NB/T 10415-2020Glass-metal sealed direct connection evacuated solar collector tube for medium temperature (English PDF)

3.1 Glass-metal sealed direct-flow evacuated collector tube for medium temperature

Medium temperature glass-metal sealed direct connection collector tube for vacuum direct connection collector tube for medium temperature There is a vacuum space between the glass cover tube and the metal heat-absorbing tube, and the two ends are connected by Kovar transition seal to absorb solar radiation and produce The heat is transferred to the components of the heat transfer medium.

3.2 Sealing leak rate of glass and metal pipes

The amount of gas passing through the Kovar transition seal joint in a unit time between the glass cover tube and the metal heat absorption tube under a known pressure difference.

Note: The sealing leak rate is expressed in Pa·m3/s.

3.3 Metal absorber tube

The outer surface is provided with a solar selective absorption coating, which is a metal tube used to absorb solar radiation and convert it into heat energy of the fluid in the tube.

3.4 Heat loss coefficient

The heat loss power value per unit length of the straight-through tube under the given temperature condition.

4.1 Product structure

The structure and components of the straight pipe are shown in Figure 1.

1-- Glass-to-metal seal 2-- getter 3-- Glass cover tube 4-- Metal heat-absorbing tube 5-- Metal connection section 6-- Medium flow path 7-- Vacuum sandwich 8-- Corrugated elastic connecting pipe L-- the total length of the straight pipe at room temperature Lc-- length of connecting section Ls-- sealing length Dabs-- outer diameter of metal heat absorbing tube Dg-- outer diameter of glass cover tube

4.2 Structure size

Refer to Table 1 for the recommended specification sequence of the structure size of the straight-through pipe.

4.3 Product Code

The coding structure of the straight-through tube is shown in Figure 2.

Example: ZBJ-40/1.5-90/2.0-2000 means that the outer diameter of the metal heat-absorbing tube is 40mm, the wall thickness of the metal heat-absorbing tube is 1.5mm, and the outer diameter of the glass cover tube is 90mm.

The glass cover tube has a wall thickness of 2.0mm and a total length of 2000mm with a medium-temperature glass-metal sealed vacuum straight-through solar collector tube.

5.1 Appearance

5.1.1 The stones on the glass cover tube should comply with the provisions in 6.1.3 of GB/T 19775-2005, and the nodules should comply with the provisions of GB/T 19775-2005.

According to the provisions of 6.1.4, the length of the gas line shall comply with the provisions of 6.1.5 of GB/T 19775-2005.

5.1.2 The heat-absorbing body coating on the metal heat-absorbing tube should be uniform in color, free of fingerprints, dirt, peeling, peeling, and obvious scratches.

5.2 Dimensional deviation

The curvature of the glass cover tube should not be greater than 0.2%; the outer diameter and wall thickness of the metal heat-absorbing tube should meet the relevant regulations of GB/T 17395;

The measured length of the tube should not be greater than ±0.5% of the nominal value, and the measured outer diameter of the glass cover tube should not be greater than ±5mm of the nominal value.

5.3 Circumference grade

The circumcision grade of the glass cover tube should not be greater than HQ-6.

5.4 Optical performance

5.4.1 The solar transmittance of the glass cover tube should not be less than 0.90 (AM1.5) (the transition area at both ends of the non-glass cover tube).

5.4.2 The solar absorption ratio of the metal heat-absorbing tube coating should not be less than 0.92 (AM1.5).

5.4.3 The hemispheric emission ratio of the solar selective absorption coating should not be greater than 0.08 (150°C±1°C).

5.5 Sealing leakage rate

The leak rate of glass and metal sealing should be less than 1.0×10-10 Pa·m3/s.

5.6 Vacuum performance

The gas pressure in the vacuum interlayer of the straight pipe should not be greater than 5 x 10^-2Pa. During the test, there should be weak fluorescence on the glass wall, and there should be no Glow discharge, sparks penetrate the glass wall or sparks diverge without fluorescence on the glass wall.

5.7 Mechanical strength

5.7.1 The straight-through pipe should be able to withstand the impact of a solid steel ball with a diameter of 30mm and a height of not less than 1.4m without being damaged.

5.7.2 After the corrugated elastic connecting pipe has undergone 12,000 simulated displacement tests, the sealing leakage rate shall meet the requirements of 5.5.

5.8 Heat loss coefficient

The heat loss coefficient of the straight-through pipe should meet the requirements of Table 3.

5.9 Weather resistance

5.9.1 High temperature deformation curvature

After the straight pipe deformation and curvature test, the deformation curvature per meter of the straight pipe should not be greater than 5mm.

5.9.2 External thermal shock

After the external thermal shock test, the glass cover tube should be free of damage such as bursting or cracking, and the glass-metal seal should not be deformed, bursting, or leaking.

5.9.3 Low temperature resistance

After the low temperature resistance test, the through pipe should be undamaged.

6.1 Appearance

6.1.1 Inspect the stones, nodules and the length of the air line on the glass cover tube, and record the inspection results.

6.1.2 Visually inspect the appearance of the heat-absorbing body coating on the metal heat-absorbing tube, and record the inspection result.

6.2 Dimensional deviation

Place the straight-through pipe horizontally on the V-shaped test support, and the two ends are sealed at the supporting point. Use a dial indicator to measure the middle of the straight pipe The maximum and minimum radial dimensions of, the sum of the maximum and minimum radial dimensions divided by 2 times the length of the glass cover tube is the curvature of the glass cover tube; use accuracy Measure and record the outer diameter and wall thickness of the metal heat-absorbing tube with a 0.02mm micrometer; measure and record the length of the straight pipe with a steel tape with an accuracy of 1mm;

Measure and record the outer diameter and wall thickness of the glass cover tube with a micrometer with an accuracy of 0.02mm.

6.3 Circumference grade

The test method for the circumcision grade of the glass cover tube is carried out in accordance with the provisions of Appendix A in GB/T 29159-2012

6.4 Optical performance

6.4.1 Cut the glass cover tube in the transition area between the two ends of the non-glass cover tube on the straight tube. The sample size should meet the requirements of the spectrophotometer.

The spectrophotometer with integrating sphere is in the wavelength range of 300nm~2500nm, and the light rays are respectively with the convexity of the glass sample intercepted on the glass cover tube.

Measure the solar transmittance of the glass cover tube according to the regulations of GB/T 25968. The concave surface and the convex surface of the glass sample are each done 3 times. take the average.

6.4.2 Cut the metal heat absorption tube of the straight tube, the sample size should meet the requirements of the spectrophotometer, use a spectrophotometer with an integrating sphere In the wavelength range of 300nm~2500nm, measure the absorption ratio of the metal heat absorption tube coating according to the provisions of GB/T 25968.

6.4.3 The test method for the hemispherical emission ratio of the solar selective absorption coating is carried out in accordance with the provisions of GB/T 25965, and the test temperature is adjusted to 150°C ±1°C.

6.5 Sealing leakage rate

Connect the detection interface of the helium mass spectrometer leak detector with the exhaust nozzle of the straight pipe, and the helium mass spectrometer leak detector will pump the inner cavity of the straight pipe.

When the instrument shows that the detectable leak rate in the glass cover tube is less than 1.0×10-10 Pa·m3/s, use a gas bag filled with helium to cover all the seals and continue 30s. The leak rate displayed by the instrument should not increase.

6.6 Vacuum performance

Use a spark leak detector to detect the vacuum interlayer at the glass-metal sealing end of the through tube in a darkroom environment, and check the vacuum condition according to the discharge color Make qualitative judgments.

6.7 Mechanical strength

6.7.1 The straight-through pipe is fixed horizontally and fixedly installed on the test frame, supported by two V-grooves with 5mm thick polyurethane gaskets spaced 1500mm apart.

The steel ball with a diameter of 30mm is aligned with the middle of the collector tube and the middle of the two fulcrums. The bottom of the steel ball is 1400mm from the impact point of the glass cover tube and falls freely. Hit the straight pipe vertically.

6.7.2 Perform 12,000 simulated displacement tests on the corrugated elastic connecting pipe with a reciprocating test device, and the period of each simulated displacement test is 2s, The displacement is 2mm per wave. After the test, the sealing leakage rate test shall be carried out in accordance with 6.5.

6.8 Heat loss coefficient

The heat loss coefficient test method is carried out in accordance with Appendix A.

6.9 Weather resistance

6.9.1 High temperature deformation curvature