Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
  • H10N10/01—Manufacture or treatment
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
  • H10N10/10—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
  • H10N10/17—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the structure or configuration of the cell or thermocouple forming the device

Definitions

• thermogenerators comprising a plurality of thermocouples formed of p-type thermoelements and n-type thermoelements. These thermo couples are associated as in a thermoelectric module.
• a module consists of electrically connected couples.
• Each of the thermocouples consists of a material of type p (Seebeck coefficient S> 0) and of a material of type n (Seebeck coefficient S ⁇ 0), having a conduction by holes and electrons respectively.
• the materials constituting the thermoelements are joined by a conductive material whose thermoelectric power is assumed to be zero.
• the two branches (p and n) of the thermocouple and all the thermo couples forming the module are, on the one hand, electrically connected in series and, on the other hand, thermally parallel.
• These modules may, depending on the constituent materials used in cooling (the Peltier effect) or power generation (thermo ⁇ generator Seebeck effect).
• the invention relates to a method for producing thermo-generators.
• thermo-generator comprising a plurality of thermocouples, formed of an alternation of p-type and n-type thermoelements, located in the same plane.
• the step of placing the thermoelements in the insulating matrix and their densification is done in a single step by sintering.
• thermo-generators make it possible to recover energy when there is a heat source creating a temperature gradient.
• the hot source is at a moderate temperature, generally below 200 ° C.
• This hot source can be in the form of gas, solid and / or possibly liquid.
• thermoelectricity is particularly used for cooling applications, often of low power (fridge-bars, etc.).
• Applications in electrical power generation although less developed, involve much higher powers because, in any industrial environment, a significant or even major fraction of the energy consumed by the systems is often dissipated unnecessarily in thermal form.
• Due to the low efficiency of thermoelectric materials and the complex shaping of thermo-generators, energy recovery solutions are inefficient, expensive and difficult to implement. In the field of low temperature gradients with ambient temperature, two cases may occur:
• thermoelectric cooling To dissipate the thermal energy by thermoelectric cooling, more reliable system than the fans, to protect a device, it is for example the case of the electronic components;
• thermoelectric modules based on Bi 2 e 3 in particular, are generally of small surface, a few square centimeters at most.
• thermo-generators including thermoelements and their connections are inserted between supports which are generally alumina, silicon or other type. These supports provide the mechanical rigidity of the assembly. Thermoelements electrically interconnected between these supports are surrounded by air or, in some cases, by thermal insulating materials avoiding possible corrosion.
• thermo-generators do not make it possible to achieve electricity production at reasonable costs, because of low efficiency and high cost of their production (labor related to the cutting of and n to realize the thermo ⁇ elements p and n, to their establishment and to their connection).
• the present invention aims to achieve in one step the realization of thermoelements p and n and their implementation and greatly reduce costs.
• thermo-generators and low cost for energy recovery applications from extended heat sources, low temperature gradient, could achieve much larger electricity production because competitive from an economic point of view.
• thermo-generators The method for producing the known thermo-generators is, as illustrated in FIG. 1, by defining metal connections on a support and then placing alternating p- and n-type thermocouples therein. This set "thermoelements / metal connections and first support" is then covered by another also provided with metal connections. The assembly with the second support, as shown in FIG. 1, makes it possible to obtain a thermo-generator of known type.
• the present invention aims to enable the realization of thermo-generators with alternating placement of thermoelements in a plane and electrical insulation between elements p and n in one step, the surfaces may be larger than thermo generators ⁇ known, thereby achieving electricity production at reasonable costs from energy recovery from low temperature sources (especially below 200 ° C).
• a first object of the invention relates to a method of producing a thermo-generator comprising a plurality of thermocouples formed of p-type thermoelements and n-type thermoelements, the p-type thermoelements and respectively of type n comprising a p-type thermoelectric material or an n-type thermoelectric material, characterized in that the following steps are carried out:
• an insulating plate is brought thermally and electrically, the plate having a first face and a second face, the second face being opposed to the first face, the first face being provided with a plurality of first non-through holes extending into direction of the second face, the second face being provided with a plurality of second non-through holes extending in the direction of the first face; the non-through holes of the two faces being offset,
• thermoelectric material powder and n-type thermoelectric material powder are supplied; and c) a first layer is formed from one of the p-type or n-type thermoelectric material powders. the first layer against the first face of the plate,
• thermoelements formed in the second holes open into the first face the thus reduced plate forms a matrix in which the thermoelements are contents
• thermoelements p while maintaining the matrix, the thermoelements p are connected to the thermoelements n to form thermocouples, whereby a thermo-generator is obtained.
• thermoelements of the p and n type constituting the thermo-generator obtained by this process are therefore integrated in the thermally and electrically insulating plate (or matrix) having a final thickness equal to the final height of the thermoelements.
• the thermally and electrically insulating plate may be of any kind, for example being ceramic, but it may be particularly advantageous to choose a polymer or plastic material of low cost and allowing the plate to have a certain flexibility. This material must, however, preferentially have a melting point or a glass transition temperature. higher than the sintering temperature T of the materials used to form the thermoelements p and n.
• thermally and electrically insulating plate also allows the development of low-cost large-area components, the perforation of the plate to form the non-through holes being particularly easy, even for very small hole diameters.
• thermo-generator In various embodiments of the thermo-generator according to the invention, one or more of the following provisions may also be used:
• steps e) and f) are carried out simultaneously,
• steps e) and f) are carried out by sintering preferably by flash sintering or by hot-sintering techniques such as HIP (Hot Isostatic Pressing) or HUP (Hot Uniaxial Pressing),
• the duration D variable according to the dimensions of the plate and the holes and according to the material, is less than or equal to 60 minutes, but can be as low as 5 minutes, in particular in the case of flash sintering.
• the duration D can in fact vary according to the desired final particle size of the thermoelements p and n.
• thermo-generator comprising a plurality of thermocouples formed of thermo ⁇ p-type elements and thermoelements n comprising a thermally and electrically insulating matrix in which the p-type thermoelements and the thermoelements of type n are contained.
• thermo ⁇ generator embodiments according to the invention may optionally be furthermore employed one and / or the other of the following arrangements: the matrix comprises a material chosen from polymers and ceramics,
• the matrix comprises a material chosen from polymers which has a glass transition temperature higher than the sintering temperature of the p-type and n-type thermoelectric materials,
• the matrix comprises a material chosen from ceramics which has a sintering temperature higher than the sintering temperature of the p-type and n-type thermoelectric materials.
• FIG. 1 schematically represents the method for producing a known thermo-generator
• FIG. 2A represents a thermo-generator according to the invention
• FIG. 2B represents a method of producing a thermo-generator according to the invention
• Figures 3A and 3B show the photographs of an exemplary embodiment of the invention.
• thermo generator 10 comprising a plurality of thermocouples formed of p-type thermoelements 12 and a plurality of n-type thermocouples 14.
• thermo ⁇ elements 12, 14 respectively p-type and n-type are contained in a matrix 16, as best seen in the drawing (a) of Figure 2A.
• thermoelements 12, 14 respectively p-type and n-type are preferably alternately distributed in the matrix 16 as illustrated for example in drawing (b) of FIG. 2A.
• the matrix 16 is made of a thermally insulating material and electrically insulating.
• the matrix 16 preferably comprises a material chosen from polymers and ceramics.
• the matrix When the matrix comprises a polymeric material, it must have a glass transition temperature Tg greater than the sintering temperature of the p-type and n-type thermoelectric materials.
• the polymer used to form this matrix 16 may be, for example, of the family of polyimides, having glass transition temperatures Tg greater than 350 ° C.
• the electrically insulating matrix may also comprise a ceramic material, having a sintering temperature greater than the sintering temperature of the p-type and n-type thermoelectric materials.
• the matrix may comprise alumina, apatite and / or glass).
• thermo generator such a thermo generator
• an insulating plate 18 is brought thermally and electrically, preferably in one of the materials as mentioned above (polymer or ceramic).
• This plate 18 has a first face 18a and a second face 18b opposite the first face 18a.
• the first face 18a is provided with a plurality of first holes 20a which are non-through and extend towards the second face. These first holes 20a are all preferably oriented substantially transversely to the first face 18a of the plate 18.
• the faces 18a and 18b of the parallelepiped plate 18 are substantially flat and parallel to each other; it follows that the first holes 20a and the second holes 20b are substantially parallel to each other and extend substantially perpendicular to the two faces 18a and 18b.
• the plate 18 has this plurality of first holes 20a and second holes 20b which are arranged by being preferably distributed homogeneously and alternately first holes 20a with the second holes 20b. It is thus understood that between two first holes 20a is preferably a second hole 20b.
• an amount of p-type thermoelectric powder 22 and an amount of n-type thermoelectric powder 24 are then fed.
• a first layer of these powders is available, for example a p-type powder layer 22 on which the plate 18 is just disposed, and then the n-type powder 24 is placed on top of the plate 18.
• the second face 18b of the plate 18 is placed on a p-type powder layer 22, and then a layer of n-type powder 24 is placed on the first face 18a of the plate 18. It is understood that it would be possible to invert the arrangement of the faces and put the first face 18a on the p-type powder layer 22 and cover the second face 18b with a n-type powder layer 24. Similarly, it is also possible to invert and first put a layer of n-type powder 24, then come to deposit the plate 18, which is then covered with a p-type powder layer 22.
• step (c) of FIG. 2B pressure is then applied to these p- and n-type layers so that the powder enters the respective holes.
• a pressure P is applied to each of the layers, so that the p-type powder 22 enters the second holes 20b and the n-type powder 24 enters the first holes 20a.
• a pressure P of the same value is applied preferably on both sides of the plate 18; this uni-axial pressure allows the powder to penetrate properly into the non-through holes by filling them and this symmetrically between the first face 18a and the second face 18b.
• the plate 18 has a thickness el8, the first non-through holes 20a have a depth e20a and the second holes 20b have a depth e20b.
• the depths e20a of the first holes 20a and e20b of the second holes 20b are preferably of the same value and, of course, less than the thickness e18 of the plate 18.
• T this set formed by the matrix 18 and the powders 22 and 24 of type p and n.
• the temperature T is greater than or equal to the sintering temperature of the p- and n-type powders 22 and 24, so that during this heating operation, the p-type powder 22 and the n-type powder 24 will sinter.
• this heating operation is carried out simultaneously with the application of the pressure P, so that the p-type powder 22 and the n-type powder 24 respectively penetrate into the first and second holes by filling them completely and by sintering inside these.
• the heating is carried out by flash sintering also called “Spark Plasma Sintering" (allowing very short heating times D and also allowing to reach high temperatures).
• the total heating time D ie rise time at temperature T and keeping at temperature T, excluding cooling
• the total heating time D is preferably less than or equal to 60 minutes, but can be as low as 5 minutes.
• Other techniques more conventional hot sintering (HIP or HUP) are also possible.
• thermocouples 14 and p-type thermoelements 12 are obtained in the first holes 20a. These thermoelements 12 and 14 are contained in the plate 18 by being solidly anchored mechanically and chemically. It is understood that the thermoelements 12 and 14 are somehow set in the plate 18.
• step (d) of FIG. 2B After heating, the excess powder 22 of type p and type n24 which has not penetrated holes 20a and 20b is removed, as illustrated in step (d) of FIG. 2B. This reduction in the thickness of the assembly is carried out until the first holes 20a and the second holes 20b become open.
• the thickness E of the assembly is reduced after sintering, for example by polishing or cutting the first and second faces, or by any other material removal technique, so as to reduce the thickness of the assembly until at a thickness elO.
• This thickness elO corresponding to the thickness at which the first holes 20a and the second holes 20b respectively open into the second face 20b and the first 20a. It is understood that this thickness elO obtained after reduction of the thickness E is less than or equal to the depth e20a and e20b respectively of the first holes and second holes 20b.
• the reduction in thickness can be done symmetrically or not. Indeed, it is understood that depending on the thickness of p-type powder 22 remaining in excess on the first face 18a, the thickness of n-type powder 24 remaining in excess on the second face 18b, and the respective depths e20a and e20b of the first and second holes 20a and 20b, it is necessary to make a removal of more or less important material on each side of the assembly until each of the first holes 20a and each of the second holes 20b all open in the opposite face, respectively in the second face 18b and in the first face 18a.
• an assembly having a thickness elO such as illustrated in step (e) of FIG. 2B is obtained.
• This set then comprises a matrix 16 (corresponding to the plate 18 of reduced thickness) in which the first holes 20a contain n-type thermocouples 14 and the second holes of the p-type thermoelements 12.
• thermocouples 12 are electrically connected with the n-type thermocouples 14 to form thermocouples.
• This assembly formed of thermocouples p and n contained (crimped) in the matrix 16, forms the thermo-generator 10 according to the invention.
• the matrix 16 (from the initial plate 18) thus makes it possible to space and maintain the thermocouples p and n.
• thermo-generator An example embodiment of a thermo-generator is shown below (see FIGS. 3A and 3B).
• ⁇ plate 18 Kapton (the poly-imide) having a glass transition temperature Tg equal to 390 ° C
• ⁇ p-type 22 powder Bio.5Sb1.5Te3.4 with a sintering temperature of 360 ° C
• Type n powder Bi 2 Seo.3Te2.7 with a sintering temperature of 360 ° C ⁇ Spark Plasma Sintering Settings:
• Diameter of the graphite matrix used to apply the pressure P 8 mm.
• This thermo-generator was made with a total duration D (temperature ramp and bearing) equal to 10 minutes; the duration D, by flash sintering, can be reduced to 5 minutes when the temperature T is lower. On the contrary, this total duration D can be increased up to 60 minutes if the temperature T is higher or in the case of a conventional sintering type HUP or HIP.
• thermo-generator 10 as described above, can therefore be of a fairly large size up to several hundred millimeters in diameter.
• thermo-generator having a more or less flexible mechanical structure.
• This flexibility can be sought in particular in the field of thermal energy recovery in nuclear power plants or electrical transformer stations for example (flexible envelope of thermoelectric to fit around pipelines at temperatures compatible with the temperature of the polymer ) or for the generation of cold in the case of civil or military applications (flexible stretchers cooling for the wounded).

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• 2010
  • 2010-12-10 FR FR1060389A patent/FR2968837B1/fr not_active Expired - Fee Related
• 2011
  • 2011-12-06 CN CN2011800650061A patent/CN103460422A/zh active Pending
  • 2011-12-06 US US13/992,353 patent/US20130255740A1/en not_active Abandoned
  • 2011-12-06 WO PCT/FR2011/052885 patent/WO2012076809A1/fr not_active Ceased
  • 2011-12-06 JP JP2013542589A patent/JP2014504007A/ja active Pending
  • 2011-12-06 KR KR1020137017179A patent/KR20140021522A/ko not_active Withdrawn
  • 2011-12-06 EP EP11805107.7A patent/EP2649657A1/de not_active Withdrawn

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