CN114414622A - Universal composite heat insulation method suitable for vacuum and normal pressure environments - Google Patents
Universal composite heat insulation method suitable for vacuum and normal pressure environments Download PDFInfo
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- CN114414622A CN114414622A CN202210086750.XA CN202210086750A CN114414622A CN 114414622 A CN114414622 A CN 114414622A CN 202210086750 A CN202210086750 A CN 202210086750A CN 114414622 A CN114414622 A CN 114414622A
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- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000009413 insulation Methods 0.000 title claims abstract description 22
- 239000002131 composite material Substances 0.000 title claims abstract description 17
- 239000010935 stainless steel Substances 0.000 claims abstract description 32
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 32
- 239000004810 polytetrafluoroethylene Substances 0.000 claims abstract description 25
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims abstract description 25
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 20
- 239000011888 foil Substances 0.000 claims abstract description 20
- 230000005855 radiation Effects 0.000 claims abstract description 9
- 239000010410 layer Substances 0.000 claims description 41
- 239000011229 interlayer Substances 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000012546 transfer Methods 0.000 claims description 6
- 238000004364 calculation method Methods 0.000 claims description 4
- 230000001133 acceleration Effects 0.000 claims description 3
- 230000008878 coupling Effects 0.000 claims description 3
- 238000010168 coupling process Methods 0.000 claims description 3
- 238000005859 coupling reaction Methods 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 238000002076 thermal analysis method Methods 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 239000012774 insulation material Substances 0.000 claims description 2
- 238000012360 testing method Methods 0.000 abstract description 5
- 239000011810 insulating material Substances 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 2
- 238000011160 research Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
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- General Physics & Mathematics (AREA)
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- Investigating Or Analyzing Materials Using Thermal Means (AREA)
- Thermal Insulation (AREA)
- Laminated Bodies (AREA)
Abstract
The invention discloses a universal composite heat insulation method suitable for vacuum and normal pressure environments, which comprises the following parts: a. the composite heat insulating material is characterized in that a plurality of layers of aluminum foil-coated stainless steel sheets and aluminum foil-coated PTFE sheets are fixed through connecting pieces to form a 9-layer structure of stainless steel, an air layer, PTFE, an air layer, stainless steel, an air layer, PTFE, an air layer and stainless steel. The invention develops a new composite heat insulation method by combining a heat radiation heat insulation method taking radiation as a main heat exchange way in a vacuum environment and a heat convection heat insulation method taking convection as a main heat exchange way, gives consideration to radiation, convection and heat conduction, is verified by actual engineering use and actual heat test, has excellent effect, has low air release rate, can keep the normal temperature of the outer wall of equipment when a test piece in the equipment is between 196 and 300 ℃, is convenient to install and use and is 10 DEG C‑4Pa (vacuum) -105The heat insulation performance is good in the whole range between Pa (normal pressure).
Description
Technical Field
The invention relates to the technical field of space environment simulation, in particular to a universal composite heat insulation method suitable for vacuum and normal pressure environments.
Background
In the research process of special materials for space, the quantitative research of the temperature characteristics of the materials at different temperatures in a vacuum environment and an atmospheric environment is a key concern. In order to support special research on the temperature characteristics of the special materials, a special space environment simulator capable of simulating wide-range temperatures in vacuum and atmospheric environments becomes an important research tool. One key technical challenge of the important development tool is to find a method for effective heat insulation in both vacuum environment and atmospheric normal pressure environment.
The method can maintain the outer wall of the special space environment simulator in a normal temperature state in both a vacuum environment and an atmospheric normal pressure environment and in an extremely low temperature environment and an extremely high temperature environment, and ensures that the test of the material is smoothly carried out.
Disclosure of Invention
The invention aims to: in order to solve the problems, the general composite heat insulation method suitable for vacuum and normal pressure environments is provided.
In order to achieve the purpose, the invention adopts the following technical scheme:
a universal composite thermal insulation method suitable for vacuum and normal pressure environments comprises the following parts:
a. the composite heat insulating material is set, wherein a plurality of layers of aluminum foil-coated stainless steel sheets and aluminum foil-coated PTFE sheets are fixed through connecting pieces to form a 9-layer structure of stainless steel, an air layer, PTFE, an air layer, stainless steel, an air layer, PTFE, an air layer and stainless steel;
b. thermal analysis: setting the wall temperature of the first stainless steel layer to be liquid nitrogen temperature-196 ℃, the wall temperature of the ninth stainless steel layer to be 40 ℃, and setting the wall temperature of the middle sheet to be the average temperature of the two side sheets and the wall temperatures of the two side sheets to be equal, so that the wall temperature of the PTFE of the 3 rd sheet to be-137 ℃, the wall temperature of the stainless steel of the 5 th sheet to be-78 ℃, the wall temperature of the PTFE of the 7 th sheet to be-19 ℃ are calculated, natural convection can occur in the air in the interlayer, and the natural convection is mainly determined by the Grating's number (Gr) and the Nussel number (Nu) which are characterized by the thickness delta:
in the formula:
g is the acceleration of gravity;
α is the coefficient of bulk expansion;
Δ t is the temperature difference between the two sides of the interlayer;
v is the kinematic viscosity of air;
k is the thermal conductivity.
Preferably, the surfaces of the aluminum foil-coated stainless steel sheet and the aluminum foil-coated PTFE sheet are insulated from heat radiation, and a narrow air layer is formed between each two layers to reduce air convection and increase the overall heat conduction resistance.
Preferably, the equivalent heat conductivity coefficient of the air layer between the aluminum foil-coated stainless steel sheet and the aluminum foil-coated PTFE sheet is calculated by adopting a correlation formula of natural convection heat transfer coefficients between vertical/horizontal narrow walls, the coupling apparent heat conductivity coefficient of the multilayer structure is calculated by adopting a series thermal resistance formula, and the obtained sheets are 2mm in thickness, 4mm in thickness of the air layer and 26mm in total thickness of the material.
Preferably, Gr in bδNumber of<2000, heat transfer in interlayer depends on heat conduction, Nu in correlation is calculatedδIs 1; when 2000<Grδ<2×105When the temperature of the water is higher than the set temperature,
(H is a clipThe height of the layer);
equivalent heat conductivity coefficient calculation formula:
the equivalent thermal conductivity of the multilayer insulation process was found to be about 0.0558W/m/K at 1 atmosphere.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
the method is combined with a thermal radiation heat insulation method taking radiation as a main heat exchange way in a vacuum environment and a thermal convection heat insulation method taking convection as a main heat exchange way, a new composite heat insulation method is developed, radiation, convection and heat conduction are considered, the method is verified by actual engineering use and actual heat test, the effect is excellent, the method has low air release rate, and when a test piece in the equipment is between 196 ℃ and 300 ℃, the normal temperature of the outer wall of the equipment can be kept, the installation and the use are convenient, and the temperature is 10 DEG C-4Pa (vacuum) -105The heat insulation performance is good in the whole range between Pa (normal pressure).
Drawings
FIG. 1 illustrates a schematic structural view of a composite structural insulating material provided in accordance with an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating calculation of natural convection parameters in a sandwich according to an embodiment of the present invention;
FIG. 3 shows a schematic diagram of parameters for each layer of insulation material provided according to an embodiment of the present invention.
Illustration of the drawings:
1. coating an aluminum foil stainless steel sheet; 2. coating an aluminum foil PTFE sheet; 3. a connecting member.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-3, the present invention provides a technical solution:
a universal composite thermal insulation method suitable for vacuum and normal pressure environments comprises the following parts:
a. the composite heat insulating material is arranged, wherein a multi-layer aluminum foil-coated stainless steel sheet 1 and an aluminum foil-coated PTFE sheet 2 are fixed through a connecting piece 3 to form a 9-layer structure of stainless steel, an air layer, PTFE, an air layer, stainless steel, an air layer, PTFE, an air layer and stainless steel;
b. thermal analysis: setting the wall temperature of the first stainless steel layer to be liquid nitrogen temperature-196 ℃, the wall temperature of the ninth stainless steel layer to be 40 ℃, and setting the wall temperature of the middle sheet to be the average temperature of the two side sheets and the wall temperatures of the two side sheets to be equal, so that the wall temperature of the PTFE of the 3 rd sheet to be-137 ℃, the wall temperature of the stainless steel of the 5 th sheet to be-78 ℃, the wall temperature of the PTFE of the 7 th sheet to be-19 ℃ are calculated, natural convection can occur in the air in the interlayer, and the natural convection is mainly determined by the Grating's number (Gr) and the Nussel number (Nu) which are characterized by the thickness delta:
in the formula:
g is the acceleration of gravity;
α is the coefficient of bulk expansion;
Δ t is the temperature difference between the two sides of the interlayer;
v is the kinematic viscosity of air;
k is the thermal conductivity.
Specifically, as shown in fig. 1, the surfaces of the aluminum foil-coated stainless steel sheet 1 and the aluminum foil-coated PTFE sheet 2 are insulated from heat radiation, and a narrow air layer is formed between the layers to reduce air convection and increase overall thermal conductivity and resistance.
Specifically, as shown in fig. 2, the equivalent thermal conductivity of the air layer between the aluminum-clad stainless steel sheet 1 and the aluminum-clad PTFE sheet 2 is calculated by using a correlation formula of natural convection heat transfer coefficients between vertical and horizontal narrow walls, and the coupling apparent thermal conductivity of the multilayer structure is calculated by using a series thermal resistance formula, so that the sheet thickness is 2mm, the air layer thickness is 4mm, and the total material thickness is 26 mm.
Specifically, as shown in FIG. 3, Gr in bδNumber of<2000, heat transfer in interlayer depends on heat conduction, Nu in correlation is calculatedδIs 1; when 2000<Grδ<2×105When the temperature of the water is higher than the set temperature,
(H is the height of the interlayer);
equivalent heat conductivity coefficient calculation formula:
the equivalent thermal conductivity of the multilayer insulation process was found to be about 0.0558W/m/K at 1 atmosphere.
The previous description of the embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (4)
1. A universal composite heat insulation method suitable for vacuum and normal pressure environments is characterized by comprising the following parts:
a. the composite heat insulation material is arranged, wherein a multi-layer aluminum foil-coated stainless steel sheet (1) and an aluminum foil-coated PTFE sheet (2) are fixed through a connecting piece (3) to form a 9-layer structure of stainless steel, an air layer, PTFE, an air layer, stainless steel, an air layer, PTFE, an air layer and stainless steel;
b. thermal analysis: setting the wall temperature of the first layer of stainless steel to be liquid nitrogen temperature-196 ℃, the wall temperature of the ninth layer of stainless steel to be 40 ℃, the wall temperature of the middle sheet to be the average temperature of the two side sheets, and the wall temperatures of the two side sheets are equal, calculating to obtain the PTFE wall temperature of the 3 rd layer sheet to be-137 ℃, the stainless steel wall temperature of the 5 th layer sheet to be-78 ℃, the PTFE wall temperature of the 7 th layer sheet to be-19 ℃, natural convection can occur in the air in the interlayer, and the natural convection is mainly determined by the Grating Xiaoff number (Gr) and the Knudel number (Nu) which are characterized by the thickness delta:
in the formula:
g is the acceleration of gravity;
α is the coefficient of bulk expansion;
Δ t is the temperature difference between the two sides of the interlayer;
v is the kinematic viscosity of air;
k is the thermal conductivity.
2. The universal composite thermal insulation method suitable for vacuum and normal pressure environment as claimed in claim 1, wherein the surface of the aluminum foil coated stainless steel sheet (1) and the aluminum foil coated PTFE sheet (2) is insulated from heat radiation, and a narrow air layer is formed between each layer to reduce air convection and increase the overall thermal conductivity and resistance.
3. The general composite heat insulation method suitable for the vacuum and normal pressure environment as claimed in claim 2, wherein the equivalent heat conductivity of the air layer between the aluminum foil-coated stainless steel sheet (1) and the aluminum foil-coated PTFE sheet (2) is calculated by adopting a correlation formula of natural convection heat transfer coefficients between vertical and horizontal narrow walls, the coupling apparent heat conductivity of the multilayer structure is calculated by adopting a series thermal resistance formula, and the obtained sheets have the thickness of 2mm, the thickness of the air layer of 4mm and the total thickness of the material of 26 mm.
4. The method of claim 1, wherein Gr in b is the Gr valueδNumber of<2000, heat transfer in interlayer depends on heat conduction, Nu in correlation is calculatedδIs 1; when 2000<Grδ<2×105When the temperature of the water is higher than the set temperature,
(H is the height of the interlayer);
equivalent heat conductivity coefficient calculation formula:
the equivalent thermal conductivity of the multilayer insulation process was found to be about 0.0558W/m/K at 1 atmosphere.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210086750.XA CN114414622B (en) | 2022-01-25 | 2022-01-25 | Universal composite heat insulation method suitable for vacuum and normal pressure environment |
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| CN202210086750.XA CN114414622B (en) | 2022-01-25 | 2022-01-25 | Universal composite heat insulation method suitable for vacuum and normal pressure environment |
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| CN114414622A true CN114414622A (en) | 2022-04-29 |
| CN114414622B CN114414622B (en) | 2024-03-19 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US6742926B1 (en) * | 2000-07-10 | 2004-06-01 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Methods of testing thermal insulation and associated test apparatus |
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| US9678025B1 (en) * | 2009-06-12 | 2017-06-13 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Guarded flat plate cryogenic test apparatus and calorimeter |
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| US20190126591A1 (en) * | 2016-04-28 | 2019-05-02 | Natureworks Llc | Polymer foam insulation structure having a facing of a multi-layer sheet that contains a heat resistant polymer layer and a polylactide resin layer |
| CN209284113U (en) * | 2018-11-07 | 2019-08-23 | 新麦机械（中国）有限公司 | A kind of layer of furnace door structure |
| CN110998166A (en) * | 2017-08-01 | 2020-04-10 | Lg电子株式会社 | Vacuum insulator and refrigerator |
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2022
- 2022-01-25 CN CN202210086750.XA patent/CN114414622B/en active Active
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6742926B1 (en) * | 2000-07-10 | 2004-06-01 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Methods of testing thermal insulation and associated test apparatus |
| US20100251653A1 (en) * | 2007-03-16 | 2010-10-07 | Ball Aerospace & Technologies Corp. | Integrated Multilayer Insulation |
| CN101619797A (en) * | 2009-06-09 | 2010-01-06 | 深圳市金士康实业有限公司 | Heat-insulation film and preparation method thereof |
| US9678025B1 (en) * | 2009-06-12 | 2017-06-13 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Guarded flat plate cryogenic test apparatus and calorimeter |
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