RU2778010C1 - Method for manufacturing a thermoelectric generator based on composite materials - Google Patents

Abstract

FIELD: energy conversion.

SUBSTANCE: invention relates to the field of direct conversion of thermal energy into electrical energy, in particular to a method for manufacturing thermoelectric generators used either for installation on the engine body of an aircraft, or for manufacturing the engine body of an aircraft itself with obtaining additional electrical power. Essence: a flexible substrate is taken, which is a tape made of composite materials of the class of carbon fibers. Two different types of conductive components are alternately applied to a flexible substrate, which are either a metal wire or a thread made of a number of semiconductor materials. Each conductive component is applied in such a way that it is the side of an isosceles triangle, the angle between these sides lies in the range from 10 to 170°. Each subsequent conductive component is applied inseparably from the previous one to form a contact of the components at the vertex of the angle of the isosceles triangle and at the vertices of the corners of the base of this triangle. In this case, each type of conductive component is applied parallel to the side of the previous triangle from the same conductive component. Further, welding of these conductive components is provided at the points of their contact, thus forming a set of electrical junctions. The resulting composite substrate with a thermoelectric structure is laid in a leaflet format so that the bend location corresponds to each junction of conductive components. The resulting leaflet is placed either in a flat shape or the desired radius of curvature and geometric shape are provided. Then the leaflet is stitched through with a composite carbon fiber thread in places where the junction does not pass. Further, the upper and lower sides of the leaflet are glued with a composite material from the class of carbon fibers in one or more layers, depending on the required geometric parameters of the thermoelectric generator.

EFFECT: expansion of the range of solutions to manufacture thermoelectric generators.

1 cl, 7 dwg

Description

The invention relates to the field of direct conversion of thermal energy into electrical energy, in particular to a method for manufacturing thermoelectric generators used, for example, for manufacturing an aircraft engine housing with additional electrical power.

In the world, there is a problem of insufficient power of the mechanical electric generator of aircraft (hereinafter - LA), since more powerful generators have large weight and size characteristics, which leads to the weight of the aircraft itself. At the same time, it is known that the body element of the aircraft engine must be resistant to high-temperature loads and have sufficient strength in the presence of a radius of curvature.

One of the ways to solve these problems is to generate additional electricity by introducing thermoelectric generators (hereinafter - TEG) into the structure of the aircraft engine. At the same time, TEGs can be installed both on the engine housing and used as the engine housing element itself, partially or completely. The use of TEG makes it possible to partially abandon the mechanical power generator, reduce the weight and size characteristics of the aircraft and obtain additional electrical power. In this case, the TEG must meet the properties of the engine casing element, namely, resistance to high-temperature loads and sufficient strength in the presence of a curvature radius.

From the studied prior art, the applicant has identified methods for producing TEGs with different technical characteristics.

Known invention according to patent No. WO2017059392 "Flexible thermoelectric generator", the essence is a thermoelectric generator containing: a lot of insulating garlands; a plurality of thermoelectric strings woven in the form of curved lines through the insulating strings, the insulating strings serve as weft lines, the thermoelectric strings contain alternating segments of the first semiconductor material and the second semiconductor material, and the first semiconductor material and the second semiconductor material have different electrochemical potentials, the first and second segments of a semiconductor material connected by a conductive contact; a cold side substrate connected to the first plurality of conductive contacts; and a hot side substrate connected to the second plurality of conductive contacts.

The disadvantages of the known technical solution is that the proposed TEG is made in the form of a thin film and is used only for sources with low heat flux, that is, this device is not intended for use in high temperature operating modes.

Thus, the invention is known according to patent No. RU2154325 "Method of manufacturing a thermoelectric module", the essence is a method for manufacturing a thermoelectric module, in which the named module is made from a plurality of thermoelectric crystals forming a matrix between the first and second substrates made of a dielectric, characterized in that the matrix includes sequentially into an electrical circuit in such a way as to heat the surface of the first substrate and cool the surface of the second substrate as a result of the electrothermal Peltier effect that occurs in thermoelectric crystals, while in this method a plurality of oblong p-type and n-type thermoelectric bars are used, which are said thermoelectric crystals, and a first conductive substrate with a plurality of first contacts forming a matrix, wherein adjacent first contacts forming a matrix row are interconnected respectively by horizontal bridges, while in in the direction of the column, these named first contacts are separated from each other; wherein said method includes the following steps: connecting said first conductive board with said first substrate to fix the first conductive board with said first substrate; placing a plurality of said p-type and n-type elongated thermoelectric bars on said first contacts in said rows so that, in the direction of the matrix column, the p-type bars alternate with the n-type bars with an interval between them; connecting one face of each thermoelectric bar with said first contacts forming a row; cutting each elongated thermoelectric bar into said thermoelectric crystals, and simultaneously cutting said horizontal jumpers to distribute the resulting thermoelectric crystals among individual first contacts; a plurality of second contacts are placed on said crystals opposite the first contacts to obtain a series-connected electrical circuit consisting of said crystals in combination with said first contacts, and the second substrates, in which said second contacts are installed, are connected with the named first substrate to form a connection between them.

The disadvantages of the known technical solution is that a TEG is obtained in a known way, having a fragile dielectric substrate, which is made of either ceramic or plastic material, while it is impossible to set the required radius of curvature.

An invention is known according to patent No. US2012266930 "Thermoelectric conversion module and manufacturing method", the essence is a method for manufacturing a thermoelectric conversion module, including: the first stage of manufacturing a braided wire A, built by weaving a conductive wire, and a braided wire B, built by weaving a conductive wire, moreover braided wire B is shorter than braided wire A; and a second step of sequentially connecting each of the plurality of P-type thermoelectric conversion elements and each of the plurality of N-type thermoelectric conversion elements by braided wire A and braided wire B to obtain a module in which each of the P N-type thermoelectric conversion elements and each of N-type thermoelectric conversion elements are electrically connected in series, wherein in the second step, one end surface of one of the P-type thermoelectric conversion elements and one end surface of one of the N-type thermoelectric conversion elements are connected by a braided wire A, while the other end surface of one of thermoelectric conversion elements The P-type thermoelectric conversion elements and the other end surface of one of the N-type thermoelectric conversion elements are connected by braided wire B. th transformation according to claim 8, further comprising: the step of preparing two or more modules of the module, including the module, the step includes the first step and the second step; and a step of electrically connecting the plurality of modules to each other in parallel.

The disadvantages of the known technical solution is that this device is a braided thermoelectric wire, which is spirally wound around a tube (heat source). This thermoelectric wire cannot have sufficient strength characteristics (more than 1000 MPa) in order to be a housing element that is partially or completely integrated into the structure.

Also known is the invention according to patent No. WO2018047882 "A functional element with a serial cell structure of π-type thermoelectric converters and a method for its manufacture", the essence is a method for manufacturing a functional element according to claims 1-13. One of the n-type yarn and the p-type yarn is the first yarn, the other is the second yarn, one of the front and back surfaces of the insulating substrate is the first surface, and the other is the second surface. In the state where the first yarn is wavy-stitched on the insulating base material, when the second twisted yarn is wavy-sewn side by side in parallel with the first twisted yarn that was wavy-stitched, the part exposed on the first surface of the first twisted yarn that was sewn a step before on the first surface, crossing and sewing after twisting at least once. Then, when the first twisted yarn is wavy sewn side by side in parallel with the second twisted yarn that has been wavy stitched, the second surface is opened to the second surface of the second twisted yarn that has been sewn one step before. Crossing the crossed parts and twisting at least once. By repeating the above steps, a current path is formed in a direction orthogonal to the wave crosslinking direction, and a series connection of a π-type structure is formed along the current path.

The disadvantages are:

- a well-known invention is a thread made from thermoelectric and composite material (carbon nanotubes), however, the insulating base material is a fabric or paper, or a material selected from foamed polymers, elastomers, cotton fillers and gel-like fillers processed in the form of a plate or sheet , which limits the possibility of operating this device at high thermal loads (more than 300 ° C), and also makes it impossible to use it as a housing element;

- the manufacture of known TEG does not provide for the presence of a radius of curvature.

The closest set of features, chosen by the applicant as a prototype, is the invention according to patent No. US2015311421 "Flexible thermoelectric devices, methods for their preparation and methods for waste disposal using heat", the essence is a method for forming a thermoelectric device, including deposition of the first conductive component and the second, characterized by a conductive component, on a flexible substrate to form a plurality of electrical junctions. The method of claim 14, wherein the flexible substrate defines a first surface spaced from the second surface, and wherein the first and second conductive components are deposited such that a plurality of electrical junctions are arranged on respective surfaces in an alternating manner. The method of claim 14, comprising one or both of forming and folding the flexible substrate of one or both of them before and after deposition of the first and second conductive components. The method of claim 14, wherein applying one or both of the first and second conductive components comprises sewing the conductive thread or yarn to the flexible substrate. The method of claim 14 wherein applying one or both of the first and second conductive components comprises applying conductive ink to the flexible substrate.

The disadvantages of the prototype are:

- a thermoelectric device cannot be integrated into the structure as a body element, since when the required radius of curvature or shape is specified, this thermoelectric device is not able to retain its shape when exposed to high-temperature loads (more than 350 ° C) due to the fact that the flexible substrate is formed from a fibrous material which includes a material selected from the group consisting of polyesters, cotton, polyamides, poly-N-vinylcarbazole, cellulosic materials, polyvinyl alcohol, polypropylene, polyethylene terephthalate, fiberglass, and combinations thereof; these materials cannot be used at high temperatures and strength loads.

- an increase in the weight and size parameters of the design in which this invention is applied, due to the fact that the thermoelectric device is made in the form of a flexible film of various thicknesses, then it is either wound on a tube (heat source) or wrapped around the surface (heat source), this concept of heat removal and the generation of additional electrical energy leads to a clear increase in the weight and size parameters of the structure, so its operation is applicable only in ground-based industrial installations, since optimization of weight and size characteristics plays an important role in the rocket and aviation industry.

Thus, by known methods, including the prototype, devices are obtained that have the following main disadvantages:

1) either have a fragile dielectric substrate, which limits the presence of a radius of curvature, and cannot be used as a body element;

2) either have a flexible substrate of insufficient thickness, which does not provide the possibility of using a thermoelectric generator as a body element;

3) either have a limited range of operating temperatures, which makes it impossible to use a thermoelectric generator at high thermal loads.

4) or have insufficient strength characteristics, which does not allow using them as body elements.

These problems can be solved by using composite materials as a substrate.

A composite material is a multi-component material made from two or more components with substantially different physical and/or chemical properties, which, when combined, result in a new material with characteristics that are different from those of the individual components and are not a simple superposition of them. At the same time, individual components remain the same in the structure of composites, distinguishing them from mixtures and solid solutions [https://ru.wikipedia.org/wiki/Composite material].

Carbon fibers [https://e-plastic.ru/specialistam/composite/kompozicionnye-materialy/]

(carbon plastics) are a composite material consisting of a polymer binder (matrix) and a hardener in the form of carbon fibers (carbon fibers).

The high C-C bond energy of carbon fibers allows them to maintain strength at very high temperatures (in neutral and reducing media up to 2200°C), as well as at low temperatures. The fibers are protected from oxidation by protective coatings (pyrolytic). Unlike glass fibers, carbon fibers are poorly wetted by a binder (low surface energy), so they are etched. This increases the degree of activation of carbon fibers by the content of the carboxyl group on their surface. The interlaminar shear strength of carbon fiber increases by 1.6-2.5 times. Whiskerization of TiO[pic], AlN and Si[pic]N[pic] whisker crystals is used, which gives an increase in interlayer rigidity by 2 times and strength by 2.8 times. Spatially reinforced structures are used.

The binders are synthetic polymers (polymeric carbon fibers); synthetic polymers subjected to pyrolysis (coked carbon fibers); pyrolytic carbon (pyrocarbon carbon fibers).

Carbon fiber with carbon matrix.

Coking materials are obtained from conventional polymeric carbon fibers subjected to pyrolysis in an inert or reducing atmosphere. At a temperature of 800-1500°C, carbonized carbonized ones are formed, at 2500-3000°C, graphitized carbon fibers are formed. To obtain pyrocarbon materials, the hardener is laid out according to the shape of the product and placed in an oven into which a gaseous hydrocarbon (methane) is passed. Under a certain regime (temperature 1100°C and residual pressure 2660 Pa), methane decomposes and the resulting pyrolytic carbon is deposited on the fibers of the hardener, binding them.

Carbofiber with a carbon matrix of the KUP-VM type in terms of strength and impact strength is 5-10 times superior to special graphites; when heated in an inert atmosphere and vacuum, it retains strength up to 2200°C, oxidizes in air at 450°C and requires a protective coating. The coefficient of friction of one carbon fiber with a carbon matrix on the other is high (0.35-0.45), and the wear is low (0.7-1 microns for braking).

Carbon fibers (carbon plastics) have density values less than aluminum and titanium alloys, with higher or comparable values of strength and modulus of elasticity, which plays an important role when used in the rocket and aviation industry, as it leads to a decrease in the weight and size characteristics of the aircraft [https:// moluch.ru/archive/27/2963/]:

Material Density,
ρ, kg / m ³ Strength,
Ϭ, MPa CFRP 1500 1200 Boroplast 2000 1200 fiberglass 2000 2000 Aluminum alloys 2700 600 titanium alloys 4500 1100

The task and technical result of the claimed technical solution is expansion of the arsenal of methods for manufacturing thermoelectric generators with the possibility of their use for the manufacture of an aircraft engine housing, while achieving:

- obtaining the required radius of curvature or shape due to the use of a flexible substrate made of composite materials of the carbon fiber class (carbon fiber), as a result of which the thermoelectric generator can be integrated into the aircraft structure as an engine body element, since it is able to maintain a given shape when exposed to high-temperature loads (more than 350 °C) and high strength loads (more than 1300 MPa).

- increase in the generation of additional electrical energy (with simultaneous heat removal) while reducing the weight and size parameters of the design of the device in which the TEG will be used, for example, as a body element of an aircraft engine, which plays an important role in the rocket and aviation industry.

The essence of the claimed technical solution is a method for manufacturing a thermoelectric generator based on composite materials, which consists in taking a flexible substrate, which is a tape of composite materials of the carbon fiber class, two different types of conductive component are alternately applied to the flexible substrate, which are either a metal wire or a metal thread made of a number of semiconductor materials, each conductive component is applied in such a way that it is the side of an isosceles triangle, the angle between these sides lies in the range from 10 to 170 °, while each subsequent conductive component is applied inseparably from the previous one, while forming contact between the components at the apex angle of an isosceles triangle and at the vertices of the corners of the base of this triangle, while each type of conductive component is applied parallel to the side of the previous triangle from the same conductive component, then welding to the specified conductive components at the points of their contact, thus forming a plurality of electrical junctions and providing electrical p- and n-junctions, while the number of junctions between two dissimilar conductive components is equal to m, where m>1 (m is a natural series of numbers), with in this case, hot junctions are located on the side of a warm source, cold junctions are on the side of a cooling source; the resulting composite substrate with a thermoelectric structure is laid in a leaflet format so that the fold corresponds to each junction of the conductive components, thus forming the hot and cold sides of the thermoelectric generator; the resulting leaflet is laid either in a flat shape, or the desired radius of curvature R and geometric shape are provided depending on the required geometric parameters of the resulting thermoelectric generator, then the leaflet is stitched through with a carbon fiber composite thread in places where the junction does not pass; further, the upper and lower sides of the leaflet are glued with a composite material from the class of carbon fibers in one or several layers, depending on the required geometric parameters of the resulting thermoelectric generator.

The claimed technical solution is illustrated in Fig.1 - Fig.7.

Figure 1 shows the location of the conductive components on the substrate in the form of a tape of composite material.

Figure 2 shows a thermoelectric generator with a substrate made in the form of a tape with a radius of curvature R1.

Figure 3 shows a substrate in the form of a tape of a composite material with conductive components, folded in leaflet format.

Figure 4 shows a thermoelectric generator with a substrate made in the form of a cylinder with a radius of curvature R2.

Figure 5 shows Table 1, which presents the parameters of manufacturing a thermoelectric generator from various composite materials in various modes.

Figure 6 shows an experimental stand that simulates the operation of the engine of an unmanned aerial vehicle.

Figure 7 shows Table 2, which presents the test results of the aircraft engine housing made from a thermoelectric generator (TEG) based on composite materials obtained by the claimed method.

The positions on the figures indicate:

1 - a substrate in the form of a tape made of a composite material,

2 - conductive component 1,

3 - conductive component 2,

4 - electrical junctions,

R, R1, R2 - radii of curvature.

5 - discharge pipe,

6 - thermoelectric generator obtained by the claimed method

7 - hot air gun,

8 - measuring complex,

9, 10 - thermocouples for fixing thermo-EMF on the hot and cold sides of the generator,

11 - multimeter,

12 - multifunctional pressure meter.

Further, the applicant provides a description of the claimed technical solution.

The present invention relates to methods for manufacturing thermoelectric devices, specifically thermoelectric generators. The thermoelectric generator, obtained by the claimed method, contains a flexible substrate made of a composite material of the class of carbon fibers (carbon fiber) with the first and second various current-conducting components deposited on it in such a way that a plurality of electrical transitions (junctions) are formed. At the same time, hot junctions are located in the inner part of the thermoelectric generator, and cold junctions are located in the outer part. The thermoelectric generator obtained by the claimed method can be used to generate electric current from the waste heat of the aircraft engine by making the body of the aircraft engine itself from it (TEG).

The claimed technical result is generally achieved by making a thermoelectric generator from known as such composite materials of the class of carbon fibers (carbon fiber plastics) with the formation of junctions between two dissimilar conductive components in the amount of m (junctions), where m>1 (m is a natural series of numbers). The number m depends on the required geometric characteristics of the future TEG. In this case, hot junctions are located on the side of a warm source (for example, an engine), cold junctions are on the side of a cooling source (for example, ambient air).

The claimed thermoelectric generator can be made in the form of a tape with a radius of curvature R1 (Figure 2) or a cylinder with a radius of curvature R2 (Figure 4).

At the same time, the thermoelectric generator does not have a fragile dielectric substrate, the electrical junctions of two dissimilar conductive components are deposited on a substrate made of composite materials of the carbon fiber class (carbon fiber plastics). A thermoelectric base is obtained by laying a wire or thread from two dissimilar conductive components onto a composite material at an angle of 10 to 170°. Then, using, for example, a laser process unit or a laser, welding (formation of electrical junctions) of said conductive components is carried out.

Next, the resulting substrate of composite materials with a thermoelectric structure is laid in the leaflet format, which is then given the required radius of curvature and geometric shape.

Then the substrate is stitched with a composite thread in places where the junction does not pass.

The obtained thermoelectric generator can be integrated as a housing element into the aircraft engine.

Further, the applicant provides a detailed sequence of actions of the claimed method.

1) They take a flexible substrate, which is a tape made of composite materials of the class of carbon fiber (carbon fiber), for example, carbon (for example, according to GOST 32667-2014), carbon fabric (carbon fiber) (for example, according to GOST R 57407-2017), carbon tape (for example , according to GOST 28005-88), carbon fiber (for example, according to GOST R 57970-2017). The tape can have any length (L), width (W) and thickness (T) depending on the required geometric characteristics of the future TEG.

2) On a substrate of a composite material, two different types of conductive component are alternately applied, which can be either a metal wire or a metal thread made of semiconductor materials (for example, according to GOST 22622-77). Each conductive component is applied so that it is the side of an isosceles triangle, the angle between these sides lies in the range from 10 to 170° (Fig.1). Each subsequent conductive component is applied inseparably from the previous one, thus forming a contact of the components at the vertex of the angle of the isosceles triangle and at the vertices of the corners of the base of this triangle. Each kind of conductive component is applied parallel to the side of the previous triangle from the same conductive component.

3) Using, for example, a laser technological installation or a laser, welding of the specified conductive components is ensured at the points of their contact, that is, at the vertices of the corners of an isosceles triangle, thus forming a plurality of electrical junctions and providing electrical p- and n-junctions. The number of junctions between two dissimilar conductive components is equal to m, where m>1 (m is a natural series of numbers). The number m depends on the required geometric characteristics of the future TEG. In this case, hot junctions are located on the side of a warm source (for example, an engine), cold junctions are on the side of a cooling source (for example, ambient air).

4) The resulting composite tape with a thermoelectric structure is laid in the leaflet format in such a way that the folds correspond to each junction of the conductive components. In this way, the hot and cold sides of the TEG are formed.

5) The resulting leaflet is laid either in a flat shape, or the desired radius of curvature R and the geometric shape (for example, a cylinder) are provided, depending on the required geometric parameters of the resulting TEG, then the leaflet is stitched through with a carbon fiber composite thread in places where the junction does not pass.

6) The upper and lower surfaces of the leaflet are glued with a composite material from the carbon fiber class (similar to the carbon fibers specified in paragraph 1) in one or more layers, depending on the required geometric parameters of the resulting TEG. Sizing is carried out by methods known as such, for example, either in a matrix [https://sagrit.ru/tehnologii/tehnologiya-propitki-pod-davleniem-tehnologiya-rtm/], or by the vacuum method [https://www.skb-077 .ru/blog/post/composite].

Get thermoelectric generator (TEG).

Further, the applicant provides examples of the implementation of the claimed technical solution.

Example 1. Production of a thermoelectric generator from carbon.

1) Take a flexible substrate, which is a tape, for example, made of carbon. The tape measures, for example, W x D x D = 20 x 50 x 5 mm.

2) Two different types of conductive component in the form of a metal wire, for example, from chromel and copel, are alternately applied to the carbon tape. Each conductive component is applied so that it is the side of an isosceles triangle, the angle between these sides is, for example, 10° (Figure 1). Each subsequent chromel and kopel conductive component is applied inseparably from the previous one, while forming a contact between the chromel and kopel components at the apex of the angle of the isosceles triangle and at the vertices of the corners of the base of this triangle. Each type of conductive component is applied parallel to the previous side of the triangle of the same conductive component.

3) Using, for example, a laser technological installation or a laser, welding of the specified conductive components is ensured at the points of their contact, that is, at the vertices of the corners of an isosceles triangle, thus forming a plurality of electrical junctions and providing electrical p- and n-junctions. The number of junctions m between two dissimilar conductive components is, for example, 1000. In this case, hot junctions are located on the side of a warm source (for example, an engine), cold junctions are on the side of a cooling source (for example, ambient air).

4) The resulting composite tape with a thermoelectric structure is laid in the leaflet format in such a way that the folds correspond to each junction of the conductive components. In this way, the hot and cold sides of the TEG are formed.

5) The resulting leaflet is laid in a flat shape, then stitched through with a composite carbon fiber thread in places where the junction does not pass.

6) The upper and lower sides of the leaflet are glued with a composite material - carbon in one layer, depending on the required geometric parameters of the resulting TEG. Sizing is carried out by methods known as such, for example, in a matrix [https://sagrit.ru/tehnologii/tehnologiya-propitki-pod-davleniem-tehnologiya-rtm/].

Get thermoelectric generator (TEG).

Example 2 - 5. Manufacturing of thermoelectric module from various composite materials according to various modes.

Carry out a sequence of actions similar to Example 1, changing the composite materials and modes. The results are shown in Table 1 in Fig.5.

From the data given in Table 1, it can be concluded that the applicant has manufactured a thermoelectric module according to the claimed method using all the features listed in the claims, including intervals of continuous values and feature options.

Example 6Thermoelectric generator test, obtained by the claimed method.

To prove the achievement of the claimed technical result, as well as the conditions of patentability "industrial applicability", the applicant tested a thermoelectric generator obtained by the claimed method, when used as a housing element of an unmanned aerial vehicle (UAV) engine.

For an experimental study of the characteristics of a thermoelectric generator, an experimental stand was developed and created that simulates the operation of an unmanned aerial vehicle engine, shown in Fig. 6. The main elements of the stand are the injection pipe 5, the thermoelectric generator 6, obtained by the claimed method, the hot air gun 7, which provides heating of the air flow to the required temperature and the measuring complex 8. The thermoelectric generator 6 converts the temperature gradient into an electric current, recorded by the combined electrical measuring instrument. The experimental setup is equipped with measuring instruments: thermocouples 9, 10 for fixing thermo-EMF on the hot and cold sides of the generator, multimeter 11, multifunctional pressure meter 12.

Imitation of the UAV engine housing with housing elements in the form of a thermoelectric generator is a collapsible structure: thermoelectric modules are fixed in the pipe (∅50 mm) in the places of square holes, 40x40x10 mm in size with a curvature radius of 5 mm, this square tube is built into the "cold" pipe . Further, the structure is attached to the discharge pipe through a flange connection.

The device and principle of operation of the experimental stand are as follows: hot air, passing through the pipe through the TEG, gives off a certain amount of heat to the latter and goes into the room. The coolant is pumped into the TEG from the environment by means of a blower and is also discharged into the room.

Heating of the surface of thermoelements occurs mainly due to convective heat transfer. Cooling of thermoelement junctions occurs due to the flow of cold air flowing in a cavity bounded by metal cases, which leads to the appearance of a temperature difference between the "cold" and "hot" junctions of thermoelements. At the junctions, due to the Seebeck effect, a thermo-EMF arises, which can be directed to on-board consumers through special down conductors. The work used TEGs manufactured by the claimed method according to Table 1.

The test results of the aircraft engine housing from TEG, manufactured according to the claimed method, are shown in Table 2 in Fig.7.

The experiments were carried out with different flow variations - variant I and variant II.

In variant I, the speed of the heating flow, washing the internal surface of the TEG - a reproduction of the internal part of the engine, remained unchanged, its temperature was 450°C. The speed of the cooling flow varied within 20-80 m/s.

In variant II, the velocity of the flow around the outer surface of the TEG remained constant; its temperature was 15°C.

During the experiment, it was found that when simulating different engine operation modes at a certain flight altitude (i.e., while maintaining a constant cooling flow rate and changing the hot flow rate), the temperature difference between the hot and cold junctions systematically increases.

From the data given in Table 2, it can be seen that the body of the aircraft engine, made of TEG obtained by the claimed method, can withstand the specified temperature and strength loads. At the same time, the maximum generation of electric power at a TEG with an area of 64 cm ² was 2 W (for a prototype of the same area, this figure is 1.5 W). The reduction in weight and size characteristics compared to the prototype of the same area was 100 g.

Thus, from the above, we can conclude that the applicant has achieved the claimed technical result, namely: the arsenal of methods for manufacturing thermoelectric generators has been expanded with the possibility of their use for manufacturing an aircraft engine housing, while:

- TEGs with the required radius of curvature or shape were obtained by using a flexible substrate made of composite materials of the carbon fiber class (carbon fiber) (Table 1 in Fig. 5), as a result of which the thermoelectric generator is integrated into the aircraft structure as a body element of the engine, as it is able to maintain the specified shape when exposed to high temperature loads (more than 350°C) and high strength loads (more than 1300 MPa) (Table 2 in Fig. 7).

- increased production of additional electrical energy (with simultaneous heat removal) up to 33% (Table 2 in Fig. 7) while reducing the weight and size parameters of the aircraft design due to the fact that the thermoelectric generator is integrated into the aircraft as a body element of the engine, which plays an important role in rocket and aviation industry.

The claimed technical solution complies with the "novelty" patentability condition for inventions, since the applicant has not identified technical solutions with the declared set of essential features from the studied state of the art.

The claimed technical solution complies with the "inventive step" patentability condition for inventions, since no technical solutions have been identified that have features that coincide with the distinctive features of the claimed invention, and the influence of the distinctive features on the claimed technical result has not been established.

The claimed technical solution meets the condition of patentability "industrial applicability" for inventions, as it can be manufactured on standard equipment using known materials and parts.

Claims (1)

A method for manufacturing a thermoelectric generator based on composite materials, which consists in in that a flexible substrate is taken, which is a tape of composite materials of the carbon fiber class, two different types of conductive component are alternately applied to the flexible substrate, which are either a metal wire or a thread from a number of semiconductor materials, each conductive component is applied in such a way that it was the lateral side of an isosceles triangle, the angle between these sides lies in the range from 10 to 170 °, while each subsequent conductive component is applied inseparably from the previous one, while forming a contact of the components at the vertex of the angle of the isosceles triangle and at the vertices of the corners of the base of this triangle, with in this case, each type of conductive component is applied parallel to the side of the previous triangle from the same conductive component, then the specified conductive components are welded at their points of contact, thus forming a plurality of electrical junctions and about provide electrical p- and n-junctions, while the number of junctions between two dissimilar conductive components is equal to m, where m>1 (m is a natural series of numbers), while hot junctions are on the side of a warm source, cold ones are on the side of a cooling source; the resulting composite substrate with a thermoelectric structure is laid in a leaflet format so that the fold corresponds to each junction of the conductive components, thus forming the hot and cold sides of the thermoelectric generator; the resulting leaflet is laid either in a flat shape, or the desired radius of curvature R and geometric shape are provided depending on the required geometric parameters of the resulting thermoelectric generator, then the leaflet is stitched through with a carbon fiber composite thread in places where the junction does not pass; further, the upper and lower sides of the leaflet are glued with a composite material from the class of carbon fibers in one or several layers, depending on the required geometric parameters of the resulting thermoelectric generator.

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