阅读说明：本技术 一种大换热量低流阻低温氦舱制造方法 (Manufacturing method of low-temperature helium tank with large heat exchange amount and low flow resistance ) 是由 吴克平 张启勇 李云恒 刘志敏 贺瑞聪 邢立明 朱志刚 陆小飞 夏根海 宋庆勇 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种大换热量低流阻低温氦舱制造方法。包括有辐射紫铜板、紫铜冷却盘管、氦舱支架组成,所述氦舱辐射紫铜板内部喷涂特种低温黑漆使内部发射率>0.92,大大提高了辐射效率,所述紫铜冷却盘管采用三股流并联冷却氦舱辐射紫铜板,减小了冷却氦流的温升,使整个氦舱温差很小。采用专用设备的低温冷冻紫铜管弯制工艺保证冷却盘管不凹陷、皱褶,使得冷却氦流流阻满足要求。优化的低温锡焊焊接工艺,以及使用紫铜压片和专用铝箔都大大提高了传热面积,保证了传热效率。(The invention discloses a method for manufacturing a low-temperature helium tank with large heat exchange quantity and low flow resistance. The helium cabin radiation red copper plate cooling device comprises a radiation red copper plate, a red copper cooling coil and a helium cabin support, wherein special low-temperature black paint is sprayed inside the helium cabin radiation red copper plate to enable the internal emissivity to be larger than 0.92, the radiation efficiency is greatly improved, the red copper cooling coil adopts three strands of flow to be connected in parallel to cool the helium cabin radiation red copper plate, the temperature rise of cooling helium flow is reduced, and the temperature difference of the whole helium cabin is small. The low-temperature freezing copper tube bending process adopting special equipment ensures that the cooling coil pipe does not sag or fold, so that the flow resistance of the cooling helium flow meets the requirement. The optimized low-temperature tin soldering welding process and the use of the red copper pressing sheet and the special aluminum foil greatly improve the heat transfer area and ensure the heat transfer efficiency.)

1. A method for manufacturing a low-flow-resistance low-temperature helium chamber with large heat exchange amount is characterized by comprising the following steps of:

(1) calculating the resistance of the pipelines according to the heat load and the required cooling flow, and determining the number of the cooling parallel pipelines;

(2) establishing a heat transfer model according to the sectional diagrams of the cooling pipeline and the welded pipeline of the integral plate to check whether the temperature difference between the inlet and the outlet reaches the design requirement;

(3) determining the length of the pipeline and the flow of cooling the pipeline according to the design, and blanking, soldering, splicing and leveling the copper plate according to the size requirement;

(4) cleaning and degreasing the copper tube and the copper plate (3), clamping by using a clamp, intermittently riveting the cooling copper tube and the copper plate together by using a copper pressing plate (4), and then performing low-temperature tin soldering by adopting a sectional vertical welding method;

(5) the helium tank support (1) is assembled on the bench worker platform according to the size, and then the helium tank cold screen is installed on the helium tank support (1);

(6) and special low-temperature black paint spraying is carried out on the inner part of the helium tank, so that the emissivity of the copper plate is increased.

2. The method according to claim 1, characterized in that in step (1) a plurality of flow resistance calculations are performed in order to ensure a flow resistance of <0.1bar for the cooled helium flow from the refrigerator.

3. The method according to claim 1, wherein in the step (3), the helium chamber is cooled by three flows, a copper pipe without a joint is used as a cooling disc, and a cooling coil is bent by a low-temperature freezing method.

4. The method according to claim 1, wherein in the step (4), the copper tube is straightened and blanked, and is bent by using a special low-temperature freezing platform according to the size requirement.

5. The method according to claim 1, wherein in the step (5), the whole helium tank cold shield has 5 blocks, and copper pipes between the 5 blocks are welded by adopting stainless hoses; and then carrying out vacuum helium mass spectrum leak detection to ensure that a welding seam is not leaked.

6. The method of claim 1, wherein in step (5), a thermally insulating gasket is installed between the helium vessel cold shield and the support (1).

7. The method of claim 1, wherein in step (6), aluminum foil is attached to the exterior of the helium tank.

Technical Field

The invention relates to the technical field of low-temperature vacuum and aerospace, and mainly relates to a manufacturing method of a low-temperature helium chamber with large heat exchange quantity and low flow resistance.

Background

In the fields of scientific research and aerospace, instruments and equipment need to work in an extremely low-temperature vacuum environment, and therefore a 20K low-temperature helium cabin needs to be designed, the helium cabin cools the instruments and equipment to 100K temperature through radiation heat transfer to work, and meanwhile huge heat generated by the equipment needs to be absorbed on the helium cabin to be taken away through the radiation heat transfer mode. The helium tank consists of 5 radiation cold shields, each cold shield is formed by welding a red copper plate and a cooling coil pipe through low-temperature tin soldering, the cold shields are hung on a support through bolts, and the overall structure is shown in figure 1. The instrumentation is placed inside a helium chamber, and the entire helium chamber is placed inside a vacuum vessel. Inside the coil is a cryogenic helium flow provided by a cryogenic helium refrigerator through a cryogenic cooling line. The temperature of the cryogenic helium vessel is controlled by the cryogenic helium flow and the overall system principle is shown in figure 2.

The temperature of the instrument and equipment is 100k higher than the cold screen temperature of the helium tank by 20k, heat generated by the instrument and equipment is absorbed on the red copper plate of the helium tank through radiation heat transfer in a vacuum environment, then the red copper helium plate transfers the heat to the cooling coil, and the heat is taken away by low-temperature helium flow. The whole helium tank is hung on a helium tank support, and in order to reduce heat conduction, heat insulation gaskets are designed between the helium tank and the support and between the support and the base.

Meanwhile, instrument equipment requires that the temperature of the whole helium chamber is uniform and the temperature difference is small, so that the cooling coil adopts a plurality of flows to cool the helium chamber in parallel, and after the low-temperature helium flow is heated and heated, the temperature difference between an inlet and an outlet is small in amplitude, and the optimal cooling flow and cooling flow are calculated through the flow.

In addition, the allowable flow resistance of the cooling helium flow provided by the helium refrigerator is less than 0.1bar, the manufacturing requirement on the cooling coil is high, each cooling path adopts one whole pipe, the resistance generated by a joint is reduced, an elbow is smooth and cannot be folded or sunken, the requirement on the bending process of the copper tube is high, and the difficulty is high.

Since the amount of heat generated by the equipment is large (maximum 500W), it is necessary to greatly improve the efficiency of radiation heat transfer by ensuring that the heat is transferred to the copper plate of the helium tank by radiation heat transfer. How to ensure that the heat absorbed by the red copper plate is conducted to the red copper tube and further to the cooling helium flow needs to optimize the welding process to increase the soldering welding area, and meanwhile, various methods are adopted to increase the heat transfer area between the red copper tube and the red copper plate as much as possible.

Disclosure of Invention

The invention provides a manufacturing method of a low-temperature helium chamber with large heat exchange quantity and low flow resistance, which introduces the manufacturing process of each link of production and manufacturing in detail, and the manufactured low-temperature helium chamber meets the special application requirements in the fields of aerospace and low-temperature vacuum.

The invention is realized by the following technical scheme:

a method for manufacturing a low-flow-resistance low-temperature helium tank with large heat exchange amount comprises the following steps:

(1) calculating the resistance of the pipelines according to the heat load and the required cooling flow, and determining the number of the cooling parallel pipelines;

(2) establishing a heat transfer model according to the sectional diagrams of the cooling pipeline and the welded pipeline of the integral plate to check whether the temperature difference between the inlet and the outlet reaches the design requirement;

(3) determining the length of the pipeline and the flow of cooling the pipeline according to the design, and blanking, soldering, splicing and leveling the copper plate according to the size requirement;

(4) cleaning and degreasing the copper tube and the copper plate, clamping by using a clamp, intermittently riveting the cooling copper tube and the copper plate together by using a copper pressing plate, and then performing low-temperature tin soldering by adopting a sectional vertical welding method;

(5) the helium tank support is well assembled on the bench worker platform according to the size, and then the helium tank cold screen is arranged on the helium tank support;

(6) and special low-temperature black paint spraying is carried out on the inner part of the helium tank, so that the emissivity of the copper plate is increased.

Further, in step (1), to ensure that the flow resistance of the cooling helium flow from the refrigerator is <0.1bar, a plurality of flow resistance calculations are performed.

Further, in the step (3), the helium chamber is determined to be cooled by three streams, the copper tube without the joint is used as a cooling disc, and the cooling coil is bent by adopting a low-temperature freezing method.

Further, in the step (4), the red copper tube is straightened and blanked, and a special low-temperature freezing platform is adopted to bend the red copper tube according to the size requirement.

Further, in the step (5), 5 cold screens are arranged on the whole helium cabin, and copper pipes among the cold screens are welded by adopting stainless hoses; and then carrying out vacuum helium mass spectrum leak detection to ensure that a welding seam is not leaked.

Further, in the step (5), an insulating gasket is arranged between the helium tank cold screen and the bracket.

Further, in step (6), aluminum foil is attached to the outside of the helium tank.

In terms of ensuring that a large amount of heat exchange is achieved, the following measures are taken:

1. and spraying low-temperature F952 black paint inside the helium tank cold screen. The process comprises the following steps:

a. the pre-sprayed article is protected as required.

b. And wiping the pre-sprayed helium tank with acetone or aviation gasoline, and airing the surface of the helium tank.

c. The F952 heat sink black paint was shaken for 30 minutes to homogenize it. After the surface is dried or baked, the coating is sprayed, and the phenomenon of sagging is preferably avoided during each spraying. After the surface is dried (about 10-20 minutes) every time of spraying, the subsequent spraying is carried out, the spraying is repeated for 8-10 times, and the thickness of the black coating is controlled to be 40-80 microns. And (5) finishing spraying.

d. And blowing the surface for more than 3 hours by using a hot air blower.

The F952 low-temperature black paint sprayed on the glass plate is not easy to fall off in a low-temperature environment of 20K, the helium cabin cold screen coated with the low-temperature black paint is changed into a high-emissivity plate, and the reflectivity is greater than 0.92 through professional tests, so that the radiation heat exchange efficiency is greatly improved, and the heat of up to 500W of instrument and equipment can be absorbed on the red copper plate of the helium cabin cold screen through radiation heat transfer.

2. In order to ensure the heat conduction between the red copper plate and the copper tube, the copper tube and the copper plate are riveted together at intervals by using the red copper pressing sheets to ensure the close fit between the copper tube and the copper plate, and then the low-temperature tin soldering welding process of the red copper tube and the red copper plate is optimized without cold soldering. A method of sectional vertical welding (shown in figure 3) is adopted, a copper plate is erected by a clamp, one side of a copper pipe is welded, the other side of a red copper pipe is welded in reverse, soldering tin fills a gap between the copper pipe and the copper plate to the greatest extent, finally, after the welding is finished, a layer of special aluminum foil (shown in figure 4) is attached to the whole cold shield, and the heat transfer area between the copper pipe and the copper plate is greatly increased again.

3. In order to ensure that the flow resistance of cooling helium flow from a refrigerator is less than 0.1bar and the temperature difference is small, firstly, calculation is carried out through multi-flow resistance, then model analysis is carried out to ensure that the temperature difference meets the requirement, finally, the three-flow cooling helium cabin is determined, a DN25X1.5mm copper tube without a joint is used as a cooling disc, a pipe bender is used for bending a cooling coil pipe by adopting a low-temperature freezing method (see figure 5), and the phenomenon that the coil pipe is sunken and folded is avoided so as to avoid increasing the resistance.

4. The helium tank support is made of aluminum alloy sections, so that the helium tank support is convenient to disassemble, assemble and transport, G10 gaskets with extremely small heat conductivity are designed between the support and the helium tank and between the support and the base, and heat leakage is reduced.

5. The size of the helium tank is large, and in order to ensure the accuracy of the size, the support installation of the helium tank and the integral assembly of the helium tank are completed by being placed on a bench worker platform.

The invention has the advantages that:

1. the special low-temperature black paint is sprayed inside the helium cabin cold screen by adopting a special process, so that the emissivity of the red copper plate is improved, and a large heat exchange amount is possible.

2. The tin soldering welding process is optimized, the red copper pressing sheet and the special aluminum foil for application are adopted, the conduction area between the copper plate and the copper pipe is greatly increased, and the heat transfer efficiency is improved.

3. The helium chamber is cooled by multiple flows, and a cooling coil is bent by using special equipment and a low-temperature freezing mode. The requirement of small temperature difference and low flow resistance of the helium tank is met.

Drawings

FIG. 1 is a schematic view of a helium vessel according to the present invention;

FIG. 2 is a schematic diagram of a helium vessel cooling system of the present invention;

FIG. 3 is a process diagram of cold shield soldering of a helium vessel in accordance with the present invention;

FIG. 4 is a view of the helium chamber cold shield aluminum foil application of the present invention;

FIG. 5 is a view of a cryogenic bending cooling coil of the present invention;

FIG. 6 is an exterior view of the helium vessel of the present invention in its assembled configuration.

In the figure, 1-bracket, 2-cooling coil, 3-copper plate and 4-copper pressing plate.

Detailed Description

The invention is described in detail below with reference to the figures and the embodiments. The following examples are only for explaining the present invention, the scope of the present invention shall include the full contents of the claims, and the full contents of the claims of the present invention can be fully realized by those skilled in the art through the following examples.

As shown in fig. 1, the whole helium tank mainly comprises a bracket 1, a cooling coil 2, a red copper plate 3, a red copper pressing plate 4 and the like, wherein the cooling coil 2 is firstly specified on the red copper plate 3 by the red copper pressing plate 4 through rivet riveting, and then the cooling coil 2 and the red copper plate 3 are welded together through tin soldering (as shown in fig. 3), so that a helium tank cold shield is formed, and the helium tank has 5 cold shields in the front, the rear, the left, the right and the top. Support 1 is that 100X100 standard aluminum alloy section bar forms through removable fastener equipment, and the cold screen passes through removable bolt and installs on support 1.

FIG. 2 is a schematic diagram of the helium vessel cooling system of the present invention. As shown in fig. 2, the instrumentation is placed inside the helium vessel, and the entire helium vessel is placed in a vacuum vessel. Inside the coil is a cryogenic helium flow provided by a cryogenic helium refrigerator through a cryogenic cooling line. The temperature of the cryogenic helium vessel is controlled by the cryogenic helium flow.

As shown in fig. 3-6, the method for manufacturing the low-flow-resistance low-temperature helium tank with large heat exchange amount is implemented as follows:

1. and calculating the resistance of the pipelines according to the heat load and the required cooling flow, and determining the number of the cooling parallel pipelines. Preferably, to ensure that the flow resistance of the cooled helium flow from the refrigerator is <0.1bar, a multiple flow resistance calculation is performed.

2. And establishing a heat transfer model according to the cooling pipeline and the integral plate welding pipeline sectional diagram to check whether the temperature difference between the inlet and the outlet reaches the design requirement.

3. And determining the length of the pipeline and the flow of the cooling pipeline according to the design, and blanking, soldering, splicing and leveling the copper plate according to the size requirement. The copper tube is straightened and blanked, and is bent according to the size requirement by adopting a special low-temperature freezing platform (as shown in figure 5). Preferably, three-stream cooling helium chambers are determined, copper tubes without joints are used as cooling discs, and a low-temperature freezing method is adopted to bend cooling coils.

4. Cleaning and degreasing the copper tube and the copper plate 3, clamping by using a clamp, intermittently riveting the cooling copper tube and the copper plate together by using a copper pressing plate 4, then carrying out low-temperature tin soldering by adopting a sectional vertical welding method, cleaning a helium chamber cold shield after welding, and drying by using hot nitrogen (as shown in figure 3).

5. The helium tank bracket 1 is assembled on a bench platform according to the size, then the helium tank cold shield is arranged on the helium tank bracket 1 by using bolts, and a heat insulation gasket made of G10 material is arranged between the helium tank cold shield and the bracket 1. The whole helium tank cold shield has 5 blocks, and copper pipes between the 5 blocks are welded by stainless hoses. And then carrying out vacuum helium mass spectrum leak detection to ensure that a welding seam is not leaked.

6. The special low-temperature F952 black paint spraying is carried out on the inner part of the helium tank by adopting a special process, the emissivity of the copper plate is increased, and the heat transfer between the copper pipe and the copper plate is further increased and the heat transfer efficiency is improved by sticking a special aluminum foil on the outer part of the helium tank.

The invention has not been described in detail and is part of the common general knowledge of a person skilled in the art. The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and the preferred embodiments are not exhaustive and do not limit the invention to the precise embodiments described. Various modifications and improvements of the technical solution of the present invention may be made by those skilled in the art without departing from the spirit of the present invention, and the technical solution of the present invention is to be covered by the protection scope defined by the claims.