Sandwich type cooling and power generation integrated device and design method thereof

Abstract

The invention relates to the field of aerospace engines, in particular to a sandwich type cooling and power generation integrated device and a design method thereof.The sandwich type cooling and power generation integrated device comprises a heat exchanger surrounding the outer side of a combustion chamber and a thermoelectric converter arranged between the combustion chamber and the heat exchanger; the heat absorption end of the thermoelectric converter is connected with the wall surface of the combustion chamber, and the heat release end is connected with the wall surface of the heat exchanger. According to the embodiment of the invention, the thermoelectric converter is arranged between the combustion chamber and the heat exchanger, so that on one hand, the temperature of the wall surface of the combustion chamber is reduced, and on the other hand, additional electric energy is generated, thereby solving the problems of cooling of the combustion chamber of an aerospace vehicle and insufficient electric energy of a storage battery.

Description

Technical Field

[0001] The present invention relates to the field of aerospace engines, and particularly to a sandwich-type cooling and power generation integrated device and a design method thereof. Background Art

[0002] The development of hypersonic vehicles and engine technologies highly depends on thermal protection technologies. A cooling device that can ensure the structural safety of the engine combustion chamber during long-term operation is an essential part of studying engine performance. As the flight Mach number and flight duration continue to increase, the aerodynamic heat and combustion heat generated during flight will become more obvious.

[0003] For example, for an aerospace engine combustion chamber with an inlet Mach number of 2.5, the internal aerodynamic heating temperature is as high as 1650K. Coupled with the heat released by combustion, the temperature is even as high as 2650K. This series of temperatures exceeding the heat resistance limit of materials will damage the combustion chamber structure and lead to flight failure.

[0004] Therefore, one of the key technologies restricting the development of the hypersonic flight field is an effective and reliable thermal protection system. Among them, the most difficult is the cooling of specific structural components of the aerospace engine combustion chamber.

[0005] In addition, due to the large volume and weight of existing storage batteries, power supply is also a major problem for long-endurance hypersonic vehicles.

[0006] For example, a flight duration of more than a thousand seconds corresponds to a battery mass of several tons. Still taking the aerospace engine combustion chamber with an inlet Mach number of 2.5 as an example, when the total temperature of the air flow is 1650K, the heat flux density on the combustion chamber wall will be as high as the megawatt level.

[0007] Under such high heat flux conditions, how to effectively solve the power supply problem of hypersonic vehicles while ensuring the reliability of the aerospace engine combustion chamber mechanism is a huge design challenge. Summary of the Invention

[0008] The purpose of the present invention is to provide a sandwich-type cooling and power generation integrated device and a design method thereof to solve the cooling problem of the combustion chamber of aerospace vehicles and the problem of insufficient electrical energy of storage batteries.

[0009] To solve the above technical problems, the present invention specifically provides the following technical solutions:

[0010] A sandwich-type cooling and power generation integrated device includes: a heat exchanger surrounding the outside of the combustion chamber, and a thermoelectric converter disposed between the combustion chamber and the heat exchanger. The heat absorption end of the thermoelectric converter is connected to the wall surface of the combustion chamber, and the heat release end of the thermoelectric converter is connected to the wall surface of the heat exchanger.

[0011] Furthermore, it further includes: a heat insulation layer laid on the inner side of the combustion chamber.

[0012] Furthermore, 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. A heat exchange chamber is formed inside the heat conduction layer. A cooling working medium outlet that penetrates the heat conduction layer and communicates with the heat exchange chamber is provided on one side of the heat conduction layer. A cooling working medium flow channel is formed inside the matrix layer. A cooling working medium inlet that penetrates the matrix layer and communicates with the cooling working medium flow channel is provided on one side of the matrix layer. The cooling working medium flow channel is connected to the heat exchange chamber through an atomizing nozzle.

[0013] Furthermore, the thickness of the heat insulation layer is 0.2 - 0.15 mm, the thickness of the wall surface of the combustion chamber is 5 - 15 mm, the thickness of the thermoelectric converter is 8 - 13 mm, the thickness of the heat conduction layer is 2 - 5 mm, the thickness of the matrix layer is 5 - 15 mm, the diameter of the atomizing nozzle is 0.1 - 1 mm, the injection spacing of the atomizing nozzle is 0.5 - 5 mm, the divergence angle α of the atomizing nozzle is 120 degrees. The cross-section of the heat absorption end of the thermoelectric converter is square, and the ratio of the side length of the heat absorption end of the thermoelectric converter to the side length of the wall surface of the combustion chamber is 3:4 to 4:5.

[0014] Furthermore, 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.

[0015] Furthermore, the heat exchange chamber is in a flat three-dimensional rectangular shape.

[0016] Furthermore, a flow meter, a flow controller, and a temperature sensor are installed at both the cooling working medium inlet and the cooling working medium outlet, and temperature sensors are installed at both the heat absorption end and the heat release end of the thermoelectric converter.

[0017] A design method for a sandwich-type integrated cooling and power generation device, which is used to design a sandwich-type integrated cooling and power generation device. The design method includes the following steps:

[0018] Step 1: Specify the incoming flow temperature T0 of the heat insulation layer and the heat transfer coefficient h1 of the superalloy layer;

[0019] Step 2: Determine the diameter d of the atomizing nozzle, the divergence angle α of the atomizing nozzle, and the injection spacing l of the atomizing nozzle;

[0020] Step 3: Determine the temperature T6 of the cooling working medium and the heat transfer coefficient h2 of the cooling working medium;

[0021] Step 4: Determine the thickness δ1 of the thermal insulation layer, the thickness δ2 of the superalloy layer, the thickness δ3 of the thermoelectric converter, the thickness δ4 of the heat conduction layer, the thickness δ5 of the substrate layer, and the ratio D / L of the side length of the heat absorption end of the thermoelectric converter to the side length of the superalloy layer through theoretical analysis and multi-parameter optimization method;

[0022] Step 5: Solve the energy transfer equations of the thermoelectric and cooling integrated device based on the thermoelectric theory relationship and the thermal resistance analysis of the laminated structure;

[0023] Step 6: Obtain the temperature of the heat absorption end of the thermoelectric converter, and determine whether the hot end temperature of the thermoelectric device is less than the maximum tolerable temperature of the thermoelectric device. If so, execute Step 7; otherwise, execute Step 2;

[0024] Step 7: 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 8; otherwise, execute Step 4;

[0025] Step 8: Determine the parameters of the sandwich-type cooling and power generation integrated model;

[0026] Step 9: Manufacture the sandwich-type cooling and power generation integrated model, and verify the temperature of the heat absorption end of the thermoelectric converter and the energy conversion efficiency of the thermoelectric converter through experiments.

[0027] Furthermore, the sandwich-type cooling and power generation integrated model includes, connected in sequence: the thermal insulation layer, the superalloy layer, the thermoelectric converter, the heat conduction layer, and the substrate layer; wherein, the heat absorption end of the thermoelectric converter is connected to the superalloy layer, the heat release end of the thermoelectric converter is connected to the heat conduction layer, a heat exchange chamber is formed inside the heat conduction layer, a cooling working fluid outlet that penetrates the heat conduction layer and communicates with the heat exchange chamber is arranged on one side of the heat conduction layer, a cooling working fluid flow channel is formed inside the substrate layer, a cooling working fluid inlet that penetrates the substrate layer and communicates with the cooling working fluid flow channel is arranged on one side of the substrate layer, and the cooling working fluid flow channel is connected to the heat exchange chamber through the atomizing nozzle.

[0028] Further, given that the incoming flow temperature T0 of the heat insulation layer is 1650 K, the heat transfer coefficient h1 of the superalloy layer is 700 W / m2K, the cooling working fluid is RP-3 aviation kerosene, the temperature T6 of the cooling working fluid is 300 K, the heat transfer coefficient h2 of the cooling working fluid is 100 - 10000 W / m2K, the diameter d of the atomizing nozzle is 0.1 - 1 mm, the injection spacing l of the atomizing nozzle is 0.5 - 5 mm, and the divergence angle α of the atomizing nozzle is 120 degrees; then calculate the thickness δ1 of the heat insulation layer, the thickness δ2 of the superalloy layer, the thickness δ3 of the thermoelectric converter, the thickness δ4 of the heat conducting layer, the thickness δ5 of the substrate layer, and the ratio D / L of the side length of the heat absorption end of the thermoelectric converter to the side length of the superalloy layer.

[0029] The present application has the following beneficial effects compared with the prior art:

[0030] Provided is a sandwich-type cooling and power generation integrated device and its design method. By arranging a thermoelectric converter between a combustion chamber and its heat exchanger, on the one hand, the temperature of the wall surface of the combustion chamber is reduced, and on the other hand, additional electric energy is generated, thereby solving the cooling problem of the combustion chamber of aerospace vehicles and the problem of insufficient electric energy of storage batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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 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.

[0032] Figure 1 is a perspective view of the sandwich-type cooling and power generation integrated model of the present invention;

[0033] Figure 2 is a perspective transparent view of the sandwich-type cooling and power generation integrated model of the present invention;

[0034] Figure 3 is a sectional view of one perspective of the sandwich-type cooling and power generation integrated model of the present invention;

[0035] Figure 4 is a sectional view of another perspective of the sandwich-type cooling and power generation integrated model of the present invention;

[0036] Figure 5 is a flowchart of the design method of the sandwich-type cooling and power generation integrated model of the present invention;

[0037] Figure 6It is the correlation between the temperature of the heat absorption end of the thermoelectric converter of the present invention and the average heat transfer coefficient of spray cooling on the surface to be cooled;

[0038] Figure 7 It is the correlation between the temperature difference between the heat absorption end temperature and the heat release end temperature of the thermoelectric converter of the present invention and the average heat transfer coefficient of spray cooling on the surface to be cooled;

[0039] Figure 8 It is the correlation between the energy conversion efficiency of the thermoelectric converter of the present invention and the average heat transfer coefficient of spray cooling on the surface to be cooled;

[0040] Figure 9 It is the correlation between the output power per unit area of the thermoelectric converter of the present invention and the average heat transfer coefficient of spray cooling on the surface to be cooled;

[0041] Figure 10 It is the cooling effect diagram of the thermoelectric converter of the present invention on the superalloy layer;

[0042] The labels in the figure respectively represent the following:

[0043] 1 - thermal insulation layer; 2 - superalloy layer; 3 - thermoelectric converter; 4 - heat conduction layer; 5 - matrix layer; 6 - cooling working medium outlet; 7 - atomizing nozzle; 8 - cooling working medium inlet. Specific embodiments

[0044] 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] Thermoelectric conversion is a technology with broad application prospects in the thermal protection system of hypersonic aircraft. On the one hand, thermoelectric conversion technology can convert thermal energy into electrical energy, reducing the requirements for the battery capacity of the aircraft and improving the payload ratio. On the other hand, thermoelectric conversion technology can absorb the heat of the combustion chamber wall of aerospace engines, thereby improving the cooling performance.

[0046] Based on the above concept, the following provides a sandwich-type integrated cooling and power generation device, including: a heat exchanger surrounding the outside of the combustion chamber, and a thermoelectric converter 3 disposed between the combustion chamber and the heat exchanger. The heat absorption end of the thermoelectric converter 3 is connected to the wall of the combustion chamber, and the heat release end of the thermoelectric converter 3 is connected to the wall of the heat exchanger.

[0047] The combustion chamber generates high temperature on its own wall through the combustion of fuel inside itself, and the heat exchanger generates low temperature on its own wall through the flow of cooling working fluid inside itself. As a result, there is a large temperature difference between the heat absorption end and the heat release end of the thermoelectric converter 3. The thermoelectric converter 3 absorbs heat from the combustion chamber, releases heat to the heat exchanger, and converts part of the heat into electric work, thus achieving the purpose of integrating cooling and power generation.

[0048] Among them, the material of the thermoelectric converter 3 is a half-Heusler alloy. The heat exchange methods that the heat exchanger can adopt include film cooling, regenerative cooling, impinging jet cooling, spray cooling, etc., that is, an active cooling structure in the wall structure, and the heat is absorbed and the wall temperature is reduced by using the flow and heat exchange characteristics of the cooling working fluid.

[0049] In this embodiment, the heat exchanger includes a heat conduction layer 4 and a matrix layer 5. The material of the heat conduction layer 4 is selected as a copper alloy, and the material of the matrix layer 5 is selected as stainless steel. The heat conduction layer 4 is directly attached to the heat release end of the thermoelectric converter 3, and the matrix layer 5 is attached to the side of the heat conduction layer 4 away from the thermoelectric converter 3. A heat exchange chamber is formed inside the heat conduction layer 4. A cooling working fluid outlet 6 that penetrates the heat conduction layer 4 and communicates with the heat exchange chamber is provided on one side of the heat conduction layer 4. A cooling working fluid flow channel is formed inside the matrix layer 5. A cooling working fluid inlet 8 that penetrates the matrix layer 5 and communicates with the cooling working fluid flow channel is provided on one side of the matrix layer 5. The cooling working fluid flow channel is connected to the heat exchange chamber through an atomizing nozzle 7.

[0050] The cooling working fluid source, the cooling working fluid inlet 8, the cooling working fluid flow channel, and the atomizing nozzle 7 are connected in sequence. The atomized cooling working fluid is sprayed into the interior of the heat exchange chamber through the atomizing nozzle 7. The heat exchange chamber is in the shape of a flat three-dimensional rectangle and has a large inner surface area. The cooling working fluid sprayed through the atomizing nozzle 7 can be evenly sprayed on the inner wall of the heat exchange chamber, quickly reducing the temperature of the heat conduction layer 4. The droplets of the cooling working fluid can converge into a liquid flow and be discharged through the cooling working fluid outlet 6.

[0051] In addition, flow meters, flow controllers, and temperature sensors are installed at both the cooling working fluid inlet 8 and the cooling working fluid outlet 6, and temperature sensors are installed at both the heat absorption end and the heat release end of the thermoelectric converter 3. The temperature sensors can adopt K-type thermocouples, and the power generation end of the thermoelectric converter is connected to a power test system.

[0052] The functions of the flow meters, flow controllers, and temperature sensors are to detect the temperature of the thermoelectric converter 3, adjust the flow rate of the cooling working fluid, and ensure that the temperature of the thermoelectric converter 3 is within the normal working range. The power test system is used to detect the energy conversion efficiency of the thermoelectric converter.

[0053] Furthermore, the sandwich-type integrated cooling and power generation device further includes: a heat insulation layer 1 laid on the inner side of the combustion chamber.

[0054] The thermal insulation layer 1 can be prepared by using any one or a combination of the following materials: zirconia ceramics, silicon nitride ceramics, ceramic matrix composites, carbon-carbon composites, SiC-based composites, etc.

[0055] The thermal insulation layer 1 is used to withstand the high-temperature, high-speed, and high-heat-flux environment of the combustion chamber of an aerospace engine, so that the temperature rise rate of the heat absorption end of the thermoelectric converter 3 is within a controllable range.

[0056] On the other hand, in order to verify the feasibility of the above embodiments, refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 Hereinafter, a sandwich-type integrated cooling and power generation model is provided, including a thermal insulation layer 1, a superalloy layer 2, a thermoelectric converter 3, a heat conduction layer 4, and a matrix layer 5 connected in sequence. Among them, the thermal insulation layer 1 and the superalloy layer 2 are used to simulate the combustion chamber, and the heat conduction layer 4 and the matrix layer 5 are used to simulate the heat exchanger.

[0057] The relevant parameters of the design method of the sandwich-type integrated cooling and power generation device include:

[0058] The incoming flow temperature T0 of the thermal insulation layer 1, the thickness δ1 of the thermal insulation layer 1; the heat transfer coefficient h1 of the superalloy layer 2, the thickness δ2 of the superalloy layer 2; the thickness δ3 of the thermoelectric converter 3; the thickness δ4 of the heat conduction layer 4; the thickness δ5 of the matrix layer 5; the diameter d of the atomizing nozzle 7, the divergence angle α of the atomizing nozzle 7, the injection spacing l of the atomizing nozzle 7; the temperature T6 of the cooling working fluid, the heat transfer coefficient h2 of the cooling working fluid; the ratio of the side length of the heat absorption end of the thermoelectric converter 3 to the side length of the superalloy layer 2.

[0059] In the sandwich-type integrated cooling and power generation model, both the heat absorption end of the thermoelectric converter 3 and the superalloy layer 2 are square. The side length of the heat absorption end of the thermoelectric converter 3 is D, and the side length of the superalloy layer 2 is L. The ratio of the side length of the heat absorption end of the thermoelectric converter 3 to the side length of the superalloy layer 2 can be simply expressed as D / L.

[0060] Refer to Figure 5 The design method of the sandwich-type integrated cooling and power generation device includes:

[0061] Step 1: Given the incoming flow temperature T0 of the thermal insulation layer 1 and the heat transfer coefficient h1 of the superalloy layer 2;

[0062] Step 2: Determine the diameter d of the atomizing nozzle 7, the divergence angle α of the atomizing nozzle 7, and the injection spacing l of the atomizing nozzle 7.

[0063] Step 3: The temperature T6 of the cooling working fluid, the heat transfer coefficient h2 of the cooling working fluid.

[0064] Step 4: Determine the thickness δ1 of the thermal insulation layer 1, the thickness δ2 of the superalloy layer 2, the thickness δ3 of the thermoelectric converter 3, the thickness δ4 of the heat conduction layer 4, the thickness δ5 of the substrate layer 5, and the ratio D / L of the side length of the heat absorption end of the thermoelectric converter 3 to the side length of the superalloy layer 2 through theoretical analysis and multi-parameter optimization method.

[0065] Step 5: Solve the energy transfer equations of the thermoelectric and cooling integrated device based on the thermoelectric theory relationship and the thermal resistance analysis of the laminated structure.

[0066] Step 6: Calculate the temperature of the heat absorption end of the thermoelectric converter 3, and determine whether the hot end temperature of the thermoelectric device is less than the maximum tolerance temperature of the material. If so, execute Step 7; otherwise, execute Step 2.

[0067] Step 7: Obtain the energy conversion efficiency and the output power per unit area of the thermoelectric converter 3, and determine whether the energy conversion efficiency is greater than the predetermined requirement. If so, execute Step 8; otherwise, execute Step 4.

[0068] Step 8: Determine the specific parameters of the sandwich-type cooling and power generation integrated model.

[0069] Step 9: Manufacture the sandwich-type cooling and power generation integrated model, and verify the temperature of the heat absorption end of the thermoelectric converter 3 and the energy conversion efficiency of the thermoelectric converter 3 through experiments.

[0070] Specifically, in Step 4, since the thickness δ3 of the thermoelectric converter 3 and the ratio D / L of the side length of the heat absorption end of the thermoelectric converter 3 to the side length of the superalloy layer 2 are two key parameters, and these two parameters affect the heat flow distribution and electrical performance of the thermoelectric converter 3. Therefore, the following takes the thickness δ3 of the thermoelectric converter 3 and the ratio D / L of the side length of the heat absorption end of the thermoelectric converter 3 to the side length of the superalloy layer 2 as examples to illustrate the specific steps of determining parameters through experimental experience:

[0071] 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 working temperature range.

[0072] The optimal thickness of the bismuth telluride (Bi2Te3) thermoelectric converter is usually between 3 mm and 5 mm. The thickness within this range can ensure sufficient thermoelectric conversion efficiency while avoiding the increase in thermal resistance caused by excessive thickness.

[0073] The optimal thickness range of the Half-Heusler thermoelectric converter 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.

[0074] The thickness of a multi - cascaded thermoelectric converter is usually greater because multiple layers of materials need to be stacked to achieve higher thermoelectric conversion efficiency.

[0075] In practical applications, thermoelectric converters are usually arranged in a sandwich form, and a certain amount of space needs to be reserved in the sandwich for wiring and to avoid mutual thermal interference. Experiments show that when the side - length ratio D / L is 3 / 4, the performance of the thermoelectric converter is optimal.

[0076] In summary, those skilled in the art can determine the thickness δ3 of the thermoelectric converter 3 and the ratio D / L of the side - length of the heat - absorbing end of the thermoelectric converter 3 to the side - length of the superalloy layer 2 through experimental experience. Other parameters, such as the thickness δ1 of the thermal insulation layer 1, the thickness δ2 of the superalloy layer 2, the thickness δ4 of the heat - conducting layer 4, and the thickness δ5 of the substrate layer 5, can also be obtained by the same means and will not be elaborated herein.

[0077] Next, a theoretical analysis is carried out: By establishing a thermal resistance analysis model and combining the Seebeck effect of thermoelectric materials with the relationship of thermoelectric conversion performance, the temperature characteristics and power - generation performance of the integrated sandwich - type cooling and power - generation model are analyzed.

[0078] Thermoelectric conversion efficiency:

[0079]

[0080] Among them, T H and T C are the temperatures of the hot end and the cold end 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, and T is the absolute temperature of the thermoelectric material, which takes the average temperature of the cold end and the hot end of the device when used in thermoelectric conversion devices.

[0081] The model can investigate the influence laws of parameters such as the thickness δ1 of the thermal insulation layer 1, the thickness δ2 of the superalloy layer 2, the thickness δ3 of the thermoelectric converter 3, the thickness δ4 of the heat - conducting layer 4, the thickness δ5 of the substrate layer 5, and the ratio D / L of the side - length of the heat - absorbing end of the thermoelectric converter 3 to the side - length of the superalloy layer 2 on the temperature and power - generation characteristics of the integrated model.

[0082] Then, multi - parameter optimization is carried out: Based on the genetic algorithm (GA), under the constraint of the maximum heat - resistant temperature (1123K) of the thermoelectric conversion device, global optimization is performed on parameters such as the thickness δ1 of the thermal insulation layer 1, the thickness δ2 of the superalloy layer 2, the thickness δ3 of the thermoelectric converter 3, the thickness δ4 of the heat - conducting layer 4, the thickness δ5 of the substrate layer 5, and the ratio D / L of the side - length of the heat - absorbing end of the thermoelectric converter 3 to the side - length of the superalloy layer 2 to improve the system energy conversion efficiency and the output power per unit area.

[0083] Specifically, in step five, the energy transfer equation set of the thermoelectric and cooling integrated device includes:

[0084] T0 - T1 = Q / (h1L2);

[0085] T1 - T2 = Qδ1 / (k1L2);

[0086] T2 - T3 = Qδ2 / (k2L2);

[0087] T3 - T4 = (1 - η / 2)Qδ3 / (k3D2);

[0088] T4 - T5 = (1 - η)Qδ4 / (k4L2);

[0089] T5 - Tc = (1 - η)Q / (hcL2);

[0090] η = (T3 - T4) / T3(sqrt(1 + Z(T3 + T4) / 2) - 1) / (sqrt(1 + Z(T3 + T4) / 2) + T4 / T3);

[0091] Wherein, Q is the total heat passing through the integrated model; Tc is the temperature of the cooling medium, and hc is the heat transfer coefficient of the cooling medium.

[0092] k1 - k4 are the thermal conductivities corresponding to each layer respectively, and the thermal conductivity varies with temperature, that is: K1 is the thermal conductivity of insulation layer 1, K2 is the thermal conductivity of superalloy layer 2, K3 is the thermal conductivity of thermoelectric converter 3, and K4 is the thermal conductivity of heat conduction layer 4.

[0093] T1 - T5 are the temperatures of the hot ends of each layer from top to bottom, that is: T1 is the hot end temperature of insulation layer 1, T2 is the hot end temperature of superalloy layer 2, T3 is the hot end temperature of thermoelectric converter 3, T4 is the hot end temperature of heat conduction layer 4, and T5 is the hot end temperature of substrate layer 5.

[0094] In addition, it should be noted that the temperature of the cold end of the other layer in contact with the hot end of each layer is the same. For example: T3 is both the hot end temperature of thermoelectric converter 3 and the cold end temperature of superalloy layer 2.

[0095] A specific embodiment of a sandwich - type cooling power generation integrated model is given below.

[0096] Designed according to the combustion chamber of an aerospace engine with an inlet Mach number of 2.5, the total temperature T0 of the isolation section is given as 1650K. The convective heat transfer coefficient h1 is obtained as 700W / m2K through flow field calculation. A single - nozzle spray cooling design is adopted, the cooling medium is RP - 3 aviation kerosene, the temperature T6 of the cooling medium is 300K, and the average heat transfer coefficient of the spray cooling on the surface to be cooled is calculated by the correlation formula as 100 - 10000W / m2K.

[0097] Specific dimensions of the integrated model:

[0098] The thickness δ1 of the heat insulation layer 1 is 0.2 - 0.15 mm (preferably 1 mm), the thickness δ2 of the superalloy layer 2 is 5 - 15 mm (preferably 9 mm), the thickness δ3 of the thermoelectric converter 3 is 8 - 13 mm (preferably 10 mm), the thickness δ4 of the heat conducting layer 4 is 2 - 5 mm (preferably 4 mm), the thickness δ5 of the substrate layer 5 is 5 - 15 mm (preferably 10 mm), the diameter d of the atomizing nozzle 7 is 0.1 - 1 mm, the injection spacing l of the atomizing nozzle 7 is 0.5 - 5 mm, the side length D of the heat absorption end of the thermoelectric converter 3 is 20 - 40 mm (preferably 30 mm), the ratio of the side length D of the heat absorption end of the thermoelectric converter 3 to the side length L of the superalloy layer 2 is 3:4 to 4:5 (preferably 3:4), and the opening angle α of the atomizing nozzle 7 is 120 degrees.

[0099] One-dimensional heat transfer calculations are carried out using a thermoelectric-cooling integrated coupling equation set based on the thermoelectric theory relationship and thermal resistance analysis. The variation laws of the hot-end temperature, hot-cold end temperature difference, energy conversion efficiency, and output power per unit area of the thermoelectric converter 3 with the convective heat transfer coefficient of the cooling channel are as Figure 6 , Figure 7 , Figure 8 , Figure 9 shown.

[0100] Among them, when the average heat transfer coefficient h2 of spray cooling is greater than 4000 W / m2K, the hot-end temperature of the thermoelectric converter 3 is less than the maximum heat-resistant temperature of 1123 K of the half-Heusler thermoelectric material, meeting the safety requirements for the use of the device.

[0101] At the same time, with the increase of the average heat transfer coefficient of spray cooling, the hot-cold end temperature difference, energy conversion efficiency, and output power per unit area of the thermoelectric converter 3 all increase significantly, indicating that enhancing cooling significantly improves the power generation characteristics of the integrated system.

[0102] In a complex thermal environment such as the combustion chamber wall surface, the hot-end temperature T2 of the superalloy layer 2, as one of the key design parameters, directly affects the safety and performance of the combustion chamber. To evaluate the influence of the thermoelectric converter 3 on the hot-end temperature of the superalloy layer 2, a comparative analysis of the hot-end temperature T2 of the superalloy layer 2 before and after installing the thermoelectric converter 3 was carried out under the condition of keeping the structural parameters, incoming flow parameters, and cooling parameters constant.

[0103] The results are as Figure 10 shown. The data shows that after installing the thermoelectric converter 3, the hot-end temperature T2 of the superalloy layer 2 has decreased significantly by 20 K to 30 K. Considering that the tolerance temperature of the superalloy is about 1200 K, this temperature drop significantly improves the cooling effect of the combustion chamber wall surface and provides an important guarantee for the safe operation of the combustion chamber.

[0104] The maximum energy conversion efficiency of the sandwich-type integrated cooling and power generation model is 9.4%, and the maximum output power per unit area is 18.3 kW / m2, both corresponding to the average heat transfer coefficient of spray cooling with h2 equal to 20000 W / m2K.

[0105] 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 sandwich type cooling and power generation integrated device, characterized in that: include: A heat exchanger is surrounded on the outside of the combustion chamber, and a thermoelectric converter (3) is arranged between the combustion chamber and the heat exchanger, wherein the heat absorption end of the thermoelectric converter (3) is connected to the wall of the combustion chamber, and the heat release end of the thermoelectric converter (3) is connected to the wall of the heat exchanger.

2. A sandwich type cooling and power generation integrated device according to claim 1, characterized in that: Also includes: A heat insulation layer (1) is laid on the inner side of the combustion chamber.

3. The sandwich type cooling and power generation integrated device according to claim 2, characterized in that: The heat exchanger comprises a heat-conducting layer (4) and a base layer (5); the heat-conducting layer (4) is directly attached to the heat-releasing end of the thermoelectric converter (3); the base layer (5) is attached to a side of the heat-conducting layer (4) away from the thermoelectric converter (3); a heat exchange chamber is formed inside the heat-conducting layer (4); a cooling medium outlet (6) penetrating the heat-conducting layer (4) and communicating with the heat exchange chamber is provided on one side of the heat-conducting layer (4); a cooling medium flow channel is formed inside the base layer (5); a cooling medium inlet (8) penetrating the base layer (5) and communicating with the cooling medium flow channel is provided on one side of the base layer (5); the cooling medium flow channel is connected to the heat exchange chamber via an atomizing nozzle (7).

4. The sandwich type cooling and power generation integrated device according to claim 3, characterized in that: The thickness of the heat insulation layer (1) is 0.2-1.5 mm, the thickness of the wall of the combustion chamber is 5-15 mm, the thickness of the thermoelectric converter (3) is 8-13 mm, the thickness of the heat conductive layer (4) is 2-5 mm, the thickness of the substrate layer (5) is 5-15 mm, the diameter of the atomizing nozzle (7) is 0.1-1 mm, the spray spacing of the atomizing nozzle (7) is 0.5-5 mm, the opening angle α of the atomizing nozzle (7) is 120 degrees, the cross-section of the heat absorption end of the thermoelectric converter (3) is a square, and the ratio of the side length of the heat absorption end of the thermoelectric converter (3) to the side length of the wall of the combustion chamber is 3:4 to 4:

5.

5. The sandwich type cooling and power generation integrated device according to claim 3, characterized in that: The material of the heat-conducting layer (4) is a copper alloy, the material of the base layer (5) is stainless steel, and the material of the thermoelectric converter (3) is a half-Heusler alloy.

6. The sandwich type cooling and power generation integrated device according to claim 3, characterized in that: The heat exchange chamber is in a flat three-dimensional rectangular shape.

7. The sandwich type cooling and power generation integrated device according to claim 3, characterized in that: The cooling medium inlet (8) and the cooling medium outlet (6) 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 (3) are both equipped with a temperature sensor.

8. A design method for a sandwich type cooling and power generation integrated device, characterized in that: The design method is used to design the sandwich-type cooling and power generation integrated device described in any one of claims 3 to 7, and the design method comprises the following steps: Step 1: Given the incoming flow temperature T0 of the heat insulation layer (1) and the heat transfer coefficient h1 of the high-temperature alloy layer (2); Step 2, determining the diameter d of the atomizing nozzle (7), the opening angle α of the atomizing nozzle (7), and the spraying distance l of the atomizing nozzle (7); Step 3, determine the temperature T6 of the cooling medium and the heat transfer coefficient h2 of the cooling medium; Step 4: Determine the thickness δ1 of the thermal insulation layer (1), the thickness δ2 of the high-temperature alloy layer (2), the thickness δ3 of the thermoelectric converter (3), the thickness δ4 of the heat-conducting layer (4), the thickness δ5 of the substrate layer (5), and the ratio D / L of the side length of the heat-absorbing end of the thermoelectric converter (3) to the side length of the high-temperature alloy layer (2) by theoretical analysis and a multi-parameter optimization method; Step 5: Solve the energy transfer equations of the thermoelectric and cooling integrated device based on the thermoelectric theory relationship and the thermal resistance analysis of the layer structure; Step 6, obtaining the temperature of the heat-absorbing end of the thermoelectric converter (3), and determining whether the temperature of the hot end of the thermoelectric device is less than the maximum tolerance temperature of the thermoelectric device. If yes, proceed to step 7; otherwise, proceed to step 2; Step 7, obtaining the energy conversion efficiency and the output power per unit area of ​​the thermoelectric converter (3), and determining whether the energy conversion efficiency is greater than a predetermined requirement, if so, executing step 8, otherwise executing step 4; Step 8, determining the parameters of the sandwich cooling and power generation integrated model; Step nine: manufacture a sandwich-type cooling and power generation integrated model, and verify the heat absorption end temperature of the thermoelectric converter (3) and the energy conversion efficiency of the thermoelectric converter (3) through experiments.

9. The design method of a sandwich type cooling and power generation integrated device according to claim 8, characterized in that: The sandwich-type cooling and power generation integrated model comprises: the heat insulation layer (1), the high-temperature alloy layer (2), the thermoelectric converter (3), the heat conduction layer (4) and the substrate layer (5) connected in sequence; The heat absorbing end of the thermoelectric converter (3) is connected to the high-temperature alloy layer (2), the heat releasing end of the thermoelectric converter (3) is connected to the heat conducting layer (4), the heat exchanging chamber is formed inside the heat conducting layer (4), one side of the heat conducting layer (4) is provided with the cooling medium outlet (6) which penetrates the heat conducting layer (4) and is connected to the heat exchanging chamber, the cooling medium flow channel is formed inside the base layer (5), one side of the base layer (5) is provided with the cooling medium inlet (8) which penetrates the base layer (5) and is connected to the cooling medium flow channel, and the cooling medium flow channel is connected to the heat exchanging chamber via the atomizing nozzle (7).

10. The design method of a sandwich type cooling and power generation integrated device according to claim 9, characterized in that: Given that the incoming flow temperature T0 of the heat insulation layer (1) is 1650K, the heat transfer coefficient h1 of the high-temperature alloy layer (2) is 700W / m2K, the cooling medium is RP-3 aviation kerosene, the temperature T6 of the cooling medium is 300K, the heat transfer coefficient h2 of the cooling medium is 100-10000W / m2K, the diameter d of the atomizing nozzle (7) is 0.1-1mm, the spray spacing l of the atomizing nozzle (7) is 0.5-5mm, and the opening angle α of the atomizing nozzle (7) is 120 degrees; Then, the thickness δ1 of the thermal insulation layer (1), the thickness δ2 of the high-temperature alloy layer (2), the thickness δ3 of the thermoelectric converter (3), the thickness δ4 of the heat-conducting layer (4), the thickness δ5 of the substrate layer (5), and the ratio D / L of the side length of the heat-absorbing end of the thermoelectric converter (3) to the side length of the high-temperature alloy layer (2) are calculated.

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