JPS5828901B2 - solar collector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the performance and construction of solar collectors.

Many structures have been put into practical use as solar heat collectors, but the mainstream structure is a combination of a metal flat plate with a solar heat absorbing film formed on its surface and a heat pipe or metal tube through which a heat transfer fluid flows. .

In other words, flat plate collectors are made by forming a solar heat absorbing film on one side of a flat plate made of copper, aluminum, stainless steel, etc., using this side as the solar heat absorbing surface, and forming a metal tube on the other side, or by welding or crimping the metal tube. It had a structure in which a heat medium liquid was allowed to flow through it, and a heat pipe was welded or crimped.

Vacuum tube type collectors are also made by enclosing a metal tube with metal plate fins or a heat pipe inside a vacuum glass tube in order to reduce convection loss of heat. It is the same as a flat collector in that it has a solar heat absorbing surface and a metal tube or heat pipe as a heat transfer means.

This basic structure is shown in FIGS. 11 and 12.

In the drawing, 6 is a heat pipe for heat transfer, 9 is a metal tube through which a heat medium fluid flows, and 11 is a metal flat plate with a solar heat absorbing film formed on its sunlight incident surface.

These materials include copper if the main focus is on thermal conductivity,
Aluminum is often used when light weight is important, and stainless steel is often used when corrosion resistance is considered.

There are still many points to be improved in these conventional solar collector structures.

Solar heat utilization using solar heat collectors is rapidly becoming popular, but these problems are obstacles to its application to general households, which consume the most energy.

The major problem with these problems lies in the high cost of solar heat utilization systems, and the high cost of solar heat collectors is a major factor in this problem.

Furthermore, from the viewpoint of collector performance, a large light-receiving area is required, which increases the overall cost.

Many of the causes of this problem are due to the basic structure of solar collectors.

As is clear from Fig. 11, in the case of the metal tube method,
In order to increase heat exchange efficiency, a large number of long metal tubes are required by meandering narrow tubes to increase heat exchange efficiency, a large amount of expensive heat conductive metal is used, and the complicated structure increases manufacturing and maintenance costs.

In addition, in order to force the heat transfer liquid to flow through such a long thin metal tube, a fairly powerful pump is required, which also results in energy loss and increases maintenance costs. Met.

In particular, solar collectors can withstand high temperatures of 100°C or higher.
A complex structure increases the chance of failure because the tube repeatedly expands and contracts due to intense temperature cycles until it reaches temperatures as low as 30 degrees Fahrenheit.Furthermore, metal tubes are dependent on the internal pressure of the heat transfer liquid that is forced to circulate within them. Since internal stress (the internal force that tries to create a straight line is particularly large) is added, it is necessary to increase the safety factor in the design, which is also a factor in increasing costs.

In FIG. 12, a heat pipe is used for heat transfer to prevent the collector structure from becoming complicated and from increasing internal stress due to temperature changes.

This structure does not require a pump for circulating the heat medium, and relies on the heat pipe's excellent thermal response, heat transfer ability, and heat exchange efficiency to improve performance and simplify the structure.

However, the cost improvement is not sufficient due to the use of a large number of relatively expensive heat pipes.

In addition, since the heat medium liquid or water is heated through a large number of heat pipe terminals, the structure of the heat exchange part becomes complicated, making assembly difficult, which is a disadvantage compared to the metal tube method. Become.

The necessity of mounting metal tubes and heat pipes at high density as shown in FIGS. 11 and 12 is fundamentally due to the fact that the heat absorption plate is a metal plate.

No matter how good a metal is in thermal conductivity, there is a limit to increasing its heat transfer rate or reducing its thermal resistance. It just makes you listen.

In collectors currently in practical use, the spacing between metal tubes is 80 mm to 125 mm, and the spacing between heat pipes is approximately 170 mm.

When the flat plate is configured as an in-board attached to a tube or heat pipe, the width of one fin is called i.

In addition, the flat collector has heat conduction loss and radiation loss from the back surface of the metal plate, and making the fin width a dog increases this loss as well, so the above-mentioned width is the limit.

In addition, the vacuum tube type solar collector has no heat conduction loss or convection loss, so theoretically it should be possible to increase the metal fin width to a large extent, but the vacuum glass tube's strength and cost make it smaller. It is between 60mm and 80mm.

Therefore, vacuum tube type collectors, whether they are metal tube type or heat pipe type, have high performance but are extremely expensive and are not suitable for general household use.

As shown above, unless the basic structure of solar collectors is changed, it is currently extremely difficult to significantly reduce costs and improve performance.

We have filed Japanese Patent Application No. 54-115578 and No. 54-129268 in order to improve the complexity of the structure, which is an important point of such solar collectors, and to greatly increase the performance.
No. 1, and Japanese Patent Application No. 155964/1984, we proposed a solar heat collector based on the application of flat heat pipes.

However, in order to withstand the high vacuum inside the container and the vapor pressure of the working fluid at high temperatures, a typical flat heat pipe needs to have a thick metal flat plate, and it is also necessary to insert a pressure-resistant support into the container. Naturally, it is also necessary to form a sufficient amount of wick inside the container, and it has never been possible to manufacture it at a low cost.

Therefore, even though it is possible to simplify the structure and greatly improve the performance of a solar collector using a flat heat pipe, it has not been possible to expect much in terms of cost reduction.

The present invention improves the basic structure of the solar heat collector as described above, makes it possible to increase the spacing between metal tubes or heat transfer heat pipes to at least 500 m or more, and shorten the length of the metal tubes or heat transfer heat pipes. The objective is to reduce the number of solar heat collectors and simplify the structure of the solar heat collector, as well as to provide a new structure that can be mass-produced, thereby achieving a significant price reduction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A novel flat heat pipe used in a solar heat collector according to the present invention and an application example of a solar heat collector using the flat heat pipe will be described in detail below with reference to the drawings.

FIG. 1 shows a flat heat pipe of a novel structure used in a solar heat collector according to the present invention.

The flat heat pipe consists of two metal thin plates 1 and 2,
As shown in the figure, a large number of embossments of an arbitrary cross-sectional shape are applied in parallel to either only 1 or both 1゜2.
2, the embossed part 3 is formed as shown in FIGS. 2, 3,
As shown in FIG. 4, a large number of parallel sealed containers 3 of various cross-sectional shapes are formed.

Each sealed container is sealed with an appropriate amount of working fluid under high vacuum pressure, and if necessary, a support is provided to prevent the container from collapsing and buckling due to high vacuum pressure reduction, as shown in Figure 3. Alternatively, insert an auxiliary wick that also serves as a support.

In other words, two thin metal plates are connected to a large number of small cross-sectional area heat pipes (
Hereinafter referred to as unit heat pipe.

) are arranged in parallel and closely connected to constitute a flat heat pipe.

1 and 2 are bonded in a wide area around the periphery to ensure a high vacuum condition for the entire flat heat pipe for many years, and each unit heat is bonded between each embossed part. The pipes are linearly and thinly glued so that each pipe operates as an independent heat pipe, and the flat heat pipe has better flexibility.

Further, when bonding 1 and 2, since the thickness of the metal sheet can be made very thin, continuous and high-speed welding can be performed by means such as ultrasonic welding or light beam welding.

Also, since the unit heat pipe is formed by welding two flat plates, both lines have a wedge-shaped cross section as shown in the cross-sectional shapes in FIGS. 2, 3, and 4. A contact area with minute gaps is naturally formed due to the shape and the seam of the two thin plates, and this area acts as an excellent group type wick and capillary wick, and is particularly useful when inserting a wick. , no need to form.

Since the formation or insertion of the wick accounts for the largest proportion of the manufacturing cost of a heat pipe, the wick can be omitted because the unit heat pipe and its parallel connections are the main part of the flat heat pipe of the present invention. This greatly reduces the manufacturing cost of the product.

A unit heat pipe with such performance and structure is completely different from a normal cylindrical heat siphon or a wickless heat pipe, and as is clear from each cross-sectional view, the unit heat pipe has a sufficiently large cross-sectional area compared to the unit heat pipe cross-sectional area. The wedge-shaped cross-sectional area and the sufficient width of the thin plate contact area make it a perfect heat pipe that exhibits a strong wicking effect.

Therefore, the unit heat pipe is not only used for vertical bottom heating, but also works well as a heat pipe whether it is used for horizontal heating or for vertical top heating of a certain length.

The flat heat pipe of the novel structure as detailed above has the following features compared to a normal flat heat pipe.

(1) The manufacturing process is extremely simple, and a large number of unit heat pipes can be continuously produced in a connected state.Furthermore, the metal sheet can be made extremely thin at a speed of around 0.05m, so the wick can be specially made. The cost is extremely low as there is no need to form it.

(2) The container wall thickness is extremely thin and there is no need to insert wick material such as mesh, so it is extremely light in weight.

(3) For the above reasons, the thermal response speed of the flat heat pipe is extremely fast, reaching 25 times that of copper and five times that of a normal heat pipe.

(4) Since the unit heat pipes are arranged in parallel, the heat transfer direction is limited to the axial direction of the unit heat pipes.

However, each unit heat pipe has a larger heat transfer capacity than a cylindrical heat pipe with the same cross-sectional area, and the flat heat pipe that is a parallel connection thereof has a much larger heat transfer capacity than a normal flat heat pipe.

This is because the unit heat pipe is wickless, so it has a steam passage with a cross-sectional area several times larger than that of a heat pipe with the same cross-sectional area. This depends on the fact that the contact area between the two thin plates has sufficient size and capacity to allow a large amount of working fluid to flow back with little resistance.

(5) Since the flat heat pipe has a soft structure, it can be attached to the object to be heated with very low contact thermal resistance.

As mentioned above, the flat heat pipe is extremely low cost and has high performance, so it is extremely effective when used as a solar heat absorbing flat surface of a solar heat collector.

In other words, it can absorb solar heat and supply thermal energy to the heat transfer means with several hundred times the heat transfer capacity and heat transfer rate and several tens of times the thermal response speed compared to the solar heat absorption plane of a normal flat plate collector. I can do it.

In FIGS. 1 to 4, reference numeral 4 denotes a solar heat absorbing film for using the flat heat pipe as a solar heat absorbing plane.

In the drawing, the uneven surface of the unit heat pipe is used as the solar heat absorption plane, and the solar heat absorption film is provided only on that surface, but which surface to use can be determined depending on the structure of the collector, and therefore the drawing The opposite surface may be used, or if necessary, a solar heat absorbing film may be provided on both surfaces to use both surfaces as solar heat absorbing surfaces.

5 and 9 are schematic diagrams of an embodiment of the solar collector according to the present invention, and only the heat absorption and transfer portions are shown, with the housing, protective glass, heat insulating layer, etc. being omitted.

A solar heat absorbing film is formed on one surface of the unit heat pipe parallel-connected flat heat pipe according to the present invention illustrated in FIGS. 5 and 9 to form a solar heat absorbing plane 5.

FIG. 5 shows an example in which a heat vibro for heat transfer is used as the heat transfer means.

The solar heat absorbing plane 5 has a heat absorbing part 6 of a heat vibro for heat transfer near one side of the back surface so as to be orthogonal to the unit heat pipe.
′ is attached tightly.

In order to reduce thermal resistance, it is preferable that this attachment part be completely adhered by brazing, soldering, etc.

In addition, in order to improve the circulation of the working fluid of the unit heat pipe and improve the heat transfer efficiency, the solar heat absorption plane 5 should be set at 10 degrees with respect to the horizontal plane so that the heat absorption part 6' of the heat transfer heat pipe is on the upper side. It is better to give an inclination angle of 90°C to 90°C.

This is because most of the circulation of the working fluid in the unit heat pipe of the flat heat pipe according to the present invention depends on the action of the wedge-shaped cross-section formed on both edges of the unit heat pipe as a group type wick. The wicking action of is highly dependent on gravity.

The length of the solar heat absorbing plane 5 in the longitudinal direction of the unit heat pipe is determined depending on the length at which the unit heat pipe operates efficiently.

If the cross-sectional area of a unit heat pipe is equivalent to a 4mvtφ cylinder, the length for efficient operation is approximately 50cm, which is 6mmφ.
The effective length when corresponding to a cylinder is about 1 m.

Therefore, when constructing a solar collector using a solar heat absorbing plane as a unit using a flat heat pipe as illustrated in FIGS. 5 and 9, the heat pipe for heat transfer is 50 cm.

They will be placed at the above intervals.

The solar heat energy absorbed by the solar heat absorption plane 5 is absorbed by the heat absorption part 6' of the heat transfer heat vibro.

As mentioned above, the heat transfer speed in this case is several hundred times faster than the mesh plane of a normal flat plate type collector, and the thermal response speed is several tens of times faster.

Thermal energy absorbed by the heat absorbing section 6' is transferred to the heat dissipating section 6'' at high speed and efficiency unique to heat pipes, and is circulated between the water in the water storage tank 8 or the heat storage tank via the fins 7. It is dissipated into the heat transfer liquid and heats them.

6, FIG. 1, and FIG. 8 show the state in which the heat transfer heat vibro is attached or welded to the solar heat absorbing plane 5.

FIG. 6 shows a state in which the unit heat pipe is welded to the surface opposite to the protruding surface at a position approximately in the middle of the length of the unit heat pipe, perpendicular to the unit heat pipe group.

In this case, the solar heat absorption plane must be kept horizontal.

If it is tilted, the part of the unit heat pipe where the heat transfer heat pipe is installed will become bottom heat and the circulation of the working fluid will be helped by gravity and it will work efficiently, but the part which is above the position. This is because the top heats up and the working fluid has to circulate against gravity, reducing efficiency.

In FIG. 1, a heat transfer heat pipe is bonded to the end of a group of unit heat pipes so as to be perpendicular to the unit heat pipes, and the solar heat absorption plane 5 is held vertically.

The terminal portion of the solar heat absorbing plane is bonded in an arc shape in contact with the outer periphery of the heat transfer heat pipe.

Since the unit heat pipe group operates vertically, the heat transfer efficiency of the flat heat pipe as a solar heat absorption plane is maximum.

In Fig. 8, the mounting position of the heat transfer heat pipe with respect to the solar absorption plane 5 is the same, but the heat exchange area is expanded by making the heat transfer heat vibro have a rectangular cross section. be.

Moreover, the solar heat absorbing plane 5 is given a slight inclination angle with respect to the horizontal plane.

Although FIG. 6, FIG. 7, and FIG. 8 illustrate the installation of a heat transfer heat pipe, the same applies to the installation of a metal tube through which a heat transfer liquid flows.

However, in the case of heat exchange using a heat transfer liquid, it is desirable to bond the tubes to the common heat absorbing planes for the forward and return trips, so two tubes are often installed in parallel.

FIG. 9 is a schematic diagram of a solar collector in which a heat exchange metal tube is attached instead of a heat transfer heat vibro.

5 is a flat heat pipe of the present invention, which is a solar heat absorbing plane;
9 is a metal tube, and the arrow indicates the direction of the heat transfer fluid flowing through the metal tube.

Reference numeral 9 indicates a heat medium liquid flow through postp 8, and a heat storage tank 10 indicates a heat exchange device.

The heat transfer liquid heated by the heat absorption plane 5 is conveyed by a metal tube into a heat storage tank or a water storage tank and heated by a heat exchange device 10 to heat the water therein.

Compared to heat transfer using heat pipes, the heat exchange efficiency between the metal tube and the heat absorption plane is lower, so it is necessary to increase the number of tubes.

The heat loss is slightly increased due to the low heat transfer rate between the thermal storage tanks or water storage tanks.

A pump is required for circulating the heat medium liquid, which consumes energy, resulting in an increase in overall energy loss.

Pump system maintenance is required.

There are some disadvantages in this regard. However, compared to the conventional flat plate type collector, the structure is simpler, the length of the metal tube used is shorter, and the energy consumption of the heat medium liquid transfer pump is therefore lower.

There is no doubt that this is a major improvement in terms of higher solar heat utilization efficiency.

In order to improve the heat exchange efficiency between the metal tube 9 and the heat absorption plane 5, FIG.
′ is shown as an example.

In this case, the heat medium liquid is directly heated by the unit heat pipe, and the contact area between the two can be increased, so that performance can be improved.

Since the solar heat collector according to the present invention illustrated in FIGS. 5 and 9 and detailed in the text has the above-described structure, it has the following effects in conjunction with the effects of the flat heat pipe illustrated in FIG. 1. be effective.

(1) The heat transfer speed on the heat absorption plane is fast, and the heat transfer is not carried out by surface propagation on the heat absorption plane, but is transferred very quickly and directly from the heat absorption part to the heat radiation part by the vapor of the working fluid, so the heat absorption plane There is no time for heat conduction loss or heat dissipation loss from the back surface on the light-receiving side, so heat loss is drastically reduced compared to conventional solar heat absorption planes.

(2) It has a high-speed thermal response several ten times faster than that of a conventional flat-plate solar collector and several times faster than a heat pipe-type collector, making it extremely efficient in absorbing heat from rapidly changing sunlight.

It can also be operated with high sensitivity even to weak sunlight in cold regions.

(3) Since it is possible to use a thin metal plate of 0.02 m to 0.051 m as the solar heat absorbing plane, the weight of the plane becomes extremely light.

Furthermore, the amount of heat transfer heat pipes and metal tubes used is reduced to a fraction of a second, and the total weight of the collector is also significantly reduced.

Furthermore, as mentioned above, the heat transfer rate within the flat plate is several IO times as high as that of the flat plate type collector, and there is no time for heat conduction loss or heat radiation loss, so the amount of heat insulating material used can be reduced.

Therefore, the thickness of the casing of the solar heat collector can also be significantly reduced.

This reduction in weight and thickness is thought to facilitate the acceptance of solar thermal application systems in general homes.

Moreover, it is estimated that its application range is wide due to its light weight, such as application to existing houses and wall-mounted collectors.

(4) The structure is simple.

Both metal tubes and heat transfer heat pipes are used in small quantities.

Therefore, maintenance is easy and the failure rate is low.

(5) The price can be extremely reduced.

Flat heat pipes can be produced continuously and in large quantities.

The structure is simple and the assembly cost is low. Very few materials are used.

For these reasons, the price can be significantly reduced.

This, combined with its outstanding performance, is expected to contribute to the spread of solar heat utilization systems.

(6) Depending on the selection of the hydraulic fluid, it can be easily made into a completely non-freezing type, so it can withstand use in cold regions.

(7) Since it is a heat absorption plane with many unit heat pipes arranged in parallel, the working fluid can be changed for each unit heat pipe, for example, methanol and water can be used alternately to achieve both low temperature and high temperature operation. good.

It is possible to construct a solar collector with a wide applicable temperature range.

Also, use a hydraulic fluid suitable for the area where the collector is used.
It can be configured as a solar heat collector for high temperature areas or a solar heat collector for low temperature areas.

That is, the solar collector according to the present invention is characterized by an extremely wide range of applications without being limited by the purpose or area of use.

As detailed above, the solar collector with the novel structure of the present invention has numerous advantages not only over the flat plate solar collector with the conventional structure but also over the heat vib type solar collector. It is believed that this will greatly contribute to improving the performance of solar heat utilization systems and their widespread use.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the structure of a flat heat pipe constituting the solar heat absorbing surface of the solar collector according to the present invention, Fig. 2 is a sectional view of the main part of Fig. 1, and Figs. 3 and 4 are A sectional view showing another embodiment of the present invention, FIG. 5 is a schematic diagram of the structure of a solar collector according to the present invention using a heat pipe as a heat transfer means, and FIGS. 6, 7, and 8 are flat plates, respectively. Cross-sectional view of a connection example of a shaped heat pipe and a heat transfer heat pipe, No. 9
The figure is a schematic diagram of the structure of a solar heat collector according to the present invention in which a metal tube is used as a heat transfer means. Figure 10 is a cross-sectional view of a heat transfer tube formed directly on the back surface of a flat heat pipe. FIG. 12 is a schematic diagram showing the structure of a flat solar collector. FIG. 12 is a schematic diagram showing the structure of a conventional heat pipe type solar collector. 1.2...Metal thin plate, 3...Embossed or unit heat pipe, 3...Pressure resistant support or auxiliary wick that also serves as support, 4... Solar heat absorption film, 5... Flat heat pipe illustrated in FIG. 1 on the solar heat absorption plane of the solar heat collector according to the present invention, 6.
...Heat pipe for heat transfer, 6' ... Heat absorption part as above, 6" ... Heat radiation part same as above, 7 ......
Radiation fin, 8...Water tank or heat storage tank, 9...
. . . Metal tube for heat medium liquid flow through, 10 .

Claims (1)

[Claims] 1. Embossed (drawing) metal thin plate and similar embossing (drawing) at symmetrical positions.
Metal sheet that is embossed or completely embossed (
A large number of elongated airtight containers each having a small cross-sectional area are made independent of each other by bonding thin metal plates that have not been subjected to drawing processing) to each other, and a large number of these containers are connected in parallel to form a flat plate. A contact portion having a wedge-shaped cross section formed by two thin metal plates and a fine gap formed by the seam of the thin metal plates is formed in each of the two classes of the sealed container, and each of the sealed containers is provided with a high vacuum. A suitable amount of working fluid is sealed in a reduced pressure state, and a support to prevent buckling due to reduced pressure or a wick that also serves as a support is inserted to form a large number of heat pipes. A book is used as a unit heat pipe, and a large number of unit heat pipes are connected in parallel to form a flat heat pipe.A solar heat absorption film is formed on one surface of the flat heat pipe, and a solar heat absorbing film is formed on one surface of the flat heat pipe. In this case, a heat pipe with an arbitrary cross section such as a cylindrical shape or a rectangular shape, or a bent metal tube through which a heat medium liquid passes through the inside, is attached closely to the heat pipe, or it is directly formed on a flat heat pipe. The flat heat pipe is a solar heat absorbing plane, and the heat pipe or metal tube with an arbitrary cross section is used as a thermal energy transfer means to heat a water storage tank, a heat storage tank, and other solar heat utilization equipment. A solar collector featuring: