FR3048554A1 - THERMOELECTRIC DEVICE - Google Patents

Abstract

The invention relates to a thermoelectric device (10), comprising a thermoelectric generator (12) capable of generating an electric current under the action of a temperature gradient in contact with a cold source (F1) on the one hand, and a hot source (F2) on the other hand, said device further comprising an electrode (20), said device being configured so that a portion of the electric current generated by the thermoelectric generator (12) is adapted to supplying said electrode (20), said electrode (20) being intended to electrically charge toxic particles of a first fluid so as to agglomerate said toxic particles together.

Description

In the automotive field, thermoelectric devices have already been proposed using elements, called thermoelectric elements, making it possible to generate an electric current in the presence of a temperature gradient between two of their opposite faces according to the phenomenon known as the effect. Seebeck. These devices are also called thermoelectric generators.

It is known to position these thermoelectric generators in a motor vehicle exhaust line, or even in the recirculated exhaust gas circuit for motor vehicles having such a circuit between the exhaust and the intake of the engine. The objective is the use of the exhaust heat of motor vehicles to generate electrical energy.

The treatment of the exhaust gas is then necessary, in particular to prevent the release of toxic particles in the open air. This gas treatment is a function distinct from that of the generation of electrical energy by the generators mentioned above.

One of the aims of the present invention consists in proposing a solution making it possible to improve the existing one, in particular by means of a combination of functions within the same set. The invention relates to a thermoelectric device, comprising a thermoelectric generator capable of generating an electric current under the action of a temperature gradient in contact with a cold source on the one hand, and a hot source on the other hand .

According to the invention, said device further comprises an electrode, said device being configured in such a way that a part of the electric current generated by the thermoelectric generator is able to supply said electrode, said electrode being intended to electrically charge toxic particles of a first fluid so as to agglomerate said toxic particles together.

The device of the invention is a thermoelectric device that allows the generation of an electric current from a temperature gradient and, on the other hand, the agglomeration of toxic particles of a fluid participating in this generation of current. . Indeed, it is intended to agglomerate these toxic particles within said thermoelectric device, in particular by electrically charging said particles.

Thus, the thermoelectric device of the invention has the advantage of improving the existing thermoelectric devices by proposing to combine, within the same set, two previously separate technical functions.

According to various embodiments of the invention, which may be taken together or separately: said first fluid constitutes said hot source, said cold source is constituted by ambient air, said electrode is disposed upstream of said generator, the electric generator comprises a plurality of thermoelectric elements capable of generating an electric current under the action of a temperature gradient exerted between two of their faces; said plurality of elements is in contact with the hot source via a first plurality of thermally conductive fins, - said fins are configured to retain, on their surfaces, agglomerates of toxic particles, - said fins are metallic, - said thermoelectric elements are parallelepiped elements, - said plurality of elements is in contact with the cold source via a second plurality of fins thermoelectric conductors, in particular metallic, the thermoelectric device of the invention is configured so that a part of the electric current generated by the thermoelectric generator is able to supply, in addition, the charge of a capacitor, thermoelectric device of the invention is intended to be coated with a protective outer casing, said housing, so as to be positioned in a motor vehicle exhaust line so that the exhaust gas flowing in said line define said first fluid and / or in a motor vehicle recirculated exhaust gas circuit such that said recirculated exhaust gas flowing in said circuit defines said first fluid. The invention will be better understood, and other objects, details, features and advantages thereof will become more clearly apparent in the following detailed explanatory description of at least one embodiment of the invention given to As a purely illustrative and non-limiting example, with reference to the attached schematic drawing.

In this drawing: - Figure 1 is a schematic illustration of an embodiment of a thermoelectric device according to the invention, said device being shown in the longitudinal direction.

As illustrated in FIG. 1, the invention relates to a thermoelectric device 10 comprising a thermoelectric generator 12 capable of generating an electric current under the action of a temperature gradient in contact with a cold source F1 on the one hand, and a hot source F2 on the other hand.

FIG. 1 schematically illustrates, in effect, a thermoelectric generator 12, in particular when it is positioned in a motor vehicle exhaust line 14 and / or in a recirculated exhaust gas circuit of a motor vehicle. The exhaust gases of said motor vehicle are used here as hot source F2 to generate a temperature gradient with the cold source F1.

Said device 10 further comprises an electrode 20. The term "electrode" means an electrical means capable of electrostatically charging elementary particles, in particular nanoparticles.

According to the invention, said device 10 is configured so that a part of the electric current generated by the thermoelectric generator 10 is able to supply said electrode 20. This has the advantage of using locally the electrical energy generated by said generator 12.

Said electrode 20 is intended to electrically charge toxic particles of a first fluid so as to agglomerate said toxic particles together. Advantageously, said first fluid constitutes said hot source F2; in the example described here, said first fluid is formed by the exhaust gas. On the other hand, said cold source F1 is constituted by ambient air. This has the advantage of avoiding any risk of local short circuit, risk existing when the cold source is, for example, in liquid form. Here, this ambient air comes from the air flowing under the floor of the car, especially since the exhaust line 14 is so designed that it is close to said floor. The ambient air may also come from a different place, for example from outside the passenger compartment of the car; it depends on the architecture chosen for said exhaust line.

It should be noted that the electrical generator comprises a plurality of thermoelectric elements 30 capable of generating an electric current under the action of a temperature gradient exerted between two of their faces. The elements 30 are advantageously of parallelepipedal shape. This allows them optimal integration within the thermoelectric generator 12; this also allows an optimal contact with a first and a second plurality of thermally conductive fins 32, 34, also of parallelepipedal shape.

It should be noted that such elements 30 operate, according to the Seebeck effect, by making it possible to create an electric current in a load connected between said faces subjected to the temperature gradient. In a manner known to those skilled in the art, such elements 30 consist, for example, of Bismuth and Tellurium (Bi2Te3).

The thermoelectric elements 30 may be, for a first part, elements of a first type, called P, making it possible to establish an electric potential difference in a direction, called positive, when they are subjected to a given temperature gradient , and, for the other part, elements of a second type, called N, allowing the creation of an electric potential difference in the opposite direction, called negative, when they are subjected to the same temperature gradient

Said thermoelectric elements 30 have, for example, two opposite parallel flat faces, a first one in contact with the first plurality of fins 32 and an opposite second, in contact with the second plurality of fins 34.

The first plurality of fins 32 is intended to facilitate heat transfer between the hot source F2, here the exhaust gas, and the thermoelectric elements 30, at least with the face that is in contact with said fins 32. These fins 32 will preferably be provided metal. On the other hand, said fins 32 are configured to retain, on their surfaces, the agglomerates of toxic particles. In other words, the electrode 20, advantageously disposed upstream of the generator 12 in the direction of circulation of the exhaust gases, electrically charges these particles, which attract each other. They then form agglomerates of particles, agglomerates which are then retained on the surface of said fins 32. This makes it possible to depollute the exhaust gases by filtration.

Thus, the device of the invention uses the exhaust gas as hot source F2 for the thermoelectric generator 12, and at the same time, allows its depollution by filtering the toxic particles that it contains, this before its release out of the exhaust line 14 (reference F2 'in Figure 1).

It should be noted that the flow direction is represented by arrows in FIG.

The regeneration of the thermoelectric generator 12 of the invention, consisting of cleaning the fins 32 of the particle agglomerates, in particular by pyrolysis, is initiated, locally, by an electric arc generated by a capacitor (not shown here). It should be noted that the charge of such a capacitor is advantageously provided by the thermoelectric device 10 of the invention.

This contributes to the autonomy of the device 10 of the invention, which generates current, participates in the depollution of the exhaust gas that it uses as a hot source, and electrically supplies the elements for its own regeneration.

Thus, the device of the invention acts as a filter for the exhaust gases, more precisely as a high voltage filter. This is why it is advantageous for said device to be as integrated and autonomous as possible, in particular since any high voltage in a motor vehicle must remain local. For example, the voltage generated here may be of the order of about 3,000

Volts. On the other hand, a housing 40 will advantageously be placed around the thermoelectric generator 12 to guide the hot source F2. Said housing 60 will also serve as a protective outer casing, in particular to allow the positioning of said generator 12 in the exhaust line 14 of the motor vehicle and / or in a recirculated exhaust gas circuit of the motor vehicle (circuit not shown). right here).

It should be noted that the plurality of thermoelectric elements 30 are in contact with the cold source, the ambient air, via the second plurality of thermally conductive fins 34. These fins 34 are preferably metallic. They will advantageously be mounted on the case 40. By way of example, the hot source F2 will have a temperature of several hundred degrees, for example about 700 ° C., whereas the cold source F1 will have a temperature of a few tens of degrees, while being less than about 60 ° C.

It should also be noted that variant embodiments are of course possible. In particular, in a further embodiment (not shown), such a depollution electrode 20 is configured to be positioned in a heat exchanger, this ignoring the thermoelectric elements inserted here in the housing.

Claims (12)

claims 1. Thermoelectric device (10), comprising a thermoelectric generator (12) capable of generating an electric current under the action of a temperature gradient in contact with a cold source (F1) on the one hand, and a hot source (F2) on the other hand, said device further comprising an electrode (20), said device being configured so that a portion of the electric current generated by the thermoelectric generator (12) is able to supply said electrode (20), said electrode (20) being for electrically charging toxic particles of a first fluid to agglomerate said toxic particles together. 2. Thermoelectric device (10) according to the preceding claim, wherein said first fluid constitutes said hot source (F2). Thermoelectric device (10) according to any one of claims 1 or 2, wherein said cold source (Fl) is constituted by ambient air. Thermoelectric device (10) according to any one of the preceding claims, wherein said electrode (20) is disposed upstream of said generator (12). Thermoelectric device (10) according to any one of the preceding claims, wherein the electric generator (12) comprises a plurality of thermoelectric elements (30) capable of generating an electric current under the action of a temperature gradient. exercised between two of their faces. Thermoelectric device (10) according to the preceding claim, wherein said plurality of elements (30) is in contact with the hot source via a first plurality of thermally conductive fins (32). 7. thermoelecthque device (10) according to the preceding claim, wherein said fins (32) are configured to retain, on their surfaces, agglomerates of toxic particles. 8. thermoelectric device (10) according to the preceding claim, wherein said fins (32) are metallic. The thermoelectric device (10) according to any one of claims 5 to 8, wherein said thermoelectric elements (30) are parallelepiped elements. The thermoelectric device (10) according to any one of claims 5 to 9, wherein said plurality of elements (30) is in contact with the cold source (F1) via a second plurality of thermally heated fins (34). conductive. 11. Thermoelectric device (10) according to any one of the preceding claims, configured so that a portion of the electric current generated by the thermoelectric generator (12) is able to supply, in addition, the charge of a capacitor . 12. thermoelectric device (10) according to any one of the preceding claims, intended to be coated with a protective outer casing, said housing (40), so as to be positioned in an exhaust line (14) of a motor vehicle so that the exhaust gas flowing in said line (14) defines said first fluid and / or in a recirculated motor vehicle exhaust gas circuit so that said recirculated exhaust gas flowing in said circuit defines said first fluid fluid.