Some standard content:
National Standard of the People's Republic of China
Aluminum Coreless Gravity Heat Window
Wickless Aluminum Gravity Heat PipesSubject Content and Scope of Application
GB9082.2—88
This standard specifies the varieties, specifications, technical requirements and inspection methods of straight-arm aluminum coreless gravity heat pipes. This standard applies to the design, manufacture and inspection of aluminum coreless gravity heat pipes. 2 Reference Standards
GB2828: Counting Sampling Procedure and Sampling Table for Batch Inspection (Applicable to Continuous Batch Inspection)GB9082.1 Coreless Gravity Heat Pipe Aluminum Tubes3 Varieties and Specifications
3.1 Tubes and Working Fluids
3.1.1 The tubes used for aluminum coreless gravity heat pipes shall comply with the provisions of GB9082.1. 3.1.2 The working fluids used for heat pipes and the working temperature range of heat pipes are shown in Table 1. The working temperature of heat pipes refers to the vapor temperature of the working fluid in the heat pipes. Table 1 Heat pipe working fluid and corresponding working temperature range Working fluid
Heat pipe working temperature range, core
3.2 Pipe diameter and pipe length
—60~～+60
Pipe diameter and preferred pipe length are shown in Table 2 and Table 3.
4 Technical performance indicators
4.1 Heat pipe outer surface quality
4.1.1 The outer surface is silvery white metallic luster. Indole
—20～+120
Freon 12
-- 50-- - 50
Table 2 Aluminum heat pipe outer diameter
Table 3 Aluminum heat pipe preferred length
【500
4.1.2 The surface shall not have cracks, pits and burrs, the weld shall be flat and smooth, and the fins shall be regular. 4.2 Evaporation and condensation heat transfer coefficients 4.2.1 Definition of evaporation and condensation heat transfer coefficients Evaporation heat transfer coefficient A. (tew t) Approved by the Ministry of Aerospace Industry of the People's Republic of China on April 14, 1988 25% 21% 60~+60% Chloride 11,113 20~~+120% Implementation on November 1, 1988 Condensation heat transfer coefficient Where: GB 9082.2-88
Evaporation heat transfer coefficient, W/(m2.C)I
Condensation heat transfer coefficient, W/(m2.C);
d---Heat flow of evaporation section, W;
Heat flow of condensation section, w;
Inner surface area of evaporation section tube, m\;
Inner surface area of condensation section tube, ㎡
Arithmetic mean temperature of inner wall of evaporation section tube, ℃: working medium vapor temperature, ℃;
Arithmetic mean overflow of inner wall of condensation section tube, ℃. 4.2.2 Evaporation and condensation heat transfer coefficients A of various working fluids
...( 2)
When the heat pipe is placed vertically, the operating temperature is 50±5℃, and the radial heat flux density (calculated based on the inner surface) is greater than 10W/m\, the evaporation and condensation heat transfer coefficients of aluminum coreless gravity heat pipes with various working fluids are shown in Table 4. Table 4 Evaporation and condensation heat transfer coefficients
Evaporation heat transfer coefficient part
Condensation heat transfer coefficient point
Axial heat transfer limit heat flow
>5 000
>5 000
×1 500
W/(m2 . C)
Oxygen 11, 12.21, 113
>1 000
>1 000
When the heat pipe is placed in a vertical state, the working temperature is 50±5℃, and the radial heat flux density of the evaporation section (calculated based on the inner surface) is in the range of 1×101～~5×101W/m\, the axial heat transfer limit heat flow is shown in Table 5. Table 5 Axial heat transfer limit heat flux plate
Tube inner diameter
Fluorine single ang11,12,21,113
Other tube inner diameters The axial heat transfer limit heat flux of the heat pipe can be obtained by interpolation and extrapolation according to the values in Table 5, which is proportional to the square of the tube inner diameter.
4.4 Temperature resistance
After the heat resistance test under the conditions specified in Table 6, there is no obvious deformation of the appearance, and there is no leakage in the seal and weld. Table 6 Temperature resistance test conditions
Adiabatic section temperature, ℃
Holding time, min
4.5 Service life
110±5
150±5
Freon 12, 21
100±5
Freon 11, 113
150±5
After 5 years of use under non-corrosive conditions, the evaporation and condensation heat transfer coefficients of aluminum coreless gravity heat pipes shall not be less than 80% of the values specified in 4.2.
5 Performance test method
Test of evaporation and condensation heat transfer coefficients
GB 9082.2-88
5.1.1 See Figure 1 for the schematic diagram of the experimental system. The evaporation section and condensation section shall ensure uniform heat flux density, and the unevenness shall be less than 10%. The evaporation section is generally heated by electricity, and the condensation section is cooled by air or water. Figure 1 Schematic diagram of heat transfer performance test of heat pipewww.bzxz.net
1—Cooling jacket; 2—Thermoelectric installation point; 3—Heat pipe; 4—Insulation layer; 5—Electric heater
5.1.2 The insulation section length of the test heat pipe should not be less than one-third of the total length of the heat pipe. 5.1.3 The total heat leakage through the insulation layer of the evaporation section and the insulation section should be less than 5% of the axial heat flow of the heat pipe. 5.1.4 The temperature measuring element is a calibrated secondary thermocouple with a diameter not greater than 0.2mm, and the resolution of the measuring instrument is better than 10μV. There are no less than 5 temperature measuring points on the outer wall of the evaporation section and the condensation section, and no less than 3 temperature measuring points in the insulation section. The temperature measuring points of each section are evenly distributed. The temperature measuring points at the end of each section should be at least 20mm away from the end of the heat pipe at the junction of each section. When the thermocouple is installed in the evaporation section, it is 3~5mm away from the heating wire and tightly wrapped around the wall for two weeks. In the case of water cooling, the thermocouple is attached to the pipe wall and tightly wrapped around the wall for two weeks, and the thermocouple is partially wrapped with insulation material.
5.1.5 In order to ensure the stability of the working conditions, the temperature measurement data should be obtained when the temperature fluctuation is less than 1'C every 10 minutes. 5.1.6 During the test, the uniformity of the outer wall of the evaporation section should be within 5℃, the uniformity of the outer wall temperature of the adiabatic section and the condensation section should be within 3℃, and the average temperature of the inner wall of the evaporation section and the condensation section should be replaced by the average temperature of the outer wall. 5.2 Determination of the axial heat transfer limit heat flux
On the basis of the test in 5.1, the axial heat transfer limit heat flux of the heat pipe is determined according to the conditions in 4.3. The heat flux increases gradually. When the local wall temperature of the evaporation section increases significantly (the temperature continues to rise and is higher than the temperature of the measuring point of the adiabatic section by more than 30 degrees), the minimum heat flux is the axial heat transfer limit heat flux of the heat pipe.
5.3 Simplified test of thermal performance
5.3.1 Insert the heat pipe into water at about 50℃, and the insertion depth is 1/5 to 1/4 of the total length of the heat pipe. The heat pipe is cooled by natural convection. Select two measuring points A and B in the condensation section of the heat pipe. Point A is 20mm (for pipes with a length of 1.5m and below) and 40mm (for pipes with a length of 2m and above) from the end, and point B is 200mm from the water surface, see Figure 2. Figure 2 Simplified test diagram of thermal performance of heat pipe 1. Heat pipe, 2-hot water, 3-container
5.3.2 Thermocouples measure the temperature difference between the pipe wall at points A and B. 5.4 Temperature resistance test
Under safe protection conditions outdoors, tilt the heat pipe more than 10 degrees or place it vertically and fix it. Use electric heating to heat up the heat pipe, wrap the rest of the heat pipe with insulation material, measure the wall temperature of the heat pipe with a thermocouple, and conduct a temperature resistance test according to the conditions in Table 6. 6 Product Identification Test
Before formal mass production or when production is resumed after more than one year of suspension or when major changes are made to the production process, the heat pipe produced according to the specified production process shall be subjected to a product identification test. 6.1 Extraction of test heat pipes
After producing more than 10 heat pipes and storing them for one month, randomly extract 3 for identification test. 6.2 Identification items
6.2.1 Check the external dimensions and appearance of the heat pipe. 6.2.2 Determine the evaporation and condensation heat transfer coefficients according to 5.1. 6.2.3 Determine the axial heat transfer limit heat flux according to 5.2. 6.2.4 Conduct a temperature resistance test according to 5.4. 6.2.5 Provide life test data.
6.3 Appraisal and re-inspection
The performance of all sampled heat pipes shall meet all performance indicators specified in Chapter 4. If one of the heat pipes fails to meet the requirements, double the number of heat pipes shall be sampled for re-inspection. During the re-inspection, if one of the heat pipes still fails to meet the requirements, the product shall not pass the appraisal. 7 Product acceptance inspection
7.1 Acceptance inspection items
7.1.1. Appearance and appearance inspection.
GB 9082.2 -88
7.1.2 After one month of storage, the thermal performance of the heat pipe shall be inspected according to the simplified test method in 5.3. 7.2 Acceptance rules
7.2.1 The heat pipe shall be inspected by the supplier's technical supervision department and the product quality shall be guaranteed to meet the requirements of this standard. 7.2.2 All heat pipes shall be inspected for appearance and appearance and shall comply with the provisions of 4.1. 7.2.3 Under normal circumstances, the thermal performance of heat pipes shall be fully inspected. According to the simplified test method in 5.3, for heat pipes with ammonia as the working fluid, the temperature difference between points A and B shall not be greater than 2°C. For heat pipes with acetone and oxychloride as the working fluid, the temperature difference between points A and B shall not be greater than 3°C. Products exceeding this temperature difference are unqualified products.
7.2.4 In the case of continuous large quantities (more than 200 pieces), the thermal performance of heat pipes can be inspected by sampling. The sampled heat pipes shall be inspected according to the indicators specified in 7.2.3. The sampling method shall be implemented in accordance with GB2828, and it is stipulated that: a. The qualified quality level AQL value of the thermal performance test is 1.5%, and this value can be adjusted appropriately through consultation between the user and the production unit: b. The inspection level shall be based on the general inspection level I, c. A normal inspection sampling plan
8 Packaging, marking, transportation, and storage
8.1 The packaging, marking, transportation and storage of heat pipes shall comply with the provisions of GB3199. 8.2 During packaging and packing, it shall be ensured that the heat pipes (especially the head protection sleeves) are not damaged, and the tough sheet tubes shall ensure that the warping sheets are not deformed. 8.3 The working medium type, number, factory date and factory mark shall be marked in a conspicuous place on each heat pipe (steel stamps are not allowed on the tube body). Additional notes:
This standard was drafted by the Fifth Design Department of the Fifth Institute of the Ministry of Aerospace Industry
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