JPS5953457B2 - Method for manufacturing heat collector plates for vacuum tube solar collectors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a vacuum tube type solar collector, and provides a highly reliable and easy-to-manufacture heat collector plate.

In general, vacuum tube type solar collectors have a vacuum around the heat collector plate, so there is almost no heat conduction loss due to air convection, and they are characterized by the highest heat collection efficiency among the various heat collectors.

However, their disadvantages include that they are more expensive than flat plate heat collectors, and from another point of view, they are complicated to manufacture.

Of course, the vacuuming process and vacuum sealing process are complicated, but another important point is the heat collecting plate.

In other words, in a flat plate type heat collector, for example, one large heat collecting plate is used.
Compared to the vacuum tube type heat collector, which requires only one piece to be manufactured,
Due to its structure, it is necessary to manufacture a large number of elongated heat collecting plates, for example 8 to 15 pieces.

It goes without saying that each heat collecting plate must be provided with a heat medium pipe, and various measures have already been taken to bring the two into contact with each other for good heat conduction.

For example, as shown in the cross-sectional view in FIG. As shown in FIG. 2, a method is used in which a heat medium tube 2 is welded to a flat heat collecting plate 1 using, for example, brazing material.

In addition, as another conventional example, as shown in the cross-sectional view in Fig. 3, in the case of iron or stainless steel whose thermal conductivity is not very high, metal plates 3, 3 are formed so that a passage 4 is formed in the center. It is also possible to stack two sheets on top of each other and then seamlessly weld both ends to completely weld the entire periphery to prevent liquid from leaking.

Furthermore, it has already been considered to form a heat medium path by welding both ends of the plate and then expanding it using water pressure, oil pressure, etc., without molding the plate as described above.

However, the above manufacturing process has the disadvantage that it requires complicated steps such as welding the plates and tubes, machining the heat collecting plate into a concave shape, and welding the entire periphery of the metal plates.

Particularly in the latter case, where two plates are stacked one on top of the other, there is no need for steel pipes, which is advantageous in terms of material, but the entire periphery must be welded to ensure there is no leakage.

The conventional method of using metal tubes as heat transfer paths has the advantage of ensuring high reliability against liquid leakage, is inexpensive, and is expected to produce heat collecting plates and heat transfer paths with higher heat transfer rates. There is.

The present invention relates to improving the heat collecting plate of a vacuum tube type heat collector and alleviates the above-mentioned problems.

That is, as shown in FIG. 4, a pipe made of iron or stainless steel is vertically compressed and flattened to form a heat collecting plate 6 having a certain heat medium path 5.

A selective absorption film, for example, is attached to the surface to collect solar heat and transfer it to the heat carrier in the center.

In addition, as shown in FIGS. 5 and 6, the front and back surfaces are brought into partial contact at one or two locations in the center and electrically welded to improve the pressure resistance of the heat medium path 5 through which the heat medium flows. can also be improved.

The biggest feature of the heat collector plate and heat transfer path made in this way is that the heat collector plate can be made as long as 2m without welding or special machining, and can be simply pressurized or partially pressed. It is easy to manufacture as it only requires spot welding.

In particular, compared to the conventional example shown in FIG. 3, there is no need for seamless welding around the periphery, so there is no need for liquid leakage from this area.

Further, since there are few welded parts, processing is easy, and since corrosion easily progresses at welded parts, reliability against corrosion can be greatly improved.

Note that although the glass outer tube is usually vacuum-sealed with a special alloy, it is necessary to pass the heat medium in and out through this metal plate, and this portion is preferably a tubular heat medium passage.

Therefore, it is preferable that both ends (inlet/outlet) of the heat collecting plate remain tubular, and in some cases, they may be connected to a tube with a small diameter and then led out of the glass tube.

Further, the welding location at the center shown in FIGS. 5 and 6 may be arbitrarily selected depending on the thickness and width of the heat collecting plate or the required pressure resistance value.

Continuous welding in the length direction is also possible, and it is sufficient to weld for reinforcement to an extent that does not significantly impede the flow of the medium.

Furthermore, the material of the metal tube that serves as the heat collecting plate may be any metal that is not dissolved or corroded by the flowing heat medium, but generally iron, stainless steel, copper, aluminum, etc. are used.

Among these, iron and stainless steel are particularly effective, since they have low thermal conductivity and need to be brought into contact with the heat medium over a wide area.

[Brief explanation of drawings]

1, 2, and 3 are cross-sectional views of a heat collecting plate of a vacuum tube type heat collector as a conventional example, and FIGS. 4, 5, and 6 are cross-sectional views of a heat collecting plate according to the present invention. It is a cross-sectional schematic diagram of a hot plate. 5... Heat medium path, 6... Heat collecting plate.

Claims (1)

[Claims] 1. A vacuum tube characterized in that a tube made of metal is compressed from the outside to make it flat, a heat medium path is formed inside, and a solar heat collecting material is provided on the surface to obtain a heat collecting plate. Method for manufacturing heat collection plates for type solar heat collectors. 2. A method for manufacturing a heat collecting plate for a vacuum tube type solar heat collector according to claim 1, characterized in that a place where front and back metal plates are contacted and welded is provided in the center of the heat collecting plate. 3. The method for manufacturing a heat collector plate for a vacuum tube solar collector according to claim 1, wherein the metal tube is made of iron or stainless steel.