Satellite passive thermal management structure based on multi-stage nonlinear heat conduction

Abstract

The application discloses a kind of passive thermal management technology for spacecraft such as satellite, it is related to engineering thermophysics technical field, solve the following problems of existing satellite thermal management technology:1.Satellite needs not only heat dissipation in high temperature under the direct sunlight, but also needs to maintain a certain temperature when there is no solar radiation to avoid internal device damage.Static spectral surface radiation heat dissipation method cannot regulate heat dissipation power, only additional energy consumption can be heated when low temperature is kept warm.2.Dynamic spectrum adaptive heat dissipation can reduce the radiation heat dissipation power when low temperature, but existing materials have the following problems: spectrum is not perfect, cannot be prepared on a large scale, life is low in space working condition and the like.The application is based on static spectrum surface, modularization is introduced into heat switch device of different trigger conditions of radiator, so as to adjust heat dissipation thermal resistance according to temperature, realize passive spacecraft temperature management.In addition, heat dissipation coating adopts modular design, and can be adapted to the space folding of spacecraft components.

Description

Technical Field

[0001] This invention relates to the field of engineering thermophysics, and in particular to a satellite passive thermal management structure based on multi-stage nonlinear heat conduction. Background Technology

[0002] Satellites and other devices in the space environment can only dissipate heat through thermal radiation. When exposed to sunlight, their temperature rises, requiring cooling measures; when not exposed to sunlight, their temperature decreases, requiring heating to maintain their normal operating temperature. Using static spectral radiation coatings to cool spacecraft only achieves temperature reduction at high temperatures; the heat radiation effect is reversed at low temperatures, requiring greater heating power to maintain the temperature. While dynamic spectral radiation coatings can achieve strong thermal radiation at high temperatures and weak thermal radiation at low temperatures, they present numerous challenges in terms of cost, lifespan, and manufacturing processes. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the background technology by proposing a passive thermal management structure for satellites based on multi-level nonlinear heat conduction. Its core is a heat dissipation module composed of multiple "thermal switches + radiative heat dissipation layers," which adjusts the thermal resistance for heat dissipation according to the device temperature: when the temperature is high, the thermal switch closes, allowing heat inside the device to dissipate into space through the radiative heat dissipation layer; when the temperature is low, the thermal switch opens, preventing heat from reaching the radiative heat dissipation layer. By setting different threshold temperatures for the thermal switches, the thermal resistance of multiple heat dissipation modules can be independently adjusted, allowing the device temperature to change in a stepwise manner within a certain range.

[0004] The technical solution of this invention is a satellite passive thermal management structure based on multi-level nonlinear heat conduction, which includes multiple heat dissipation modules. The heat dissipation modules are installed on the spacecraft components to be cooled. The different heat dissipation modules are independent of each other, which facilitates the spatial folding of spacecraft components.

[0005] The surface of the spacecraft's components to be cooled is coated with a heat-uniforming coating; the heat dissipation module is arranged from top to bottom as a heat dissipation coating, a heat-uniforming substrate for the coating, and a thermal switch.

[0006] The heat dissipation coating has extremely high emissivity in the infrared band, which can radiate heat outwards in large quantities through Planck blackbody radiation, providing heat dissipation for the device; it also has extremely high reflectivity in the solar band, which can reflect solar radiation in large quantities, preventing the device temperature from becoming too high when exposed to sunlight.

[0007] The heat-uniforming substrate is used to support the flexible heat-dissipating coating and ensure its temperature uniformity. It possesses extremely high thermal conductivity and high shear strength in the normal direction, allowing it to support the unfolding of the flexible heat-dissipating coating while maintaining uniform temperature across the surface.

[0008] Thermal switches are used to determine whether to open or close based on temperature, thereby regulating the thermal resistance of the device. Multiple different threshold temperatures are set according to thermal management objectives. When the temperature of a thermal switch exceeds its threshold temperature, the switch closes to reduce the thermal resistance of its corresponding heat dissipation module; when its temperature is below its threshold temperature, the switch opens to increase the thermal resistance of its corresponding heat dissipation module.

[0009] The heat-dissipating coating has an extremely high thermal conductivity, which can keep the heat generated inside the spacecraft's components from being dissipated evenly distributed within the surface.

[0010] The heat dissipation components of a spacecraft are the parts of the spacecraft body that generate heat due to the operation of internal components. Their operating temperature is generally limited to -40℃ to 70℃, and their thermal power is generally 10-500 watts per square meter.

[0011] Compared with the prior art, the present invention has the following beneficial technical effects:

[0012] The thermal management structure in this application, based on a low-cost, long-lasting, and technologically mature static thermal radiation heat dissipation surface, introduces a thermally adjustable thermal switch device. The on / off state of the thermal switch is determined by temperature: when the temperature is too high, the thermal switch closes, allowing heat to flow through the switch to the radiation surface for dissipation; when the temperature is too low, the thermal switch opens, preventing heat loss. Furthermore, by designing and controlling the on / off state of thermal switches in multiple different heat dissipation modules, temperature can be adjusted to achieve approximately smooth temperature changes within a certain range. This significantly reduces heating power consumption at low temperatures while maintaining the temperature within the target range. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the satellite passive thermal management structure based on multi-level nonlinear heat conduction according to the present invention;

[0014] Figure 2 This is a schematic diagram of the shape memory alloy thermal switch in the open state in Embodiment 1 of the present invention;

[0015] Figure 3 This is a schematic diagram of the closed state of the shape memory alloy thermal switch in Embodiment 1 of the present invention;

[0016] Figure 4 This is a schematic diagram of the single-stage nonlinear thermal management system in Embodiment 2 of the present invention;

[0017] Figure 5 This is a schematic diagram of the thermal path in Embodiment 2 of the present invention;

[0018] Figure 6 This is an application example diagram of Embodiment 2 of the present invention;

[0019] Figure 7This is a schematic diagram of the thermal management system based on multi-level nonlinear heat conduction in Embodiment 3 of the present invention;

[0020] Figure 8 This is a schematic diagram of the thermal path in Embodiment 3 of the present invention;

[0021] Figure 9 This is an application example diagram of Embodiment 3 of the present invention.

[0022] Reference numerals: 1. Heat dissipation coating; 2. Coating heat-dissipating substrate; 3. Thermal switch; 4. Heat-dissipating plating layer; 5. Spacecraft component to be cooled. Detailed Implementation

[0023] like Figure 1 As shown, the satellite passive thermal management structure based on multi-level nonlinear heat conduction includes multiple heat dissipation modules, all of which are installed on the spacecraft's heat-dissipating component 5; the different heat dissipation modules are independent of each other;

[0024] The surface of the spacecraft component 5 to be cooled is coated with a uniform heat coating layer 4; the heat dissipation module is arranged from top to bottom as a heat dissipation coating layer 1, a uniform heat coating substrate 2, and a thermal switch 3.

[0025] Different heat dissipation modules are configured with different on / off conditions.

[0026] The overall working principle of the device is as follows: For any heat dissipation module, the heat generated inside the spacecraft component 5 to be cooled is homogenized on the surface by the heat-uniforming coating 4, flows evenly through each thermal switch 3, enters the heat-uniforming substrate 2, and is finally dissipated into the space environment in the form of thermal radiation through the heat dissipation coating 1. When the temperature of the spacecraft component 5 to be cooled is low, the thermal switch is open to maintain the maximum heat dissipation thermal resistance, thus having the maximum heat preservation capacity; when the temperature of the spacecraft component 5 to be cooled rises to the judgment temperature of a certain thermal switch 3, the thermal switch closes, the heat dissipation thermal resistance decreases, thus enhancing the heat dissipation capacity; when the temperature of the spacecraft component 5 to be cooled is greater than the judgment temperature of all thermal switches 3, all thermal switches 3 close, at which point the heat dissipation thermal resistance is the lowest, and the heat dissipation capacity is the maximum.

[0027] Example 1

[0028] like Figure 2-3 The diagram shown illustrates the working principle of a shape memory alloy thermal switch as an example. When the temperature is below the set temperature, such as... Figure 2 As shown, the shape memory alloy wire relaxes, the thermal switch opens, the thermal resistance increases, and the heat in the component to be cooled cannot flow through the thermal switch into the heat dissipation coating; when the temperature is higher than the determination temperature, such as Figure 3 As shown, the shape memory alloy wire shrinks, the thermal switch closes, the thermal resistance decreases, and the heat in the component to be cooled flows through the thermal switch into the heat dissipation coating and enters the space environment in the form of thermal radiation.

[0029] Example 2

[0030] like Figure 4 The diagram shown illustrates the principle of thermal management based on single-stage nonlinear heat conduction. The device has only one thermal switch or all thermal switches have the same determination temperature. Figure 5 This is a schematic diagram of the thermal path. The thermal power of the device to be cooled is set to q. generation =50W / m 2 The thermal resistance of the thermal switch is

[0031]

[0032] Radiative thermal resistance is defined as

[0033]

[0034] Where T device T represents the temperature of the device to be cooled. radiation T represents the surface temperature of the heat dissipation coating. space The values ​​represent the ambient temperature in space, all in Kelvin. ε = 0.8 represents the average infrared emissivity of the heat dissipation coating surface, and σ = 5.67 × 10⁻⁸. -8 W / (m 2 ·K 4 ) represents the Stefan Boltzmann constant. The governing equations of the overall system are:

[0035]

[0036] Where r = 0.85 is the average solar reflectance of the heat dissipation coating surface, and q solar Solar radiation power, measured in W / m² 2 . Figure 6 One application example of this solution: The two dashed lines, from top to bottom, represent 70℃ and -40℃, respectively, indicating the required operating temperature range for aerospace components in the scenario; the two dashed lines, from top to bottom, represent the temperatures of the component to be cooled when the thermal switch is open and closed under a certain light intensity; the solid line represents the operating temperature of the component to be cooled after applying a single-stage nonlinear thermal management system. If traditional static spectral radiation cooling is used, if the system's thermal resistance is set too low, the operating temperature of the component to be cooled will be too low under no light or weak light conditions, requiring a large amount of energy for heating and insulation; if the system's thermal resistance is set too high, the operating temperature of the component to be cooled will be too high under strong light conditions, and the component will not function properly. When a single-stage nonlinear heat conduction system is applied, the thermal switch opens under no light or weak light conditions, automatically increasing the thermal resistance to maintain a higher temperature for the component to be cooled, reducing the energy consumption required for insulation; under strong light conditions, the thermal switch closes, automatically decreasing the thermal resistance, significantly reducing the temperature of the component to be cooled, allowing it to function normally.

[0037] Example 3

[0038] like Figure 7-9 The diagram shows a thermal management principle based on multi-stage nonlinear heat conduction and an application example. The difference from a single-stage thermal management system is that different thermal switches have different threshold temperatures. In this example, the two types of thermal switches with different threshold temperatures each account for half and are connected in parallel.

[0039]

[0040]

[0041]

[0042] like Figure 9 As shown, this is an application example of this solution: the two dashed lines, from top to bottom, represent 70℃ and -40℃ respectively, indicating the operating temperature range required by the aerospace components in the scenario; the three dashed lines, from top to bottom, represent the temperatures of the components to be cooled when the thermal switch is fully open, partially open and partially closed, and fully closed under a certain light intensity; the solid line represents the operating temperature of the components to be cooled after applying a multi-level nonlinear thermal management system. At this time, the thermal management system not only has... Figure 3 The advantages of a single-stage nonlinear system include: maintaining the temperature of the device under heat dissipation within the required operating range; reducing heat preservation power in the absence of light or under weak light conditions; and making the temperature variation range of the device smaller, resulting in more stable operation. Consequently, the higher the number of nonlinear thermal conduction stages (i.e., the more types of temperature ranges the thermal switch can detect), the smoother the operating temperature of the device under heat dissipation, and the more stable its operation.

[0043] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A multi-stage non-linear heat conduction based passive thermal management structure for satellites comprising a plurality of heat dissipation modules, characterized in that, The heat dissipation module is arranged on the spacecraft component to be cooled (5); different heat dissipation modules are independent of each other, and different heat dissipation modules are provided with different on-off conditions. The surface of the spacecraft component to be cooled (5) is plated with a uniform heat plating layer (4); the uniform heat plating layer (4) is in close mechanical connection and thermal contact with the spacecraft component to be cooled (5). The heat dissipation module is sequentially provided with a heat dissipation coating (1), a coating uniform heat base (2) and a thermal switch (3) from top to bottom; one end of the thermal switch (3) is in close mechanical connection and thermal contact with the uniform heat plating layer (4); the other end of the thermal switch (3) is connected with the coating uniform heat base (2) and keeps thermal contact; the heat dissipation coating (1) is uniformly covered on the surface of the coating uniform heat base (2); the coating uniform heat base (2) is used for supporting the flexible heat dissipation coating (1) and making the temperature uniform. When the device is directly irradiated by sunlight or the temperature is too high, the thermal switch (3) is closed to reduce the heat dissipation thermal resistance, the heat dissipation coating (1) radiates heat outward and reflects sunlight to reduce the temperature. When the device is not irradiated by sunlight or the temperature is too low, the thermal switch (3) is opened to increase the heat dissipation thermal resistance, and the heat in the device is difficult to be dissipated by the heat dissipation coating (1), so that the temperature is maintained. The thermal switch (3) sets multiple groups of different judgment temperatures according to the heat management target; when the temperature of a certain thermal switch (3) exceeds the judgment temperature, the thermal switch (3) is closed to reduce the heat dissipation thermal resistance of the corresponding heat dissipation module; when the temperature is lower than the judgment temperature, the thermal switch (3) is opened to increase the heat dissipation thermal resistance of the corresponding heat dissipation module.

2. The multi-stage non-linear heat conduction based passive thermal management structure for satellites of claim 1, wherein, The heat dissipation coating (1) has an emissivity greater than 0.85 in the infrared waveband of 4-30 microns, and can radiate a large amount of heat outward through Planck blackbody radiation; the heat dissipation coating (1) has a reflectivity greater than 0.8 in the sunlight waveband of 0.3-2.5 microns, and can reflect a large amount of sunlight; and has a service life of more than 1 year in the space environment.

3. The multi-stage non-linear heat conduction based passive thermal management structure for satellites of claim 2, wherein, The material of the heat dissipation coating (1) is a mixture of a resin base and metal oxide microbeads, wherein the content of the metal oxide is between 30-60%. Or other two-dimensional and three-dimensional materials, reflective paint materials with the same spectrum.

4. The multi-stage non-linear heat conduction based passive thermal management structure for satellites of claim 3, wherein, The material of the heat dissipation coating (1) is a porous polytetrafluoroethylene film ePTFE, porous silicon dioxide, and polydimethylxylene PDMS.

5. The multi-stage non-linear heat conduction based passive thermal management structure for satellites of claim 1, wherein, The thermal conductivity of the coating uniform heat base (2) is greater than 200 W / (m-K), and the shear strength is greater than 10 kg / mm2.

6. The multi-stage non-linear heat conduction based passive thermal management structure for satellites of claim 1, wherein, The thermal switch (3) is a thermal switch device with a switch ratio greater than 100 in a vacuum condition, and the on-off judgment condition is temperature, which can be adjusted according to requirements.

7. The multi-stage non-linear heat conduction based passive thermal management structure for satellites of claim 1, wherein, The thermal switch (3) is a paraffin thermal switch or a memory alloy thermal switch.

8. The multi-stage non-linear heat conduction based passive thermal management structure for satellites of claim 1, wherein: The thermal conductivity of the uniform heat plating layer (4) is greater than 200 W / (m-K).

9. The multi-stage non-linear heat conduction based passive thermal management structure for satellites of claim 1, wherein: The spacecraft component to be cooled (5) is a part of the spacecraft body that generates heat due to the operation of internal devices, and the working temperature is between -40℃ and 70℃, and the thermal power is 10-500 watts per square meter.

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