters mounted in tanks containing urea or ammonia, and often used in the exhaust air pollution control systems of motor vehicles "SCR".
Par «système SCR», on entend désigner un système de réduction catalytique des NOx contenus dans les gaz d'échappement d'un moteur à combustion interne, de préférence d'un véhicule, et utilisant de l'urée comme précurseur d'ammoniac liquide.  By "SCR system" is meant a system for catalytic reduction of NOx contained in the exhaust gas of an internal combustion engine, preferably a vehicle, and using urea as a precursor of liquid ammonia .
Lorsque les conditions hivernales deviennent sévères et que la température extérieure s'abaisse en dessous d'un certain seuil, l'urée contenue dans le réservoir gèle.  When winter conditions become severe and the outside temperature drops below a certain threshold, the urea contained in the tank freezes.
Aussi pour maintenir le bon fonctionnement du système antipollution, il est nécessaire de réchauffer le réservoir de manière à conserver un volume d'urée sous forme liquide pour assurer le bon fonctionnement du dispositif de pompage et d'injection.  Also, to maintain the proper functioning of the anti-pollution system, it is necessary to heat the tank so as to maintain a volume of urea in liquid form to ensure the proper operation of the pumping device and injection.
A cet effet, le réservoir est équipé d'éléments de chauffage disposés sur le fond ou sur les côtés du réservoir.  For this purpose, the tank is equipped with heating elements arranged on the bottom or on the sides of the tank.
Ces éléments de chauffage peuvent se présenter sous la forme de feuilles souples épousant la forme des parois du réservoir. Ils sont en règle générale formés d'un élément conducteur en acier inoxydable, faisant office de résistance chauffante, enserré entre deux feuilles de matériau protecteur, par exemple deux feuilles minces de silicone.  These heating elements may be in the form of flexible sheets matching the shape of the walls of the tank. They are generally formed of a conductive element of stainless steel, acting as a heating resistor, sandwiched between two sheets of protective material, for example two thin sheets of silicone.
On observe toutefois que les cycles successifs de gel et de dégel entraînent des mouvements de contraction et d'extension des couches de protection conduisant, dans certains cas, à l'apparition de craquelures autorisant la pénétration de l'urée ou de l'ammoniac entre les couches de protection de la résistance chauffante. However, it is observed that the successive cycles of freezing and thawing result in contraction and extension movements of the protective layers leading in some cases to the appearance of cracks allowing the penetration of urea or ammonia between the protective layers of the heating resistor.
Ces liquides sont particulièrement corrosifs et peuvent altérer sérieusement l'acier inoxydable formant la résistance chauffante.  These liquids are particularly corrosive and can seriously alter the stainless steel forming the heating resistor.
L'invention a pour objet de proposer une solution alternative plus robuste.  The object of the invention is to propose a more robust alternative solution.
L'élément chauffant, selon l'invention, qui est destiné à être placé dans un réservoir contenant un liquide corrosif, comprend une résistance électrique formée par un conducteur en aluminium ou en titane sur la surface duquel est déposée respectivement une couche d'oxyde d'aluminium ou une couche d'oxyde de titane composée :  The heating element, according to the invention, which is intended to be placed in a tank containing a corrosive liquid, comprises an electrical resistance formed by an aluminum or titanium conductor on the surface of which is deposited respectively a layer of oxide of aluminum or a layer of titanium oxide composed of:
- d'une couche d'oxyde dense, disposée au contact de la surface du conducteur, et a dense oxide layer disposed in contact with the surface of the conductor, and
- d'une couche d'oxyde poreuse surmontant la couche d'oxyde dense. Prévue à l'origine pour traiter le cas d'un élément chauffant placé dans une solution d'urée, l'élément chauffant selon l'invention présente les mêmes propriétés anticorrosives pour d'autres liquides que l'urée tels que les solutions acides et alcalines contenant à titre d'exemple de l'acide chlorhydrique, sulfurique, phosphorique, nitrique, borique, tartrique oxalique, etc a porous oxide layer surmounting the dense oxide layer. Originally intended to treat the case of a heating element placed in a solution of urea, the heating element according to the invention has the same anticorrosive properties for other liquids than urea such as acid solutions and alkaline containing by way of example hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, boric acid, tartaric acid, etc.
La corrosion désigne ici l'ensemble des phénomènes par lesquels un métal ou un alliage métallique tend à s'oxyder sous l'influence de réactifs gazeux ou en solution.  Corrosion refers here to all the phenomena by which a metal or a metal alloy tends to oxidize under the influence of gaseous reactants or in solution.
A l'état naturel l'aluminium ou le titane tendent également à s'oxyder, et leur surface est recouverte dune couche de trois ou quatre nanomètres d'épaisseur, d'oxyde d'aluminium AI2O3, ou d'oxyde de titane Ti02.. In the natural state aluminum or titanium also tend to oxidize, and their surface is covered with a layer of three or four nanometers thick, aluminum oxide AI2O3, or titanium oxide Ti0 2 ..
Cette couche d'oxyde est une couche protectrice ayant pour effet de préserver le métal contre les agressions naturelles. Pour renforcer cette protection, il est proposé d'augmenter l'épaisseur de la couche d'oxyde à l'aide d'un procédé d'anodisation électrochimique. Cette couche d'épaisseur augmentée se présente alors sous la forme d'une couche d'oxyde dense, sans porosités, surmontée d'une couche d'oxyde poreuse. L'effet des pores est d'empêcher, sous l'effet des mécanismes de tensions de surface, la pénétration de l'élément corrosif vers la couche d'oxyde dense disposée directement sur la surface du conducteur.  This oxide layer is a protective layer that has the effect of preserving the metal against natural aggressions. To reinforce this protection, it is proposed to increase the thickness of the oxide layer by means of an electrochemical anodizing process. This layer of increased thickness is then in the form of a dense oxide layer, without porosity, surmounted by a porous oxide layer. The effect of the pores is to prevent, under the effect of surface tension mechanisms, the penetration of the corrosive element to the dense oxide layer disposed directly on the surface of the conductor.
L'oxyde d'aluminium ou de titane forme une couche anticorrosion particulièrement résistante à la solution d'urée, et constitue une barrière efficace à la perméation des molécules d'ammoniac susceptibles d'altérer les propriétés de l'aluminium ou du titane se présentant sous forme métallique.  The aluminum oxide or titanium oxide forms a corrosion resistant layer particularly resistant to the urea solution, and is an effective barrier to the permeation of ammonia molecules likely to alter the properties of aluminum or titanium is presented in metallic form.
L'élément chauffant selon l'invention peut aussi comprendre isolément ou en combinaison les caractéristiques suivantes :  The heating element according to the invention can also comprise in isolation or in combination the following characteristics:
La couche d'oxyde d'aluminium ou d'oxyde de titane a une épaisseur totale inférieure à 2000nm, et préférentiellement entre 100nm et 1500nm.  The aluminum oxide or titanium oxide layer has a total thickness of less than 2000 nm, and preferably between 100 nm and 1500 nm.
La couche d'oxyde dense a une épaisseur comprise entre 10nm et 10Onm.  The dense oxide layer has a thickness of between 10 nm and 10 nm.
La couche d'oxyde poreuse a une épaisseur comprise entre 100nm et 1400nm. The porous oxide layer has a thickness of between 100 nm and 1400 nm.
La couche d'oxyde poreuse comprend des pores, se présentant sous la forme de canaux creux, dont une extrémité est ouverte vers l'extérieur. The porous oxide layer comprises pores in the form of hollow channels, one end of which is open to the outside.
Les pores ont un diamètre intérieur qui est compris entre 10nm et 400nm. The pores have an inner diameter which is between 10nm and 400nm.
La couche d'oxyde poreuse a une densité de pores comprise entre 109 et 10 11 pores/cm2. The porous oxide layer has a pore density of between 10 9 and 10 11 pores / cm 2 .
Le conducteur est une couche en aluminium ou en titane, d'épaisseur comprise entre 10μηι et 100μηι. La couche d'oxyde d'aluminium ou d'oxyde de titane est déposée sur au moins une des faces de la couche métallique formant le conducteur. The conductor is a layer of aluminum or titanium, of thickness between 10μηι and 100μηι. The aluminum oxide or titanium oxide layer is deposited on at least one of the faces of the metal layer forming the conductor.
La résistance électrique est placée entre deux feuilles de protection en matériau plastique. La rigidité en flexion de l'élément chauffant est inférieure ou égale à 4000 N.m, préférentiellement inférieure ou égale à 100 N.m plus préférentiellement inférieure ou égale à 10 N.m, et encore plus préférentiellement inférieure ou égale à 1 N.m. The electrical resistance is placed between two protective sheets made of plastic material. The bending stiffness of the heating element is less than or equal to 4000 Nm, preferably less than or equal to 100 Nm, more preferably less than or equal to 10 Nm, and even more preferably less than or equal to 1 Nm.
L'invention s'intéresse également à un réservoir, dans lequel est installé un dispositif de chauffage comprenant un élément chauffant selon l'une quelconque des caractéristiques qui précèdent. Ce réservoir peut contenir de l'eau, de l'urée, un mélange d'eau et d'urée ou encore un mélange d'eau, d'urée et d'alcool tel que du méthanol, de l'éthanol, de l'éthylène- glycol ou de l'isopropanol. The invention also relates to a tank, in which is installed a heating device comprising a heating element according to any one of the preceding characteristics. This reservoir may contain water, urea, a mixture of water and urea or a mixture of water, urea and alcohol such as methanol, ethanol, water, ethylene glycol or isopropanol.
L'invention sera mieux comprise à la lecture des figures annexées, qui sont fournies à titre d'exemples et ne présentent aucun caractère limitatif, dans lesquelles :  The invention will be better understood on reading the appended figures, which are provided by way of examples and are in no way limiting, in which:
La figure 1 représente une vue en perspective d'un élément chauffant, comprenant un conducteur formé d'une couche mince.  Figure 1 shows a perspective view of a heating element, comprising a conductor formed of a thin layer.
La figure 2 représente une vue en coupe selon A-A du conducteur illustré à la figure FIG. 2 represents a sectional view along A-A of the driver illustrated in FIG.
1 . 1.
La figure 2a représente une vue en coupe d'un conducteur en forme de fil cylindrique.  Figure 2a shows a sectional view of a conductor shaped cylindrical wire.
La figure 3 représente une vue schématique en perspective de la couche d'oxyde. Les figures 4 et 5 sont des photographies prises au microscope électronique d'une couche d'oxyde d'aluminium en vue de dessus et en vue de côté.  Figure 3 shows a schematic perspective view of the oxide layer. Figures 4 and 5 are photographs taken under an electron microscope of an aluminum oxide layer in top view and in side view.
La figure 1 illustre une vue en écorché d'un élément chauffant 1 dans lequel la résistance électrique 10 est prise en sandwich entre deux feuilles de protection 11 . FIG. 1 illustrates a cutaway view of a heating element 1 in which the electrical resistance 10 is sandwiched between two protective sheets 11.
Destiné à être en contact direct avec le liquide contenu dans le réservoir, le matériau formant les feuilles de protection est choisi pour sa souplesse et pour sa résistance chimique à l'ammoniac ou à ses dérivés.  Intended to be in direct contact with the liquid contained in the tank, the material forming the protective sheets is chosen for its flexibility and for its chemical resistance to ammonia or its derivatives.
La résistance électrique 10 illustrée à la figure 2 est formée par une couche mince d'un métal conducteur de l'électricité 101 , en aluminium ou en titane formant une piste continue, prise en sandwich entre deux couches d'oxyde 102, de largeur I donnée, d'épaisseur totale e2, et cheminant selon un parcours défini sur la surface de l'élément chauffant 1 . The electrical resistance 10 illustrated in FIG. 2 is formed by a thin layer of an electrically conductive metal 101, made of aluminum or titanium forming a continuous track, sandwiched between two oxide layers 102, of width I given, of total thickness e 2 , and traveling along a path defined on the surface of the heating element 1.
L'épaisseur ei de la couche de conducteur 101 peut utilement être comprise entre 10 μηι et 100 μιτι. Cette épaisseur ei , est ajustée en fonction du type de métal formant le conducteur et de la largeur I, de manière à obtenir une résistance ohmique de la valeur recherchée, pour fournir la quantité de chaleur nécessaire à la décongélation du liquide contenu dans le réservoir dans un temps compatible avec l'usage du véhicule. La puissance de chauffe est généralement comprise entre 100W et 500W. The thickness ei of the conductor layer 101 can usefully be between 10 μηι and 100 μιτι. This thickness ei, is adjusted according to the type of metal forming the conductor and the width I, so as to obtain an ohmic resistance of the desired value, to provide the amount of heat necessary for thawing the liquid contained in the reservoir in a time compatible with the use of the vehicle. The heating power is generally between 100W and 500W.
L'élément chauffant peut alors utilement présenter des propriétés de souplesse et de flexibilité lui permettant d'épouser les formes des parois ou du fond du réservoir, ou encore être arrangé aisément sur un module technique ou un composant tel qu'un baffle fixé dans le réservoir.  The heating element can then usefully have properties of flexibility and flexibility allowing it to match the shapes of the walls or the bottom of the tank, or be easily arranged on a technical module or a component such as a baffle fixed in the tank.
Par le qualificatif «flexible» on entend en fait dire «aisément déformable» et ce généralement de manière réversible. Généralement, ceci correspond à une rigidité en flexion (définie comme étant égale à (Eh3/12(l-v2)) où E est le module de Young de la partie flexible mesuré selon la norme ASTM D790-03, h est son épaisseur, et v est le coefficient de poisson de son matériau constitutif) inférieure de préférence à 4000 N.m, la rigidité de la partie flexible est inférieure ou égale à 1000 N.m, voire à 100 N.m voire même 10 N.m et de manière tout particulièrement préférée, inférieure ou égale à 1 N.m. By the term "flexible" we mean actually "easily deformable" and this usually reversibly. Generally, this corresponds to a bending stiffness (defined as being equal to (Eh 3/12 (lv 2)) where E is the Young's modulus of the flexible portion measured according to ASTM D790-03, h is its thickness, and v is the fish coefficient of its constituent material) preferably lower than 4000 Nm, the rigidity of the flexible part is less than or equal to 1000 Nm, or even 100 Nm or even 10 Nm and very particularly preferably, lower or equal to 1 Nm
L'élément chauffant peut également comprendre une ou plusieurs piste(s) résistive(s) apposée(s) sur une feuille, ou disposée(s) entre deux feuilles, c'est-à-dire deux supports substantiellement plats, dont le matériau et l'épaisseur sont tels qu'ils sont flexibles.  The heating element may also comprise one or more resistive track (s) affixed to a sheet, or disposed between two sheets, ie two substantially flat supports, the material of which and the thickness are such that they are flexible.
Des conducteurs électriques 12 sont reliés aux deux extrémités du chemin parcouru par la résistance 10, de manière à amener la puissance électrique permettant d'élever la température de l'élément chauffant par effet Joule. Electrical conductors 12 are connected to both ends of the path traveled by the resistor 10, so as to bring the electric power to raise the temperature of the heating element by Joule effect.
Lorsque l'élément chauffant comprend plusieurs pistes, ces pistes sont raccordées en parallèle, de sorte que, si l'une des pistes est endommagée, elle ne met pas en péril le fonctionnement des autres pistes  When the heating element comprises several tracks, these tracks are connected in parallel, so that, if one of the tracks is damaged, it does not jeopardize the operation of the other tracks
Les feuilles de protection sont de préférence en matière plastique (bien que tout autre matériau isolant puisse convenir) et en particulier, à base d'élastomère. Les feuilles flexibles peuvent être en résine silicone, en polyoléfine (polyéthylène ou polypropylène), élastomère thermoplastique (ou TPE), polyester, polyimide (tel que la résine KAPTON®). De préférence, elles sont à base de silicone, polyoléfine ou TPE compte tenu du fait que le polyester et le polyimide ont une résistance plus faible à l'urée, en particulier à haute température.  The protective sheets are preferably made of plastic (although any other insulating material may be suitable) and in particular, based on elastomer. The flexible sheets may be silicone resin, polyolefin (polyethylene or polypropylene), thermoplastic elastomer (or TPE), polyester, polyimide (such as KAPTON® resin). Preferably, they are based on silicone, polyolefin or TPE, given that the polyester and the polyimide have a lower resistance to urea, especially at high temperature.
La couche d'oxyde 102 peut être disposée sur les deux faces de la couche formée par le métal conducteur 101 comme cela est proposé à la figure 2 ou, selon certains arrangements, sur une seule des faces du conducteur. Dans l'exemple de la figure 2, les couches supérieure et inférieure d'oxyde 102 ont une épaisseur identique égale à e2. Cette caractéristique n'est pas limitative, et les deux couches peuvent, selon les besoins, avoir des épaisseurs différentes. The oxide layer 102 may be disposed on both sides of the layer formed by the conductive metal 101 as proposed in Figure 2 or, in some arrangements, on only one side of the conductor. In the example of FIG. 2, the upper and lower oxide layers 102 have an identical thickness equal to e 2 . This feature is not limiting, and the two layers may, depending on the needs, have different thicknesses.
Lorsque le conducteur est un fil d'aluminium ou de titane, la couche d'oxyde 102 est déposée sur toute la surface du fil, comme cela est illustré à la figure 2a.  When the conductor is an aluminum or titanium wire, the oxide layer 102 is deposited over the entire surface of the wire, as shown in FIG. 2a.
Le conducteur 101 peut également avoir une forme cylindrique et former un fil de diamètre donné comme cela est illustré à la figure 2a, ou se présenter sous la forme d'une couche mince comme cela est illustré à la figure 2.  The conductor 101 may also have a cylindrical shape and form a wire of given diameter as illustrated in Figure 2a, or be in the form of a thin layer as shown in Figure 2.
Les conducteurs électrique 101 en aluminium ou en titane sont connus pour leurs propriétés conductrices, pour leur capacité à transmettre la chaleur, pour leur ductilité..  Electrical conductors 101 made of aluminum or titanium are known for their conductive properties, for their ability to transmit heat, for their ductility.
De plus, le module d'élasticité de l'aluminium ou du titane est relativement peu élevé ce qui permet d'obtenir une résistance chauffante plus robuste face aux variations géométriques du réservoir lors des cycles de congélation ou de décongélation de l'urée.  In addition, the modulus of elasticity of aluminum or titanium is relatively low which allows to obtain a heating resistance more robust to the geometric variations of the reservoir during freezing or thawing cycles of urea.
Enfin, la conductivité de l'aluminium ou du titane est excellente, ce qui permet de concevoir une résistance chauffante de même efficacité qu'une résistance en acier, présentant une masse et un coût très inférieurs.  Finally, the conductivity of aluminum or titanium is excellent, which allows to design a heating resistance of the same efficiency as a steel resistance, having a mass and a much lower cost.
La couche d'oxyde 102 est obtenue, selon un procédé connu, par anodisation d'une couche d'aluminium ou de titane formant le conducteur proprement dit. The oxide layer 102 is obtained, according to a known method, by anodizing a layer of aluminum or titanium forming the actual conductor.
Le conducteur est alors plongé dans un bain électrolytique et relié au pôle négatif d'un générateur pour former l'anode. Le bain électrolytique est à base d'acide sulfurique, mais peut également être formé par de l'acide borique ou encore de l'acide phosphorique. La cathode est formée par un métal inerte tel que du platine connecté au pôle positif du générateur. La croissance de la couche d'oxyde est alors contrôlée en fonction de la densité du courant électrique généré, de manière à obtenir une structure de la couche d'alumine telle qu'illustrée à la figure 3. The conductor is then immersed in an electrolytic bath and connected to the negative pole of a generator to form the anode. The electrolytic bath is based on sulfuric acid, but may also be formed by boric acid or phosphoric acid. The cathode is formed by an inert metal such as platinum connected to the positive pole of the generator. The growth of the oxide layer is then controlled as a function of the density of the generated electric current, so as to obtain a structure of the alumina layer as illustrated in FIG.
Lorsque le conducteur est en aluminium, la réaction à l'anode est du type : 2AI+3H20 > AI2O3+3H2., et la réaction à la cathode est du type : 6 H++6 e~ > 3 H2. When the conductor is aluminum, the reaction at the anode is of the type: 2AI + 3H 2 0> AI 2 O 3 + 3H 2. , And the reaction at the cathode is of the type: 6 H + + 6 e ~ > 3 H 2 .
Lorsque le conducteur est en titane, la réaction à l'anode est du type Ti+2H20 > Ti02+2H2, et la réaction à l'anode est du type : 4 H+ 4e~ > 2H2. When the conductor is made of titanium, the reaction at the anode is of the Ti + 2H 2 O> TiO 2 + 2H 2 type , and the reaction at the anode is of the type: 4H + 4e ~ > 2H 2 .
La couche d'oxyde comporte une première couche 103, d'épaisseur e3, reposant directement sur le métal 101 du conducteur. L'épaisseur e3 de la couche 103 est utilement comprise entre 10nm et 100nm. On considère que cette couche est dense en ce qu'elle est formée d'oxyde d'aluminium ou d'oxyde de titane pur, et qu'elle ne comprend pas de porosités. The oxide layer comprises a first layer 103, of thickness e 3 , resting directly on the metal 101 of the conductor. The thickness e 3 of the layer 103 is advantageously between 10 nm and 100 nm. This layer is considered to be dense in that it is formed of oxide aluminum or pure titanium oxide, and that it does not include porosities.
La couche 104 est disposée au-dessus de la couche 103. Cette couche 104 est formée de pores, se présentant sous la forme de canaux creux, dont le diamètre intérieur Φ est compris entre 10nm et 400nm. Les extrémités des canaux, situées à l'opposé à la couche d'oxyde dense, sont ouvertes vers l'extérieur. Les parois 105 des pores sont formées d'oxyde pur. Les pores ont une profondeur β comprise entre 100nm et 1400nm.  The layer 104 is disposed above the layer 103. This layer 104 is formed of pores, in the form of hollow channels, whose inner diameter Φ is between 10 nm and 400 nm. The ends of the channels, located opposite the dense oxide layer, are open to the outside. The walls 105 of the pores are formed of pure oxide. The pores have a depth β of between 100 nm and 1400 nm.
Comme cela a été indiqué ci-dessus, les pores permettent de renforcer l'effet anticorrosif de l'oxyde en réduisant l'accès du liquide corrosif à la couche de protection en oxyde dense 102 qui constitue la barrière ultime de protection.  As indicated above, the pores make it possible to reinforce the anticorrosive effect of the oxide by reducing the access of the corrosive liquid to the dense oxide protective layer 102 which constitutes the ultimate barrier of protection.
Cette configuration augmente également la souplesse de la couche d'oxyde en évitant qu'elle ne se brise en cas de flexion du conducteur. This configuration also increases the flexibility of the oxide layer by preventing it from breaking in the event of bending of the conductor.
L'épaisseur totale e2 de la couche d'oxyde est donc inférieure à 2000nm et préférentiellement comprise entre 100nm et 1500nm. The total thickness e 2 of the oxide layer is therefore less than 2000 nm and preferably between 100 nm and 1500 nm.
La figure 4 est une photographie en vue de dessus d'une couche d'oxyde d'aluminium 102 prise à l'aide d'un microscope électronique sur laquelle on distingue clairement les pores de diamètre Φ débouchant vers la surface extérieure. La densité de pores est utilement comprise entre 109 et 1011 pores/cm2. FIG. 4 is a photograph in plan view of an aluminum oxide layer 102 taken with the aid of an electron microscope on which the pores of diameter Φ opening towards the outer surface are clearly distinguished. The pore density is advantageously between 10 9 and 10 11 pores / cm 2 .
La figure 5 est une photographie en vue de côté de la couche d'alumine 102 sur laquelle on distingue la partie dense 103 et la partie poreuse 104 de ladite couche d'alumine 102.  FIG. 5 is a side view photograph of the alumina layer 102 on which is distinguished the dense portion 103 and the porous portion 104 of said alumina layer 102.
La couche d'oxyde de titane formée à la surface d'un conducteur en titane présente les mêmes caractéristiques que celles illustrées aux figures 4 et 5. The titanium oxide layer formed on the surface of a titanium conductor has the same characteristics as those illustrated in FIGS. 4 and 5.
L'invention concerne enfin un réservoir, destiné à contenir un liquide corrosif, dans lequel est disposé un dispositif de chauffage comprenant un élément chauffant selon les caractéristiques qui précèdent. Ce liquide corrosif peut être de nature basique avec un pH supérieur à 8, ou un acide avec un pH inférieur à 1 .  The invention finally relates to a reservoir for containing a corrosive liquid, in which a heating device is arranged comprising a heating element according to the preceding characteristics. This corrosive liquid may be basic in nature with a pH greater than 8, or an acid with a pH below 1.
Préférentiellement, le liquide corrosif est de l'urée.  Preferably, the corrosive liquid is urea.
Par le terme «urée», on entend désigner toute solution, généralement aqueuse, contenant de l'urée. L'invention donne de bons résultats avec les solutions eutectiques eau/urée pour lesquelles il existe un standard qualité : Par exemple, selon la norme DIN 70070, dans le cas de la solution d'AdBlue®, également connue sous l'appellation anglo-saxonne DEF (Diesel Ehaust Fluid), la teneur en urée est comprise entre 31 ,8 % et 33,2 % (en poids) (soit 32.5 +/- 0.7 % en poids) d'où une quantité d'ammoniac disponible comprise entre 18,0 % e 18,8 %. La solution Adblue gèle à partir d'une température de -11 °C. L'invention peut également s'appliquer aux mélanges urée/formate d'ammonium en solution aqueuse également et vendus sous la marque Denoxium™ et dont l'une des compositions (Denoxium-30) contient une quantité équivalente en ammoniac à celle de la solution d'Adblue®. Ces derniers présentent comme avantage, le fait de ne geler qu'à partir de -30°C (par rapport à -11 °C), mais présentent comme inconvénients, des problèmes de corrosion liés à la libération éventuelle d'acide formique. By the term "urea" is meant any solution, generally aqueous, containing urea. The invention gives good results with eutectic solutions water / urea for which there is a quality standard: For example, according to DIN 70070, in the case of the solution of AdBlue®, also known under the name English Saxon DEF (Diesel Ehaust Fluid), the urea content is between 31.8% and 33.2% (by weight) (ie 32.5 +/- 0.7% by weight) from which a quantity of available ammonia between 18.0% e 18.8%. Adblue solution freezes from a temperature of -11 ° C. The invention can also apply also urea mixtures / ammonium formate in aqueous solution and sold under the trade name Denoxium ™ and one of the compositions (Denoxium-30) contains an equivalent amount of ammonia to that of the Adblue® solution. These have the advantage of freezing only from -30 ° C (relative to -11 ° C), but have as disadvantages, corrosion problems related to the possible release of formic acid.
La présente invention est aussi particulièrement intéressante dans le cadre des solutions eutectiques eau/urée, ou encore des solutions ternaires composées d'eau, d'urée et d'un alcool tel que du méthanol, de l'éthanol, de l'éthylène-glycol ou de l'isopropanol.  The present invention is also particularly advantageous in the context of water / urea eutectic solutions, or alternatively ternary solutions composed of water, urea and an alcohol such as methanol, ethanol, ethylene- glycol or isopropanol.
II va de soi que l'invention peut être également être utilisée pour des réservoirs contenant de l'eau. It goes without saying that the invention can also be used for tanks containing water.
Cet ensemble, présente une résistance à l'agression du liquide contenu dans le réservoir très supérieure à celle de l'acier ou de l'acier inox utilisé jusqu'à aujourd'hui, et présente de surcroit l'avantage d'être peu coûteux en raison du faible coût de l'élément chauffant tel que décrit ci-dessus, en particulier lorsque l'on choisit un conducteur en aluminium. This assembly has resistance to aggression of the liquid contained in the tank much higher than that of steel or stainless steel used until today, and also has the advantage of being inexpensive because of the low cost of the heating element as described above, particularly when selecting an aluminum conductor.
Nomenclature Nomenclature
1 Elément chauffant. 1 Heating element.
10 Résistance de chauffage.  10 Heating resistance.
101 Couche de métal conducteur. 101 Conductive metal layer.
102 Couche d'oxyde d'aluminium ou d'oxyde de titane. 102 Layer of aluminum oxide or titanium oxide.
103 Couche d'oxyde dense. 103 Dense oxide layer.
104 Couche d'oxyde poreuse.  104 Porous oxide layer.
105 Paroi des pores.  105 Pore wall.
11 Feuille de protection. 11 Protection sheet.
12 Conducteurs d'alimentation électrique.  12 Power supply conductors.
2 Fond du réservoir.  2 Bottom of the tank.
21 Dispositif de mesure de niveau.  21 Level measuring device.
22 Dispositif de pompage.  22 Pumping device.
e1 Epaisseur du conducteur e1 Thickness of the driver
e2 Epaisseur de la couche d'oxyde. e2 Thickness of the oxide layer.
e3 Epaisseur de la couche d'oxyde dense. e3 Thickness of the dense oxide layer.
e4 Epaisseur de la couche d'oxyde poreuse. e4 Thickness of the porous oxide layer.
Φ Diamètre des pores.  Φ Pore diameter.

Claims

REVENDICATIONS
1 . Elément chauffant (1 ), destiné à être placé dans un réservoir contenant un liquide corrosif, caractérisé en ce que ledit élément chauffant (1 ) comprend une résistance électrique (10) formée d'un conducteur en aluminium ou en titane (101 ) sur la surface duquel est déposée respectivement une couche d'oxyde d'aluminium ou une couche d'oxyde de titane (102) composée : 1. Heating element (1), intended to be placed in a tank containing a corrosive liquid, characterized in that said heating element (1) comprises an electrical resistance (10) formed of an aluminum or titanium conductor (101) on the surface of which is deposited respectively an aluminum oxide layer or a titanium oxide layer (102) composed of:
- d'une couche d'oxyde dense (103), disposée au contact de la surface du conducteur (101 ), et  a dense oxide layer (103) arranged in contact with the surface of the conductor (101), and
- d'une couche d'oxyde poreuse (104) surmontant la couche d'oxyde dense (103). a porous oxide layer (104) surmounting the dense oxide layer (103).
2. Elément chauffant selon la revendication 1 dans lequel la couche d'oxyde (102) a une épaisseur totale (e2) inférieure à 2000nm, et préférentiellement comprise entre 100nm et 1500nm. 2. heating element according to claim 1 wherein the oxide layer (102) has a total thickness (e 2 ) less than 2000nm, and preferably between 100nm and 1500nm.
3. Elément chauffant selon la revendication 1 ou la revendication 2, dans lequel la couche d'oxyde dense (103) a une épaisseur (e3) comprise entre 10nm et 100nm. 3. Heating element according to claim 1 or claim 2, wherein the dense oxide layer (103) has a thickness (e 3 ) of between 10 nm and 100 nm.
4. Elément chauffant selon l'une quelconque des revendications 1 à 3, dans lequel la couche d'oxyde poreuse (104) a une épaisseur (e4) comprise entre 100nm et 1400nm. 4. A heating element according to any one of claims 1 to 3, wherein the porous oxide layer (104) has a thickness (e4) between 100nm and 1400nm.
5. Elément chauffant selon l'une des revendications 1 à 4, dans lequel la couche d'oxyde poreuse (104) comprend des pores, se présentant sous la forme de canaux creux, dont une extrémité, opposée à la couche d'oxyde dense, est ouverte vers l'extérieur. 5. Heating element according to one of claims 1 to 4, wherein the porous oxide layer (104) comprises pores, in the form of hollow channels, one end, opposite the dense oxide layer , is open to the outside.
6. Elément chauffant selon la revendication 5, dans lequel les pores ont un diamètre intérieur (Φ) qui est compris entre 10nm et 400nm.  The heating element of claim 5 wherein the pores have an inside diameter (Φ) of between 10 nm and 400 nm.
7. Elément chauffant selon la revendication 5 dans lequel la couche poreuse (104) a une densité de pores comprise entre 109 et 1011 pores/cm2. The heating element of claim 5 wherein the porous layer (104) has a pore density of between 10 9 and 10 11 pores / cm 2 .
8. Elément chauffant selon l'une quelconque des revendications précédentes, dans lequel le conducteur en aluminium ou en titane est une couche métallique, d'épaisseur (ei) comprise entre 10μηι et 100μηι.  8. Heating element according to any one of the preceding claims, wherein the conductor of aluminum or titanium is a metal layer, of thickness (ei) between 10μηι and 100μηι.
9. Elément chauffant selon la revendication 8, dans lequel la couche d'oxyde (102) est formée sur au moins une des faces de la couche métallique (101 ).  The heating element of claim 8, wherein the oxide layer (102) is formed on at least one of the faces of the metal layer (101).
10. Elément chauffant selon l'une quelconque des revendications précédentes, dans lequel la résistance électrique (10) est placée entre deux feuilles de protection en matériau plastique Heating element according to any one of the preceding claims, wherein the electrical resistance (10) is placed between two plastics protective sheets.
1 1 . Elément chauffant selon l'une quelconque des revendications précédentes, présentant une rigidité en flexion inférieure ou égale à 4000 N.m, préférentiellement inférieure ou égale à 100 N.m, plus préférentiellement inférieure ou égale à 10 N.m, et encore plus préférentiellement inférieure ou égale à 1 N.m. 1 1. Heating element according to any one of the preceding claims, having a flexural stiffness of less than or equal to 4000 Nm, preferably less than or equal to 100 Nm, more preferably less than or equal to 10 Nm, and even more preferably less than or equal to 1 Nm.
12. Réservoir dans lequel est installé un dispositif de chauffage comprenant un élément chauffant selon l'une quelconque des revendications 1 à 11 .  12. A tank in which a heating device is installed comprising a heating element according to any one of claims 1 to 11.
13. Réservoir selon la revendication 12 contenant un liquide choisi parmi les éléments suivants :  13. Tank according to claim 12 containing a liquid chosen from the following elements:
- de l'eau,  - some water,
- de l'urée dissout dans de l'eau,  - urea dissolved in water,
un mélange composé d'eau, d'urée et d'un alcool tel que du méthanol, de l'éthanol, de l'éthylène-glycol ou de l'isopropanol.  a mixture of water, urea and an alcohol such as methanol, ethanol, ethylene glycol or isopropanol.
PCT/EP2017/079881 2016-11-21 2017-11-21 Device for heating a tank containing a corrosive liquid WO2018091727A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0756808A1 (en) * 1994-04-16 1997-02-05 Ceramaspeed Limited Method of manufacturing an electrical resistance heating means
DE102007005154A1 (en) * 2007-01-29 2008-07-31 Thyssenkrupp Vdm Gmbh Use of iron-chromium-aluminum alloys with specified composition in 0.020 -0.300 mm thick foils for heating elements is new
EP2860228A1 (en) * 2013-10-14 2015-04-15 General Electric Company Heater assembly with protective coating and method of applying same
WO2016108693A1 (en) * 2014-12-31 2016-07-07 Metalmembranes.Com B.V. Heater element, device provided therewith and method for manufacturing such element

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0756808A1 (en) * 1994-04-16 1997-02-05 Ceramaspeed Limited Method of manufacturing an electrical resistance heating means
DE102007005154A1 (en) * 2007-01-29 2008-07-31 Thyssenkrupp Vdm Gmbh Use of iron-chromium-aluminum alloys with specified composition in 0.020 -0.300 mm thick foils for heating elements is new
EP2860228A1 (en) * 2013-10-14 2015-04-15 General Electric Company Heater assembly with protective coating and method of applying same
WO2016108693A1 (en) * 2014-12-31 2016-07-07 Metalmembranes.Com B.V. Heater element, device provided therewith and method for manufacturing such element

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