JPS5924342B2 - Heat pipe type solar collector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar collector using a heat pipe.

Recent solar collectors (hereinafter simply referred to as collectors) have changed from the conventional non-vacuum type (so-called flat plate type) to prevent heat loss due to convection of the heated fluid and increase heat collection efficiency.
Vacuum tube type devices, in which a heat receiving element is sealed inside a vacuum container, are being replaced.

As this vacuum tube type collector, a so-called heat pipe type collector as shown in FIG. 1, which uses a heat pipe as a heat receiving element and improves heat collection efficiency due to good thermal conductivity, is considered to be promising.

In the figure, reference numeral 1 denotes a cylindrical glass tube with a bottom, into which a heat pipe 2 whose outer envelope is made of a metal material and whose surface is coated with a selective absorption membrane 1 is inserted. Tube 1 and heat pipe 2 are sealed.

The glass tube 1 is evacuated from an exhaust pipe (not shown) connected to the other end and then tipped off, and the inside 5
is kept in a vacuum state.

4 in the figure indicates a tip-off portion.

Note that the support spring 6 is attached to the outside of the heat pipe 2 in order to reduce the moment at the seal portion 3 and reduce the internal stress inside the glass tube in this portion.

The heat pipe 2 is connected to the header 8 by providing a hole in the side surface of the header 8 and passing through the heat dissipation part 9 of the heat pipe 2 in the hole as shown in the figure in order to perform good heat exchange. Usually, the header 8 is brought into contact with the heated fluid 10 flowing through the header 8 .

Since the collector described above has a structure in which the pipes 1 to 2 and the vacuum container (glass tube) 1 are inseparable, for example, if a crack occurs in the seal part 3 during long-term use,
It is necessary to replace the entire collector including the heat pipe, which is not only extremely uneconomical, but also because the heat dissipation part 9 of the heat pipe 2 is buried in the header, there is no possibility of receiving heat from the header 8 during the replacement work. Repairs such as preventing the heating fluid 10 from leaking also become very large-scale.

Furthermore, due to its nature, the outer envelope of the heat pipe 2 is generally made of a metal material, and the sealing work between the glass tube 1 and the heat pipe 2 requires extremely high-level work to maintain airtightness. Skill is required, and there is also a high risk of damage such as cracks in the part due to residual stress inside the glass after sealing 1 and thermal stress during use.

Furthermore, it takes a long time to vacuum the container because gas is released from the heat pipe sealed inside the container.

The present invention has been made in view of the above circumstances, and aims to facilitate repair work when the vacuum container is damaged during use by configuring the vacuum container and the heat pipe to be separable. .

Another object of the present invention is to make the vacuum container extremely easy to form by making it from a single material such as glass, and to improve reliability during use.

Still another object of the present invention is to perform the vacuum evacuation operation in a short time.

Other objects of the invention will become apparent from the following description of the examples.

FIG. 2 is a sectional view of the collector of the present invention, and the same parts as in FIG. 1 are denoted by the same symbols.

In FIG. 2, reference numeral 11 denotes a double wall structure consisting of a large diameter cylindrical glass outer wall 1 with a bottom and a small diameter bottomed cylindrical inner glass wall 1' having a selective absorption membrane I coated on the outer surface. In this heat-insulating container, the inner and outer walls 1' and 1 of the core are fused together at a sealing part 3 to form a hermetically insulated space 5.

The inside of this heat insulating space 5 is evacuated from the tip-off portion 4 and is in a vacuum state.

6 stably holds the ring-shaped support spring inner wall 1' fitted on the outer periphery of the inner wall 1' with respect to the outer wall 1, and reduces the moment at the seal portion 3.

Reference numeral 2 denotes a heat pipe having a heat absorption part 2a inserted into the container 1a, and a heat radiation part 9 of the heat pipe 2 is inserted into and connected to the ladder pipe 8.

Reference numeral 11 denotes a liquid having good heat transfer properties, such as silicone oil, which is filled between the heat absorbing portion 2a and the inner wall 1'.

12 is an opening 12. of the container 1a. A sealing plug prevents the liquid from flowing out.

It is preferable that the stopper 12 and the opening 128 of the container 1& are separable from each other, but they may be fixed with a sealing adhesive such as silicone sealer.

Although the plug 12 is fixed to the heat pipe 2, it is only watertightly fitted to the inner wall 1', so the difference in thermal expansion between the inner wall 1' and the heat pipe 2 is due to the plug 12 and its fitting part. will be alleviated.

Furthermore, when a silicone sealer is used, the difference in thermal expansion is particularly alleviated in this part.

Therefore, due to the difference in thermal expansion coefficient between the glass tube 1 and the heat pipe 2, which occurs in the conventional collector, cracks
This is unlikely to occur with this collector.

Reference numeral 68 is a support for stably holding the heat absorbing portion 2a of the heat pipe 2 against the inner surface of the inner wall 1', and is not necessarily required.

In order to prevent the plug 12 from slipping out due to thermal expansion, it is effective to make the liquid gradient 1 foamy in advance. Also, in order to improve heat conduction by the liquid 11, the inner diameter of the inner wall 1' It is more appropriate to configure the diameter to be as close to the diameter of the heat pipe 2 as possible.

The collector configured as above (constructed with solar heat selectively absorbing film 7
heat pipe 2 through the inner wall 1' and the liquid 11.
The heat is transmitted to the heat absorbing section 2a of the heat pipe, and further transmitted to the heat dissipating section 9 by heat pipe action to heat the fluid to be heated 10.

In the case of this collector, since the container 1a has a vacuum insulation space 5, the heat absorbed by the selective absorption membrane 1 can be absorbed by convection, conduction, etc.
Almost no heat is radiated by any radiation, and moreover, it is immediately transferred to the heated fluid 10 by the action of the heat pipe, so there is little heat loss and the heat collection efficiency is extremely high.

Although the selective absorption film I is not necessarily required in the above embodiments, if the film 1 is not provided, the amount of heat absorbed will decrease and the amount of heat released will increase, resulting in a considerably poor heat collection efficiency.

That is, without the membrane T, solar heat would be absorbed by the inner wall 1' and the liquid 1.
1, but since they are not as black as the film T, their heat absorption rate is poor.Also, even if they absorb heat, since there is no film I, a large amount of heat is radiated from the outer surface of the inner wall 1'.

In addition, when the container 1a of such a collector is damaged, repair is easy because all that is required is to remove the damaged container 1a and attach a new container to the heat absorbing portion 2a.

That is, when installing a new container 1&, it is sufficient to fill the container 1a with the liquid 11 and seal it with the stopper 12 so that the liquid 11 does not leak, so that vacuuming work and glass fusing work are not necessary. In comparison, the work is extremely simple and can be easily done outdoors.

Note that when installing a new glass tube 1 in the collector shown in FIG.
This requires extremely difficult work such as sealing the glass tube 1 and the heat pipe 2 and evacuating the inside of the glass tube 1, which cannot be done outdoors.

Therefore, when replacing the glass tube 1 of the collector shown in FIG. was.

Now, in the above collector, if the stopper 12 is separable from the container 18, then the container 1. Replacing L is very easy, but even if it is fixed with adhesive,
The work of removing the damaged container 1a and fixing the new container 18 and the stopper 12 is not as difficult as the conventional vacuuming work, and can be carried out satisfactorily at an outdoor installation location.

In addition, since the inner and outer walls 1' and 1 of the collector container 11 are made of the same material (for example, glass), it is extremely easy to seal the sealing part 3, and the internal stress can be easily removed, so that it can be used for a long time. It also has the effect of providing high reliability when used.

Furthermore, as is clear from FIG. 2, the heat insulating space 5 of the container 1a
Since the inner and outer walls 1' and 1 are made of glass and only has a built-in spring 6, the vacuuming operation is extremely easy, and another advantage is that there is no gas release.

[Other Examples]

(1) In FIG. 3, a container 1a and a heat pipe 2 can be removably screwed together, and a ring-shaped male screw 13 is welded 14 to the heat pipe 2.

Reference numeral 15 denotes a collar formed outward at the open end of the inner wall 1', and an L-shaped nut 16 is rotatably engaged with the collar 15.

The nut 16 is attached to the male screw 13 so that the collar 15 is watertightly crimped to the side surface of the male screw 13 via the heat-resistant O-ring 17.
are screwed together.

With such a structure, attachment and detachment of the container 1a becomes easier.

(2) The outer wall 1 may be made of a transparent material other than glass, such as resin.

Further, the outer periphery of the outer wall 1 may be covered with a transparent protective cover made of resin.

(3) The inner wall 1' does not have to be transparent, and its material is not limited to glass, but also resin, ceramic, metal (e.g. stainless steel,
Copper, Kovar metal), etc. may also be used.

If the inner wall 1' is made of glass, it is difficult to carve a screw in the part where it joins with the stopper 12, but if the inner wall 1' is made of metal, it is difficult to carve a screw in the part where it joins with the stopper 12. 12, and can be easily attached to and removed from the heat pipe 2.

(4) Instead of the liquid 110 having a good heat transfer rate, a solid material such as a metal having a good heat transfer rate may be filled between the heat absorbing portion 21 and the inner wall 1'.

゛Also, as shown in Fig. 4, the heat absorption part 23 of the heat pipe 2
By forming semi-cylindrical heat transfer fins 18, 18' integrally with the heat pipe 2 on the outer periphery of the heat pipe 2 and press-fitting them along the inner surface of the inner wall 1', it is possible to attach the heat pipe 2 and the container 1a. Work becomes easier.

In other words, the heat transfer fins 18, 18' serve both as a heat transfer medium and as a support 6a.

The one shown in FIG. 4 is suitable when the collector is short.

(5) When the inner wall 1' is opaque, the surface is treated with black, and when the inner wall 1' is transparent, the heat absorption rate is increased by making the good heat transfer medium black.

(6) forming a reflective film on the inner or outer surface of the outer wall 1 in order to effectively focus sunlight on the selective absorption film 7;
A reflecting means may be provided outside the container 1a.

Since the collector of the present invention has a diagonally upward configuration, it has the remarkable effect that it is extremely easy to repair the container if it is damaged.

Further, since it is easy to repair, it can be used for a long period of time, and the running cost is also significantly reduced.

[Brief Description of the Drawings] Fig. 1 is a cross-sectional view of a conventional collector, Fig. 2 is a cross-sectional view of the collector of the present invention, Fig. 3 is a cross-sectional view of main parts of another embodiment, and Fig. 4 is a cross-sectional view of a conventional collector. FIG. 7 is a sectional view of a main part of another embodiment. Code, 1a=container, 2: heat pipe, 7: selective absorption membrane, 8: header, 11: liquid, 12: plug.

Claims (1)

[Scope of Claims] 1. A heat absorption part of a heat pipe whose heat dissipation part is provided adjacent to the heated part is heated by solar heat, and heat is supplied to the heated part using the heat transfer action of the heat pipe. In this solar collector, the heat absorbing part of the heat pipe is removably inserted into a container with a double wall structure that has a vacuum insulation space formed between a transparent outer wall and an inner wall. A heat pipe type solar collector characterized in that it is thermally connected to an inner wall using a good heat transfer medium and the opening of the container is sealed. 2. The heat pipe type solar collector according to claim 1, wherein the inner and outer walls each have a cylindrical shape with a bottom. 3. The heat pipe type solar collector according to claim 2, wherein both the inner and outer walls are made of bottomed cylindrical tubes. 4. The heat pipe type solar collector according to claim 1, 2, or 3, characterized in that a selective absorption film is provided on the outer surface of the inner wall. 5. The heat pipe type solar collector according to claim 4, wherein both the inner and outer walls are made of glass. 6. The heat pipe type solar collector according to claim 4, wherein the inner wall is made of metal. 7. The heat pipe type solar collector according to claim 1, 2, 3, 4, 5, or 6, wherein the good heat transfer medium is a liquid. 8. The heat pipe type solar collector according to claim 7, wherein the container is filled with a liquid good heat transfer medium and sealed liquid-tightly with an upper stopper. 9. Claims 1, 2, 3, 4, 5 or 9, wherein the good heat transfer medium is a heat transfer fin integrally formed with the heat pipe. 7. The heat pipe type solar collector according to item 6. 10. The heat pipe type solar collector according to claim 9, wherein the heat absorbing part of the heat pipe provided with the heat transfer fins is press-fitted into the container, and the transfer fins are directly pressed onto the inner surface of the inner wall. 11. The heat pipe type solar collector according to claim 1, 5 or 6, wherein the opening of the container is sealed with a removable plug.