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

Abstract

The present application relates to the field of aerospace engine, in particular to a sandwich type cooling power generation integrated device and a design method thereof, wherein the sandwich type cooling power generation integrated device comprises: a heat exchanger surrounding the outside of the 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 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. The embodiment of the present application sets the thermoelectric converter between the combustion chamber and the heat exchanger, on the one hand, reduces the temperature of the wall surface of the combustion chamber, and on the other hand, generates additional electric energy, thereby solving the problems of insufficient battery power and cooling of the combustion chamber of the aerospace vehicle.

Description

Technical Field

[0001] This invention relates to the field of aerospace engines, and more specifically to a sandwich-type integrated cooling and power generation device and its design method. Background Technology

[0002] The development of hypersonic aircraft and engine technology relies heavily on thermal protection technology. Cooling devices that can operate for extended periods to ensure the structural safety of the engine combustion chamber are an essential part of engine performance research. As flight Mach numbers and flight times continue to increase, the aerodynamic and combustion heat generated during flight will become increasingly significant.

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

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

[0005] In addition, the large size and weight of existing batteries pose a significant challenge to power supply for long-endurance hypersonic aircraft.

[0006] For example, flight times exceeding a thousand seconds correspond to battery masses in the range of several tons. Taking an aerospace engine combustion chamber with an inlet Mach number of 2.5 as an example, when the total airflow temperature is 1650K, the heat flux density on the combustion chamber walls will reach megawatt levels.

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

[0008] The purpose of this invention is to provide a sandwich-type integrated cooling and power generation device and its design method to solve the problems of cooling the combustion chamber of aerospace vehicles and insufficient battery power.

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

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

[0011] Furthermore, it also includes: a heat insulation layer laid inside the combustion chamber.

[0012] Furthermore, the heat exchanger includes a heat-conducting layer and a substrate layer. The heat-conducting layer is directly attached to the heat-dissipating end of the thermoelectric converter, and the substrate layer is attached to the side of the heat-conducting layer away from the thermoelectric converter. A heat exchange chamber is formed inside the heat-conducting layer. A cooling medium outlet is provided on one side of the heat-conducting layer, penetrating the heat-conducting layer and connecting to the heat exchange chamber. A cooling medium flow channel is formed inside the substrate layer, and a cooling medium inlet is provided on one side of the substrate layer, penetrating the substrate layer and connecting to the cooling medium flow channel. The cooling medium flow channel is connected to the heat exchange chamber via an atomizing nozzle.

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

[0014] Furthermore, the material of the heat-conducting layer is a copper alloy, the material of the substrate layer is stainless steel, and the material of the thermoelectric converter is a semi-Hersler alloy.

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

[0016] Furthermore, both the cooling medium inlet and the cooling medium outlet are equipped with flow meters, flow controllers, and temperature sensors, and both the heat absorption end and the heat release end of the thermoelectric converter are equipped with temperature sensors.

[0017] A design method for a sandwich-type integrated cooling and power generation device, the design method comprising the following steps:

[0018] Step 1: Given the incoming flow temperature T0 of the insulation layer and the heat transfer coefficient h1 of the high-temperature alloy layer;

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

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

[0021] Step 4: Determine the thickness δ1 of the heat insulation layer, the thickness δ2 of the high-temperature alloy 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-absorbing end of the thermoelectric converter to the side length of the high-temperature alloy layer through theoretical analysis and multi-parameter optimization methods.

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

[0023] Step 6: Obtain the heat-absorbing end temperature of the thermoelectric converter, and determine whether the hot end temperature of the thermoelectric device is less than the maximum withstand temperature of the thermoelectric device. If yes, proceed to step 7; otherwise, proceed to step 2.

[0024] Step 7: Obtain the energy conversion efficiency and output power per unit area of ​​the thermoelectric converter, and determine whether the energy conversion efficiency is greater than the predetermined requirement. If yes, proceed to step 8; otherwise, proceed to step 4.

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

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

[0027] Furthermore, the sandwich-type integrated cooling and power generation model includes, in sequence, the following: the heat insulation layer, the high-temperature alloy layer, the thermoelectric converter, the heat-conducting layer, and the substrate layer; wherein, the heat-absorbing end of the thermoelectric converter is connected to the high-temperature alloy layer, the heat-releasing end of the thermoelectric converter is connected to the heat-conducting layer, the heat exchange chamber is formed inside the heat-conducting layer, a cooling medium outlet is provided on one side of the heat-conducting layer, penetrating the heat-conducting layer and connecting to the heat exchange chamber, a cooling medium flow channel is formed inside the substrate layer, a cooling medium inlet is provided on one side of the substrate layer, penetrating the substrate layer and connecting to the cooling medium flow channel, and the cooling medium flow channel is connected to the heat exchange chamber through the atomizing nozzle.

[0028] Further, given that the incoming flow temperature T0 of the insulation layer is 1650K, the heat transfer coefficient h1 of the high-temperature alloy layer is 700W / m2K, the cooling medium is RP-3 aviation kerosene, the temperature of the cooling medium T6 is 300K, the heat transfer coefficient h2 of the cooling medium is 100-10000W / m2K, the diameter d of the atomizing nozzle is 0.1-1mm, the spray spacing l of the atomizing nozzle is 0.5-5mm, and the opening angle α of the atomizing nozzle is 120 degrees; then calculate the thickness δ1 of the insulation layer, the thickness δ2 of the high-temperature alloy 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-absorbing end of the thermoelectric converter to the side length of the high-temperature alloy layer.

[0029] Compared with the prior art, this application has the following advantages:

[0030] This invention provides a sandwich-type integrated cooling and power generation device and its design method. By setting a thermoelectric converter between the combustion chamber and its heat exchanger, the temperature of the combustion chamber wall is reduced on the one hand, and additional electrical energy is generated on the other hand, thereby solving the problems of combustion chamber cooling and insufficient battery power in aerospace vehicles. Attached Figure Description

[0031] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

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

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

[0034] Figure 3 This is a cross-sectional view of the sandwich-type integrated cooling and power generation model of the present invention.

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

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

[0037] Figure 6This relates the temperature of the heat-absorbing end of the thermoelectric converter of the present invention to the average heat transfer coefficient of the spray cooling on the surface to be cooled;

[0038] Figure 7 This relates the temperature difference between the heat-absorbing end and the heat-releasing end of the thermoelectric converter of the present invention to the average heat transfer coefficient of the spray cooling on the surface to be cooled.

[0039] Figure 8 This relates the energy conversion efficiency of the thermoelectric converter of the present invention to the average heat transfer coefficient of the spray cooling on the surface to be cooled;

[0040] Figure 9 This relates the output power per unit area of ​​the thermoelectric converter of the present invention to the average heat transfer coefficient of the spray cooling on the surface to be cooled;

[0041] Figure 10 This is a diagram illustrating the cooling effect of the thermoelectric converter of the present invention on the high-temperature alloy layer;

[0042] The labels in the diagram represent the following:

[0043] 1-Insulation layer; 2-High temperature alloy layer; 3-Thermoelectric converter; 4-Heat-conducting layer; 5-Base layer; 6-Cooling medium outlet; 7-Atomizing nozzle; 8-Cooling medium inlet. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection 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 of the aircraft for battery capacity and improving the load ratio. On the other hand, thermoelectric conversion technology can absorb heat from the combustion chamber walls of aerospace engines, thereby improving cooling performance.

[0046] Based on the above concept, a sandwich-type integrated cooling and power generation device is provided below, 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 temperatures on its walls through the combustion of fuel inside, while the heat exchanger generates low temperatures on its walls through the flow of cooling medium inside. This results in 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 some of the heat into electrical work, thus achieving the goal of integrated cooling and power generation.

[0048] Among them, the thermoelectric converter 3 is made of semi-Hersler alloy. The heat exchanger can use heat exchange methods such as film cooling, regenerative cooling, impingement jet cooling, and spray cooling, that is, an active cooling structure in the wall structure, which uses the flow and heat exchange characteristics of the cooling working fluid to absorb heat and reduce the wall temperature.

[0049] In this embodiment, the heat exchanger includes a heat-conducting layer 4 and a substrate layer 5. The heat-conducting layer 4 is made of copper alloy, and the substrate layer 5 is made of stainless steel. The heat-conducting layer 4 is directly attached to the heat-dissipating end of the thermoelectric converter 3, and the substrate layer 5 is attached to the 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 is provided on one side of the heat-conducting layer 4, which penetrates the heat-conducting layer 4 and connects to the heat exchange chamber. A cooling medium flow channel is formed inside the substrate layer 5, and a cooling medium inlet 8 is provided on one side of the substrate layer 5, which penetrates the substrate layer 5 and connects to the cooling medium flow channel. The cooling medium flow channel and the heat exchange chamber are connected by an atomizing nozzle 7.

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

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

[0052] The flow meter, flow controller, and temperature sensor are used to detect the temperature of thermoelectric converter 3, adjust the flow rate of the cooling medium, and ensure that the temperature of thermoelectric converter 3 is within the normal operating range. The power testing system is used to detect the energy conversion efficiency of the thermoelectric converter.

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

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

[0055] The heat insulation layer 1 is used to withstand the high temperature, high speed and high heat flow environment of the aerospace engine combustion chamber, 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 The following provides a sandwich-type integrated cooling and power generation model, which includes a heat insulation layer 1, a high-temperature alloy layer 2, a thermoelectric converter 3, a heat conduction layer 4, and a substrate layer 5 connected in sequence. The heat insulation layer 1 and the high-temperature alloy layer 2 are used to simulate the combustion chamber, and the heat conduction layer 4 and the substrate layer 5 are used to simulate the heat exchanger.

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

[0058] The incoming flow temperature T0 of the insulation layer 1, the thickness δ1 of the insulation layer 1; the heat transfer coefficient h1 of the high-temperature alloy layer 2, 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; the diameter d of the atomizing nozzle 7, the opening angle α of the atomizing nozzle 7, the spray spacing l of the atomizing nozzle 7; the temperature T6 of the cooling medium, the heat transfer coefficient h2 of the cooling medium; and the ratio 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.

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

[0060] refer to Figure 5 The design methods for sandwich-type integrated cooling and power generation devices include:

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

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

[0063] Step 3: Temperature T6 of the cooling medium and heat transfer coefficient h2 of the cooling medium.

[0064] Step 4: Determine the thickness δ1 of the 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 through theoretical analysis and multi-parameter optimization methods.

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

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

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

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

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

[0070] Specifically, in step four, since 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 high-temperature alloy layer 2 are two key parameters, which affect the heat flow distribution and electrical performance of the thermoelectric converter 3, the following uses 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 high-temperature alloy layer 2 as examples to illustrate the specific steps for determining these parameters through experimental experience:

[0071] Different thermoelectric materials have different optimal thickness ranges, which mainly depend on the material's thermoelectric properties (such as Seebeck coefficient, electrical conductivity, and thermal conductivity) and operating temperature range.

[0072] The optimal thickness for bismuth telluride (Bi2Te3) thermoelectric converters is typically between 3mm and 5mm. This thickness range ensures sufficient thermoelectric conversion efficiency while avoiding increased thermal resistance due to excessive thickness.

[0073] The optimal thickness range for half-Heusler thermoelectric converters is relatively wide, typically between 8 mm and 13 mm. The thermoelectric properties of this material are better at higher temperatures, thus requiring greater thickness to accommodate higher heat flux densities.

[0074] Multi-stage thermoelectric converters are typically thicker because they require multiple layers of material to achieve higher thermoelectric conversion efficiency.

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

[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 high-temperature alloy layer 2 through experimental experience. Other parameters, such as the thickness δ1 of the heat insulation layer 1, the thickness δ2 of the high-temperature alloy 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 upon in this article.

[0077] Next, a theoretical analysis will be conducted: by establishing a thermal resistance analysis model and combining the Seebeck effect of thermoelectric materials with the relationship between thermoelectric conversion performance, the temperature characteristics and power generation performance of the sandwich-type integrated cooling and power generation model will be analyzed.

[0078] Thermoelectric conversion efficiency:

[0079]

[0080] Among them, T H and T C ZT represents the temperatures of the hot and cold ends of the thermoelectric converter, respectively. ZT is the dimensionless figure of merit 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 is used in thermoelectric conversion devices to take the average temperature of the cold and hot ends of the device.

[0081] The model can examine the influence of parameters such as the thickness δ1 of the 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 on the temperature and power generation characteristics of the integrated model.

[0082] Then, multi-parameter optimization is performed: Based on the genetic algorithm (GA), under the constraint of the highest heat resistance temperature of the thermoelectric conversion device (1123K), the thickness δ1 of the 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 globally optimized to improve the system energy conversion efficiency and the output power per unit area.

[0083] Specifically, in step five, the energy transfer equations for the integrated thermoelectric and cooling device include:

[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] Where Q is the total heat generated by 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 conductivity of each layer, which varies with temperature. Specifically, K1 is the thermal conductivity of the insulation layer 1, K2 is the thermal conductivity of the high-temperature alloy layer 2, K3 is the thermal conductivity of the thermoelectric converter 3, and K4 is the thermal conductivity of the heat-conducting layer 4.

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

[0094] In addition, it should be noted that the temperature of the cold end of the other layer that the hot end of each layer contacts is the same. For example, T3 is both the hot end temperature of thermoelectric converter 3 and the cold end temperature of high-temperature alloy layer 2.

[0095] The following is a specific embodiment of a sandwich-type integrated cooling and power generation model.

[0096] Based on the design of 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 calculated to be 700W / m2K through flow field calculation. A single-nozzle spray cooling design is adopted, with RP-3 aviation kerosene as the cooling medium and a cooling medium temperature T6 of 300K. The average heat transfer coefficient of the spray cooling on the surface to be cooled is calculated to be 100-10000W / m2K by correlation.

[0097] The specific dimensions of the integrated model:

[0098] The thickness δ1 of the heat insulation layer 1 is 0.2-0.15mm (preferably 1mm), the thickness δ2 of the high-temperature alloy layer 2 is 5-15mm (preferably 9mm), the thickness δ3 of the thermoelectric converter 3 is 8-13mm (preferably 10mm), the thickness δ4 of the heat-conducting layer 4 is 2-5mm (preferably 4mm), the thickness δ5 of the substrate layer 5 is 5-15mm (preferably 10mm), 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, the side length D of the heat-absorbing end of the thermoelectric converter 3 is 20-40mm (preferably 30mm), the ratio of the side length D of the heat-absorbing end of the thermoelectric converter 3 to the side length L of the high-temperature alloy 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 were performed using a thermoelectric-cooling integrated coupled equation set based on thermoelectric theory and thermal resistance analysis. The calculated variations of the hot-end temperature, hot-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 follows: Figure 6 , Figure 7 , Figure 8 , Figure 9 As shown.

[0100] When the average heat transfer coefficient h2 of the spray cooling is greater than 4000W / m2K, the hot end temperature of the thermoelectric converter 3 is less than the maximum heat resistance temperature of the semi-Hersler thermoelectric material 1123K, which meets the requirements for safe use of the device.

[0101] Meanwhile, as the average heat transfer coefficient of spray cooling increases, the temperature difference between the hot and cold ends of thermoelectric converter 3, the energy conversion efficiency, and the output power per unit area all increase significantly, indicating that enhanced cooling significantly improves the power generation characteristics of the integrated system.

[0102] In complex thermal environments such as the combustion chamber wall, the hot-end temperature T2 of the high-temperature alloy layer 2 is one of the key design parameters, and its value directly affects the safety and performance of the combustion chamber. To evaluate the impact of the thermoelectric converter 3 on the hot-end temperature of the high-temperature alloy layer 2, the hot-end temperature T2 of the high-temperature alloy layer 2 before and after the installation of the thermoelectric converter 3 was compared and analyzed while keeping the structural parameters, incoming flow parameters, and cooling parameters constant.

[0103] The results are as follows Figure 10 As shown in the data, after installing the thermoelectric converter 3, the hot-end temperature T2 of the high-temperature alloy layer 2 decreased significantly by 20K to 30K. Considering that the high-temperature alloy can withstand temperatures of approximately 1200K, this temperature reduction significantly improves the cooling effect of the combustion chamber wall, providing an important guarantee for the safe operation of the combustion chamber.

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

[0105] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered as falling within the scope of protection of the embodiments of the present invention.

Claims

1. A sandwich-type integrated cooling and power generation device, characterized in that, include: A heat exchanger surrounding the outside of the combustion chamber, and a thermoelectric converter (3) disposed between the combustion chamber and the heat exchanger, wherein the heat-absorbing end of the thermoelectric converter (3) is connected to the wall of the combustion chamber, and the heat-releasing end of the thermoelectric converter (3) is connected to the wall of the heat exchanger; It also includes: a heat insulation layer (1) laid inside the combustion chamber; The heat exchanger includes a heat-conducting layer (4) and a substrate layer (5). The heat-conducting layer (4) is directly attached to the heat-dissipating end of the thermoelectric converter (3). The substrate layer (5) is attached to the 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) is provided on one side of the heat-conducting layer (4) that penetrates the heat-conducting layer (4) and connects to the heat exchange chamber. A cooling medium flow channel is formed inside the substrate layer (5). A cooling medium inlet (8) is provided on one side of the substrate layer (5) that penetrates the substrate layer (5) and connects to the cooling medium flow channel. The cooling medium flow channel is connected to the heat exchange chamber through an atomizing nozzle (7). The thickness of the heat insulation layer (1) is 0.2-1.5 mm, the thickness of the combustion chamber wall is 5-15 mm, the thickness of the thermoelectric converter (3) is 8-13 mm, the thickness of the heat-conducting 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-absorbing end of the thermoelectric converter (3) is square, and the ratio of the side length of the heat-absorbing end of the thermoelectric converter (3) to the side length of the combustion chamber wall is 3:4~4:

5.

2. The sandwich-type integrated cooling and power generation device according to claim 1, characterized in that, The thermal conductive layer (4) is made of copper alloy, the substrate layer (5) is made of stainless steel, and the thermoelectric converter (3) is made of semi-Hersler alloy.

3. The sandwich-type integrated cooling and power generation device according to claim 1, characterized in that, The heat exchange chamber is a flat, three-dimensional rectangular shape.

4. The sandwich-type integrated cooling and power generation device according to claim 1, characterized in that, The cooling medium inlet (8) and the cooling medium outlet (6) are both equipped with flow meters, flow controllers and temperature sensors, and the heat absorption end and heat release end of the thermoelectric converter (3) are both equipped with temperature sensors.

5. A design method for a sandwich-type integrated cooling and power generation device, characterized in that, The design method is used to design the sandwich-type integrated cooling and power generation device according to any one of claims 1-4, and the design method includes the following steps: Step 1: Given the incoming flow temperature T0 of the insulation layer (1) and the heat transfer coefficient h1 of the high-temperature alloy layer (2); Step 2: Determine the diameter d of the atomizing nozzle (7), the opening angle α of the atomizing nozzle (7), and the spray spacing 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 heat 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) through theoretical analysis and multi-parameter optimization methods. Step 5: Solve the energy transfer equations of the thermoelectric and cooling integrated device based on thermoelectric theory and thermal resistance analysis of the layered structure; Step 6: Obtain the heat absorption end temperature of the thermoelectric converter (3), and determine whether the hot end temperature of the thermoelectric device is less than the maximum withstand temperature of the thermoelectric device. If yes, proceed to step 7; otherwise, proceed to step 2. Step 7: Obtain the energy conversion efficiency and output power per unit area of ​​the thermoelectric converter (3), and determine whether the energy conversion efficiency is greater than the predetermined requirement. If yes, proceed to step 8; otherwise, proceed to step 4. Step 8: Determine the parameters of the sandwich-type integrated cooling and power generation model; Step 9: Create a sandwich-type integrated cooling and power generation 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.

6. The design method of a sandwich-type integrated cooling and power generation device according to claim 5, characterized in that, The sandwich-type integrated cooling and power generation model includes the following components connected in sequence: the heat insulation layer (1), the high-temperature alloy layer (2), the thermoelectric converter (3), the heat-conducting layer (4), and the substrate layer (5). The heat-absorbing end of the thermoelectric converter (3) is connected to the high-temperature alloy layer (2), and the heat-releasing end of the thermoelectric converter (3) is connected to the heat-conducting layer (4). The heat exchange chamber is formed inside the heat-conducting layer (4). A cooling medium outlet (6) is provided on one side of the heat-conducting layer (4) that penetrates the heat-conducting layer (4) and connects to the heat exchange chamber. A cooling medium flow channel is formed inside the substrate layer (5). A cooling medium inlet (8) is provided on one side of the substrate layer (5) that penetrates the substrate layer (5) and connects to the cooling medium flow channel. The cooling medium flow channel and the heat exchange chamber are connected by the atomizing nozzle (7).

7. The design method of a sandwich-type integrated cooling and power generation device according to claim 6, 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 of the cooling medium T6 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 calculate the thickness δ1 of the heat 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).

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