WO2022267417A1 - High-vacuum multi-layer flexible thermal insulation tube for high-temperature superconducting cable and fabrication method - Google Patents

Abstract

A high-vacuum multi-layer flexible thermal insulation tube for a high-temperature superconducting cable and a fabrication method, the flexible thermal insulation tube comprising an outer tube (15), an inner tube (14), and an interface flange (7). The flexible thermal insulation tube further comprises: a vacuum interlayer (1), which is located between the inner tube and the outer tube; a multi-layer thermal insulation material (2), which is located on the side of the vacuum interlayer close to an outer wall of the inner tube for thermal insulation; and protrusions (3) are provided on the outer wall of the inner tube so as to reduce the contact area between the multi-layer thermal insulation material and the outer wall of the inner tube. The contact area between the thermal insulation material of the flexible thermal insulation tube and the outer wall of the inner tube is small, the evacuation efficiency is high, and the thermal insulation performance is good. Moreover, in the fabrication method, heat leakage data of different thermal insulation tubes is accurately calculated and simulated, which provides a strong guarantee for the design of thermal insulation tubes and the verification of the performance of thermal insulation tubes.

Description

High-vacuum multi-layer flexible heat-insulating tube for high-temperature superconducting cables and manufacturing method technical field

The invention relates to the field of superconducting cables, in particular to a high-vacuum multilayer flexible heat-insulating tube for high-temperature superconducting cables and a manufacturing method.

Background technique

The application of superconducting technology in power systems is diverse, and it is also one of the main directions of superconducting application research in recent years. Compared with power cables, superconducting cables have great advantages, such as: strong power transmission capacity, cost saving, small footprint, extremely low line impedance, small transmission loss, and strong anti-magnetic interference ability; relatively low The voltage can be used for long-distance transmission, and it can also be transmitted underground to avoid noise, electromagnetic pollution and safety hazards caused by ultra-high-voltage high-altitude transmission, and to protect the ecological environment.

As an important part of the high-temperature superconducting cable, the flexible insulating tube can ensure that the superconducting tape inside it is kept at a fixed ambient temperature for a long time without affecting the transmission performance of the superconducting tape due to heat leakage or heat transfer. However, the prior art has not yet provided an accurate and reasonable design scheme of the heat insulation pipe that can meet the heat insulation performance of the heat insulation pipe and the design requirements of the superconducting cable.

Therefore, there is an urgent need for a high-vacuum multi-layer flexible heat-insulating pipe and a manufacturing method for high-temperature superconducting cables.

Contents of the invention

In order to solve the deficiencies in the prior art, the purpose of the present invention is to provide a high-vacuum multi-layer flexible heat-insulated pipe for high-temperature superconducting cables and a manufacturing method, the heat-insulated pipe has protrusions on the outer wall of the inner pipe, The contact area between the heat insulating material and the outer wall of the inner pipe can be reduced, thereby improving the evacuation efficiency of the vacuum interlayer. In addition, the manufacturing method of the present invention accurately estimates the heat leakage of the heat insulation pipe by calculating the heat leakage of the heat insulation pipe, and obtains an optimal design scheme of the heat insulation pipe.

The present invention adopts the following technical solutions.

The first aspect of the present invention relates to a high-vacuum multi-layer flexible heat-insulating pipe for high-temperature superconducting cables, including an outer pipe, an inner pipe, and an interface flange, wherein the flexible heat-insulating pipe also includes: a vacuum interlayer 1 located inside Between the tube and the outer tube; the multi-layer thermal insulation material 2 is located on the side of the vacuum interlayer close to the outer wall of the inner tube for heat insulation; the outer wall of the inner tube has protrusions 3 to reduce the distance between the multi-layer thermal insulation material and the outer wall of the inner tube Contact area.

Preferably, the height of the protrusions on the outer wall of the inner tube is between 3 and 5 mm, which is used to reduce the contact area between the multi-layer heat insulating material and the outer wall of the inner tube, so as to improve the evacuation efficiency of the vacuum interlayer.

Preferably, the protrusions on the outer wall of the inner tube are equally spaced on the outer wall of the inner tube.

Preferably, the multi-layer heat insulation material includes a multi-layer heat insulation unit; wherein, each layer of heat insulation unit also includes at least a reflective screen material and a heat insulation material, and the heat insulation material is glass fiber paper or chemical fiber paper.

Preferably, the vacuum interlayer of the flexible heat-insulated pipe also includes a support 4 located in the middle of the pipe, a hydrogen removal agent 5 located at one end of the pipe, and a low-temperature adsorbent 6 located at the other end of the pipe; the support 4 is helically wound outside the heat-insulating material Teflon tube or perforated Teflon ring.

The second aspect of the present invention relates to a method for manufacturing a high-vacuum multi-layer flexible heat-insulating tube for high-temperature superconducting cables as in the first aspect of the present invention, which includes the following steps: Step 1, based on the simulation test of liquid nitrogen flow in the corrugated tube , superconducting cable design index to obtain the size parameters of the flexible insulation tube used for high-temperature superconducting cables; step 2, put the pre-designed multi-layer insulation material in the calorimeter to obtain the heat leakage of the multi-layer insulation material, and simulate Obtain the heat conduction of the support; step 3, design the internal structure of the thermal insulation tube based on the thermal insulation requirements of the thermal insulation tube, and evaluate the design of the internal structure of the thermal insulation tube based on the heat leakage calculation.

Preferably, the dimensional parameters of the flexible heat insulating pipe obtained based on step 1 at least include: inner pipe diameter and outer pipe diameter of the heat insulating pipe.

Preferably, step 2 also includes: placing a pre-designed multi-layer thermal insulation material in the measuring cylinder of the calorimeter and the vacuum cavity outside the thermal insulation cover; injecting coolant into the protective cylinder to make the temperature of the calorimeter equal to the high temperature Superconducting cable; connect the measuring cylinder in the calorimeter with the flowmeter, and measure the leakage heat of different types of pre-designed multi-layer insulation materials to select the optimal model.

Preferably, step 2 further includes: simulating the structure of the support to obtain the structural temperature and heat leakage distribution of the support.

Preferably, the calculation of heat leakage in step 3 is specifically as follows: step 3.1, based on the material, size, temperature of the inner and outer pipes in the flexible insulation pipe, and the number of layers of radiation screens between the inner and outer pipes, the inner and outer pairs of the outer and outer pipes in the flexible insulation pipe are obtained. The heat radiation value of the tube; step 3.2, based on the vacuum degree of the vacuum interlayer, the size and temperature of the inner and outer tubes to obtain the value of the residual gas leakage heat in the vacuum layer; step 3.3, set the value of the heat leakage of the support ; Step 3.4, based on the value of heat radiation from the outer tube to the inner tube, the value of the heat leakage of the residual gas in the vacuum layer, and the value of the heat leakage of the support to obtain the total heat load of the heat insulating tube.

The beneficial effect of the present invention is that, compared with the prior art, a high-vacuum multi-layer flexible heat-insulating tube for high-temperature superconducting cables and its manufacturing method in the present invention can reduce the The contact area between the heat insulating material and the outer wall of the inner pipe improves the evacuation efficiency of the vacuum interlayer, thereby ensuring the heat insulation efficiency of the heat insulating pipe. The manufacturing method of the heat insulating tube in the present invention can accurately calculate and simulate the heat leakage data of the heat insulating tube in different heat insulating tube design schemes, so as to provide a strong guarantee for the design of the heat insulating tube and the verification of the performance of the heat insulating tube.

Description of drawings

Fig. 1 is the structural representation of the high vacuum multi-layer flexible heat-insulated tube with projections on the inner tube outer wall used for high temperature superconducting cables in the present invention;

Figure 2: a first thermal insulation unit; b second thermal insulation unit; c third thermal insulation unit;

3 is a schematic flow chart of the steps of the manufacturing method of the high-vacuum multi-layer flexible heat-insulated tube used for high-temperature superconducting cables in the present invention;

Fig. 4 is the calorimeter structure schematic diagram in the manufacturing method of the high-vacuum multi-layer flexible heat-insulated pipe used in the high-temperature superconducting cable in the present invention;

5 is a schematic diagram of the appearance of the calorimeter in the manufacturing method of the high-vacuum multi-layer flexible heat-insulated tube used for high-temperature superconducting cables in the present invention;

Fig. 6 is a schematic diagram of the simulation situation of the external structure temperature and heat conduction distribution of the support member of the polytetrafluoroethylene tube in the manufacturing method of the high-vacuum multi-layer flexible heat-insulated tube used for high-temperature superconducting cables in the present invention;

Fig. 7 is a schematic diagram of the simulation situation of internal structure temperature and heat conduction distribution of the support member of the polytetrafluoroethylene tube in the manufacturing method of the high-vacuum multi-layer flexible heat-insulated tube for high-temperature superconducting cables in the present invention.

Reference signs:

1-vacuum interlayer,

2- multi-layer insulation material,

3- bumps,

4-support,

5- Hydrogen remover,

6- low temperature adsorbent,

7-Interface flange,

8 - vacuum chamber,

9 - Measuring cylinder,

10-Protection cylinder filling pipe,

11 - protection tube,

12 - insulation quilt,

13 - flow meter,

14 - inner tube,

15 - outer tube,

16 - glass wool.

detailed description

The application will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, but not to limit the protection scope of the present application.

Fig. 1 is a schematic structural diagram of a high-vacuum multi-layer flexible heat-insulated tube used in a high-temperature superconducting cable in the present invention. As shown in FIG. 1 , a high-vacuum multi-layer flexible heat-insulating pipe for high-temperature superconducting cables includes an outer pipe, an inner pipe, and an interface flange 7 .

The flexible heat-insulated pipe also includes: a vacuum interlayer 1, located between the inner pipe and the outer pipe; multi-layer insulation material 2, located in the vacuum interlayer close to the outer wall of the inner pipe, for heat insulation; there are protrusions on the outer wall of the inner pipe 3. To reduce the contact area between the multi-layer insulation material and the outer wall of the inner pipe.

In the research process of high vacuum multilayer insulation, it is found that the interlayer pressure of multilayer insulation material 2 is usually 1 to 2 orders of magnitude higher than the pressure of vacuum interlayers and protrusions. There is still interlayer residual gas that has not been evacuated. Because the heat conduction of interlayer residual gas will lead to insufficient heat insulation effect, how to reduce interlayer residual gas and increase the vacuum degree between multilayer insulation materials cannot be ignored. In addition, due to the large evacuation resistance of the multi-layer thermal insulation material, the evacuation efficiency is low and the evacuation time is long, which not only causes energy consumption during the evacuation process, but also has an unsatisfactory evacuation effect. For this reason, the present invention proposes a high-vacuum multi-layer heat insulation scheme with protrusions 3 on the outer wall of the inner tube of the heat-insulation tube on the basis of high-vacuum multi-layer heat insulation.

Since the protrusions 3 are added on the outer wall of the heat insulating tube, this effectively reduces the contact area between the multi-layer material and the outer wall of the inner tube, thereby greatly reducing the solid heat conduction. Since an air gap is formed between the protrusions 3, the air gap can enable the vacuum device to effectively evacuate the air existing between the multi-layer material and the outer wall of the inner tube. At the same time, as the pressure between the multi-layer insulation materials decreases, the heat conduction of the gas decreases, and the evacuation efficiency will be further improved.

Preferably, the height of the protrusions 3 on the outer wall of the inner tube is between 3 and 5 mm, which is used to reduce the contact area between the multi-layer heat insulating material 2 and the outer wall of the inner tube, so as to improve the evacuation efficiency of the vacuum interlayer.

Preferably, the protrusions 3 on the outer wall of the inner tube are distributed at equal intervals on the outer wall of the inner tube. Specifically, the protrusions 3 are regularly arranged on the outer wall of the inner tube at regular intervals, while keeping other structures on the outer wall of the inner tube unchanged.

Preferably, the multilayer heat insulation material 2 includes multilayer heat insulation units; wherein, each layer of heat insulation units also includes at least reflective screen material and heat insulation material, and the heat insulation material is glass fiber paper or chemical fiber paper. In an embodiment of the present invention, the multi-layer heat insulation material may be three layers, and the composition of each layer of heat insulation material is different, and each layer of heat insulation material may also have multiple layers of different materials made by pressing, etc., but All of them must contain a reflective screen layer for anti-radiation and a thermal insulation layer for thermal insulation. In an embodiment of the present invention, the material and number of layers of the heat insulation material in each layer of the multilayer heat insulation material are different. Specifically, in each layer of heat insulating material, absorbing material, anti-radiation material, heat insulating material and fixing material may be included. For example, adsorption materials are used to adsorb interlayer gases, such as water vapor, nitrogen, and oxygen, to increase the vacuum degree between material layers, thereby reducing the heat conduction of interlayer gases and improving thermal insulation performance. Anti-radiation materials can act as reflective screens to reduce radiative heat transfer. Heat insulation materials such as glass fiber paper and chemical fiber paper can be used to space reflective screens to prevent direct contact between reflective screens and reduce heat conduction. Fixing materials such as glass fiber tape can be used to fix each layer of insulation material to prevent damage to the insulation tube caused by material falling off and ensure the firmness and safety of the insulation structure.

Preferably, the vacuum interlayer 1 of the flexible heat-insulated pipe also includes a support 4 located in the middle of the pipe, a hydrogen removal agent 5 located at one end of the pipe, and a low-temperature adsorbent 6 located at the other end of the pipe; Teflon tube or perforated Teflon ring.

The second aspect of the present invention relates to a method for manufacturing a high-vacuum multi-layer flexible heat-insulating tube for high-temperature superconducting cables. Fig. 2 is a schematic flowchart of the steps of the manufacturing method of the high-vacuum multi-layer flexible heat-insulated tube used for high-temperature superconducting cables in the present invention. As shown in FIG. 2 , the method of the present invention includes Step 1 to Step 3 .

The flexible heat insulating pipe in the present invention is based on the calculation of the heat leakage of the flexible heat insulating pipe. Generally speaking, there are two methods for calculating heat leakage of thermal insulation materials. The first is to calculate the heat leakage of each layer of material in the multilayer insulation material layer by layer. The second is to independently calculate the radiation, convection, and heat conduction of multilayer insulation materials, and then algebraically sum the above data. However, since multilayer insulation materials not only involve radiation, convection, and heat conduction between gas and solid, there will also be secondary effects between the above-mentioned radiation and heat conduction, and because the heat leakage performance of multilayer insulation materials is more easily affected by the pre-treatment process , wrapping implementation process, material vacuum performance and other factors, therefore, the theoretical calculation results of multilayer insulation materials can not well meet the needs of practical engineering.

In actual engineering experience, the method of engineering calorimeter experimental test can be used to obtain the thermal insulation performance of multilayer materials under high vacuum. At the same time, based on the heat transfer theory, the heat conduction of structures such as supports, internal and external pipelines can be calculated, so as to finally obtain the total leakage heat of the heat insulating pipe.

Step 1, based on the liquid nitrogen flow simulation test in the bellows and the design index of the superconducting cable, the size parameters of the flexible heat insulating tube used for the high temperature superconducting cable are obtained.

Preferably, the dimensional parameters of the flexible heat insulating pipe obtained based on step 1 at least include: inner pipe diameter and outer pipe diameter of the heat insulating pipe. In one embodiment of the present invention, the diameter of the stainless steel inner tube that can be provided with the heat insulating tube is 120 mm, and the diameter of the stainless steel outer tube is 180 mm.

In addition, according to the design size parameters of the superconducting cable core cable, it can be set that when the conductor core is cabled, the outer diameter of the cable inside the stainless steel inner tube is 100mm. According to the welding requirements, protection requirements, forming requirements and production experience of the bellows, the welding gap of the heat insulating pipe is set. Wherein, the welding gap of the inner tube may be 20 mm, and the welding gap of the outer tube may be 18 mm. In addition, the thickness of the metal mesh sleeve can also be set to 1mm, the thickness of the inner support to 5mm, the thickness of the outer support to 6mm, the thickness of the heat insulation layer to 9mm and so on.

Step 2: Put the pre-designed multi-layer insulation material in the calorimeter to obtain the leakage heat of the multi-layer insulation material, and simulate to obtain the heat conduction of the support.

Preferably, step 2 also includes: placing a pre-designed multi-layer thermal insulation material in the measuring cylinder of the calorimeter and the vacuum cavity outside the heat insulation cover; injecting coolant into the protective cylinder to make the temperature of the calorimeter equal to the high temperature superconducting cables;

The measuring cylinder in the calorimeter is connected with a flow meter, and the leakage heat of different types of pre-designed multi-layer heat insulation materials is measured to select the optimal type.

Fig. 3 is a schematic diagram of the structure of the calorimeter in the manufacturing method of the high-vacuum multi-layer flexible heat-insulated tube used for high-temperature superconducting cables in the present invention. Fig. 4 is a schematic diagram of the appearance of the calorimeter in the manufacturing method of the high-vacuum multi-layer flexible heat-insulated tube used for high-temperature superconducting cables in the present invention. As shown in FIG. 3 and FIG. 4 , the interior of the calorimeter includes a vacuum chamber 8 , a measuring cylinder 9 interconnected with a flowmeter 13 , and a protection cylinder and a protection cylinder filling pipe 10 for adding refrigerating liquid. The measuring cylinder 9 and the protection cylinder 11 are in the shape of a cylinder, and are arranged coaxially with the cylindrical shell of the calorimeter. A thermal insulation quilt 12 is also arranged on the outside of the protection cylinder and the measurement cylinder.

In step 2, a plurality of different multi-layer heat insulating materials expected to be used in the present invention can be laid sequentially on the outer layer of heat insulation. Add liquid, for example, liquid nitrogen, into the protection cylinder through the liquid feeding pipe, so that the temperature inside the calorimeter is consistent with the normal working state of the superconducting cable under liquid nitrogen. The flow data of the measuring cylinder is obtained through the flowmeter, and the leakage heat of the multi-layer insulation material is obtained from this.

Since three different multi-layer heat insulating materials are pre-designed in the present invention. Here, the three different multilayer insulation materials, ie, the first, second and third insulation units shown in FIG. 2 , can be referred to as empty composite insulation units, multilayer insulation units, and protrusion insulation units in sequence. The number of layers and laying arrangements of different materials in these three insulation materials are different.

After testing the heat leakage of these three materials, the heat leakage performance of the three multilayer insulation materials can be compared.

Table 1. Thermal insulation performance table of three different multilayer thermal insulation materials pre-designed

The calorimeter is used to measure the leakage heat of the multi-layer heat insulating material provided in the cylindrical environment with an inner pipe diameter of 120 mm and an outer pipe diameter of 180 mm. The total heat leakage was found to be 250W for the empty composite insulation, 103W for the multilayer insulation, and 90W for the raised insulation. In addition, since the heat transfer areas of the three materials are equal and are all 150m ² , the specific heat flow of the three materials can be obtained as 1.67W/m ² , 0.69W/m ² and 0.60W/m ² respectively.

Comparing the specific heat flow parameters of the three materials, it can be seen that the thermal insulation performance of the protrusion insulation material is the best, that of the multilayer insulation material is second, and that of the empty composite insulation material is the worst. Therefore, according to the above experiments, the verified heat insulating material can be selected for use in the heat insulating pipe.

In addition, in step 2, the heat conduction of the support is also checked. In the present invention, two different support structures can be used. The first is a Teflon tube with an outer helically wound insulation material, and the second is a Teflon ring with holes.

Specifically, step 2 also includes: simulating the structure of the support to obtain the structural temperature and heat leakage distribution of the support. Fig. 5 is a schematic diagram of the temperature and heat conduction distribution simulation of the support of the polytetrafluoroethylene tube in the manufacturing method of the high-vacuum multi-layer flexible heat-insulated tube for high-temperature superconducting cables in the present invention. Fig. 6 is a schematic diagram of the simulation situation of internal structure temperature and heat conduction distribution of the support member of the polytetrafluoroethylene tube in the manufacturing method of the high-vacuum multi-layer flexible heat-insulated tube for high-temperature superconducting cables in the present invention. As shown in Fig. 5 and Fig. 6, the structure of the supporting member is simulated by the simulation software commonly used in the prior art, and the temperature and heat leakage at different parts of the supporting member are simulated. The heat leakage of the support used in the present invention was 8.1W.

Step 3: Design the internal structure of the thermal insulation tube based on the thermal insulation requirements of the thermal insulation tube, and evaluate the design of the internal structure of the thermal insulation tube based on the heat leakage calculation.

According to the heat leakage data of the multi-layer insulation material and the heat conduction data of the support obtained in step 2, and comparing the heat insulation requirements of the superconducting cable insulation pipe, the internal structure of the heat insulation pipe can be preliminarily designed.

Specifically, in the present invention, three different design methods can be adopted for the internal structure of the heat insulating tube. The first method is to add multiple layers of heat insulating material and glass wool between the inner and outer pipes of the heat insulating pipe. The temperature of the inner and outer tubes is insulated by means of thermal insulation material and ultra-fine glass wool. The second method is to use a high vacuum multi-layer insulation flexible sleeve. The inner tube is provided with multiple layers of heat insulating material, such as three layers of heat insulating material, and the inner and outer tubes are sealed and pumped into a vacuum state, and the heat insulation is carried out by the vacuum and the heat insulating material. Because in the second method, there will be a large amount of air in the gap between the heat insulating material and the inner pipe, and it is difficult to be extracted by the vacuum equipment. Therefore, in the present invention, the third method is adopted. The third method is to use a high-vacuum multi-layer heat-insulating flexible sleeve, and the outer wall of the inner tube is provided with protrusions in a certain order. Due to the existence of the protrusions, the air between the outer wall of the inner pipe and the multi-layer heat insulation material is more easily drawn out, thereby ensuring the heat insulation performance of the vacuum interlayer. Therefore, compared with the second method, the third method has a better heat insulation effect, can increase the heat insulation efficiency by 8% to 10%, and can increase the evacuation efficiency by about 30%.

Specifically, the calculation of the heat leakage theory can be carried out according to the design scheme to evaluate the design scheme.

Preferably, the heat leakage calculation in step 3 is specifically as follows:

Step 3.1, based on the material, size, temperature of the inner and outer pipes in the flexible insulating pipe, and the number of layers of radiation screens between the inner and outer pipes, the value of the heat radiation from the outer pipe to the inner pipe in the flexible insulating pipe is obtained.

The formula for calculating the heat radiation from the outer tube to the inner tube in the flexible insulating tube is:

In the formula, ε is emissivity;

σ is the Stefan-Boltzmann constant, and σ=5.67×10 ^-8 W/(m ² ·K ⁴ );

A is the surface area of the inner tube of the flexible thermal insulation tube;

T ₂ is the temperature of the outer tube, and in the embodiment of the invention, T ₂ =300K;

T ₁ is the temperature of the inner tube, and in the embodiment of the present invention, T ₁ =68K;

F _1-2 is the angle coefficient of radiation heat transfer, and there is F _1-2 =1;

n is the number of layers of the radiation screen, which is related to the composition of the multi-layer insulation material.

In addition, for the parameter ε _1-2 , its calculation formula is:

Among them, ε ₁ and ε ₂ are the emissivity of stainless steel at normal temperature and low temperature (ie 68K) respectively.

Substituting formula (2) into formula (1), the heat radiation value Q ₁ =0.132W/m from the outer tube to the inner tube in the heat insulating tube can be obtained.

Step 3.2, based on the vacuum degree of the vacuum interlayer, the size and temperature of the inner tube and the outer tube, the residual gas leakage heat value of the vacuum layer is obtained.

In the inventive method, the calculation formula of residual gas leakage heat is:

Q ₂ =k×a×p×(T ₂ −T ₁ )×A (3)

In the formula, k is a coefficient, and k=1.2001;

a is thermal adaptation coefficient, and a=1;

p is the vacuum degree of the interlayer, and in the present invention, p=0.01Pa.

According to the method in the present invention, Q ₂ =1.01W/m.

Step 3.3, setting the leakage heat value of the support.

In the present invention, the heat leakage value of the support can also be set, or the value of the heat leakage of the support can be approximated by a simulation method. In the present invention, the leakage heat of the support can be set as Q ₃ =0.713W/m.

Step 3.4, based on the heat radiation value of the outer tube to the inner tube, the residual gas leakage heat value of the vacuum layer, and the heat leakage heat value of the support member to obtain the total heat load of the heat insulating pipe.

In the present invention, the calculation formula of the total heat load of the heat insulating pipe is:

Q＝Q ₁ +Q ₂ +Q ₃ (4)

According to the method in the present invention, it can be known that the total heat load Q≈1.9W/m of the heat insulating pipe.

The beneficial effect of the present invention is that, compared with the prior art, a high-vacuum multi-layer flexible heat-insulating tube for high-temperature superconducting cables and its manufacturing method in the present invention can reduce the The contact area between the heat insulating material and the outer wall of the inner pipe improves the evacuation efficiency of the vacuum interlayer, thereby ensuring the heat insulation efficiency of the heat insulating pipe. The manufacturing method of the heat insulating tube in the present invention can accurately calculate and simulate the heat leakage data of the heat insulating tube in different heat insulating tube design schemes, so as to provide a strong guarantee for the design of the heat insulating tube and the verification of the performance of the heat insulating tube.

The applicant of the present invention has made a detailed illustration and description of the implementation examples of the present invention in conjunction with the accompanying drawings, but those skilled in the art should understand that the above implementation examples are only preferred implementations of the present invention, and the detailed description is only to help readers better To understand the spirit of the present invention rather than to limit the protection scope of the present invention, on the contrary, any improvement or modification made based on the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. A high-vacuum multi-layer flexible heat-insulating tube for high-temperature superconducting cables, including an outer tube, an inner tube, and an interface flange, is characterized in that:

   The flexible heat insulation pipe also includes:

   a vacuum interlayer (1), located between the inner tube and the outer tube;

   A multi-layer heat insulating material (2), located in the vacuum interlayer on a side close to the outer wall of the inner tube, for heat insulation;

   There are protrusions (3) on the outer wall of the inner tube to reduce the contact area between the multi-layer heat insulating material and the outer wall of the inner tube.
2. The high-vacuum multi-layer flexible heat-insulating pipe for high-temperature superconducting cables according to claim 1, characterized in that:

   The height of the protrusions on the outer wall of the inner tube is between 3 and 5 mm, which is used to reduce the contact area between the multi-layer heat insulating material and the outer wall of the inner tube, so as to improve the evacuation efficiency of the vacuum interlayer.
3. The high-vacuum multi-layer flexible heat-insulating pipe for high-temperature superconducting cables according to claim 2, characterized in that:

   The protrusions on the outer wall of the inner tube are distributed at equal intervals on the outer wall of the inner tube.
4. The high-vacuum multi-layer flexible heat-insulating pipe for high-temperature superconducting cables according to claim 1, characterized in that:

   The multilayer insulation material includes a multilayer insulation unit;

   Wherein, each layer of heat insulation unit also includes at least reflective screen material and heat insulation material, and the heat insulation material is glass fiber paper or chemical fiber paper.
5. The high-vacuum multi-layer flexible heat-insulating pipe for high-temperature superconducting cables according to claim 1, characterized in that:

   The vacuum interlayer of the flexible heat-insulating tube also includes a support (4) located in the middle of the tube, a hydrogen removal agent (5) located at one end of the tube, and a low-temperature adsorbent (6) located at the other end of the tube;

   The supporting member (4) is a polytetrafluoroethylene tube or a perforated polytetrafluoroethylene ring that is helically wound outside the heat insulating material.
6. The method for manufacturing the high-vacuum multi-layer flexible heat-insulated pipe for high-temperature superconducting cables as claimed in claims 1-5, characterized in that it comprises the following steps:

   Step 1, based on the liquid nitrogen flow simulation test in the bellows and the design index of the superconducting cable, the size parameters of the flexible insulation tube used for the high-temperature superconducting cable are obtained;

   Step 2, placing the pre-designed multi-layer thermal insulation material in a calorimeter to obtain the leakage heat of the multi-layer thermal insulation material, and simulate to obtain the heat conduction of the support;

   Step 3: Design the internal structure of the thermal insulation tube based on the thermal insulation requirements of the thermal insulation tube, and evaluate the design of the internal structure of the thermal insulation tube based on the heat leakage calculation.
7. According to the manufacturing method of the high-vacuum multi-layer flexible heat-insulating pipe for high-temperature superconducting cables described in claim 6, it is characterized in that:

   The dimensional parameters of the flexible heat insulating pipe obtained based on step 1 at least include: inner pipe diameter and outer pipe diameter of the heat insulating pipe.
8. The method for manufacturing a high-vacuum multi-layer flexible heat-insulating tube for high-temperature superconducting cables according to claim 6, characterized in that:

   Said step 2 also includes:

   The pre-designed multi-layer insulation material is placed in the measuring cylinder of the calorimeter and the vacuum cavity outside the insulation cover;

   injecting coolant into the protective cylinder to make the temperature of the calorimeter equal to that of the high temperature superconducting cable;

   The measuring cylinder in the calorimeter is connected with a flow meter, and the leakage heat of different types of pre-designed multi-layer heat insulation materials is measured to select the optimal type.
9. According to the manufacturing method of the high-vacuum multi-layer flexible heat-insulating pipe for high-temperature superconducting cables described in claim 6, it is characterized in that:

   Said step 2 also includes:

   The structure of the support is simulated to obtain the structural temperature and heat leakage distribution of the support.
10. The method for manufacturing a high-vacuum multi-layer flexible heat-insulating tube for high-temperature superconducting cables according to claim 6, characterized in that:

    The heat leakage operation in the step 3 is specifically:

    Step 3.1, based on the material, size, temperature of the inner and outer pipes in the flexible heat-insulated pipe, and the number of radiation shield layers between the inner and outer pipes, the thermal radiation of the outer pipe to the inner pipe in the flexible heat-insulated pipe is obtained measured value;

    Step 3.2, based on the vacuum degree of the vacuum interlayer, the size and temperature of the inner tube and the outer tube, the value of the heat leakage of the residual gas in the vacuum layer is obtained;

    Step 3.3, setting the leakage heat value of the support member;

    In step 3.4, the total heat load of the heat insulating pipe is obtained based on the heat radiation value of the outer pipe to the inner pipe, the heat leakage value of the residual gas in the vacuum layer, and the heat leakage value of the support member.

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