JPS5949506B2 - Dry heating prevention solar collector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar collector with improved durability by preventing dry firing when operation is stopped.

In general, a flat solar collector, in which a heat collecting mechanism consisting of a heat collecting plate, a heat collecting pipe connected to the heat collecting plate, and a header pipe communicating with the heat collecting pipe is housed in a collector case, is used during the installation work. When the operation is stopped, it will be in a dry firing state.

In this dry firing state, for example, the temperature of a heat collecting plate with a selective absorption surface reaches twice the temperature during operation.
This caused significant deterioration of durability, such as damage to connecting parts of component parts and deterioration of insulation materials.

In order to prevent such dry heating, a prevention structure like the conventional method has been adopted.

■There are ventilation holes on both ends of the collector case that can be opened and closed.
This structure works in conjunction with the water pressure in the tank or heat collection system to open the vent holes for air cooling during dry firing, and closes them during operation.

■Multiple reflectors are tiltably installed below the transparent plate provided on the top of the collector case to cover the heat collecting plate, and the reflectors can be tilted during operation in conjunction with changes in water pressure in the tank or heat collecting system. It has a structure in which sunlight is irradiated onto the heat collecting plate and the sunlight is blocked by a reflector plate when the operation is stopped.

Alternatively, there is a structure in which a water circulation circuit for the heat radiation system is installed in parallel with the heat collection system, and when the operation is stopped, the circuit is switched to the water circulation circuit for the heat radiation system to circulate water.

However, the conventional dry heating prevention device has the following problems.

The air-cooled type mentioned above has a problem with the watertightness of the opening/closing part of the ventilation hole, and the insulating performance of the insulation material decreases due to the intrusion of rainwater from here, and the heat collection efficiency decreases due to the decrease in the light transmittance of the transparent plate due to condensation. There are problems such as a decline in

In addition, in the case of type (■) equipped with a reflector plate, the distance between the transparent plate and the heat collecting plate is usually 10 to 25 mm for efficiency reasons, but this distance must be widened, which increases the size of the device. However, since a large number of reflectors are attached, the structure is complicated and the manufacturing cost is high.

In addition, the water-cooled type (2) has various drawbacks, such as an increase in the number of heat collecting plates, which increases the equipment cost and is economically disadvantageous.

The present invention has been made in view of these conventional drawbacks, and has developed a solar collector that has a simple structure, low manufacturing cost, excellent watertightness, reliably prevents dry firing, and improves durability. be.

That is, the present invention provides a heat collecting mechanism consisting of a heat collecting plate, a heat collecting pipe connected to the heat collecting plate, and a header pipe communicating with the heat collecting pipe, in a metal collector case whose upper surface is covered with a transparent plate. A dry heating system in which heat transfer plates are attached to the heat collecting mechanism or the collector case so as to be able to come into contact with and separate from the heat transfer plate, and the two are thermally connected so that heat leaks to the collector case side during dry heating. Prevent solar heat collector.

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 3 show an embodiment of the present invention. In the figures, 1 is a heat collecting mechanism, and 2 is a collector case that houses the heat collecting mechanism 1. FIG.

The heat collecting mechanism 1 is provided on the back side of a heat collecting plate 3 made of a metal plate with excellent thermal conductivity such as aluminum or stainless steel copper plate.
A plurality of heat collecting pipes 4 are installed in parallel or in a meandering manner, and header pipes 5 and 5' communicating with the heat collecting pipes 4 are installed at both ends of the heat collecting pipes 4.

The collector case 2 is made of metal such as aluminum, iron, or stainless steel, and has a rectangular box shape with an open top surface.A transparent plate 6 made of glass, plastic, etc. is attached to the top surface, and the interior of the case is It has a watertight structure.

Furthermore, a heat insulating board 7 made of foamed plastic, glass wool, asbestos, etc. is provided on the inner surface and bottom surface of the collector case 2 except for one surface on the header pipe 5 side.

Further, 8 is a plate-shaped heat transfer plate having one end bonded to the header pipe 5 by brazing or the like and the other end being free.

This heat exchanger plate 8 has a support rod 9 inserted inside the bent part on the header pipe side to give the heat exchanger plate 8 an elastic force, and the free lower end side is bent to form a collector. It is designed to come into close contact with the inner wall surface of the case 2.

Further, a thermostat 10 is provided at the bottom of the header pipe 5 along its longitudinal direction.

This thermostat 10 has a spiral bimetal 12 inserted into a metal outer cylinder 11 that contacts the header pipe 5, and is fixed to one end of the outer cylinder 11, and the other end of the bimetal 12 is fixed to the outer cylinder 11. Rotating shaft 1 provided in the center of the cylinder 11
It is fixed at 3.

Furthermore, a bent arm 14 is attached to the end of the rotary shaft 13 protruding from the outer cylinder 11, and the tip of the arm 14 is connected to the heat transfer plate 8, and as the arm 140 rotates, The heat exchanger plate 8 comes into contact with and separates from the inner wall surface of the collector case 2.

In the solar collector having the above structure, when the heat collecting plate 3 is heated when the operation is stopped, the header pipe 5 is also heated by heat conduction.

Accordingly, the spiral bimetal 12 of the thermostat provided in contact with the header pipe 5 expands thermally, causing the rotation shaft 13 to rotate.

This rotation causes the arm 14 to rotate, and in conjunction with this, the heat transfer plate 8 rotates from the separated state shown by the imaginary line and contacts the inner wall surface of the collector case 2, as shown in FIG. By connecting it to the collector case 2 and leaking heat to the collector case 2 side, dry heating can be prevented.

In the above embodiment, the structure is shown in which the arm 14 is rotated to move the heat exchanger plate 8 toward and away from the heat transfer plate 8, but a structure in which the heat exchanger plate 8 is moved toward and away from each other by telescopic movement may also be used.

In addition, the temperature detection mechanism is not limited to those that utilize thermal expansion of metal, but also includes gas, liquid, etc. sealed in the cylinder.
A structure that utilizes the thermal expansion may also be used.

Furthermore, the above embodiment has a structure suitable for discontinuous operation such as when a large number of solar collectors are arranged adjacent to each other and only some of the collectors are operated, or when they are operated intermittently. However, if only some solar collectors are operated for hot water except for heating in winter,
Alternatively, if the installation is to be suspended for a long period of time, such as during a construction period, a structure as shown in FIG. 4 is preferable.

This solar heat collector has a screw hole 15° 15 in the collector case 2 on the side where the header pipe 5 is placed, and screws the pole 16 and 16 into this hole so that the pole protrudes inward.
A curved heat exchanger plate 8 is attached to the tip of 16.16.

By rotating the bolts 16, the heat exchanger plate 8 is brought into contact with the header pipe 5, and is thermally connected to the collector case 2 via the heat exchanger plate 8 and the port 16. This prevents dry firing by leaking water.

In the above embodiment, the heat exchanger plate 8 is manually brought into contact with and separated from the heat exchanger plate 8, but a structure in which the heat exchanger plate 8 is brought into contact with and separated from the heat exchanger plate 8 electrically using the driving force of a motor may be used.

Further, the mounting position and size of the heat transfer plate 8 can be appropriately selected depending on the installation location, amount of heat radiation, etc.

Therefore, the heat transfer plate 8 can be installed not only between the header pipe 5 and the collector case 2 as described above, but also when installing the solar heat collector on a flat roof or roof top, tilting the solar heat collector. A heat transfer plate 8 may be provided between the back surface of the plate 3 and the bottom surface of the collector case 2 to thermally connect the two.

In this case, if the surface of the heat exchanger plate 80 is made a reflective surface, the loss of heat during heat collection can be reduced.

As explained above, according to the dry heating prevention solar collector according to the present invention, when the operation is stopped intermittently or for a long period of time, abnormal temperature rise of the heat collection mechanism is suppressed and reliably It is possible to prevent dry firing.

As a result, it is possible to prevent the connecting portions of the structural members from being damaged due to thermal expansion and contraction, and to prevent deterioration of the heat insulating material, thereby increasing durability.

Further, the present invention has remarkable effects such as simple structure, low manufacturing cost, and excellent watertightness.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view showing an embodiment of the present invention;
2 is a longitudinal cross-sectional view of the main part taken along the line ■-■ in FIG. 1, FIG. 3 is a cross-sectional view of the main part taken along the line ■-■ in FIG. FIG. 3 is a plan cross-sectional view showing an example. 1... Heat collection mechanism, 2... Collector case, 3...
・Heat collecting plate, 4... Heat collecting pipe, 5, 5'... Header pipe, 6... Translucent plate, 7... Heat insulating material, 8... Heat transfer plate, 10... Thermostat , 12...bimetal, 14...arm.

Claims (1)

[Claims] 1. A heat collection mechanism consisting of a heat collection plate, a heat collection pipe connected to this, and a header pipe communicating with this heat collection pipe,
It is housed in a metal collector case whose top surface is covered with a transparent plate, and heat transfer plates are attached to the heat collection mechanism or the collector case so that they can be freely approached and separated from each other, and the two are thermally connected for dry firing. A solar heat collector that prevents dry firing, which sometimes causes heat to leak into the collector case side.