High-power heat-gathering thermoelectric conversion device and design method

Abstract

The invention relates to the field of thermal protection structures of low-orbit aircrafts, in particular to a high-power heat-gathering thermoelectric conversion device and a design method.The high-power heat-gathering thermoelectric conversion device comprises a high-power heat-gathering layer arranged on the inner side of the surface of an aircraft and a heat exchanger surrounding the inner side of the high-power heat-gathering layer; the heat absorption end of the thermoelectric converter is connected with the high-power heat gathering layer, and the heat release end of the thermoelectric converter is connected with the wall surface of the heat exchanger. According to the embodiment of the invention, the high-power heat gathering layer and the heat exchanger are arranged on the surface of the aircraft, so that a large temperature difference is generated between the heat absorption end and the heat release end of the thermoelectric converter arranged on the surface of the aircraft, on one hand, the surface temperature of the aircraft can be reduced, and on the other hand, power can be provided for the aircraft; therefore, the problems of thermal protection and power supply of the low-orbit aircraft are solved.

Description

Technical Field

[0001] The present invention relates to the field of thermal protection structures for low-orbit aircraft, and specifically to a high-magnification heat-gathering thermoelectric conversion device and a design method thereof. Background Art

[0002] Low-orbit aircraft have extensive application requirements in the fields of remote sensing communication, environmental monitoring, resource management, disaster response, and scientific research. They are considered a new solution for future space missions, with advantages such as high signal-to-noise ratio of instruments, high spatial mapping accuracy, low launch cost, low risk of in-orbit collision, and simple system structure. They have received widespread attention from researchers and commercial space companies and have become one of the research hotspots.

[0003] However, due to the special space environment in low orbits (orbital altitude of 100 km - 180 km), low-orbit satellites need to face numerous technical difficulties, including overcoming the significant aerodynamic heating generated by hypersonic flight in the rarefied atmosphere, mainly including convective heat, chemical heat, and radiative heat, etc. When the aircraft is at an orbital altitude of 110 km, the heat flux value in the frontal windward area is as high as 21 kW / m2. Therefore, thermal protection technology is one of the technical problems that need to be urgently solved for low-orbit aircraft.

[0004] In addition, power supply is also a major problem for low-orbit aircraft. Due to the relatively low orbit, the solar radiation is unstable, and traditional photovoltaic power generation is difficult to meet the overall power demand of the aircraft. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-magnification heat-gathering thermoelectric conversion device and a design method thereof to solve the thermal protection and power supply problems of low-orbit aircraft.

[0006] To solve the above technical problems, the present invention specifically provides the following technical solutions:

[0007] A high-magnification heat-gathering thermoelectric conversion device, comprising: a high-magnification heat-gathering layer arranged on the inner side of the aircraft surface, a heat exchanger surrounding the inner side of the high-magnification heat-gathering layer, and a thermoelectric converter arranged between the high-magnification heat-gathering layer and the heat exchanger. The heat absorption end of the thermoelectric converter is connected to the high-magnification heat-gathering layer, and the heat release end of the thermoelectric converter is connected to the wall surface of the heat exchanger.

[0008] Further, the shape of the high-magnification heat-gathering layer is a frustum of a cone or a frustum of a pyramid. The lower bottom of the high-magnification heat-gathering layer contacts the surface of the aircraft, and the upper bottom of the high-magnification heat-gathering layer contacts the heat absorption end of the thermoelectric converter.

[0009] Further, the shape of the high-magnification heat-gathering layer is a frustum of a square pyramid, and its cross-section is a square with continuously changing side lengths.

[0010] Further, the heat exchanger includes a heat conduction layer and a matrix layer. The heat conduction layer is directly attached to the heat release end of the thermoelectric converter. The matrix layer is attached to the side of the heat conduction layer away from the thermoelectric converter. An exchange chamber is formed inside the heat conduction layer, and a cooling working fluid inlet and a cooling working fluid outlet that penetrate the heat conduction layer and communicate with the exchange chamber are provided on both sides of the heat conduction layer.

[0011] Further, the exchange chamber includes a plurality of heat exchange channels with square cross-sections. The side length and spacing of each heat exchange channel are equal. Both ends of each heat exchange channel are respectively connected to the cooling working fluid inlet and the cooling working fluid outlet.

[0012] Further, the thickness δ1 of the high-magnification heat collection layer is 2 - 7 mm, the thickness δ2 of the thermoelectric converter is 8 - 13 mm, the thickness δ3 of the heat conduction layer is 2 - 5 mm, the thickness δ4 of the matrix layer is 5 - 15 mm, the cross-sectional dimension d of the heat exchange channel is 2 - 5 mm, the number n of the heat exchange channels is 5, the side length D of the heat absorption end of the thermoelectric converter is 20 - 40 mm, the ratio of the side length L of the matrix layer to the side length D of the heat absorption end of the thermoelectric converter is 5:4 to 4:3, the side length M of the lower bottom of the high-magnification heat collection layer is 90 - 134 mm, and the heat collection ratio P of the high-magnification heat collection layer is 9:1 to 16.75:1.

[0013] Further, the material of the heat conduction layer is copper alloy, the material of the matrix layer is stainless steel, and the material of the thermoelectric converter is half-Heusler alloy.

[0014] Further, flow meters, flow controllers, and temperature sensors are installed at both the cooling working fluid inlet and the cooling working fluid outlet, and temperature sensors are installed at both the heat absorption end and the heat release end of the thermoelectric converter.

[0015] A design method for a high-magnification heat collection thermoelectric conversion device, which is used to design a high-magnification heat collection thermoelectric conversion device, and the design method includes the following steps:

[0016] Step 1: Determine the total heat flux on the outer wall surface of the low-orbit spacecraft.

[0017] Step 2: Determine the heat collection ratio P of the high-magnification heat collection layer, the cross-sectional dimension d of the heat exchange channel, the number n of the heat exchange channels, the reference temperature of the cooling working fluid, and the heat transfer coefficient.

[0018] Step 3: Determine the thickness δ1 of the high-magnification heat collection layer, the thickness δ2 of the thermoelectric converter, the thickness δ3 of the heat conduction layer, the thickness δ4 of the matrix layer, the ratio D / L of the side length of the heat absorption end of the thermoelectric converter to the side length of the matrix layer through experimental experience and theoretical calculation.

[0019] Step 4: Solve the thermoelectric-cooling integrated coupling equations based on the thermoelectric theory relationship and thermal resistance analysis;

[0020] Step 5: Obtain the temperature at the heat absorption end of the thermoelectric converter, and determine whether the temperature at the heat absorption end of the thermoelectric converter is lower than the maximum tolerable temperature of its own material. If so, execute Step 6; otherwise, execute Step 2;

[0021] Step 6: Obtain the energy conversion efficiency and the output power per unit area of the thermoelectric converter, and determine whether the energy conversion efficiency is greater than the predetermined requirement. If so, execute Step 7; otherwise, execute Step 3;

[0022] Step 7: Determine the parameters of the high-concentration heat-gathering thermoelectric conversion device.

[0023] A high-concentration heat-gathering thermoelectric conversion device, the high-concentration heat-gathering thermoelectric conversion model includes, connected in sequence: the high-concentration heat-gathering layer, the thermoelectric converter, the heat conduction layer, and the substrate layer; wherein, the bottom wall of the high-concentration heat-gathering layer is used for the surface of the aircraft, the heat conduction layer is directly attached to the heat release end of the thermoelectric converter, the substrate layer is attached to the side of the heat conduction layer away from the thermoelectric converter, a heat exchange chamber is formed inside the heat conduction layer, and a cooling working fluid inlet and a cooling working fluid outlet that penetrate the heat conduction layer and communicate with the heat exchange chamber are provided on both sides of the heat conduction layer.

[0024] The present application has the following beneficial effects compared with the prior art:

[0025] Provide a high-concentration heat-gathering thermoelectric conversion device and a design method. By providing a high-concentration heat-gathering layer and a heat exchanger on the surface of the aircraft, a large temperature difference is generated between the heat absorption end and the heat release end of the thermoelectric converter provided on the surface of the aircraft. On the one hand, it can reduce the surface temperature of the aircraft, and on the other hand, it can provide electricity for the aircraft, thus solving the heat protection and power supply problems of low-orbit aircraft. Description of the Drawings

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can be obtained according to the provided drawings.

[0027] Figure 1 Is a three-dimensional view of the high-concentration heat-gathering thermoelectric conversion model of the embodiment of the present invention;

[0028] Figure 2 Is a perspective view of the high-concentration heat-gathering thermoelectric conversion model of the embodiment of the present invention;

[0029] Figure 3 A cross-sectional view of a perspective of the high-concentration heat-collecting thermoelectric conversion model according to an embodiment of the present invention;

[0030] Figure 4 A cross-sectional view of another perspective of the high-concentration heat-collecting thermoelectric conversion model according to an embodiment of the present invention

[0031] Figure 5 A flowchart of a design method for a high-concentration heat-collecting thermoelectric conversion device according to an embodiment of the present invention;

[0032] Figure 6 A correlation diagram of the orbital altitude of an aircraft and the heat flux value of the front windward area;

[0033] Figure 7 A correlation diagram of the heat collection ratio of the high-concentration heat-collecting layer and the temperature of the heat absorption end of the thermoelectric converter according to an embodiment of the present invention;

[0034] Figure 8 A correlation diagram of the heat collection ratio of the high-concentration heat-collecting layer and the temperature of the heat release end of the thermoelectric converter according to an embodiment of the present invention;

[0035] Figure 9 A correlation diagram of the heat collection ratio of the high-concentration heat-collecting layer and the energy conversion efficiency of the thermoelectric converter according to an embodiment of the present invention;

[0036] Figure 10 A correlation diagram of the heat collection ratio of the high-concentration heat-collecting layer and the output power per unit area of the thermoelectric converter according to an embodiment of the present invention;

[0037] Figure 11 An effect diagram of the cooling of the aircraft wall surface by the thermoelectric converter according to an embodiment of the present invention;

[0038] The reference numerals in the figure are respectively represented as follows:

[0039] 1 - High-concentration heat-collecting layer; 2 - Thermoelectric converter; 3 - Heat-conducting layer; 4 - Heat exchange flow channel; 5 - Matrix layer. Detailed implementation manners

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0041] Thermoelectric conversion is a technology with broad application prospects in the thermal protection system of low-orbit aircraft. On the one hand, thermoelectric conversion technology converts thermal energy into electrical energy to power the aircraft itself and on-board instruments and equipment, reducing the demand for battery capacity and high-intensity photovoltaic panels and improving the flight payload ratio.

[0042] On the other hand, thermoelectric conversion technology can absorb the heat on the surface of low-orbit aircraft through a high-concentration heat collection design, thereby achieving thermal protection of the aircraft. The combination of thermoelectric conversion technology and active cooling can not only meet the thermal protection requirements of low-orbit aircraft but also achieve "turning waste into treasure", thus improving the energy utilization efficiency of the aircraft.

[0043] Based on the above concept, a high-concentration heat collection thermoelectric conversion device is provided below, including: a high-concentration heat collection layer 1 arranged on the inner side of the aircraft surface, a heat exchanger surrounded by the high-concentration heat collection layer 1, and a thermoelectric converter 2 arranged between the high-concentration heat collection layer 1 and the heat exchanger. The heat absorption end of the thermoelectric converter 2 is connected to the wall surface of the high-concentration heat collection layer 1, and the heat release end of the thermoelectric converter 2 is connected to the wall surface of the heat exchanger.

[0044] That is, the internal structure of the aircraft from the outside to the inside is the aircraft surface, the high-concentration heat collection layer 1, the thermoelectric converter 2, and the heat exchanger. The aircraft heats up the high-concentration heat collection layer 1 through the aerodynamic heating generated by its hypersonic flight in the rarefied atmosphere. The high-concentration heat collection layer 1 concentrates the heat at the heat absorption end of the thermoelectric converter 2. The heat exchanger generates a low temperature on its wall surface through the flow of the cooling medium inside itself, so that there is a large temperature difference between the heat absorption end and the heat release end of the thermoelectric converter 2. The thermoelectric converter 2 absorbs heat from the high-concentration heat collection layer 1, releases heat to the heat exchanger, and converts part of the heat into electric work, thus achieving the purpose of integrated cooling and power generation.

[0045] The material of the thermoelectric converter 2 is a half-Heusler alloy.

[0046] The high-concentration heat collection layer 1 magnifies the limited heat flux by dozens of times when it reaches the hot end of the thermoelectric converter 2 by shrinking the cross-section to meet the energy conversion efficiency and output power requirements of the thermoelectric converter 2. The heat flux magnification factor is the heat collection ratio.

[0047] To achieve this purpose, the shape of the high-concentration heat collection layer 1 can be selected from a frustum of a cone and a prism. The lower bottom of the high-concentration heat collection layer 1 contacts the surface of the aircraft, and the upper bottom of the high-concentration heat collection layer 1 contacts the heat absorption end of the thermoelectric converter 2.

[0048] In this embodiment, the high-concentration heat collection layer 1 is made of materials with high heat resistance and high thermal conductivity, such as silicon carbide (SiC) composite materials, aluminum nitride (AlN) materials, aluminum matrix composite materials (Al-SiC), etc.

[0049] The shape of the high - magnification heat - concentrating layer 1 is a frustum of a square pyramid, and its cross - section is a square with continuously changing side lengths.

[0050] The heat exchanger is used to cool the heat - releasing end of the thermoelectric converter 2. On the premise of ensuring that the temperature of the heat - absorbing end of the thermoelectric converter 2 with a high heat flux is within the maximum tolerable temperature of the thermoelectric material, the temperature difference between the heat - absorbing end and the heat - releasing end of the thermoelectric converter 2 is increased, thereby improving the energy conversion efficiency and the output power per unit area of the thermoelectric converter 2; making the present invention have the advantages of providing electric energy, enhancing thermal protection, etc.

[0051] To achieve this purpose, the heat - transfer methods that the heat exchanger can adopt include film cooling, regenerative cooling, impinging jet cooling, spray cooling, etc., that is, actively cooling the structure in the wall surface, and using the flow and heat - transfer characteristics of the cooling working fluid to absorb heat and reduce the wall temperature.

[0052] In this embodiment, the heat exchanger includes a heat - conducting layer 3 and a matrix layer 5. The material of the heat - conducting layer 3 is selected as a copper alloy, and the material of the matrix layer 5 is selected as stainless steel. The heat - conducting layer 3 is directly attached to the heat - releasing end of the thermoelectric converter 2, the matrix layer 5 is attached to the side of the heat - conducting layer 3 away from the thermoelectric converter 2. A heat - exchange chamber is formed inside the heat - conducting layer 3, and a cooling working - fluid inlet and a cooling working - fluid outlet that penetrate the heat - conducting layer 3 and communicate with the heat - exchange chamber are arranged on both sides of the heat - conducting layer 3.

[0053] The heat - exchange chamber includes a number of heat - exchange channels 4 with square cross - sections. The side lengths and spacings of each heat - exchange channel 4 are equal, and both ends of each heat - exchange channel 4 are respectively connected to the cooling working - fluid inlet and the cooling working - fluid outlet.

[0054] In addition, flow meters, flow controllers and temperature sensors are installed at both the cooling working - fluid inlet and the cooling working - fluid outlet, and temperature sensors are installed at both the heat - absorbing end and the heat - releasing end of the thermoelectric converter 2. The temperature sensors can adopt K - type thermocouples, and the power - generating end of the thermoelectric converter 2 is connected to a power - testing system.

[0055] The uses of the flow meters, flow controllers and temperature sensors are to detect the temperature of the thermoelectric converter 2 and adjust the flow rate of the cooling working fluid to ensure that the temperature of the heat - absorbing end of the thermoelectric converter 2 is within the normal working range, and the power - testing system is used to detect the energy conversion efficiency of the thermoelectric converter 2.

[0056] On the other hand, to verify the feasibility of the above - mentioned embodiment, refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 Below, a high - magnification heat - concentrating thermoelectric conversion model is provided, including a high - magnification heat - concentrating layer 1, a thermoelectric converter 2, a heat - conducting layer 3 and a matrix layer 5 connected in sequence, wherein the bottom wall of the high - magnification heat - concentrating layer 1 is used for the surface of the aircraft, and the heat - conducting layer 3 and the matrix layer 5 are used to simulate the heat exchanger.

[0057] The relevant parameters of the design method of the high - magnification heat - concentrating thermoelectric conversion device include:

[0058] The total heat flux on the outer wall surface of the aircraft, and the heat - concentrating ratio P of the high - magnification heat - concentrating layer 1 is P = M 2 / D 2 , the cross - sectional side length d of the heat - exchange channel 4, the number n of the heat - exchange channels 4, the reference temperature of the cooling working fluid, the heat - transfer coefficient of the cooling working fluid, the thickness δ1 of the high - magnification heat - concentrating layer 1, the thickness δ2 of the thermoelectric converter 2, the thickness δ3 of the copper - alloy heat - conducting layer 3, the thickness δ4 of the stainless - steel matrix layer 5, and the scale ratio D / L of the thermoelectric converter 2 and the matrix layer 5.

[0059] Among them, M is the side length of the lower bottom of the high - magnification heat - concentrating layer 1, and the area of the lower bottom of the high - magnification heat - concentrating layer 1 is M 2 , D is the side length of the upper bottom of the high - magnification heat - concentrating layer 1, and the area of the upper bottom of the high - magnification heat - concentrating layer 1 is D 2 , L is the side length of the matrix layer 5, and the area of the matrix layer 5 is L 2 .

[0060] Reference Figure 5 , the design method of the high - magnification heat - concentrating thermoelectric conversion device includes:

[0061] Step 1: Determine the total heat flux on the outer wall surface of the low - orbit aircraft.

[0062] Step 2: Determine the heat - concentrating ratio P of the high - magnification heat - concentrating layer 1, the cross - sectional size d of the heat - exchange channel 4, the number n of the heat - exchange channels 4, the reference temperature of the cooling working fluid, and the heat - transfer coefficient.

[0063] Step 3: Determine the thickness δ1 of the high - magnification heat - concentrating layer 1, the thickness δ2 of the thermoelectric converter 2, the thickness δ3 of the heat - conducting layer 3, the thickness δ4 of the matrix layer 5, and the ratio D / L of the side length of the heat - absorbing end of the thermoelectric converter 2 and the side length of the matrix layer 5 through experimental experience and theoretical calculation.

[0064] Step 4: Solve the thermoelectric - cooling integrated coupling equations based on the thermoelectric theory relationship and thermal resistance analysis.

[0065] Step 5: Calculate the temperature of the heat - absorbing end of the thermoelectric converter 2, and judge whether the temperature of the heat - absorbing end of the thermoelectric converter 2 is less than the maximum allowable temperature of its own material. If so, execute Step 6; otherwise, execute Step 2.

[0066] Step 6: Obtain the energy conversion efficiency and the output power per unit area of the thermoelectric converter 2, and judge whether the energy conversion efficiency is greater than the predetermined requirement. If so, execute Step 7; otherwise, execute Step 3.

[0067] Step 7: Determine the parameters of the high - magnification heat - concentrating thermoelectric conversion device, fabricate a high - magnification heat - concentrating thermoelectric conversion model, and verify the accuracy of the above - mentioned parameters through experiments.

[0068] In Step 3, since the thickness δ2 of the thermoelectric converter 2 and the ratio D / L of the side length of the heat absorption end of the thermoelectric converter 2 to the side length of the base layer 5 are two key parameters that affect the heat flow distribution and electrical performance of the thermoelectric converter, the following takes the thickness δ2 of the thermoelectric converter 2 and the ratio D / L of the side length of the heat absorption end of the thermoelectric converter 2 to the side length of the base layer 5 as examples to illustrate the specific steps of determining the parameters through experimental experience:

[0069] Different thermoelectric materials have different optimal thickness ranges, which mainly depend on the thermoelectric properties of the materials (such as Seebeck coefficient, electrical conductivity, and thermal conductivity) and the operating temperature range.

[0070] The optimal thickness of bismuth telluride (Bi2Te3) thermoelectric converters is usually between 3 mm and 5 mm. The thickness within this range can ensure sufficient thermoelectric conversion efficiency while avoiding an increase in thermal resistance caused by excessive thickness.

[0071] The optimal thickness range of half-Heusler thermoelectric converters is relatively wide, usually between 8 mm and 13 mm. The thermoelectric properties of this material perform better at higher temperatures, so a larger thickness is required to adapt to a higher heat flux density.

[0072] The thickness of multi-stage cascaded thermoelectric converters is usually larger because multiple layers of materials need to be stacked to achieve higher thermoelectric conversion efficiency.

[0073] In practical applications, thermoelectric converters are usually arranged in a sandwich form, and a certain space needs to be reserved in the sandwich for wire routing and to avoid mutual thermal interference. Experiments show that the performance of the thermoelectric converter is optimal when the side length ratio D / L is 3 / 4.

[0074] In summary, those skilled in the art can determine the thickness δ2 of the thermoelectric converter 2 and the ratio D / L of the side length of the heat absorption end of the thermoelectric converter 2 to the side length of the base layer 5 through experimental experience. Other parameters, such as the thickness δ1 of the high-magnification heat accumulation layer 1, the thickness δ3 of the heat conduction layer 3, and the thickness δ4 of the base layer 5, can also be obtained by the same means and will not be elaborated in this article.

[0075] Specifically, in Step 3, the specific explanation of the theoretical calculation is as follows:

[0076] By establishing a thermal resistance analysis model and combining the Seebeck effect of thermoelectric materials with the relationship of thermoelectric conversion performance, analyze the temperature characteristics and power generation performance of the sandwich-type cooling and power generation integrated model.

[0077] Thermoelectric conversion efficiency:

[0078]

[0079] Among them, T Hand T C are the temperatures of the hot and cold ends of the thermoelectric converter, respectively; ZT is the dimensionless figure of merit coefficient of the thermoelectric converter; S is the Seebeck coefficient; k is the thermal conductivity; σ = 1 / ρ is the electrical conductivity; T is the absolute temperature of the thermoelectric material, and in the thermoelectric conversion device, the average temperature of the cold and hot ends of the device is taken.

[0080] The model can investigate the influence laws of parameters such as the thickness δ1 of the high-magnification heat collection layer 1, the thickness δ2 of the thermoelectric converter 2, the thickness δ3 of the heat conduction layer 3, the thickness δ4 of the substrate layer 5, and the ratio D / L of the side length of the heat absorption end of the thermoelectric converter 2 to the side length of the substrate layer 5 on the temperature and power generation characteristics of the integrated model.

[0081] Specifically, in step four, the thermoelectric-cooling integrated coupling equations are as follows:

[0082] T1 - T2 = Qδ1(1 / D - 1 / M) / [k1(M - D)];

[0083] T2 - T3 = (1 - η / 2)Qδ2 / (k2D2);

[0084] T3 - T4 = (1 - η)Qδ3 / (k3L2);

[0085] T4 - Tc = (1 - η)Q / (4n hc Ld);

[0086] η = (T2 - T3) / T2(sqrt(1 + Z(T2 + T3) / 2) - 1) / (sqrt(1 + Z(T2 + T3) / 2) + T3 / T2);

[0087] Among them, Q is the total heat passing through the integrated model; Tc is the temperature of the cooling working medium, hc is the heat transfer coefficient of the cooling working medium; n is the number of cooling channels, d is the side length of the cooling channel, M is the side length of the lower bottom of the high-magnification heat collection layer 1, D is the side length of the heat absorption end of the thermoelectric converter 2, L is the side length of the substrate layer 5; η is the conversion efficiency of the thermoelectric conversion device, representing the ratio of its maximum power generation to the heat flow passing through the thermoelectric conversion device.

[0088] k1 - k3 are the thermal conductivities corresponding to each layer respectively, and the thermal conductivity varies with temperature, that is: K1 is the thermal conductivity of the high-magnification heat collection layer 1, K2 is the thermal conductivity of the thermoelectric converter 2, and K3 is the thermal conductivity of the heat conduction layer 3.

[0089] T1 - T4 is the temperature of the hot end of each layer from top to bottom, that is: T1 is the hot end temperature of the high-magnification heat collection layer 1, T2 is the hot end temperature of the thermoelectric converter 2, T3 is the hot end temperature of the heat conduction layer 3, and T4 is the hot end temperature of the substrate layer 5.

[0090] In addition, it should be noted that the temperatures of the cold ends of the other layers in contact with the hot end of each layer are the same. For example, T2 is both the hot end temperature of the thermoelectric converter 2 and the cold end temperature of the high-fold heat collection layer 1.

[0091] A specific example with specific parameters is given below.

[0092] Refer to Figure 6 , given that the orbital altitude of the low-orbit spacecraft is 110 km and the heat flux value in the frontal windward area is 21 kW / m2.

[0093] Dimensions of the high-fold heat collection thermoelectric conversion model: The thickness δ1 of the high-fold heat collection layer 1 is 2 - 7 mm (preferably 5 mm), the thickness δ2 of the thermoelectric converter 2 is 8 - 13 mm (preferably 10 mm), the thickness δ3 of the heat conduction layer 3 is 2 - 5 mm (preferably 4 mm), the thickness δ4 of the matrix layer 5 is 5 - 15 mm (preferably 10 mm), the cross-sectional dimension d of the heat exchange channel 4 is 2 - 5 mm (preferably 4 mm), the number n of the heat exchange channels 4 is 5, the side length D of the heat absorption end of the thermoelectric converter 2 is 20 - 40 mm (preferably 30 mm), the ratio of the side length L of the matrix layer 5 to the side length D of the heat absorption end of the thermoelectric converter 2 is 5:4 to 4:3 (preferably 4:3), the side length M of the lower bottom of the high-fold heat collection layer 1 is 90 - 134 mm, and the heat collection ratio P of the high-fold heat collection layer 1 is 9:1 to 20:1.

[0094] The cooling working fluid is liquid water with a temperature of 300 K. The flow rate of the cooling working fluid at the cooling working fluid inlet is 2 m / s, and the corresponding Reynolds number is 7000. The convective heat transfer coefficient calculated through the Dittus - Boelter correlation is 8000 W / m 2 K.

[0095] By selecting a value of the heat collection ratio P within the range of 9:1 to 20:1, the heat collection ratio P can be changed by changing the side length L of the matrix layer 5.

[0096] Refer to Figure 7 , Figure 8 , Figure 9 , Figure 10 , the heat transfer calculation is carried out using the integrated coupling equations of high-fold heat collection thermoelectric conversion and cooling based on the thermoelectric theory relationship and thermal resistance analysis. The variation laws of the hot end temperature, the temperature difference between the hot and cold ends, the energy conversion efficiency, and the output power per unit area of the 2 thermoelectric converters with respect to the heat collection ratio P are obtained.

[0097] As the average heat transfer coefficient of spray cooling increases, the temperature difference between the hot and cold ends, the energy conversion efficiency, and the output power per unit area of the 2 thermoelectric converters all increase significantly, indicating that increasing the heat collection ratio P significantly improves the power generation characteristics of the integrated system.

[0098] In a complex thermal environment such as the wall of an aircraft, the wall temperature directly affects the safety and performance of the aircraft. To evaluate the influence of the thermoelectric converter 2 on the wall temperature, under the condition of keeping the structural parameters, heat flux parameters, and cooling parameters constant, a comparative analysis of the aircraft wall temperature before and after installing the thermoelectric converter 2 was carried out through a high-concentration heat-collecting thermoelectric conversion model. The cooling effect of the thermoelectric converter 2 on the aircraft wall is as Figure 11 shown. The data shows that after installing the thermoelectric converter 2, the temperature of the aircraft wall has decreased significantly by more than 30K. Considering the temperature tolerance of the superalloy material used for the aircraft wall, this temperature drop has significantly improved the cooling effect of the aircraft wall and provided an important guarantee for the safe operation of the aircraft.

[0099] Since when the heat concentration ratio P is greater than 16.75:1, the hot-end temperature of the two thermoelectric converter 2 is greater than the maximum heat-resistant temperature of the half-Heusler thermoelectric material, which is 1123K, and does not meet the safety requirements for the use of the device. Therefore, the heat concentration ratio P of the high-concentration heat-collecting layer 1 used in the high-concentration heat-collecting thermoelectric conversion device is selected as a value in the range of 9:1 to 16.75:1.

[0100] In this specific embodiment, under the premise of meeting the heat-resistant conditions, when the heat concentration ratio P is 16.75:1, the maximum energy conversion efficiency of the high-concentration heat-collecting thermoelectric conversion model is 9.7%, and the maximum output power per unit area is 2.03kW / m 2 .

[0101] The above embodiments are only exemplary embodiments of the present invention and are not used to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements within the essence and protection scope of the present invention, and such modifications or equivalent replacements should also be regarded as falling within the protection scope of the embodiments of the present invention.

Claims

1. A high-power heat-concentrating thermoelectric conversion device, characterized in that: include: A high-power heat-collecting layer (1) is arranged on the inner side of the aircraft surface, a heat exchanger surrounded by the high-power heat-collecting layer (1), and a thermoelectric converter (2) is arranged between the high-power heat-collecting layer (1) and the heat exchanger, wherein the heat-absorbing end of the thermoelectric converter (2) is connected to the high-power heat-collecting layer (1), and the heat-releasing end of the thermoelectric converter (2) is connected to the wall surface of the heat exchanger.

2. A high-power heat concentration thermoelectric conversion device according to claim 1, characterized in that: The high-power heat-concentrating layer (1) is in the shape of a truncated cone or a polygonal cone, the lower base of the high-power heat-concentrating layer (1) contacts the surface of the aircraft, and the upper base of the high-power heat-concentrating layer (1) contacts the heat-absorbing end of the thermoelectric converter (2).

3. A high-power heat concentration thermoelectric conversion device according to claim 2, characterized in that: The high-power heat-collecting layer (1) is in the shape of a square platform, and its cross section is a square with a continuously changing side length.

4. A high-power heat concentration thermoelectric conversion device according to claim 1, characterized in that: The heat exchanger comprises a heat-conducting layer (3) and a base layer (5); the heat-conducting layer (3) is directly attached to the heat-releasing end of the thermoelectric converter (2); the base layer (5) is attached to a side of the heat-conducting layer (3) away from the thermoelectric converter (2); a heat exchange chamber is formed inside the heat-conducting layer (3); and a cooling medium inlet and a cooling medium outlet are provided on both sides of the heat-conducting layer (3) and penetrate the heat-conducting layer (3) and communicate with the heat exchange chamber.

5. A high-power heat concentration thermoelectric conversion device according to claim 4, characterized in that: The heat exchange chamber comprises a plurality of heat exchange channels (4) with square cross sections, the side length and spacing of each heat exchange channel (4) are equal, and the two ends of each heat exchange channel (4) are respectively connected to the cooling medium inlet and the cooling medium outlet.

6. A high-power heat concentration thermoelectric conversion device according to claim 5, characterized in that: The thickness δ1 of the high-power heat-collecting layer (1) is 2-7 mm, the thickness δ2 of the thermoelectric converter (2) is 8-13 mm, the thickness δ3 of the heat-conducting layer (3) is 2-5 mm, the thickness δ4 of the base layer (5) is 5-15 mm, the cross-sectional dimension d of the heat exchange channel (4) is 2-5 mm, the number n of the heat exchange channels (4) is 5, the side length D of the heat-absorbing end of the thermoelectric converter (2) is 20-40 mm, the ratio of the side length L of the base layer (5) to the side length D of the heat-absorbing end of the thermoelectric converter (2) is 5:4 to 4:3, the side length M of the bottom of the high-power heat-collecting layer (1) is 90-134 mm, and the heat collection ratio P of the high-power heat-collecting layer (1) is 9:1 to 16.75:

1.

7. A high-power heat concentration thermoelectric conversion device according to claim 4, characterized in that: The material of the heat-conducting layer (3) is a copper alloy, the material of the base layer (5) is stainless steel, and the material of the thermoelectric converter (2) is a half-Heusler alloy.

8. A high-power heat concentration thermoelectric conversion device according to claim 4, characterized in that: The cooling medium inlet and the cooling medium outlet are both equipped with a flow meter, a flow controller and a temperature sensor, and the heat absorption end and the heat release end of the thermoelectric converter (2) are both equipped with a temperature sensor.

9. A design method for a high-power heat-concentrating thermoelectric conversion device, characterized in that: The design method is used to design a high-power heat concentration thermoelectric conversion device as described in any one of claims 5 to 8, and the design method comprises the following steps: Step 1: Determine the total heat flux on the outer wall of the low-orbit spacecraft; Step 2: determining the heat concentration ratio P of the high-power heat concentration layer (1), the cross-sectional size d of the heat exchange channel (4), the number n of the heat exchange channel (4), the reference temperature of the cooling medium and the heat transfer coefficient; Step 3: Determine the thickness δ1 of the high-power heat-collecting layer (1), the thickness δ2 of the thermoelectric converter (2), the thickness δ3 of the heat-conducting layer (3), the thickness δ4 of the base layer (5), and the ratio D / L of the side length of the heat-absorbing end of the thermoelectric converter (2) to the side length of the base layer (5) through experimental experience and theoretical calculation; Step 4: Solve the thermoelectric-cooling integrated coupling equations based on thermoelectric theory relationship and thermal resistance analysis; Step 5, obtaining the endothermic temperature of the thermoelectric converter (2), and determining whether the endothermic temperature of the thermoelectric converter (2) is less than the maximum tolerance temperature of its own material, if yes, executing step 6, otherwise executing step 2; Step 6, obtaining the energy conversion efficiency and the output power per unit area of ​​the thermoelectric converter (2), and determining whether the energy conversion efficiency is greater than a predetermined requirement, if so, executing step 7, otherwise executing step 3; Step 7: Determine the parameters of the high-power heat-concentrating thermoelectric conversion device.

10. The design method of a high-power heat concentration thermoelectric conversion device according to claim 9, characterized in that: The high-power heat-concentration thermoelectric conversion model comprises: the high-power heat-concentration layer (1), the thermoelectric converter (2), the heat-conducting layer (3) and the base layer (5) connected in sequence; wherein the bottom wall of the high-power heat-concentration layer (1) is used for the surface of the aircraft, the heat-conducting layer (3) is directly attached to the heat-releasing end of the thermoelectric converter (2), the base layer (5) is attached to the side of the heat-conducting layer (3) away from the thermoelectric converter (2), the heat-exchange chamber is formed inside the heat-conducting layer (3), and the two sides of the heat-conducting layer (3) are provided with a cooling medium inlet and a cooling medium outlet which penetrate the heat-conducting layer (3) and are connected to the heat-exchange chamber.

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