JPS6015231B2 - Manufacturing method for solar heat collector tubes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar heat collecting tube, and particularly to a solar heat collecting tube in which a heat collecting plate, a heat collecting metal pipe, etc. are housed in a sealed glass tube and then evacuated and kept in a vacuum.

In order to prevent heat loss due to air convection, solar heat collector tubes are usually evacuated and maintained at a high vacuum level.

It goes without saying that solar heat collector tubes must not cause vacuum leakage during long-term use. Therefore, the processed part of the glass tube, especially the sealed part between the glass tube and the metal, can withstand the heating and cooling work in the exhaust process after {1}, or the rapid cooling caused by the rain after receiving intense solar heat in the summer, and is able to withstand cracks. , have thermal shock resistance that will not cause damage. '21 It has mechanical strength that prevents it from being damaged by external forces applied to the heat collecting metal pipes during assembly work that connects a large number of heat collecting metal pipes to each other and due to thermal expansion and contraction during use. thing. A high degree of vacuum must be maintained for long-term muscle use. {41 Materials are required to have chemical durability that will not cause deterioration or change in quality during long-term use under outdoor natural conditions. On the other hand, as a method for sealing metal members and glass tubes, [1'] the method must be suitable for mass production.

■The heat collecting plate and heat collecting metal pipe housed inside the glass tube are not heated to high temperatures during the manufacturing process. '31 A method with low manufacturing cost is required. There was no solar collector tube that met all of the above conditions. In particular, conventional solar heat collection tubes have a structure in which the heat collection plate and heat collection metal pipe are housed in a glass tube, and then the glass tube and metal stem are sealed. Even if it is sealed with a frit, the heat collecting plate and heat collecting metal pipe housed in the glass tube are exposed to considerable high temperatures during sealing, so the selective absorption film provided on the surface of the heat collecting plate may deteriorate. However, the heat collecting metal pipes were oxidized, reducing the heat collecting effect and making it difficult to create a vacuum during the exhaust process. In addition, the thermal shock resistance and mechanical strength decrease due to the strain that occurs in the sealing part, so after the bonding process, the strain is completely removed through a strain removal process to improve the thermal shock resistance and mechanical strength. There is a need.

In the strain removal process, the strain removal temperature and time differ depending on the material of the glass tube, but for example, for shelf silicate glass, it must be heated to 57,000°C or higher, and for soda and lime glass, it must be heated once to 500°C or higher, and then gradually cooled. No. Due to this strain-removal temperature, the bag heating plate and heat collecting metal pipe were exposed to high temperatures, which inevitably caused deterioration and oxidation of the materials. The present invention provides a solar heat collector tube that satisfies all of the above-mentioned conditions required for a solar heat collector tube.

Solar heat collecting pipes are roughly divided into two types, reciprocating type and through-type, depending on the path of heat collection fluid passing through the pipes.The solar heat collecting pipe of the present invention will be described in detail with reference to examples for each type.

FIG. 1 shows an embodiment of a reciprocating heat collecting tube according to the present invention.

First, one end of the glass tube 1 is sealed to form a shape like a large test tube, and the bottom plate portion 11 is formed.

An exhaust pipe 2 made of a thin glass tube is sealed to this bottom part 11. Alternatively, a separately molded bottom plate with an exhaust pipe may be sealed to the glass tube. An annular connecting fitting 3 is sealed to the other open □ end. The metal of the connecting fitting 3 is selected to have a coefficient of thermal expansion suitable for sealing, depending on the material of the glass tube. For example, if the glass tube is soda lime glass, #42 base steel (Ni
If the glass tube is shelf silicate glass, Kovar or the like is used. The method of sealing the connecting fitting 3 to the glass tube 1 is conventionally well known, such as applying a glass glaze to the sealed portion of the connecting fitting 3 in advance, using a flame electrode, or using frit glass. Any method is acceptable.

After the connecting fitting 3 is sealed to the glass tube 1, it is sent to a strain removal process, and the sealed bottom plate part 11 of the glass tube 1, the sealed part of the exhaust pipe 2,
Also, the strain generated in the sealing portion of the connecting fitting 3 is sufficiently removed.

On the other hand, a U-shaped heat collecting metal pipe 5, a metal stem 4, and a heat collecting plate 6 for passing heat collecting fluid are prepared.

The U-shaped heat collecting metal pipe 5 is usually made of an inexpensive metal with good thermal conductivity, such as a copper pipe, and a heat collecting plate 6 can be attached thereto. The metal stem 4 may be made of the same metal as the connecting fitting 3, but any metal may be used as long as it has excellent corrosion resistance and mechanical strength, is easy to process, and is inexpensive. Holes 7 are provided in two places in advance,
The two ends of the heat collecting metal pipe 5 are inserted into the hole 7, and the contact portion between the hole 7 and the metal pipe 5 is welded by brazing or welding to prevent vacuum leakage. In this way,
The metal stem 4, the heat collecting metal pipe 5, and the heat collecting plate 6 integrated into one body are inserted into the glass tube 1 from which the aforementioned strain has been sufficiently removed.

The inner wall of the connection fitting 3 is made sufficiently large so that the heat collecting plate 6
The heat collecting metal pipe 5 with the attached heat collecting metal pipe 5 can be easily inserted into the glass tube 1. Heat collecting metal pipe 5 or nest heat plate 6
is provided with a center holding odor 8 of a simple and elastic structure, which spreads in the circumferential direction within the glass tube 1 and presses the inner wall of the glass tube, thereby holding the heating light pipe 5 and the condensing plate 6 out of the glass. Hold it approximately in the center of tube 1. After inserting the heat collecting metal pipe 5 and the heat collecting plate 6 into the glass tube 1, the metal stem 4 and the connecting fitting 3 are inserted.
The contact portion 12 is welded to prevent vacuum leakage. In this case, the length of the connecting fitting 3 is determined so that the high temperature of the welded portion is not transmitted to the sealed portion between the connecting fitting 3 and the glass tube 1. It is desirable that welding be performed in an extremely narrow area and in an extremely short period of time, and arc welding or the like is suitable for this purpose. Next, the exhaust pipe 2 is evacuated by a normal method, and after the inside of the glass tube 1 reaches a predetermined degree of vacuum, the exhaust pipe 2 is closed.

In this way, a solar heat collector tube that satisfies all of the above-mentioned conditions can be obtained. FIG. 2 shows an embodiment of a through-type solar heat collecting tube according to the present invention.

The annular connecting fittings 3 and 3' used in the reciprocating type solar heat collection system are respectively sealed to both ends of the T-glass tube 1 in the same manner as in the reciprocating type, and the strain is sufficiently removed through a strain removal process.

When the connecting fitting 3 is sealed with fritted glass, it can be sealed at a temperature below the strain point of the glass tube, so there is no need to go through a separate process for removing strain. Unlike the reciprocating type, the heat collecting metal pipe 15 is straight and has a diaphragm 16 in a part of it.
etc., to absorb expansion and contraction due to temperature changes. One hole 7 into which the heat collecting metal pipe 15 is inserted is provided in the center of the metal stem 17.

The other metal stem 17' also has a hole 7' in the center for inserting the heat collecting metal pipe 15, and a small hole for inserting the metal exhaust pipe 19 at an appropriate position and brazing or welding it. 18 are provided. One end of the heat collecting metal pipe 15 is inserted into the hole 7 of one metal stem 17, and the contact portion between the hole 7 and the heat collecting metal pipe 15 is brazed or welded to prevent vacuum leakage. When the heat collecting plate 6 is attached to the metal stem 17 and inserted into the glass tube 1 through the connecting fitting 3, the pond end of the metal pipe 15 projects from the other end of the glass tube 1 to the outside through the connecting fitting 3'. The contact part 12 with the connecting fitting 3 is welded in the same way as the reciprocating type.The metal pipe 1 protruding from the end of the glass tube 1
5, the hole in the other metal stem 17'? ' Pass through. The contact portion between the metal stem 17' and the connecting fitting 3' is welded in the same manner as the other end, and then the contact portion between the metal pipe 15 and the hole 7' is brazed or welded. Similar to the reciprocating type, the heat collecting plate 6 is held by a holder 8 such as a spring so that it does not deviate from the center of the glass tube 1. Next, the exhaust pipe 19 is evacuated, and after the inside of the glass tube 1 reaches a predetermined degree of vacuum, the exhaust pipe 19 is closed.

In the reciprocating type embodiment, the exhaust pipe 2 is a glass capillary tube sealed at the sealed end of the glass tube 1. There is no problem even if you use it with it attached.

Another embodiment of the reciprocating heat collecting tube is shown in FIG. 3 (a sectional view showing only the peripheral parts of the connecting fitting 3 and the metal stem 4). In this embodiment, a glass tube 1 is connected to an annular groove 3' provided in a connecting fitting 3.
is filled with frit glass and frit-sealed. The heat collecting metal pipe 5 and the metal stem 4 are hermetically welded at the 7' portion by welding or the like, as in the embodiment shown in FIG. 1, and a heat collecting plate (not shown) is attached to the heat collecting metal pipe 5. , housed in a glass tube 1.

Next, the contact portion 12 between the connecting fitting 3 and the metal stem 4 is welded in the same manner as in the previous embodiment, and the inside of the glass tube 1 is evacuated.

As described above, the solar heat collector tube according to the present invention can completely eliminate strain on the glass tube after sealing the connecting fitting with a sufficiently large inner diameter to the end of the glass tube, and the solar heat collector tube can be housed inside the glass tube. Heat collection plates and heat collection metal pipes are attached to the heat collection metal pipes, and after brazing the metal stems to the heat collection metal pipes, the heat collection plates and heat collection metal pipes are passed through the connecting fittings into the glass tubes. ``The glass tube is not heated to high temperatures even when welding the connecting fitting and metal stem, so no distortion occurs in the glass tube.

Furthermore, since the ripening board and metal pipe are not exposed to high temperatures, their properties do not deteriorate or oxidize.

Therefore, the solar heat collection tube according to the present invention has excellent heat collection efficiency, excellent thermal shock resistance, and high mechanical strength.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view showing a reciprocating solar heat collector according to an embodiment of the present invention, Fig. 2 is a partial sectional view showing a through-type solar heat collector according to an embodiment of the present invention, and Fig. 3 is a reciprocating solar heat collector. FIG. 7 is a cross-sectional view of the vicinity of the metal stem of another example of the heat collecting tube. 1: Glass tube, 3, 3': Connection fitting, 4, 17, 17'
: Metal stem, 5, 15: Heat collecting metal pipe, 6: Heat collecting plate, 8: Medium holder. Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] 1 At least one end of the glass tube is sealed with a connecting fitting that has an inner diameter that allows easy insertion of the heat collecting metal pipe with a heat collecting plate attached, and a heat collecting metal pipe with a metal stem welded inside the glass tube. 1. A method for manufacturing a solar heat collection tube, which comprises storing a heat collection plate and welding the metal stem to a connecting fitting.