JPH0727425A - Solar concentrator and thermal storage apparatus - Google Patents

Abstract

PURPOSE:To provide a solar concentrator and thermal storage apparatus capable of effectively concentrating solarbeams or storing heat at low costs. CONSTITUTION:The title apparatus comprises a parabolic reflector having at the center thereof an opening for passing light, a concave mirror 2 arranged somewhat outwardly of a focus on a straight line connecting the opening and focus of the parabolic reflector and a light transmitting means 3 for receiving, through the opening, light reflected by the concave mirror 2. The light transmitting means is located behind the parabolic reflector. A thermal storage apparatus is formed by providing a thermal storage means at an end side of the light transmitting means 3 of the solar concentrator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light concentrating device and a heat accumulating device capable of efficiently concentrating or accumulating heat such as sunlight at low cost.

[0002]

2. Description of the Related Art In recent years, active use of solar energy has been desired as one of the clean energy alternatives to petroleum. As a device for achieving such an object, for example, an optical system for concentrating sunlight, an optical fiber for transmitting the condensed light, and an optical for projecting / illuminating the light transmitted from the optical fiber. An apparatus composed of a system is proposed by Japanese Patent Laid-Open No. 54-112653. However, the problem with this type of device is how to efficiently collect the sunlight, which is said to generate 2.0 calories / second per 1 cm ² unit, and utilize it with a low attenuation rate. However, the conventional device as described above still has various problems to be improved in this respect.

Therefore, the applicant of the present invention has previously disclosed in Japanese Patent Laid-Open No. 2-2.
A lighting device as shown in Japanese Patent No. 33505 has been proposed. In this lighting device, an aluminum vapor deposition film layer is formed on a recessed plastic substrate through a silicon dioxide film layer and a titanium dioxide film layer, and a reflected light absorber made of a fused silica material is provided at a focal position. It has a structure in which the material mirrors are permanently installed in the three directions of east, west, and south, and the reflection of sunlight is 100%.
In addition to providing a contribution mirror that is capable of total internal reflection in the near future, it is configured to efficiently collect sunlight at any time of day without installing a tracking device or the like.

[0004]

However, in this daylighting device, although the concentrating efficiency of the contribution mirror or the like is excellent, the contribution mirror must be permanently installed in three directions of east, west, and south. There was still room for improvement in terms of cost and space efficiency as a general-purpose type device. As a result of earnest studies on this type of device in view of the above circumstances, the present applicants have found that the contribution mirrors arranged on three surfaces are
The present invention aims to complete and propose a solar light concentrating device that can be used as a surface mirror, has a high light converging efficiency, is low in cost, and is excellent in space efficiency, and a heat storage device suitable for use with them.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides primary reflection such as sunlight having an opening for light transmission in the center as described in claim 1. A contribution mirror, a concave mirror for secondary reflection that is arranged slightly outside the focal position on the line connecting the opening of the contribution mirror and the focal position of the contribution mirror, and the back side of the contribution mirror. 3. A light condensing device, which is arranged at a position facing the opening of the base mirror, and comprises a light transmitting means for receiving the reflected light from the concave mirror for secondary reflection that is incident through the opening, and also the condensing device according to claim 2. As described above, the light condensing device having the illumination means is provided on the terminal side of the optical transmission means.

Further, as described in claim 3, a contribution mirror for primary reflection such as sunlight having an opening for transmitting light in a central portion, an opening of the contribution mirror and a focal position of the contribution mirror. Concave mirror for secondary reflection that is arranged slightly outside the focus position on the line that connects, and is arranged on the back side of the above-mentioned contribution mirror and at a position facing the opening of the contribution mirror, through the above-mentioned opening. 5. A heat storage device comprising an optical transmission means for receiving incident reflected light from a concave mirror for secondary reflection, and a thermal storage means provided on the terminal side of the optical transmission means, or power supply to the thermal storage means according to claim 4. There is provided a heat storage device including a heat generating means connected to a cable for use.

The heat storage means is provided with a heat dissipation means as described in claim 5, the heat storage apparatus is provided with a heat exchanger as described in claim 6, and the heat storage means is described in claim 7. Thus, there is provided a heat storage device which is granular lithium which is hermetically maintained.

[0008]

According to the concentrating device of the present invention, a concentrating device for sunlight, which has good efficiency of concentrating sunlight, is low in cost, and is excellent in space efficiency, and is suitable for use as an indoor lighting device or a heat storage device, is provided. Can be provided. Further, according to the heat storage device of the present invention, it is possible to provide a heat storage device that efficiently uses sunlight, inexpensive late-night power, and the like and is excellent in portability and space efficiency.

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of a light concentrating device according to the present invention. As shown in FIG. 1, the device is a contribution mirror 1 which is a primary reflecting mirror for concentrating sunlight, and the above-mentioned contribution mirror. The concave mirror 2 secondarily reflects the reflected light condensed from the object mirror 1 into a bundle, and the optical transmission means 3 which receives and transmits the secondary reflected light focused from the concave mirror 2. .

Although not shown, the above-mentioned base mirror 1 is formed by uniformly laminating an aluminum vapor deposition film layer on at least a silicon dioxide film layer and a titanium dioxide film layer on a concavely curved plastic substrate. And one reflection of sunlight
It enables total internal reflection of nearly 100% and focuses the reflected sunlight at its focal position. However, silver or a silver-based vapor deposition film layer is more suitable in place of the aluminum vapor deposition film layer in order to improve the adhesion preventing property of dust and the like. An opening 1a for transmitting the secondary reflected light from the concave mirror 2 is formed in the central position of the base mirror 1. The shape of the opening 1a allows the movement range of the transmitted light in the converging time zone and facilitates the workability because the shape of the opening 1a corresponds to the movement of the secondary reflected light with time accompanying the change of the incident angle of sunlight. In order to do so, a circular opening is formed (see FIG. 2A).

If the concave mirror 2 is a contribution mirror having an outer diameter of 420 °, for example, on the line connecting the center position of the opening 1a of the contribution mirror 1 and the focus position, it is about 30 mm from the outer circumference of the contribution mirror 1 (in the figure). l) Reflective surfaces 2 on the front and back sides
It is arranged with a facing the opening 1a. The concave mirror 2 is made of fused quartz and has a diameter of 420φ.
In the case of, the light is formed with a shape of about 20 mm, and the reflected light from the base mirror 1 is more efficiently condensed than the conventional planar reflecting mirror, and the secondary reflection is performed toward the opening 1a. In addition,
Although not shown, the support arm of the concave mirror 2 is formed in the same manner as a known parabolic antenna, and the support column and the like also have expansion / contraction support means capable of adjusting height and angle.

A quartz optical fiber having a high light transmittance is selected for the optical transmission means 3, and such an optical fiber material has a diameter of φ5 in the visible light range of 0.38 μ to 0.8 μ.
When the thickness is 10 mm to 10 mm, the transmittance is 98.
Since it is 5% / m, for example, when the fiber distance is 7 m, it becomes (0.985) ⁷ = 0.90, which can be set as a transmittance of 90%. Also, this optical transmission means 3
A light condensing unit 4 for the secondary reflected light that has been incident through the opening 1a is provided on the starting end side 3a of the light condensing unit 4. The light condensing unit 4 moves due to the movement of the reflected light accompanying the change in the incident angle of sunlight. In addition, the light receiving surface is formed as an elliptical light receiving surface as shown in FIG.

Next, the angle in the permanent direction of the contribution mirror 1 and the illuminance will be described by taking the case where the diameter of the contribution mirror 1 is 290φ as an example. Diameter of base mirror ... R = 290mm, solar constant ... 2
0 calories, environmental light coefficient ... 9 am-1.77
At noon-1.825 At 3 pm-1.71, coefficient for converting watts into calories ... 4.18, optical fiber attenuation rate ... In the case of 1.5 m / sec, the diameter R of the contribution mirror is 0. 9.9 × (2.0 × 4.18 / 60 × π ×
(R / 2) ² ) × 1.825 = 28.5≈290 mm. In addition, each brightness at this time was 91.6 am = 141.6 watts and 12:00 noon = 14.
6.0 watts At 3 pm = 137.6 watts.

The permanent angle of the base mirror 1 is obtained as follows.
(It is installed in the direction of the sun light at 12:00 noon on the meridian of the mid-day between the winter solstice and the equinox.) The midpoint between the winter solstice and the equinox on the ecliptic is −23.4 / 2 = −11.
The angle of the sun from the horizon to the meridian at this time is 35 degrees 5 north latitude in the case of Tokyo.
As 2 minutes, 90- {Ψ-(-11.7)} = 42 degrees 7
8 minutes. Therefore, the installation angle of the contribution mirror 1 is set to 42 degrees and 78 minutes in the sun direction at noon as described above.

In the condensing device according to the present invention, the concave mirror 2 for secondary reflection is provided at a position outside the focal position of the base mirror 1 having a mirror surface having a high reflectance as described above, and the concave mirror is provided. An opening portion 1a for transmitting light is provided in the central portion of the contribution mirror 1 in the reflection direction of 2, and the light transmission means 3 is provided on the rear surface side of the contribution mirror 1 facing the opening portion 1a.
Is provided. Therefore, the concave mirror 2 for secondary reflection
Can collect not only the primary reflected light that is focused at the focal position but also the primary reflected light that has not been received in the past, and the secondary reflected light from the concave mirror 2 is at the center of the contribution mirror 1. The light can be focused and incident on the optical transmission means 3 arranged on the back surface side of the contribution mirror 1 through the opening 1a. As described above, since the light collection efficiency is improved and the attenuation rate is prevented from lowering, when it is used as a light collection device for sunlight, it is conventionally permanently installed in three directions of east, west, and south. The contribution mirror as a surface mirror can be a one-sided contribution mirror, and it is possible to provide a solar light concentrating device that has good light collection efficiency, low cost, and excellent space efficiency.

Next, FIG. 3 is a schematic configuration diagram in the case where the above-mentioned light concentrating device is applied to an indoor lighting device, and an illuminating means 5 is provided on the terminal side 3b of the optical transmission means 3.
This illuminating means 5 is formed by laminating an aluminum vapor deposition film layer or a silver or silver-based vapor deposition film layer evenly on at least a silicon dioxide film layer and a titanium dioxide film layer on a concave plastic substrate, like the base mirror 1. The irradiated surface is formed. Further, at the focal position, a radiating portion 6a which is made of a fused silica material and which radiates the light emitted from the light transmitting means 3 toward the irradiation surface 6 is provided, whereby the radiating portion 6a from the light transmitting means 3 is provided. Almost 100% of the emitted light is applied to the installation room.

Next, the configuration example of this lighting device is shown in Table 1 below.

[0018]

[Table 1]

Next, an example of the illuminance of the illumination means 5 will be shown. That is, as described above, the time at noon is 146.0.
If the wattage is 2.450 Lm (F) from Table 1 and the surface area of this room is 7.3 m ² (A), the illuminance (E) at this time is calculated as E = F / A (Lux) Therefore, E = 2.450 / 7.3 = 335.6Lux, and 300 to 750Lux can be obtained in the illuminance standard JIS Z 900 study room / office. Therefore, if the lighting means 5 is installed in a room on the north side or a basement where the sunshine conditions are bad, the light concentrating device can provide an efficient daylighting device.

Next, as shown in FIG. 4, the heat storage means 7 is provided on the terminal side 3b of the optical transmission means 3 in the condensing device shown in FIG.
Is a heat storage device having a configuration. That is, one end of the heat pipe 8 is connected to the terminating side 3b of the light transmission means 3, and the heat pipe 8 converts the sunlight collected through the heat pipe 8 into heat energy to store the heat. The other end of 8 is inserted in the heat storage means 7. Heat storage means 7
Is configured such that a heat storage material 9 described later is housed in a heat storage tank 10 with airtightness. The heat storage tank 10 is not only airtight but also excellent in heat insulation and corrosion resistance, such as glass material and enamel. Is formed by using. Further, the heat storage means 7 is covered by a housing 11 having an excellent heat insulating property, and the housing 11 is formed by interposing a heat insulating member 11b in the wall 11a.

Conventionally known heat storage materials include heat storage materials such as water and bricks, but water has a vapor pressure at 100 ° C.,
In addition, bricks are heavy objects that have smaller heat storage characteristics than water, and their volume must be increased in order to increase the heat storage effect. Both are unsuitable for storing solar heat.

However, as the heat storage material, a composition having a high melting point / boiling point, which has a small volume / weight value and is excellent in portability and handleability, is preferable. As a result, it was found that granular lithium hydroxide (LiOH), lithium fluoride (LiF), or a mixed lithium (mixed Li) thereof is remarkably effective as the heat storage material 9. In addition, it was found that the mixing ratio of lithium hydroxide and lithium fluoride having a mixing ratio of 20% Mol: 80% Mol is particularly excellent as a heat storage material. These lithiums have a specific heat, specific gravity and molecular weight similar to that of water, and vaporize 900 times.
A heat storage device having a small volume can be formed by using latent heat at the time of melting, which is equal to or higher than ° C.

Table 2 below shows the comparison of the physical properties of lithium and water / air.

[0024]

[Table 2]

Next, the heat storage amount (δ) will be described. The amount of heat storage (δ) is the amount of irradiation energy × 1 / watt and the conversion coefficient of calories ×
It can be determined by the light collection time. Therefore, in the case of condensing for 6 hours in a 420φ contribution mirror, δ = 294w × 1 / 4.18 × 60 SEC × 60mi
n × 6H = 1,519 Kcal Further, in the case of a 340φ contribution mirror, δ = 193w × 1 / 4.18 × 60 SEC × 60mi
Since n × 6H = 997 Kcal, the 420φ contribution mirror is considered to be a general-purpose type, and the heat storage amount and handleability are also appropriate.

Next, the heat storage effect will be described. The volume (V) capable of achieving the predetermined heat storage amount (δ) can be calculated as δ × 1 / specific gravity × specific heat × temperature. The weight (M) is determined by the volume (V) × specific gravity. Therefore, as the heat storage effect in this example, the V × M value was taken as the specific heat effect value of each substance, and the results of this trial calculation are shown in Table 3 below.

[0027]

[Table 3]

As is clear from the above results, mixed lithium has the smallest volume and weight for the storage of solar heat, and the heat storage effect value is good.

Next, use after solar heat storage will be described. As an example of use, let us look at the time (T) that can be used when 1 l of air heat of 120 ° C. is taken out per second when heat is stored at a predetermined heat storage temperature. Volume x specific gravity x (constant pressure) specific heat x temperature x seconds x min = heat storage amount (δ) Air amount x specific gravity x (constant pressure) specific heat x temperature x seconds x min = air consumption heat amount (Q) heat storage amount (δ) ÷ air consumption Heat quantity (Q) = Heat storage utilization time (T) In the case of trial calculation based on the above formula, in the case of lithium fluoride at a heat storage temperature of 440 ° C., heat storage quantity (δ) = 3.423 ml × 2.64 × 0. 38
2 x (440-120) = 1.104.649cal
Air consumption heat quantity (Q) = 1.000 x 0.00116 x
0.244 × 120 × 60 × 60 Heat storage utilization time (T)
= (Δ) ÷ (Q) = 9 hours.

Lithium fluoride in each heat storage temperature range,
Table 3 below shows one example of the result of trial calculation of the heat storage utilization time for the lithium and mixed lithium.

[0031]

[Table 3]

As is clear from Table 3, according to the heat storage material 9, sunlight is collected for about 5 to 6 hours a day, and heat is stored in the mixed lithium having a high melting point and a volume of 1 l to generate heat of 120 ° C. It can continue to radiate heat for about 10 hours.

Therefore, as shown in FIG. 4, the housing 11
When the ventilation port 11c is provided in the housing 11 and the housing 11 is provided with the heat radiating means 12 driven by the motor 13, for example, a fan, it can be used as a heater using the latent heat of the heat storage material 9. In this case, the wall body 10 is made of ceramics or the like having airtightness and high heat transfer coefficient.

FIG. 5 shows a circulation type heat storage device in which the heat storage means 7 is provided with a heat exchanger 14. In this heat storage device, heat transfer circulation is performed by the circulation paths 14a and 14b, and residual heat is returned to the heat storage means 7 by the circulation path 14b.
Heat dissipation of 5 to 50 hours can be achieved.

FIG. 6 shows a heat storage device in which the heat storage means 7 is provided with a heat generation means 16 connected to the power supply cable 15, and the heat generation means 16 uses a heater or the like. According to the method, heat can be stored with inexpensive late-night power.

[0036]

As described above, according to the first aspect of the present invention, it is possible to provide a low-cost light concentrating device that has good concentrating efficiency for sunlight and excellent space efficiency. It is suitable as a light collecting device. In addition, claim 2
According to the invention described above, since it is possible to provide a light collector that efficiently collects sunlight at low cost and is also excellent in space efficiency, it is installed in a room or basement on the north side where the sunlight conditions are bad. It is suitable as a daylighting device or a daylighting device for safety measures installed in a tunnel, a subway platform, or the like. Further, according to the invention described in claim 3, since it is possible to efficiently store heat of sunlight, it can be used as a heat storage device in various fields such as baking of paint, drying of fish, and cooking for home use. Further, according to the invention as set forth in claim 4, since it is possible to store heat by utilizing inexpensive late-night power through the heat generating means, it is possible to use the heat storage device at low cost. Further, according to the invention of claim 5, efficient heat storage and heat dissipation can be performed, so that a heat storage device used for a heating device, a soaring device, a greenhouse cultivation of vegetables, etc. can be provided at low cost. Further, according to the invention of claim 6, since the surplus heat can be circulated and reused, a more efficient heat storage device can be provided. Further, according to the invention of claim 7, since it is possible to provide a heat storage material and a heat storage device which have a small volume and a small weight and a high heat storage effect and are excellent in portability, heat is stored during the summer and stored. It is also possible to transport it to cold regions and use its latent heat in winter.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a light collecting device according to the present invention.

FIG. 2 is a front view of the contribution mirror shown in FIG. 1 and a perspective view showing a starting end side of the optical transmission means.

FIG. 3 is an explanatory view showing a case where the light collecting device shown in FIG. 1 is used for a daylighting device.

FIG. 4 is an explanatory diagram showing a first embodiment of a heat storage device using the light concentrating device shown in FIG.

5 is an explanatory view showing a second embodiment of a heat storage device using the light collecting device shown in FIG.

FIG. 6 is an explanatory view showing a third embodiment of the heat storage device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Contribution mirror 2 Concave mirror 3 Optical transmission means 5 Illumination means 7 Heat storage means 9 Heat storage material 12 Heat dissipation means 14 Heat exchanger 15 Heat generation means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G02B 17/00 Z 9120-2K

Claims (7)

[Claims] Claim: What is claimed is: 1. A contribution mirror for primary reflection such as sunlight having an opening for light transmission provided in the center thereof, and a focus position on a line connecting the opening of the contribution mirror and the focus position of the contribution mirror. A concave mirror for secondary reflection that is arranged slightly outside, and a secondary mirror that is arranged on the back side of the above-mentioned contribution mirror and facing the opening of the contribution mirror, and is incident through the above-mentioned opening. A light condensing device comprising: an optical transmission unit that receives reflected light from a concave mirror. 2. The light condensing device according to claim 1, further comprising an illuminating device on the terminal side of the light transmitting device. 3. A contribution mirror for primary reflection such as sunlight having an opening for transmitting light in the center, and a focus position on a line connecting the opening of the contribution mirror and the focus position of this contribution mirror. A concave mirror for secondary reflection that is arranged slightly outside, and a secondary mirror that is arranged on the back side of the above-mentioned contribution mirror and opposite to the opening of the contribution mirror and is incident through the above-mentioned opening. A heat storage device comprising: an optical transmission unit that receives reflected light from a concave mirror; and a heat storage unit that is provided on the terminal side of the optical transmission unit. 4. A heat storage device, characterized in that the heat storage means comprises a heat generating means connected to a power supply cable. 5. The heat storage device according to claim 3, wherein the heat storage means is provided with a heat radiation means. 6. The heat storage device according to claim 3, wherein the heat storage means is provided with a heat exchanger. 7. The heat storage device according to claim 3, 4, 5 or 6, wherein the heat storage means is granular air-tight lithium.