JP2012007787A - Vacuum flat-plate type solar heat collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum flat-plate type solar heat collector which is simple in structure and can efficiently utilize solar heat.SOLUTION: In the vacuum flat-plate type solar heat collector 10, a vacuum heat insulation layer 16 having a heat insulation property higher than that of an heat insulation material such as glass wool is formed at a box 12 arranged at the backside of a heat collecting plate 18, and thereby heat collected at the heat collecting plate 18 is prevented from leaking to the backside of the box 12, thus utilizing the heat collected at the heat collecting plate 18 more efficiently than a conventional flat-plate type solar heat collector.

Description

  The present invention relates to a vacuum flat plate solar collector that heats a medium such as water by solar heat.

Conventionally, various solar collectors have been proposed by heat from a heat collecting plate in which a medium such as water is heated by sunlight (see, for example, Patent Document 1).
A heat insulating material is provided on the back side of the heat collecting plate that is not exposed to sunlight in order to suppress the heat radiation of the heat collected by the heat collecting plate.

Japanese Patent Laid-Open No. 07-139818

  In recent years, it has been required to efficiently use solar energy, which is free energy, with a simple configuration.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a vacuum plate type solar collector that has a simple structure and can efficiently use solar heat.

  This invention is made | formed in view of the said fact, Comprising: The vacuum plate type solar collector of Claim 1 comprises space by being plugged up with the heat collecting plate which receives sunlight, and the said heat collecting plate. A housing having a concave portion, a conduit member that is disposed in the space and allows the first heat medium to circulate, and a vacuum heat insulating layer provided in the housing.

Next, the operation of the vacuum flat plate solar collector according to claim 1 will be described.
In the vacuum flat plate solar collector according to claim 1, the heat collecting means receives the sunlight to heat the heat collecting plate, and the heat of the heat collecting plate heats the first heat medium inside the pipe member. By supplying the first heat medium from one end side of the pipe member, the warmed first heat medium can be discharged from the other end side of the pipe member.

  Moreover, since the housing includes a vacuum heat insulating layer between the outer surface of the housing and the inner surface of the recess, and has a higher heat insulating performance than a heat insulating material such as glass wool, the first heat medium Is suppressed from radiating to the outside through the housing, and the first heat medium can be efficiently heated.

  According to a second aspect of the present invention, in the vacuum flat plate solar collector according to the first aspect, the vacuum heat insulating layer evacuates a space formed between the outer wall constituting the recess and the outer wall of the housing. It is constituted by.

Next, the operation of the vacuum flat plate solar collector according to claim 2 will be described.
In the vacuum flat plate solar collector according to claim 2, heat insulation is performed by a vacuum heat insulating layer formed between the outer wall constituting the recess and the outer wall of the housing.

  According to a third aspect of the present invention, in the vacuum flat plate solar collector according to the first or second aspect, the space is filled with a second heat medium that contacts the pipe member.

Next, the operation of the vacuum flat plate solar collector according to claim 3 will be described.
In the vacuum flat plate solar collector according to claim 3, the second heat medium is also heated by the heat of the heat collecting plate. The first heat medium inside the pipe member receives both heat directly received from the heat collecting plate and heat received from the second heat medium. Moreover, since the 2nd heat medium can accumulate | store heat, the rapid fluctuation | variation of the temperature of the 1st heat medium in a piping member by the fluctuation | variation of solar radiation amount can be suppressed.

  According to a fourth aspect of the present invention, in the vacuum flat plate solar collector according to any one of the first to third aspects, the heat collecting plate directly receives sunlight.

Next, the operation of the vacuum flat plate solar collector according to claim 4 will be described.
Since the heat collecting plate receives sunlight directly, the vacuum flat plate type solar collector according to claim 4 can receive sunlight efficiently. For example, when the surface of the heat collecting plate is covered with a glass plate, sunlight reaching the heat collecting plate is reduced by about 20% by the glass plate, and the efficiency is lowered.

  According to a fifth aspect of the present invention, in the vacuum flat plate solar collector according to any one of the first to fourth aspects, a selective absorption film is formed on a surface of the heat collecting plate that receives the sunlight. Yes.

Next, the operation of the vacuum flat plate solar collector according to claim 5 will be described.
By forming the selective absorption film on the surface of the heat collecting plate that receives sunlight, the energy of sunlight can be efficiently absorbed and the energy radiated by the heat collecting plate itself can be suppressed.

  A sixth aspect of the present invention is the vacuum flat plate solar collector according to any one of the first to fifth aspects, wherein the surface of the heat collecting plate that receives sunlight is subjected to a hydrophilic treatment. Yes.

Next, the operation of the vacuum flat plate solar collector according to claim 6 will be described.
Since the surface of the heat collecting plate that receives sunlight is subjected to hydrophilic treatment, rainwater adhering to the surface spreads in a film form on the surface instead of water droplets, making it easier to remove dust adhering to the surface, Efficiency reduction can be suppressed.

  The invention according to claim 7 is the vacuum flat plate solar collector according to claim 6, wherein the hydrophilic treatment includes a photocatalyst.

Next, the operation of the vacuum flat plate solar collector according to claim 7 will be described.
In the vacuum flat plate solar collector according to claim 7, the surface of the heat collecting plate is hydrophilized by the photocatalyst. By irradiating the photocatalyst with sunlight, foreign matters such as dirt adhering to the heat collecting plate are decomposed, and a decrease in efficiency can be suppressed.

  As described above, according to the vacuum flat plate solar collector according to claim 1, solar heat can be efficiently used with a simple structure.

  According to the vacuum plate type solar collector according to claim 2, since the vacuum heat insulating layer is formed by evacuating the space formed between the outer wall constituting the recess and the outer wall of the housing, The score is minimal.

  According to the vacuum flat plate solar collector according to claim 3, it is possible to suppress rapid fluctuations in the temperature of the first heat medium in the piping member due to fluctuations in the amount of solar radiation.

  According to the vacuum flat plate type solar collector according to claim 4, sunlight can be received efficiently.

  According to the vacuum flat plate type solar collector according to claim 5, since the energy of sunlight can be efficiently absorbed and the energy radiated by the heat collecting plate itself can be suppressed, the second heat medium can be efficiently used. Can be heated.

  According to the vacuum flat plate type solar collector described in claim 6, dust and the like adhering to the surface of the heat collecting plate can be easily removed, and a decrease in efficiency can be suppressed.

  According to the vacuum flat plate type solar collector according to claim 7, foreign matters such as dirt attached to the surface of the heat collecting plate are decomposed, and a decrease in efficiency can be suppressed.

It is sectional drawing of the vacuum plate type solar collector which concerns on embodiment. It is the top view which made a part of vacuum plate type solar collector concerning an embodiment into a section. It is sectional drawing of the vacuum plate type solar collector which concerns on other embodiment. It is sectional drawing of the vacuum plate type solar collector which concerns on other embodiment. It is sectional drawing of the vacuum plate type solar collector which concerns on other embodiment.

Next, a vacuum flat plate solar collector 10 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the vacuum flat plate solar collector 10 of this embodiment includes a housing 12 that is rectangular in plan view. Note that the vacuum flat plate solar collector 10 shown in FIG. 1 has a rectangular shape in plan view as an example, but the shape in plan view may be square, or other shapes such as a circle, an ellipse, etc. . For example, the whole may be rectangular, and the four corners may be large arcs.

A rectangular recess 14 is formed in the housing 12 at the center of the front side (the side receiving sunlight).
The housing 12 is provided with a vacuum heat insulating layer 16 whose inside is evacuated between the outer surface and the inner surface of the recess. Although the thickness of the vacuum heat insulation layer 16 in the vacuum plate type solar collector 10 of this embodiment is about 3-6 cm, for example, it is not limited to this thickness.
In FIG. 1, the bottom surface 14 </ b> A and the side surface 14 </ b> B of the concave portion 14 are portions corresponding to the outer wall constituting the concave portion of claim 2. Further, in FIG. 1, the back surface 12 </ b> A and the side surface 12 </ b> B of the housing 12 are portions corresponding to the outer wall of the housing of claim 2.

The housing 12 can be formed from a metal plate such as a steel plate, brass, bronze, stainless steel, or aluminum that has been rust-proofed by plating or painting. The thickness of the metal plate used for the housing 12 is, for example, about 1 mm, but is not particularly limited as long as the strength necessary for the housing 12 is obtained. In consideration of installing the housing 12 on the roof, the metal plate is preferably thin and lightweight.
In order to decompress the inside of the vacuum heat insulating layer 16, for example, a check valve 30 may be attached to the housing 12, and a vacuum pump may be connected to the check valve 30 to suck the air inside. Note that a hole may be formed in the housing 12, the air inside is sucked from the hole, and the hole is closed after the inside is evacuated.

  A heat collecting plate 18 is fixed to the front side of the housing 12 so as to close the recess 14. The casing 12 and the heat collecting plate 18 can employ various fixing methods such as soldering, brazing, bonding, packing, etc., and screwing. It is important to prevent the heat medium 20 from leaking.

The heat collecting plate 18 is formed of a metal plate such as a steel plate, and a selective absorption film (not shown) is formed on the surface. A photocatalytic film (hydrophilic film) containing titanium oxide or the like is formed on the surface of the selective absorption film. When the photocatalyst film is exposed to sunlight, the surface becomes hydrophilic, and dirt adhering to the surface can be decomposed so that the dirt can easily flow with rainwater. The hydrophilic film may be other than the photocatalytic film.
In the vacuum flat plate solar collector 10 of the present embodiment, a glass plate or the like that causes a decrease in efficiency is disposed by reflecting or absorbing sunlight on the surface side (solar side) of the heat collecting plate 18. Not.

A pipe 22 bent in a zigzag shape is disposed in the recess 14 of the housing 12. The pipe 22 is formed of a metal material (for example, copper) having an excellent heat transfer coefficient. In the present embodiment, the pipe 22 is fixed to the back surface of the heat collecting plate 18, but the pipe 22 may not be in contact with the heat collecting plate 18. Examples of a method for fixing the pipe 22 to the back surface of the heat collecting plate 18 include soldering and brazing.
Both end sides of the pipe 22 are taken out through holes formed in the heat collecting plate 18 and connected to other pipes (not shown). Note that the gap between the hole of the heat collecting plate 18 and the pipe 22 is closed by soldering, brazing, or the like.

A space formed by closing the recess 14 with the heat collecting plate 18 is filled with a second heat medium 20 that is a liquid. As the second heat medium 20, for example, a liquid such as oil, water, or antifreeze can be used.
As the oil, for example, a heat medium of Soken Technics Co., Ltd., for example, NeoSK-OIL170, NeoSK-OIL1300, etc. can be used, but other oils may be used.

  Since the vacuum heat insulating layer 16 is provided inside the housing 12, a portion having a large area may be recessed due to atmospheric pressure. For this reason, in this embodiment, the bottom surface 14A of the recess 14 (the outer wall forming the recess of claim 2) and the back surface 12A of the housing 12 facing the bottom surface 14A (invention 2) are formed inside the vacuum heat insulating layer 16. The support members 26 for maintaining the distance are arranged at a plurality of locations so as to be connected to each other.

In addition, between the heat collecting plate 18 and the bottom surface 14 </ b> A of the concave portion 14, support members 28 for maintaining a distance are disposed at a plurality of locations. For example, a metal pipe can be used as the support member 26 and the support member 28, but other members may be used. Note that the support member 28 is preferably formed of a material having low thermal conductivity in order to reduce heat conduction to the rear surface side of the housing 12.
The surface of the heat collecting plate 18 (the surface of the metal plate under the selective absorption film (sun side)) and the outer surface exposed to the atmosphere of the housing 12 have as much surface roughness as possible to reduce the emissivity. Smaller and closer to the mirror surface is better.

(Function)
Next, the operation of the vacuum flat plate solar collector 10 of this embodiment will be described.
The vacuum flat plate type solar collector 10 of this embodiment is installed, for example, on the roof of a building or the like so as to face the sun, and one end side of the pipe 22 is water (first heat medium). It connects to the piping for supply, and connects and uses the other end side of the piping 22 for piping connected with water equipment.
The vacuum flat plate solar collector 10 is attached to, for example, an inclined roof on the south side. In the case of a flat roof, the vacuum flat plate solar collector 10 is attached so as to face the sun using a support member.

  When the heat collecting plate 18 of the vacuum flat plate solar collector 10 receives sunlight and is heated, the pipe 22 and the second heat medium 20 are heated by the heat collecting plate 18, and the water in the pipe is heated to hot water. It becomes.

  Here, for example, when a water device in a building (for example, a faucet, a shower, etc.) in a building is used, water is supplied from one end side (water supply side) of the pipe 22 and the vacuum flat plate solar collector 10 The hot water warmed in is discharged from the other end, and the discharged hot water is supplied to the water device.

In the vacuum flat plate solar collector 10 of the present embodiment, the housing 12 disposed on the back side of the heat collecting plate 18 is provided with the vacuum heat insulating layer 16 having higher heat insulation than a heat insulating material such as glass wool. The heat stored in the second heat medium 20 is prevented from leaking to the back side of the housing 12 (that is, the heat loss is small), and the heat collected by the heat collecting plate 18 is more efficient than the conventional flat plate solar collector. Can be used.
The heat loss to the back side of the housing 12 is only due to heat radiation, but this heat loss is also reduced by polishing the outer surface of the housing 12 to minimize unevenness and make it look like a mirror surface. And thereby reduce radiation loss.

Moreover, in the vacuum plate type solar collector 10 of this embodiment, since the surface of the heat collecting plate 18 is not covered with the glass plate, sunlight can be received efficiently.
Further, in the vacuum flat plate solar collector 10 of the present embodiment, a hydrophilic film containing a photocatalyst is formed on the selective absorption film of the heat collecting plate 18 so that the dirt adhering to the surface is decomposed and flows with rainwater. Since it becomes easy, the efficiency fall of the vacuum flat plate type solar collector 10 is suppressed.

  In the vacuum flat plate solar collector 10 of the present embodiment, since the second heat medium 20 filled in the recess 14 stores heat, rapid fluctuations in the fluid temperature in the pipe due to fluctuations in the amount of solar radiation can be suppressed.

  The vacuum flat plate solar collector 10 of the present embodiment may include the housing 14, the heat collecting plate 18, and the piping 22 (the check valve 30 may or may not be included. In the present invention, the check valve 30 is essential. However, it is composed of a small number of support members 26 and 28, and the structure is extremely simplified.

  By the way, the temperature of the second heat medium 20 is determined by the time during which the heat collecting plate 18 is exposed to sunlight and the intensity of the sunlight. The temperature of the water (first heat medium) inside the pipe 22 is determined by the temperature of the second heat medium 20 inside the collector and the flow velocity when passing through the pipe 22. If the water in the pipe is moved at a slower speed, the time for receiving heat from the second heat medium 20 becomes longer, so that the temperature of the water naturally rises to near the temperature of the second heat medium 20. Instead, the amount of hot water obtained within a certain time is reduced.

  If the area of the heat collecting plate 18 is increased, naturally a large amount of hot water can be obtained at such a high temperature. Since the heat source temperature of sunlight is about 6000 ° C., it can be said that there is no upper limit of the obtained hot water within the normal temperature range we use. The upper limit is almost determined by the application rather than technically, but is, for example, up to about 100 ° C. for home use and up to about 500 ° C. for power generation.

For example, the selective absorption film can absorb 90% or more of solar energy, and can suppress the emissivity of infrared rays from the heat collecting plate 18 whose temperature has risen to 7% or less.
Thus, for example, the energy of the sunlight collecting plate 1 m ² per undergoes a day, for example, assuming that 13 mJ / ^{m 2} (in Japan), a vacuum flatbed solar collectors 10, 13 (MJ / ^{m 2} ) × 0.9 × (1−0.07) = 10.881 MJ / m ² of energy can be collected (theoretical value).

  Note that the vacuum inner surface of the housing 12 is also preferably plated with nickel or the like so as to reduce the radiation loss and reflect the infrared rays well to suppress radiation. The heat radiation loss of the housing 12 can be reduced by providing the vacuum heat insulating layer 16 on the housing 12 to reduce heat conduction loss and polishing the surface of the metal surface to reduce the emissivity.

For example, assuming that the energy collected by the vacuum plate type solar collector 10 having a heat collecting plate 18 of 1 m ² per day is 10.9 MJ / m ² , the energy collected in one year is 10.9 × 365 = 3978 MJ. This is an average value for the year, and the amount of daily energy naturally depends on the weather of the day.

  Although the energy per unit time received during the day varies depending on the weather, in the vacuum flat plate solar collector 10 of the present embodiment, the second heat medium 20 filled in the recess 14 stores heat, so The temperature fluctuation of 1 heat medium (hot water etc.) can be suppressed.

A comparison between kerosene and solar energy will be described below.
The energy of kerosene is 44 to 47 MJ / cc, but when this is calculated as 46 MJ / cc, the vacuum plate type solar collector 10 having a heat collecting plate 18 of 1 m ² is equivalent to 3978 ÷ 46 = 86.5 (cc). You will earn kerosene. For example, if a 4 m ² vacuum flat plate solar collector 10 is installed on the roof of one house and the number of homes where the vacuum flat plate solar collector 10 is installed is 10 million, the total area of the heat collecting plate 18 is 40 million. m ² , 86.5 x 40 million = 34600 cc, that is, 3460 kiloliters of kerosene will be earned annually, the amount of kerosene used (crude oil import) will be reduced, and the generation of carbon dioxide will be greatly reduced It becomes possible.

  In the above-described embodiment, the vacuum flat plate solar collector 10 is used in a general house to obtain hot water. However, the present invention is not limited to this, and a liquid other than water is allowed to flow through the pipe 22. You may use for the use which heats liquids other than. The first heat medium may be a liquid other than water, or in some cases a gas.

  In the above-described embodiment, water is supplied from one end of the pipe 22 and hot water is discharged from the other end of the pipe 22. However, the pipe 22 is connected in a loop to circulate the first heat medium in the pipe 22. May be. In this case, the middle of the pipe 22 may be connected to a heat exchanger, and the heat of the pipe 22 may be taken out via the heat exchanger.

  For example, when the vacuum flat plate type solar collector 10 is installed on the land just below the equator, the second heat medium 20 may become high temperature. However, the second heat medium 20 boils in the collector and the inside of the collector It is preferable to use the second heat medium 20 having a high boiling point so that the pressure of the second heat medium does not increase. Further, the second heat medium 20 may include a known heat storage agent.

  In the above embodiment, the sealed internal space of the housing 12 is the vacuum heat insulating layer 16, but the back surface 12A and the side surface 12B shown in FIG. 1 are removed, and the entire outer surface of the bottom surface 14A and the side surface 14B of the recess 14 is placed inside. It is good also as a structure covered with what is called a vacuum heat insulating material which has the vacuum space.

  The casing 12 and the heat collecting plate 18 are formed by using a winding method used when joining a can lid when manufacturing canned food to the can body, and as shown in FIG. The edges of the heat collecting plate 18 can be joined to each other. If the casing 12 and the heat collecting plate 18 have a circular shape, an elliptical shape, and a rectangular shape as a whole, the corner portion has an arc shape. The plate 18 can be joined. Winding is a preferred joining method for reliably preventing liquid leakage.

  In the above embodiment, the example in which the pipe 22 is fixed to the heat collecting plate 18 and the recess 14 is filled with the second heat medium 20 has been described. However, as shown in FIG. If the heat collecting plate 18 is fixed by soldering, brazing, or the like, the heat of the heat collecting plate 18 can be directly transmitted to the pipe 22, so that the second heat medium 20 does not fill the inside of the recess 14. Also good.

  Moreover, although the example which fixed the piping 22 to the heat collecting plate 18 was demonstrated in the said embodiment, the piping 22 may be separated from the heat collecting plate 18 as shown in FIG. When the pipe 22 is separated from the heat collecting plate 18, it is necessary to fill the recess 14 with the second heat medium 20 in order to transmit the heat of the heat collecting plate 18 to the pipe 22.

DESCRIPTION OF SYMBOLS 10 Vacuum flat plate type solar collector 12 Housing | casing 12A Back surface 14 Recessed part 14A Bottom surface 16 Vacuum heat insulation layer 18 Heat collecting plate 20 2nd heat medium 22 Piping (piping member)

Claims (7)

A heat collecting plate that receives sunlight,
A housing having a recess that forms a space by being closed by the heat collecting plate;
A pipe member that is disposed in the space and allows the first heat medium to circulate;
A vacuum insulation layer provided in the housing;
A vacuum flat plate solar collector.   The vacuum flat plate solar collector according to claim 1, wherein the vacuum heat insulating layer is configured by evacuating a space formed between an outer wall constituting the recess and an outer wall of the housing.   The vacuum plate type solar collector according to claim 1 or 2, wherein the space is filled with a second heat medium that contacts the pipe member.   The vacuum plate solar collector according to any one of claims 1 to 3, wherein the heat collecting plate directly receives sunlight.     The vacuum plate type solar collector according to any one of claims 1 to 4, wherein a selective absorption film is formed on a surface of the heat collecting plate that receives the sunlight.   The vacuum plate type solar collector according to any one of claims 1 to 5, wherein a surface of the heat collecting plate that receives sunlight is subjected to a hydrophilic treatment.   The vacuum plate solar collector according to claim 6, wherein the hydrophilic treatment includes a photocatalyst.

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