FR2732819A1 - Thermoelectric generator with concentric dissipation - Google Patents

Abstract

The generator has thermal elements which have one part heated and another cooled by appropriate sources, forming two temperatures. Two electric contacts are connected, one to the hot zone, the other to the cold. These contacts collect electricity generated by the Seebeck effect. The hot temperature zone is towards the centre (17), the cold towards the periphery (19). Heat dissipation (20) is from centre towards the periphery, but the thermal element is reversible, with the centre being cold and the periphery hot. Then the heat flow is from periphery to centre. Several elements may be stacked, connected together electrically. The two temperature zones may be coaxial and the central hole may be a ceramic tubular sleeve, forming a combustion chamber.

Description

DESCRIPTION
The subject of the present invention is, as a new industrial product, a thermoelectric generator.

Such generators are already known which are mainly composed of thermocouples connected in series with one another, one of the welds of each thermocouple being subjected to a heat source, the other weld being radiant and constitutes a heat sink.

A conventional assembly consists in placing the thermocouple between two metal plates, one of which is warmed by any shine and the other cooled by ventilation or by the simple fact that said plate is radiant.

The face of the plates which is in contact with the thermocouples is coated with a dielectric to avoid the short circuit between said thermocouples.

Finally, said plates are tightened together by rods and thus take the sandwich thermocouples.

In this arrangement, the heat flow dissipates from one of the faces or ends towards the other face or end of this thermocouple.

Conventionally, thermocouple is called the assembly or the junction of two different materials having a thermoelectric power with respect to each other when the junction is subjected to a temperature different from that reigning at a different place from said junction, each of the materials that make up this thermocouple, that is to say each of the branches, is called thermoelement.

Another assembly is known which uses thermoelements constituted by wafers, generally made of semiconductors, these wafers are placed in a row one behind the other, doped alternately in P, N, P, N, P and so on. after.

Between each wafer is placed a metal plate, this plate is hot every other time and therefore cold every other time.

In this arrangement, the heat flow dissipates from one of the faces of said thermoelements to the other face of the same thermoelements.

The assembly of thermogenerators currently known has a drawback, due to the fact that it cannot locate one hundred percent of the heat released from the hot source on the appropriate faces of the thermoelements.

Another drawback of these thermogenerators lies in the difficulty of fixing and maintaining the thermoelements, due to the constraints linked to the expansion of the materials and to the brittleness of the thermoelements.

The present invention aims to remedy these drawbacks and relates to a thermoelectric generator constituted by thermoelements whose heat dissipates from the center towards the periphery and not from one to another of the faces of said thermoelement, as in the assemblies currently known .

The present invention will be better understood by referring to the description below, as well as to the accompanying drawings, of which - FIG. 1 represents a conventional thermoelement in the form of a wafer.

- Fig. 2 shows a section of FIG. 1.

- Fig. 3 shows a thermoelement according to the present invention.

- Fig. 4 shows a section of FIG. 3.

- Fig. 5 shows a thermoelement according to the present invention, comprising a central clearance.

- Fig. 6 is a section through FIG. 5.

- Fig. 7 is a thermoelement according to the present invention, comprising projecting parts intended for the electrical junction.

- Fig. 8 is a section through FIG. 7.

- Fig. 9 is a series connection of the thermoelements according to the present invention, with electrical connections.

- Fig. 10 is a side view of FIG. 9.

- Fig. 11 is a series assembly of thermoelements according to the present invention, with an electrical junction provided by the thermoelements which touch.

- Fig. 12 is a side view of FIG. 11.

- Fig. 13 shows a thermoelectric generator according to the present invention.

- Fig. 14 shows an assembly of thermoelements according to the present invention, the electrical connections of which are provided by rings.

- Fig. 15 shows the section of a thermoelement according to the present invention, in the form of a cylindrical wafer reducing in thickness towards the outer perimeter.

- Fig. 16 shows a thermoelement according to the present invention, divided into several quarters.

For the record, is represented in (1) a conventional thermoelement in the form of wafer such as currently used.

This thermoelement has a hole (2) in the center, intended for assembly.

A heat source is applied to one of its faces (3), while the other face (4) is radiant and constitutes a heat sink. Heat dissipation takes place from the hot side to the cold side, in the direction indicated by the arrow (5).

An electrical terminal (6) is placed on each of said faces and collects the electric current which it supplies to the circuit (7) used by a load (8).

The present invention relates to a thermoelement consisting of a wafer, the center (9) of which is subjected to a hot source and the perimeter (10) to a cold source.

Heat dissipation takes place in this case from the center of the wafer to its periphery, in the direction indicated by the arrow (11).

There are thus in this thermoelement two zones of different temperature, one hot located substantially towards the center, the other cold located substantially towards the periphery of said thermoelement.

the two said temperature zones are substantially concentric and / or substantially coaxial.

In (12) and (15j are shown two electrical terminals and in (15) and (16) an electrical circuit which channels the current produced by the thermoelement towards a load (16).

The terminal (12) is located substantially on the perimeter of said thermoelement and the terminal (13) is located substantially in the center of said thermoelement.

A variant of the present thermoelement according to the present invention comprises a central hole (17) intended to receive a heat source.

This heat source is applied to the field (they) of said hole and dissipates on the outer perimeter (19) of said thermoelement in the direction indicated by the arrow (20).

Another variant of the thermoelement according to the present invention comprises projecting parts, one of which (21) is located substantially towards the center and the other (22) is located substantially towards the perimeter of said thermoelement.

These two projecting parts are intended to ensure physical and / or electrical contact between two thermoelements.

In this variant, the heat is also dissipated from the center towards the perimeter of said thermoelement in the direction of the arrow (23).

Two electrical terminals (24) and (25) are each placed on one of said projecting parts.

These terminals collect the electric current produced by the thermoelement and supply an electric circuit.

A variant of the present invention consists in connecting in series a stack of thermoelements by electrical conductors (26) and (27).

The first and the last thermoelement have a terminal (28) and (29) which collects the current intended for use in an electrical circuit.

The thermoelements are made up of different materials like iron and constantan or semiconductors doped respectively and alternately in P or in N.

According to another variant of the present invention, said thermoelements can be assembled in a row and held together by at least one tiran bearing on two dielectric flanges (31) each disposed at one end of the stack formed by the thermoelements thus assembled.

In such a version of the present invention, the thermoelements touch on the one hand in the center (72) and (33) and on the other hand, on the periphery (34) and (35), the touching parts being constituted by the projecting parts (21) and (22).

Each of the thermoelements comprises one of the projecting parts on one of its faces and the other projecting part on the other of its faces.

The heat source is supplied by a current of hot air which crosses the center of the thermoelements on either side of the line which the latter form.

This current of hot air enters the stack through orifices (38) made in the flange (31) in the direction indicated by the arrow (39) and emerges from the stack on the opposite side in an identical manner in the direction indicated by the arrow (40).

Another variant of the present invention consists in integrating a heat source in the present thermoelectric generator, thus in (41) is shown a tubular ceramic sleeve in which the exhaust gases of a combustion chamber (42) circulate.

This combustion chamber receives fuel through a pipe (43) and oxidant through a pipe (44).

In one of the possible versions, the oxidizer is air.

On the outer perimeter of said thermoelements is disposed a dielectric sleeve (45) and coaxially with this sleeve is disposed a second sleeve (46).

Between the two sleeves (45) and (46), either in the space (47) air circulates intended to supply said combustion chamber.

The air thus takes up calories which dissipate on said outer perimeter of said thermoelements.

In (48) is shown the evacuation of the excess air used for cooling the periphery of the thermoelements, its exhaust gae exit from the thermoelectric stack in the direction indicated by the arrow (49).

The thermoelements are further separated by thermal and electrical insulators (55) and (56).

Another version of the present invention consists of an assembly of thermoelements in series, the electrical contact between the thermoelements is made by spacers.

Thus, in (50), (51) and (52) are represented thermoelements according to the present invention.

In (53) and (54) are shown two spacers according to the present version.

One spacer out of two (53) is located substantially at the periphery of the two thermoelements that it connects.

Alternatively, one spacer out of two is located towards the center (54) between two thermoelements which it connects.

Between the thermoelements are arranged electrical and thermal insulators (55).

There may be several spacers (57) and (58) between each thermoelement. These spacers can be identical in nature to that of a thermoelement or different in nature or of any nature known per se.

These spacers can also be made of any new material.

These spacers can have different geometries from those shown, so they can be rings, rings, torres, pellets, studs, washers. These spacers can be rigid or elastic or flexible or inflatable or impregnated or fibrous or be of any geometric configuration.

As a variant, the present thermoelement is made up of several different materials.

These different materials have the configuration of wafers and crowns placed one on top of the other. The materials are thus chosen according to their thermoelectric efficiency at the temperatures considered at each location where they are placed.

thus, the most centrally located material is made of iron-germanium (59) then the next material (60) is made of iron-silicon and finally, the material located & the periphery is made of bismuth telluride. (61).

Another variant of the present invention consists in giving a special profile known as a thermoelement, thus the thickness at the center (62) of the thermoelement is greater than that at the periphery (63).

As a variant of the present invention, the thermoelements (36) and (37) are welded together.

Another variant of the present invention consists in applying an electric current to the terminals of the present thermoelectric generator, in this case, said thermoelectric generator is transformed into a thermoelectric refrigerator on the one hand and into a heater on the other hand, the cold obtained is located in the center of said thermoelement and the heat on its periphery or 1 reverse, depending on the polarity of the direct current which is applied to the terminals.

The present thermopile is therefore reversible.

Another variant of the present invention consists in producing said thermoelement by assembling several quarters each representing a fraction (64) and (65) of said thermoelement,
Such a thermoelement can be produced by fractions each having zones of different materials.

The present invention is not limited to the above description, which is simply an example of its application, so many modifications can be made to it without departing from its scope, thus - said thermoelement may have 'other shapes than those shown, so the inner hole can be square or exagonal or have any other shape.

- The outer perimeter 5 of said thermoelement can be square or exagonal or have any other geometry.

- the thickness of said thermoelement can be different from that shown, thus it can be stronger or less strong or varied, such as heavier in the center, reduced before the periphery, then again thicker on the periphery, - said thermoelement can be covered with ceramic or any other material - The projecting parts of said thermoelement may have different configurations from those shown.

- Said thermoelement may be composed of a multitude of materials, each of these materials having identical or different characteristics, or different shapes, be arranged concentrically or asymmetrically, parallel or perpendicular.

- Said thermoelement may consist of sheet steel, copper sheets, constantan, platinum or any other6- ~~ metaus or -alloy metal or semiconductor or any other material.

- The assembly in series of several thermoelements can be maintained other than by a t; ran, thus, the thermoelements can be maintained by screws, rivets, collages, welds, cements or a casing.

- The heat source can be of a different nature than that shown, thus it can be constituted by a circulation of hot water or hot air or any heat-transfer fluid or flow or any hot or heated material introduced into the center or disposed on the periphery of said thermoelements.

It can be a combustion of coal, gas, hydrocarbon, wood or any other means producing heat.

- The hot and cold source can be reversed, either the hot source located on the outer perimeter of said thermoelement and the cold source in its center.

- Said thermoelement can be produced by any means, it can thus be obtained by melting several materials, by sintering, by growth, by epitaxy, by suspension.

- Said thermoelement can be divided into several districts welded or joined together, or separated between them.

Claims (8)

1) Thermoelement which may or may not be placed in a row or next to other thermoelements connected together by an electrical contact, the said thermoelement (s) are subjected to a hot source on the one hand and to a cold source on the other hand, comprising two temperature zones, one of which is hot and the other cold and two terminals or electrical contacts, one of which is disposed in the hot zone and the other in the cold zone, said terminals collect the electricity generated by said thermoelement by the Seebeck effect, characterized - in that one of said temperature zones is situated substantially towards the center of said thermoelement (9) and (17), - and in that the other of said temperature zones is situated approximately towards the periphery of said thermoelement (10) and (19), - and in that said zone located substantially towards said center of said thermoelement is subjected to a hot source, - and in that said zone situated substantially i the periphery of said thermoelement is subjected to a cold source, - and in that the heat dissipation takes place from the center towards (20) the periphery of said thermoelement, - and in that said thermoelement is thermally reversible, so as to be able to subject said zone located substantially at said center at a cold source and said zone situated substantially at said periphery, at a hot source, said heat dissipation being effected in this case from said periphery towards said center. 2) Thermoelement according to claim 1) characterized in that the two said temperature zones are of coaxial configuration, - and in that the two said temperature zones are of coaxial configuration. 3) Thermoelement according to one of the above claims characterized in that at least one electrical contact (13) is formed substantially in the center of said thermoelement element and in that at least one electrical contact is formed substantially i the periphery of said thermoelement, - and in that at least one of said electrical contacts is made with at least one other electrical contact disposed on another thermoelement, - and in that said electrical contact is made by two thermoelements (32) and (33) which touch, - And in that said thermoelement comprises at least one projecting part, - and in that said thermoelement touches another thermoelement by the monk one of its protruding parts (32), - and in that said thermoelement touches at least two other thermoelements, - and in that said thermoelements touch substantially at their center (32) and (33), - and in that said thermoelements ee touch sensit Lately at their periphery (94) and (35), - and in that a series of thermoelements placed one behind the other in the row touch each other, each touching its two neighbors by its substantially oartar Tartie (17 ) on one of its faces and by its substantially peripheral part (19) on the other of its faces, - and in that one of said protruding parts (21) is disposed substantially towards the center of one faces of said thermoelement and the other of said protruding parts (22) is arranged towards the periphery of the other face of said thermoelement. 4) Thermoelement according to one of the above claims caractOrisO in that at least one spacer (54) is arranged on one of its faces, - and in that said spacer has the shape of a ring, 5) Thermoelement according to one of the above claims characterized in that said thermoelement is composed of different materials and in that said different materials are arranged concentrically (59), (60), (61). 6) Thermoelement according to one of the above claims characterized in that it is composed of at least two different quarters (64) and (65), - and in that several quarters are assembled to form said thermoelement. 7) Thermoelement according to one of the claims below, characterized in that the central hole (17) arranged in said thermoelement constitutes the enclosure of a combustion chamber, - and in that said central hole is lined with a sleeve tubular (41), - and in that said tubular sleeve is made of ceramic. 8) Thermeélément according to one of the above claims characterized in that said thermoélément is reversible and produces hot in its center and cold on its periphery or the reverse if an electric current is applied to it at the terminals (12) and (15), the location of hot or cold depends on the polarity of the current applied to said terminals.