JPS6036839Y2 - Finned tube for solar heat collector - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a finned tube used, for example, in a vacuum type solar collector.

In this specification, the term aluminum is meant to include not only pure aluminum but also aluminum alloys.

Conventionally, a heat collecting plate used in a solar heat collector includes an aluminum base material, an aluminum thermally conductive layer deposited on the base material, and a heat collecting plate formed on the metal layer.
It is known that the aluminum oxide layer has a large number of pores (see Japanese Patent Publication No. 3465/1983).

However, since the base material and the thermally conductive layer coated on the base material of this conventional heat collector plate are both aluminum, the mechanical strength is low, and therefore the heat collector plate is highly deformed when it is not heated. However, there is a problem in that the cost of materials is high, and the manufacturing cost of the solar collector is high.

In addition, heat collector plates have been known in which the surface of this stainless steel is made of ferritic ultra-low carbon stainless steel containing a small amount of titanium and subjected to chemical conversion treatment using a black oxidation method.
(See Publication No. 34653).

This conventional heat collector plate uses stainless steel as a material, so it has high mechanical strength, but only when special steel made of ferritic ultra-low carbon stainless steel containing a small amount of titanium is used. Only a good selective absorption surface can be obtained,
Another problem was that it could not be applied to general stainless steels that do not contain titanium.

The purpose of this invention is to solve the above problems, have high mechanical strength, and therefore can reduce deformation during dry firing.
In addition, the material cost for the heat collecting fins is extremely low, which in turn reduces the manufacturing cost of the solar heat collector.Furthermore, the water pipes and the heat collecting fins can be firmly connected, and the solar heat collector has excellent solar heat efficiency. An object of the present invention is to provide a finned tube for a solar collector having heat collecting performance.

This invention will be explained below based on embodiments shown in the drawings.

In the drawings, a finned tube 1 for a solar heat collector according to the present invention includes a heat collecting fin 2 made of a band-shaped metal plate constituted by a core material 4 made of a steel plate and an aluminum coating layer 5 provided on both the upper and lower surfaces of the core material 4. and a water pipe 3 made of a steel pipe, and a solar heat selective absorption film 6 is provided on the surface of the upper aluminum coating layer 5a of the heat collecting fin 2, and the width of the lower aluminum coating layer 5b of the heat collecting fin 2 is A water pipe 3 is fixed to the center by high frequency welding.

As the steel plate constituting the core plate 4, general stainless steel or the like can be used.

Although it is preferable that the water pipe 3 is joined to the width center of the lower surface of the heat collecting fin 2, it may be shifted to either the left or right side from the width center of the lower surface.

In the above, there are various methods for providing the aluminum coating layer 5 on the surface of the core plate 4 made of a steel plate of the heat collecting fin 2.

Examples of this include cold welding of steel sheets and aluminum foil,
Examples include a vacuum evaporation method for aluminum, a dip plating method for aluminum, and an injection method for aluminum.

Any of these methods may be adopted.

Further, methods for providing the solar heat selective absorption film 6 on the surface of the upper aluminum coating layer 5a of the heat collecting fin 2 made of a band-shaped metal plate include an electrolytic treatment method and a chemical conversion treatment method.

In addition, the reason why copper pipes are used as water pipes 3 is because of their excellent corrosion resistance.
Since the lower aluminum coating layer 5b is provided on the lower surface, weldability by high frequency welding is very good compared to, for example, the case of steel pipe and steel plate, and high joint strength can be obtained, as well as This is because it also has good thermal conductivity.

As mentioned above, this invention is equipped with a fin for a solar heat collector, which is equipped with a heat collecting fin 2 made of a band-shaped metal plate and a water pipe 3, and a solar heat selective absorption film 6 is provided on the upper surface of the heat collecting fin 2. In the pipe, the heat collecting fins 2 are made of a core plate 4 made of a steel plate.
and an aluminum coating layer 5a provided on both the upper and lower surfaces thereof.
. The water pipes 3 are fixed by high-frequency welding, and the heat collecting fins 2 made of a band-shaped metal plate with a steel plate as the core plate 4 have extremely high mechanical strength compared to conventional heat collecting fins made of aluminum. Deformation during dry firing can be reduced, and the amount of expensive aluminum used can be reduced, resulting in extremely low material costs, which in turn can significantly reduce the manufacturing cost of solar collectors. In addition, heat collection fin 2
Ordinary stainless steel that does not contain titanium can also be used as the core plate 4, and manufacturing costs can be further reduced.

Furthermore, since a steel pipe is used as the water pipe 3, it has excellent weldability during high-frequency welding with the lower aluminum coating layer 5a of the heat collecting fin, and therefore the heat collecting fin 2 can be very firmly joined to the water pipe 3. At the same time, heat is quickly transferred from the fins 2 to the water pipes 3.

In addition, since the solar heat selective absorption film 6 is generally easily formed on the surface of aluminum, the upper aluminum coating layer 5a of the heat collecting fin 2 has an extremely good solar heat selective absorption film 6 formed thereon, so that the finned tube as a whole has a very good quality. It has excellent solar heat collection performance.

[Brief explanation of drawings]

The drawings show an embodiment of this invention, in which Fig. 1 is a partially omitted perspective view, Fig. 2 is an enlarged sectional view taken along the line ■-■ in Fig. 1,
FIG. 3 is an enlarged sectional view of a portion viewed from arrow A in FIG. 2. 1...Finned tube, 2...Heat collecting fin, 3...Water pipe, 4...Core plate, 5,
5a, 5b...Curved aluminum coating layer, 6...
Solar heat selective absorption membrane.

Claims (1)

[Scope of utility model registration request] In a finned tube for a solar heat collector that includes heat collecting fins 2 made of a band-shaped metal plate and water pipes 3, and a solar heat selective absorption film 6 is provided on the upper surface of the heat collecting fins 2, the heat collecting fins 2 are made of a steel plate. The upper aluminum coating layer 5a of the heat collecting fin 2 is composed of a core plate 4 and aluminum coating layers 5a and 5b provided on both the upper and lower surfaces of the core plate 4
A finned tube for a solar heat collector, in which a solar heat selective absorption film 6 is provided on the surface of the heat collecting fin 2, and a water pipe 3 made of a steel pipe is fixed to the lower surface of the lower aluminum coating layer 5b of the heat collecting fin 2 by high frequency welding.