JPS5852937A - Solar heat collector - Google Patents

Abstract

PURPOSE:To prevent a heat collecting pipe from being damaged due to the repetitive heating and cooling of the heat collecting pipe by a method wherein in the titled heat collector having a U-shaped finned heat collecting pipe sealed therein, a forward pipe section and a backward pipe section of the pipe are bridge-connected at their parts to which no fin is attached. CONSTITUTION:The forward pipe section 4 and the backward pipe section 5 of the heat collecting pipe 3 are brazed to the holding parts of connecting members 11 made of metallic rods and are connected to each other at the outside of both ends of the pipe. With the above structure, the thermal stress due to the difference in temperature between the forward pipe section 4 and the backward pipe section 5 generates mainly between the connecting members themselves and forces applied on the pipe sections 4 and 5 are reduced at their parts supported by the connecting members 11. Consequently, no force is applied directly on sections 9 and 10 at which both of the pipe sections 4 and 5 are fixed and the U-shaped bent section 3a to thereby prevent the heat collecting pipe 3 from being damaged.

Description

[Detailed description of the invention] The present invention relates to an improvement of a thick heat collector.

Vacuum glass tube type solar collector has a heat exchanger of +l'
Although it can be heated to J temperature, there are various problems in terms of manufacturing and lifespan.

This point will be explained with reference to the follower's vacuum glass tube two positive heat collectors shown in FIGS. 1 and 2.
．． In Figure 2, ■ is an outer glass tube that serves as a transparent cover and a box. J2 is a cylindrical heat collector with selective absorption coating applied to at least the outer surface. For example, it is made of extruded aluminum. 3 is in thermally conductive contact with the cylindrical heat collector 2, and serves as a path for a heat medium that is heated by obtaining heat from the cylindrical heat collector 2 heated by field heat. This is a heat collection vibrator made of copper pipes, etc.The three heat collection pipes are bent into a U-shape to form an outgoing pipe part 4 and an incoming pipe part 5. After inserting the cylindrical insertion hole 2aK formed inside the heating body 2, the outgoing tube part 4 is fixed internally by tube expansion.6 is a sealing plate at the end of the outer glass tube J. In order to adhere to the IC, the outer glass tube 1 is made of an iron, nickel, chromium alloy, etc. whose coefficient of expansion is similar to that of glass. - Also, the heat collecting pipe 3 is brazed.

In this way, the outer vitreous bone 1 and the seal plate 6 form a vacuum container. 7 is the Ul on the outer glass tube 1 and the seal plate 6.
This is a vacuum section formed by evacuating a chip tube (not shown) with a vacuum pump and sealing the chip tube. 8, the cylindrical heat collector 2 is connected to the outer glass tube 1
A spacer, made of, for example, ceramic, that holds the device in place inside the device. In such a collector, the force generated by the thermal expansion of the heat collecting pipe 3 is applied to the seal plate 6.
In addition to this, there is a drawback that the fused portion tends to be partially destroyed. Therefore, when sealing the glass tube l, it is necessary to make the sealing part strong by matching the thermal expansion coefficients of the glass tube l, the sealing plate 6, and the adhesive material. , 426 alloy, and hard secondary glass, Kovar or the like is used, and low melting point glasses with matching expansion coefficients are used as adhesive materials.

Now, the inventors of the present invention have found that in general, with the above-mentioned configuration, the damage prevention TTF of the collector that is repeatedly heated and cooled is a phenomenon that cannot be adequately addressed with this configuration. , (D One of them is a phenomenon in which the heat collector 2 mechanically bonded to the outgoing pipe section 4 moves from the right to the left on the pipe section 4 due to repeated heating and cooling. It is not clear why this phenomenon occurs, but it is thought to be because the thermal expansion coefficients of the heat pipes, heat collecting plate 2, aluminum (A/?), and JJ heat pipes and copper (Cu) are different. When this phenomenon occurs, for example, when the heat collector 2 moves to the right in Figure 1,
There is a risk that the fused portion of the seal plate 6, the joint portions 9 and 10 between the seal plate and the heat collecting pipe 3, or the seal plate 6 itself may be damaged.

Conversely, when moving to the left, there is a risk that the U-shaped bent portion 3a of the heat collecting pipe 3 will be suppressed by the end portion of the heat collecting plate 2 and deformed.

■ The other phenomenon is a transient phenomenon during heating or immediately after cooling, where a temperature difference occurs between the outgoing pipe section 4 to which the heat collector 2 is fixed and the return pipe section 5 to which nothing is fixed. It is. This temperature difference causes a difference in the axial length of both tube sections 4.5, resulting in a difference in the axial length of the two tube sections 4.
A stress that may cause damage may act on the joint part 9 and 10, causing the joint part 9 and 10 to come off and the seal plate 6 to crack or crack, causing a slow leak (h: air leak), or the U-shaped bent part 3a. This causes buckling as shown in Figure 3, causing problems in the circulation of the heat medium.

The phenomenon (2) above is thought to occur in the following cases when the temperature of the collector changes.

[During normal collector operation]

(a) What is the period from the beginning of solar radiation until the heat medium circulates? S
, 1 (b) Heat medium (4) If it is circulating or the amount of solar radiation or outside temperature changes (c) After the circulation of the heat medium stops near the daylight, the heat collecting plate 2, heat collecting pipe 3, etc. When approaching the outside temperature (gradient)
After that, during the period in the trench where solar radiation begins (following changes in the width of the outside air) [During abnormal operation] (E) When the heating medium is not circulated during the day and at night and the heating is carried out in an empty state 1. In this case - It is heated and cooled through the mouth to a room temperature of about 200℃, but the temperature changes drastically as in normal operation.

(to) ``In a dry-cooked oven in 1, the heating medium is suddenly turned off to 1.
In the case of 6 rings, the temperature inside the heat collection pipe is about 200℃ (C) The temperature change is large because the low-temperature heat medium is suddenly released.

[During the manufacturing process]

(g) For example, since it is heated to several hundred degrees in a VC, such as by vacuuming, it undergoes heating and cooling changes from normal temperature to one hundred degrees normal temperature.

On the other hand, the phenomenon of (2) above is caused by the fact that among the above (a) to (g), there is almost no temperature difference in the VC between the outgoing pipe section 4 and the outgoing pipe section 5 due to the circulation of the heat medium (b). It is thought that this will occur except in certain cases.

The present inventors discovered the above-mentioned phenomenon based on various experiments, and by adding a research technique, succeeded in preventing this phenomenon with an extremely simple structure.

Below, the solution will be explained using drawing i/7: 3.
3 Figures 4 and 5 are cutaway views of the solar collector of the present invention.
The same parts as in Figure 2 are indicated by the same symbols. In figure 4 number I
I is a connection work ↓ provided to prevent the above phenomenon, and is placed outside G from both ends of the heat collector 2 to bridge and hold the outgoing pipe part 4 and the return pipe part 5.

This connection J4Z is made by bending a single metal body into the shape of a pair of glasses as shown in FIG. After tightening the part a 5, the pipe part 4
, 5 are fixed by brazing or welding, respectively.

In this way, even if the connector 11 welded or glow-attached to the heat collecting pipe 2 is made of the same material as the pipe 3, it will not be misaligned during heating or cooling like the heat collecting body 2. Ganakomi.

According to the above configuration, thermal strain based on the temperature difference between the outgoing pipe section 4 and the return pipe section 5 mainly occurs between the two connectors II and 11, and the thermal strain occurs between the two pipe sections 4 and 5 based on the temperature difference. The force exerted by C is reduced at the connecting member 11 and disappears from the joint 9, 10 and the U-shaped bent portion 32. Therefore, the seal plate 6)
The seat of cracks and bends g3a! +■l can be prevented.

Note that even if there is only one connector 11, the side where it is provided is protected, so two connectors 11 are not necessarily required.

Furthermore, since the movement of the heat collector 2 is stopped at the portion where the connector II is provided, damage caused by the phenomenon (2) above can also be prevented.

As mentioned above, according to the present invention, it is possible to provide a collector that has durability against repeated heating and cooling.

[Brief explanation of drawings]

Figure 1: Cross-sectional view of a conventional solar collector, Figure 2: 1
Figure 3 is an explanatory diagram of the buckling phenomenon, Figure 4 is a cross-sectional view of the solar collector of the present invention, Figure 5 is a sectional view taken along line A-A', Figure 6 is a cross-sectional view of the connector. Plan view, Code 3: Heat collection pipe, 4: Outgoing pipe section, 5: Incoming pipe section, 11: Connector. Agent Patent Attorney Aihiko Fukushi

Claims (1)

[Scope of Claims] ], a heat collector in which a U-shaped heat collecting pipe is enclosed in a transparent container, and heat collecting fins are fixed to the heat collecting vibe; A solar heat collector characterized in that an outgoing pipe part and a return pipe part of the heat collecting pipe are bridged with a connector in a part other than the fixed neck part of the heat fin.