Composite thermal control structure, using method thereof and space low-temperature storage box

Abstract

The invention provides a composite thermal control structure, a using method thereof and a space low-temperature storage tank. The composite thermal control structure comprises a thermal resistance layer, a thermal radiation layer and an isolation layer. The thermal resistance layer covers the outside of the thermal control object, the thermal resistance layer comprises a supporting framework and a volatile material, and the volatile material is filled in a gap of the supporting framework, is used for providing thermal resistance in a ground environment and has volatility in a vacuum environment; the heat resistance layer is coated with the isolation layer and used for isolating the heat resistance layer from the external atmosphere in the ground environment, and the isolation layer is coated with the heat radiation layer and used for blocking external heat radiation heat flow in the vacuum environment. After the volatilizable material is gasified and volatilized in the external vacuum degree changing process, the radiation layer is almost not in contact with a thermal control object under vacuum, heat conduction thermal resistance can be provided in the ground state, contact thermal resistance can be reduced in the vacuum environment, cooling capacity is provided in the gasification process, and the thermal control effect is improved. And the applicability of the thermal control object in the ground normal pressure environment and the vacuum environment is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cryogenic storage tanks, and in particular to a composite thermal control structure and a use method thereof, and a space cryogenic storage tank. Background Art

[0002] Cryogenic propellants such as liquid hydrogen, liquid oxygen, and methane are all cryogenic fluids. Cryogenic fluids have low boiling points, usually below 120K, and have a large temperature difference from the normal temperature environment. After absorbing environmental heat, the propellant temperature rises to a saturated state and vaporizes. Therefore, cryogenic rockets and spacecraft need to be coated with thermal control materials during ground tests and space flights to reduce heat leakage from the ground and the cosmic environment.

[0003] At present, the common thermal control coating structure of cryogenic tanks and pipeline systems is a super insulation structure with polyurethane foam on the outside of the tank and multi-layer aluminum foil (MLI) on the outside of the polyurethane foam. Polyurethane foam mainly improves the thermal resistance in the ground thermal environment, because MLI has poor insulation effect in the atmospheric environment, and the heat leakage caused by gas convection and heat conduction is very large. If the thermal resistance is not improved by coating foam, the direct contact of the inner layer of MLI with the low-temperature outer wall of the tank will cause condensation of water vapor inside MLI, affecting the performance of MLI. In the space environment, the outside of the aircraft is a vacuum environment, without gas convection and heat conduction. At this time, MLI plays a major role in thermal control, used to isolate the heat brought by the sun and the earth's radiation, and to avoid heat leakage caused by heat conduction as much as possible. When the cryogenic propellant is in space, the amount of heat input plays a decisive role in the effective use of the propellant, so reducing the input of heat is the most critical.

[0004] The problems with current thermal control structures are: (1) The polyurethane foam, which plays the main role of thermal resistance on the ground, will increase the heat transfer between the multi-layer MLI and the tank and pipelines. In a vacuum environment, since there is no gas convection, the thermal radiation layer itself can effectively isolate the external heat flow. (2) When the MLI insulation material is coated on the surface of the polyurethane foam, it is wrapped in many layers in order to minimize radiation heat leakage, which will cause the gas inside the MLI to escape very slowly, reducing the performance of the multi-layer insulation. Summary of the invention

[0005] In view of the defects in the prior art, the purpose of the present invention is to provide a composite thermal control structure and a method of using the same, and a space low-temperature storage tank.

[0006] The composite thermal control structure provided by the present invention comprises a thermal resistance layer, a thermal radiation layer and an isolation layer which are stacked;

[0007] The thermal resistance layer is coated on the outside of the thermal control object, and the thermal resistance layer includes a support frame and a volatile material. The volatile material is filled in the gap of the support frame, and is used to provide thermal resistance in a ground environment and is volatile in a vacuum environment;

[0008] The isolation layer is coated on the outside of the thermal resistance layer and is used to isolate the thermal resistance layer from the external atmosphere in a ground environment. The thermal radiation layer is coated on the outside of the isolation layer and is used to block external thermal radiation heat flow in a vacuum environment.

[0009] Preferably, when the thermal control object is located in a vacuum environment, the volatile material in the thermal resistance layer volatilizes, and the thermal radiation layer is supported on the outer surface of the thermal control object by a supporting skeleton.

[0010] Preferably, the heat radiation layer comprises a plurality of stacked aluminum-plated thin film reflective layers, and the temperature of each layer of the aluminum-plated thin film reflective layer is different.

[0011] Preferably, a woven spacer layer is provided between the multiple stacked aluminum-plated thin film reflective layers, and the woven spacer layer is used to reduce the contact area between the aluminum-plated thin film reflective layers.

[0012] Preferably, the multiple layers of the aluminum-plated thin film reflective layer are all provided with through holes, and the through holes on each layer of the aluminum-plated thin film reflective layer are arranged in a staggered manner.

[0013] Preferably, the volatile material comprises a solid volatile material or a semi-solid volatile material.

[0014] Preferably, the isolation layer comprises a plastic film, and the support frame comprises an integrally formed carbon fiber frame.

[0015] The method for using the composite thermal control structure provided by the present invention adopts the composite thermal control structure and comprises the following steps:

[0016] Ground environment use steps: the composite thermal control structure is placed in a normal pressure atmospheric environment, the isolation layer seals the thermal resistance layer, and isolates the thermal resistance layer from the atmosphere;

[0017] Steps for using in a vacuum environment: the composite thermal control structure is placed in a vacuum environment, the isolation layer is broken, the volatile material of the thermal resistance layer is volatilized, and the thermal radiation layer is supported on the outer surface of the thermal control object by a supporting frame.

[0018] Preferably, in the vacuum environment use step, the method for breaking the isolation layer includes any one of the following:

[0019] Actively remove the isolation layer;

[0020] Actively create openings in the isolation layer;

[0021] The original gas inside the isolation layer destroys the isolation layer during the process of external air pressure reduction.

[0022] The space low-temperature storage tank provided by the present invention comprises a spherical storage tank body, the outer surface of which is covered with the composite thermal control structure.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The thermal resistance layer in the present invention is a phase-variable material, which can increase the heat transfer resistance between the radiation layer and the surface of the cryogenic container under normal pressure on the ground, realize the volatilization of the thermal resistance layer in a space vacuum environment, and reduce the contact between the radiation layer and the surface of the cryogenic container. Compared with the existing foam thermal resistance layer, the space thermal control effect is better. The present invention can provide thermal conductivity resistance in the ground state and reduce contact thermal resistance in a vacuum environment, which can further increase the applicability of the thermal control object in both the ground normal pressure environment and the vacuum environment.

[0025] 2. After the thermal resistance layer in the present invention evaporates in space, the inner side of the heat radiation layer close to the container wall is a vacuum environment, which is conducive to the release of the inner gas. Compared with the traditional coated multi-layer aluminum foil radiation layer in which the inner gas needs to pass through the radiation layer to be released from the outside of the radiation layer, the gas escape power is stronger, the release time is shorter, and the gas release is more complete. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0027] Figure 1 It is a cross-sectional structural schematic diagram of the present invention;

[0028] Figure 2 It is a partial cross-sectional structural schematic diagram of the present invention.

[0029] The figure shows:

[0030] Thermal resistance layer 1 Insulation layer 3

[0031] Radiation layer 2 Tank 4 DETAILED DESCRIPTION

[0032] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0033] The present invention discloses a composite thermal control structure and a method for using the same, as well as a space cryogenic storage tank, wherein the thermal resistance layer comprises a volatile material and a supporting frame, which can increase the heat transfer resistance between the radiation layer and the surface of the cryogenic container under normal ground pressure, and the volatile material evaporates under a space vacuum environment to reduce the contact between the radiation layer and the surface of the cryogenic container, and the thermal control object has good applicability in both normal ground pressure environments and vacuum environments.

[0034] According to the composite thermal control structure provided by the present invention, Figure 1 , 2 As shown, it includes a thermal resistance layer 1, a heat radiation layer 2 and an isolation layer 3 which are stacked;

[0035] The thermal resistance layer 1 is coated on the outside of the thermal control object, and the thermal resistance layer 1 includes a support skeleton and a volatile material. The volatile material is filled in the gap of the support skeleton, and is used to provide thermal resistance in a ground environment and is volatile in a vacuum environment. When the thermal control object is in a vacuum environment, the volatile material in the thermal resistance layer 1 volatilizes, and the thermal radiation layer 2 is supported on the outer surface of the thermal control object by the support skeleton. The support skeleton can keep the thermal radiation layer 2 from contacting or avoid heat conduction between the thermal radiation layer 2 and the tank wall in a form of less point contact. The volatile material will pass through the saturated state to reach a gaseous state when the pressure is reduced, and volatilize, and can be a pure working fluid or a compound, a hydrate, a gel, etc.

[0036] The isolation layer 3 is coated on the outside of the thermal resistance layer 1, and is used to isolate the thermal resistance layer 1 from the atmosphere in the ground normal pressure environment of 0.1MPa to prevent moisture from entering or unnecessary volatilization. The isolation layer 3 can be mechanically removed or opened in a vacuum environment, or part of the original gas inside can destroy the isolation layer 3 during the process of reducing the external air pressure, so that the thermal resistance layer 1 contacts the vacuum and volatilizes;

[0037] The heat radiation layer 2 is coated on the outside of the isolation layer 3, and is used to block the external heat radiation heat flow in a vacuum environment; the heat radiation layer 2 includes multiple layers of stacked aluminum-plated film reflective layers, each layer of the aluminum-plated film reflective layers has a different temperature, and the multiple layers of the aluminum-plated film reflective layers are punched with through holes, and the through holes on each layer of the aluminum-plated film reflective layers are staggered to facilitate the release of internal gas and achieve high vacuum. A woven spacer layer is arranged between the multiple layers of stacked aluminum-plated film reflective layers, and the woven spacer layer is used to reduce the contact area between the aluminum-plated film reflective layers, thereby reducing the thermal resistance of thermal conductivity.

[0038] The composite thermal control structure can be used for a space cryogenic propellant tank, and can ensure that the heat radiation layer 2 does not contact the tank wall both on the ground and in the space, and provides thermal resistance on the ground to increase the temperature of the innermost layer of the heat radiation layer 2 to avoid ice formation inside the heat radiation layer 2. At the same time, in the space stage, the heat radiation layer 2 is prevented from contacting the tank wall to reduce heat conduction.

[0039] The method for using the composite thermal control structure provided by the present invention adopts the composite thermal control structure and comprises the following steps:

[0040] Ground environment use steps: the composite thermal control structure is in a normal pressure atmospheric environment, the isolation layer 3 seals the thermal resistance layer 1, isolates the thermal resistance layer 1 from the atmosphere, and the thermal resistance layer 1 maintains its structural stability under the coverage of the isolation layer 3, playing the role of thermal conduction and thermal resistance;

[0041] Steps for use in a vacuum environment: The composite thermal control structure is in a vacuum environment, the isolation layer 3 is removed, the volatile material of the thermal resistance layer 1 volatilizes, and the volatile layer gradually volatilizes. The thermal radiation layer 2 is supported on the outer surface of the thermal control object by a support frame, reducing the contact heat conduction between the radiation layer and the container wall, and reducing the heat flow. The method for removing the isolation layer 3 includes any of the following: actively removing the isolation layer 3; actively making an opening on the isolation layer 3; the original gas inside the isolation layer 3 destroys the isolation layer 3 during the process of reducing the external air pressure.

[0042] The space low-temperature storage tank provided according to the present invention comprises a spherical storage tank body, the outer surface of which is coated with the composite thermal control structure according to any one of claims 1 to 7.

[0043] Example 1

[0044] In this embodiment, the thermal control object is a spherical container, which is provided with a working medium accommodating space inside, the working medium is liquid oxygen, and the volatile material is solid carbon dioxide (which has only two phases of gaseous and solid below 0.1MPa, and is solid when the temperature is lower than -56.6 degrees. The metal wall temperature of the cryogenic storage tank is 100K, which is much lower than -56.6 degrees. According to the gas-solid saturation line of carbon dioxide, when the pressure is reduced, it will pass through the saturated state to reach the gaseous state and volatilize), and the composite thermal control structure is coated on the outside of the spherical container. The thermal resistance layer 1 includes a carbon fiber 3D printing skeleton and a volatile material integrally formed. After the formation, the skeleton is inside the volatile layer. After the volatile layer volatilizes, the skeleton can support the heat radiation layer 2 without collapsing and causing a large area of ​​contact with the container wall. The storage tank can be equipped with a refrigerator to provide the thermal resistance layer with the cold required to maintain its solid characteristics in addition to the cold provided by the cryogenic storage tank. The isolation layer 3 adopts an ultra-thin plastic film, and the internal air is discharged during the coating. The heat radiation layer 2 is coated on the isolation layer 3 and is composed of aluminum foil and fiber layer. The aluminum foil and fiber layer are both perforated with small holes to facilitate the release of internal gas to achieve high vacuum. The radiation layer of the liquid oxygen tank is designed as a variable density structure. The lower the temperature, the lower the density. That is, the number of aluminum foil layers per unit distance in the inner layer is small, and the number of aluminum foil layers per unit distance near the outer layer is large. The aluminum foils are separated by fiber layers to avoid direct contact and heat conduction.

[0045] In the ground environment, after the spherical container is filled with liquid oxygen, the thermal resistance layer 1 plays a role of thermal resistance, and nitrogen is passed through the external environment of the container to reduce the content of water vapor and ensure that there is no water vapor freezing. When it reaches the space outside the atmosphere, the isolation layer 3 is destroyed, the thermal resistance layer 1 gradually turns into gas and evaporates, and the gas in the thermal radiation layer 2 is released to the outside and inside through the perforated multi-layer aluminum foil, and the interlayer gradually reaches a high vacuum state, which better exerts the effect of radiation thermal resistance.

[0046] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0047] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A composite thermal control structure, characterized in that: It comprises a thermal resistance layer (1), a heat radiation layer (2) and an isolation layer (3) which are stacked; The thermal resistance layer (1) is coated on the outside of the thermal control object, and the thermal resistance layer (1) comprises a support frame and a volatile material, wherein the volatile material is filled in the gap of the support frame, is used to provide thermal resistance in a ground environment, and is volatile in a vacuum environment; The insulating layer (3) is coated on the outside of the thermal resistance layer (1) and is used to isolate the thermal resistance layer (1) from the external atmosphere in a ground environment; the thermal radiation layer (2) is coated on the outside of the insulating layer (3) and is used to block external thermal radiation heat flow in a vacuum environment.

2. The composite thermal control structure according to claim 1, characterized in that: When the thermal control object is located in a vacuum environment, the volatile material in the thermal resistance layer (1) volatilizes, and the thermal radiation layer (2) is supported on the outer surface of the thermal control object by a supporting frame.

3. The composite thermal control structure according to claim 1, characterized in that: The heat radiation layer (2) comprises a plurality of stacked aluminum-plated thin film reflective layers, and the temperature of each layer of the aluminum-plated thin film reflective layer is different.

4. The composite thermal control structure according to claim 3, characterized in that: A woven spacer layer is arranged between the multiple layers of the aluminum-plated film reflective layers, and the woven spacer layer is used to reduce the contact area between the aluminum-plated film reflective layers.

5. The composite thermal control structure according to claim 3, characterized in that: The multiple layers of the aluminum-plated film reflective layer are all provided with through holes, and the through holes on each layer of the aluminum-plated film reflective layer are arranged in a staggered manner.

6. The composite thermal control structure according to claim 1, characterized in that: The volatile material includes a solid volatile material or a semi-solid volatile material.

7. The composite thermal control structure according to claim 1, characterized in that: The isolation layer (3) comprises a plastic film, and the support frame comprises an integrally formed carbon fiber frame.

8. A method for using a composite thermal control structure, characterized in that: The composite thermal control structure according to any one of claims 1 to 7 comprises the following steps: Ground environment use steps: the composite thermal control structure is placed in a normal pressure atmospheric environment, the isolation layer (3) seals the thermal resistance layer (1), and isolates the thermal resistance layer (1) from the atmosphere; The steps of using the composite thermal control structure in a vacuum environment are as follows: the composite thermal control structure is placed in a vacuum environment, the isolation layer (3) is broken, the volatile material of the thermal resistance layer (1) is volatilized, and the thermal radiation layer (2) is supported on the outer surface of the thermal control object by a supporting frame.

9. The method for using the composite thermal control structure according to claim 8, characterized in that: In the vacuum environment use step, the method for breaking the isolation layer (3) includes any one of the following: Actively removing the isolation layer (3); Actively creating openings in the isolation layer (3); The original gas inside the isolation layer (3) destroys the isolation layer (3) during the process of external air pressure reduction.

10. A space cryogenic storage tank, characterized in that: It comprises a spherical tank body, the outer surface of which is covered with the composite thermal control structure according to any one of claims 1 to 7.

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