JPH0426846Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a vacuum double-tube type solar heat collection tube that has a selective solar heat absorption film (hereinafter simply referred to as absorption film), and the arrangement of the absorption film is improved. This invention relates to an improved vacuum double tube type solar heat collector tube.

[Prior art] Glass tubes of different diameters, one end of which is closed and the other end of which is open, are stacked in double layers with a required gap,
Vacuum double-tube solar heat collector tubes, which are mainly composed of vacuum double tubes in which the mutual space between the inner and outer glass tubes is sealed and depressurized, have a solar heat absorption film to improve the solar heat collection efficiency. was formed on the surface of the inner glass tube constituting the double vacuum tube.

However, when forming this absorbing film on the surface of the glass tube, the glass tube itself requires careful handling, and the yield rate of vacuum double tube type solar collector tubes decreases due to the poor formation efficiency of the absorbing film.
Therefore, there was a fear that the cost of the vacuum double tube type solar heat collecting tube would increase.

[Problem that the invention attempts to solve]

This invention solves the problem of a decrease in formation efficiency when forming a solar heat absorbing film on the surface of the inner glass tube, which in turn leads to a decrease in the yield of vacuum double-tube solar heat collector tubes and an increase in the cost of vacuum double-tube solar heat collector tubes. The aim is to solve this problem and further improve the efficiency of transmitting solar heat to the heating medium.

[Means for solving problems]

As a means to solve the above-mentioned problems, the vacuum double-tube type solar heat collecting tube according to the present invention is a double-walled vacuum double-tube type solar heat collecting tube in which glass tubes of different diameters, one end of which is closed and the other end of which is open, are stacked with a required gap. The main body is a vacuum double tube, which is made by stacking the inner and outer glass tubes on top of each other, airtightly joining the open ends of the inner and outer glass tubes, and reducing the pressure in the inner space. A heat conductive cylinder having a roughly circular shape is inserted into the inner glass tube with its selective absorption membrane surface in surface contact with the inner surface of the inner glass tube, and the intermediate portion is bent into a U-shape so that the left and right sides are bent. The straight pipe portions of the heating medium conduction tubes each having a straight pipe portion are inserted into the heat conductive cylinder while elastically contacting the inner surface of the heat conductive cylinder, and the straight pipe portions are brought into contact with the straight pipe portion. The heating medium conduction tube is fixed to the inner surface of the heat conductive cylinder by partially covering the circumference of the straight pipe part with support pieces provided at key points on the inner circumferential surface of the heat conductive cylinder. be.

[Effect]

In the vacuum double tube type solar heat collecting tube of the present invention, the solar heat absorbing film formed on the outer peripheral surface of the heat conductive cylinder installed inside the inner glass tube is brought into surface contact with the inner surface of the inner glass tube. By supporting the heating medium conduit in contact with the inner surface of the heat-conducting cylinder, the solar heat absorption film absorbed by the solar heat absorption film that is in surface contact with the inner surface of the inner glass tube is formed. The heat is transmitted directly to the heating medium conduit through the heat conducting cylinder, and the heating medium is heated.

[Example 1] Reference numeral 1 denotes a vacuum double tube, including an outer glass tube 2 consisting of a transparent straight glass tube with one end closed and the other end open, and an outer glass tube 2 with one end closed and the other end open. The inner glass tube 3, which is made of a transparent straight glass tube and has a smaller diameter and length than the outer glass tube 2, is stacked concentrically in two layers with a required gap, and their open ends are hermetically joined. Then, the two are integrally connected, and the space between the inner and outer glass tubes 2 and 3 is depressurized to the required degree of vacuum, so that the heat absorbed by the inner glass tube 3 is propagated by convection between the inner and outer glass tubes 2 and 3. It is configured to prevent you from doing so.

6 has a solar heat absorbing film 7 on its outer circumferential surface, has an outer diameter slightly smaller than the inner diameter of the inner glass tube 3, and is made of a metal that is a good thermal conductor and has a length slightly shorter than the inner glass tube 3. With a thin heat conductive cylinder,
The heat conductive cylinder 6, which is formed by winding a steel plate or an aluminum plate into a cylinder shape, is inserted into the inner surface of the inner glass tube 3 with its solar heat absorbing film 7 in surface contact. The solar heat absorption film 7 has excellent heat absorption properties and also has a function of suppressing the radiation of the absorbed heat. It is desirable that the inner layer be a heat-absorbing metal oxide or composite metal carbide film, and the outer layer be a metal film with low thermal emittance that reflects heat radiated from the inner layer toward the inner layer.

Reference numeral 8 denotes a U-shaped heating medium conduction tube made of a good thermal conductor such as copper or aluminum, and the straight tube portions extending opposite from the U-shaped base end are slightly elastically deformed in the direction of mutually closing. Heat conductive cylinder 6
Both straight pipe portions are housed and supported in line contact with the inner surface of the pipe by their own elastic force.

In order to increase the contact area between the heating medium conduit tube 8 and the heat conduction cylinder 6 and to position them both, the method shown in FIG.
As shown in FIG. 2, several pairs of supporting pieces 10 and 11 facing each other in a V-shape are arranged in one line in the axial direction on the inner surface of the heat conducting cylinder 6 in correspondence with the insertion position of the heating medium conduit tube 8. The heating medium conduit tube 8 inserted into the heat conduction cylinder 6 is fixed by brazing to the supporting piece 1.
Partially caulk with 0 and 11. Also, the third
As shown in FIG. Corresponding curved surfaces 13 can also be formed along its longitudinal direction, and furthermore, as shown in FIG. It may also be pieces 14 and 15. Furthermore, in order to increase the contact force of the heating medium conduit 8 with the heat conduction cylinder 6, a biasing member such as a leaf spring 16 formed by slightly bending both sides from the center part of the heating medium conduit 8 can be attached to both sides of the heating medium conduit 8. It may be interposed between the tube parts.

[Effect of idea]

The vacuum double-tube type solar heat collecting tube of the present invention has a solar heat absorption film formed on a metal heat-conducting cylinder that is much easier to handle than a glass vacuum double-tube. Decreased formation efficiency and therefore vacuum 2
It is possible to prevent a decrease in the yield of the double-pipe type solar heat collection tube, and it is possible to achieve a cost reduction of the vacuum double-pipe type solar heat collection tube.

Furthermore, since the solar heat absorption film is directly formed on the outer peripheral surface of the heat conduction cylinder that the heating medium conduit comes into contact with, the solar heat collected by the absorption film is efficiently transferred to the heating medium conduit. can be transmitted. In that case, since the heating medium conduit is placed in contact with the inner circumferential surface of the heat conductive cylinder, the solar heat absorption film is not obstructed by the heating medium conduit, thereby increasing the effectiveness of the absorption film. The heat collection area can be utilized to the maximum extent.

Moreover, since the heat conductive cylinder has an outer diameter slightly smaller than the inner diameter of the glass tube and is tightly fitted into the inner glass tube, the solar heat absorption film formed on the outer peripheral surface of the heat conductive cylinder is It is closely attached to the inner surface of the tube, thereby narrowing the propagation space for heat absorbed from the inner glass tube to the heat conducting cylinder.
An efficient heat collection effect can be achieved by the absorption film, and the solar heat collected by the absorption film is transferred to the heating medium that is elastically supported in contact with the inner peripheral surface of the heat conductive cylinder. By directly transmitting the heat to the conduction tube, it is possible to achieve an efficient heat transfer effect to the heating medium conduction tube by the heat conduction cylinder.

In addition, if a support piece that covers and supports the heating medium conduit tube is provided on the inner peripheral surface of the heat conduction tube, the contact area between the heating medium conduit tube and the heat conduction tube can be easily increased. Therefore, the heat transfer effect of the heat conductive cylinder to the heating medium conduit can be further improved.

[Brief explanation of the drawing]

The drawings show one embodiment of the vacuum double tube type solar heat collecting tube according to the present invention, and FIG. 1 is a vertical side view;
FIG. 2 is a cross-sectional view, and FIGS. 3A to 3D are partial cross-sectional views showing details of a support piece that covers and supports the heating medium conduit. 1...Double vacuum tube, 2...Outer glass tube, 3...
... Inner glass tube, 6 ... Heat conduction cylinder, 7 ... Solar heat absorption film, 8 ... Heating medium conduction tube, 10 and 1
DESCRIPTION OF SYMBOLS 1... Support piece, 12... Support piece, 13... Curved surface, 14 and 15... Support piece, 16... Leaf spring.

Claims (1)

[Claims for Utility Model Registration] Glass tubes of different diameters, one end of which is closed and the other end of which is open, are stacked in double layers with a required gap,
The main body is a vacuum double tube made by airtightly joining the open ends of the inner and outer glass tubes and reducing the pressure in the inner space.The tube has a selective solar heat absorption membrane surface on the outer peripheral surface and has a roughly circular cross-sectional shape. A thermally conductive cylinder is inserted into the inner glass tube with its selective absorption membrane surface in surface contact with the inner surface of the inner glass tube, and the intermediate portion is bent into a U-shape, and straight tube portions are formed on the left and right sides. straight pipe portions of heating medium conduction tubes having elastic contact with the inner surface of the heat conduction cylinder, respectively, inserted into the heat conduction cylinder, and a heat conduction cylinder in contact with the straight pipe portion; A vacuum double tube consisting of a heating medium conduit tube fixed to the inner surface of a heat conductive cylinder by partially covering the circumference of the straight tube part with support pieces provided at key points on the inner peripheral surface of the body. type solar collector tube.