JP5212706B2 - Solar heat collection system - Google Patents

Description

  The present invention relates to a solar heat collection system that follows changes in the position of the sun.

A solar heat collection system that connects multiple solar heat collectors with a solar collector and a flat reflector fixed together is efficient, but in order to further increase the efficiency, this system follows the fluctuations in the position of the sun. It has been proposed by the inventor (see Patent Document 1).
JP 2002-115717 A

Seeing from the earth, the sun repeats day and night with one day as one cycle, and its position (height) changes from sunrise to sunset. In addition, the sun makes a round trip from the north return line to the south return line on the earth with one year as one cycle, and changes the position in the middle of the south.
Cited Document 1 proposes to cope with the daily fluctuation of the position of the sun by installing a plurality of solar collectors long in the east-west direction because it is based on the rotation of the earth.
In addition, the year-to-year fluctuations in the position of the sun are based on the Earth's revolution, so the solar heat collector always rotates in a one-year cycle in the north-south direction so that it always faces the sun, and the winter solstice centering on spring and autumn equinox. The elevation of the solar collector is corrected so that it is the smallest and the summer solstice is the largest.

However, there is a problem that the efficiency cannot be sufficiently increased only by installing a solar heat collector long in the east-west direction against the daily fluctuation of the sun.
Efficiency can be increased if a solar heat collection system with multiple solar heat collectors connected in the east-west direction can be reciprocally rotated 90 degrees a day in the east-west direction as well as in the north-south direction. Since it becomes enormous and expensive, it is very difficult to realize.
In Patent Document 1, it is economically very difficult to follow two dimensions because it is proposed to select whether to follow the daily fluctuation of the sun or to follow the fluctuation of one year. Because.

  This invention makes it a subject not only to follow the fluctuation | variation of the position of the sun for one year but to follow the fluctuation | variation of a day, and to raise the efficiency of the collection of solar heat.

  In order to solve the above-mentioned problems, a solar collector that integrates at least a heat collector that inputs sunlight from the lower surface and a plane reflector that concentrates and inputs sunlight on the lower surface of the heat collector in the east-west direction. Arranged in multiple rows, equipped with a rotating shaft with a fixed solar collector and a rotation control device that rotates the rotating shaft, and rotating the rotating shaft back and forth within a range of 40 to 65 degrees a year, Rotate in the direction to adjust the ground angle so that the solar collector faces the sun all year round, and finely adjust the ground angle by reciprocating the rotating shaft within a range of 0 to 7 degrees a day It is a thing.

  The present invention adjusts the ground angle so that the solar collector is directly opposed to the sun throughout the year by rotating a solar heat collection system in which a plurality of solar collectors using plane reflectors are arranged in a line in the east-west direction. And by reciprocating the north-south direction in the range of 0 to 7 degrees per day and finely adjusting the ground angle, the efficiency of heat collection of the solar heat collection system can be increased economically, and the flat reflector By using, there is an effect that it is economical and the installation place is not limited.

  A solar collector that integrates at least a collector that inputs sunlight from the lower surface and a flat reflector that inputs the sunlight by concentrated reflection on the lower surface of the collector is arranged in a row in the east-west direction, A rotating shaft with a solar collector fixed and a rotation control device that rotates the rotating shaft are provided. By rotating the rotating shaft back and forth within a range of 40 to 65 degrees in one year, the solar collector is rotated in the north-south direction. Adjust the ground angle so that the collector faces the sun, and the maximum fine adjustment angle is the angle that changes every day so that the rotation axis is about 0 degrees for spring, autumn for autumn, 6 for summer solstice, and winter solstice. By rotating the solar collector in the north-south direction by rotating it back and forth, and finely adjusting the ground angle, the efficiency of heat collection of the solar heat collection system can be improved economically. .

FIG. 1 is a diagram showing Example 1 of the present invention, and FIG. 2 is a cross-sectional view showing a solar heat collector constituting the solar heat collection system of FIG.
FIG. 1 is an explanatory diagram viewed from the north direction. A plurality of solar heat collectors 1 are arranged in a line in the east-west direction, and each solar heat collector 1 is attached to a support body 2, and the support body 2 is a common rotating shaft 3. It is fixed to. The support 2 has a frame, for example, and is attached so that the solar collector 1 is fitted into the frame.
The rotation shaft 3 is connected to a rotation control device 4 composed of a motor, a CPU, a power source and the like, and the reciprocating rotation in the north-south direction is controlled by the CPU of the rotation control device 4.

FIG. 2 is a cross-sectional view of the solar collector as viewed from the west direction of FIG. 1. The solar collector 5 constituting the solar collector 1 and the flat reflector 6 that intensively reflects sunlight and inputs it to the collector 5. Is shown.
Examples of the heat collector 5 include a metal heat collecting plate covered with a selective absorption film or a cylindrical heat collecting pipe in a glass case or a case having glass windows on both upper and lower sides. Sunlight can be inputted from both the upper and lower surfaces, sunlight is directly inputted from the upper surface, and sunlight reflected by the reflecting mirror is inputted from the lower surface. Since the main solar thermal energy is taken from the reflected light, sunlight may be incident only from the lower surface without incident sunlight from the upper surface.

In Example 1, the example which employ | adopted the vacuum plate type collector 5 is shown.
The heat collector 5 includes a housing 7, two glass windows 8 attached to the upper and lower surfaces of the housing 7, and a flat plate heat collector housed inside the housing 7 and having a selective absorption film formed on the surface. A plate 9 and a pipe 10 fixed to the heat collecting plate 9 are provided.

A plurality of plane reflecting mirrors 6 are installed for one heat collector 5, and are used so as to have a total area of about 10 to 20 times the heat receiving area of the heat collector 5.
As described above, when the reflecting mirror 6 having a sufficiently large area with respect to the heat receiving area of the heat collector 5 is used, the solar heat collecting efficiency of the solar heat collector 1 is hardly influenced by the output temperature and is usually about 60 to 70%. .
The heat loss of the heat collector 5 body is determined by the temperature, the surface area, and the emissivity of the selective absorption film, but when the surface area of the heat collector 5 is sufficiently smaller than the total area of the reflector 6, The radiation loss is negligibly small compared to the input from the reflecting mirror 6.

On the other hand, the reflecting mirror 6 is always kept at room temperature, and its efficiency is determined by the reflecting performance of the reflecting mirror 6 itself, and is constant and about 80 to 90% regardless of the output temperature.
Therefore, the efficiency of the solar heat collector 1 that collects the reflected light of the reflecting mirror 6 is constant regardless of the output temperature, taking into account some reflection that does not hit the heat collecting plate 9 and absorption through the glass. Is about 60-70%.
The fact that the collection efficiency of solar heat has little relation to the output temperature is a particularly effective characteristic when used at a high temperature such as power generation.

The plurality of reflecting mirrors 6 must be arranged with a predetermined inclination angle so that sunlight is concentratedly reflected and incident on the heat collector 5, and all parallel light from the sun passes through the glass window 8. Input to the heat collecting plate 9.
Although the position (height) of the sun varies depending on the season, as will be described later, the collector 5 and the reflecting mirror 6 are integrally formed, and the solar collector 1 always has an angle with respect to the ground surface so as to face the sun. Adjust the ground angle.
The reason why the gaps exist between the plurality of reflecting mirrors 6 is to secure the passage of the wind so that the apparatus is not destroyed by the strong wind.

FIG. 3 is a plan view of the solar heat collection system as seen from above in FIG. 1, and shows only the solar heat collector portion.
As described above, the solar collector 1 is configured by integrally fixing a plurality of reflecting mirrors 6 to a single collector 5. However, when a solar collector is used, a plurality of such solar collectors 1 are provided. Place them in a row in the east-west direction.
When actually installing, prepare a frame that can accommodate the number of solar collectors 1 according to the scale of the designed system, and fit the heat collector 5 and reflector 6 into the frame. Finalize.

As shown in FIG. 3, the heat collector 5 and the flat reflector 6 are both formed in a rectangular shape and have four rows of reflectors 6 with respect to one row of the heat collector 5. Many rows of reflectors 6 will be used.
In addition, the heat collector 5 in one row is actually assumed to have a length of several tens of meters to several hundreds of meters. The reflecting mirror 6 is also configured in the same length, but both sides in the east-west direction are made longer than the row of the heat collectors 5 in order to cover fluctuations in the position of the sun in the morning and evening.
It is expected to be used as a heat source for power generation facilities and large-scale desalination facilities by installing a plurality of solar heat collection systems configured as described above.

FIG. 4 is a front view of the solar heat collection system of FIG. 3 as viewed from the north, and shows the relationship between the heat collector and the flat reflector.
The reflecting mirror 6 is installed in parallel with the heat collector 5, but its total length is longer than the total length of the heat collector 5 as shown. The arrows indicate the paths of morning sunlight AM9 and evening sunlight PM3. The total length of the reflecting mirror 6 is made longer than that of the heat collector 5 so that the sunlight enters the heat collector 5.
By configuring in this way, the reflected light of sunlight by the reflecting mirror 6 from 9 am to 3 pm is almost absorbed by the heat collector 5. Since most of the effective thermal energy of sunlight is concentrated during this time, making the total length of the reflector 6 longer than the heat collector 5 is effective for daily fluctuations in the position of the sun. It becomes a countermeasure.

5 and 6 are diagrams showing an installation example of the solar thermal collector.
All solar collectors of the solar heat collection system are installed with a ground angle (elevation angle) with respect to the ground surface so as to face the sun throughout the year. By installing in this way, sunlight L1 is input as direct light from the upper surface of the heat collector 5, and sunlight L2 is reflected so as to be concentrated by the reflecting mirror 6, and input as reflected light from the lower surface of the heat collector 5. Is done.

The position of the sun varies from the highest summer solstice to the lowest winter solstice. FIG. 5 shows the state at the summer solstice, and FIG. 6 shows the state at the winter solstice.
The south and middle altitudes of spring and autumn are (90 degrees-north latitude of the observation point), and the north latitude of Tokyo is 35.6 degrees, so the south and middle altitudes of spring and autumn are 54.4 degrees.
The south and middle altitudes of the summer solstice and winter solstice are 77.8 degrees and 31.0 degrees, respectively, since the spring and autumn solstice altitudes are ± 23.4 degrees. Accordingly, the ground angle θ1 between the center line of the solar collector and the ground surface in FIG. 5 is about 78 degrees, and the ground angle θ2 in FIG. 6 is 31 degrees.

In this way, in order to respond to the changes in the altitude of the sun during the year, the solar collector reciprocates the ground angle from 31 degrees to about 78 degrees and adjusts the ground angle during the year. Will do.
Considering the equinox and autumn equinox, where the sun is on the equator, the south-middle altitude of the summer solstice is (shunchu, the south-middle altitude of autumn +23.4 degrees), and the south-middle altitude of the winter solstice is (shunchu, south-middle of autumn). Altitude is 23.4 degrees).
Accordingly, the adjustment angle of the ground angle of the solar collector also changes correspondingly, and FIG. 7 shows this state.

FIG. 7 is a diagram showing an adjustment angle with respect to a change in the position of the sun in one year, which is approximately indicated by a straight line. It is 0 degrees for the spring and autumn minutes, +23.4 degrees for the summer solstice, and −23.4 degrees for the winter solstice.
This reciprocating rotation is realized by reciprocatingly rotating the rotating shaft 3 to which the solar collector 1 shown in FIG. 1 is fixed under the control of the rotation control device 4, but the angle is not strictly limited to 47 degrees, Practically, it is sufficient to adjust the range of 40 to 65 degrees with a margin.

Since about 47 degrees reciprocates in one year, the angle change is only about 0.25 degrees per day. The rotation may be controlled at 0.2 to 0.4 degrees as a practical range.
For this reason, the power required to rotate a large number of solar collectors 1 with one rotating shaft 3 is small, and therefore the power of the motor of the rotation control device 4 that drives the rotating shaft 3 can be reduced.
Further, the adjustment of the ground angle does not require the rotating shaft 3 to be rotated at all times, and if it is 0.25 degrees per day, for example, it may be operated once a day at 8:00 am and rotated by 0.25 degrees. Further, it may be rotated by 1.75 degrees for seven days by rotating one day a week. In short, it can be adequately handled by rotating it once in a predetermined period. Since the angle is as small as about 0.25 degrees per day, the interval of 1 to 2 weeks has no practical problem unless the predetermined period is long.
These controls can be easily executed from the CPU of the rotation control device 4 by software.

Next, we will examine the position of the sun in the day.
As described above, the incident angle of sunlight with respect to the solar collector 1 is low as shown in FIG. 4 in the morning and evening with respect to noon in the middle of the south, and changes greatly. The collector 5 is accurately installed in the east and west directions along the way the sun travels so that it does not come off from the collector 5, and the total length of the reflector 6 is made longer than the total length of the collector 5 in the morning and evening. In particular, sunlight from 9:00 am to 3:00 pm is taken in efficiently.

Here, the reflection state of the plane reflecting mirror 6 will be examined in detail.
When sunlight enters a plane mirror attached to a rotating body having a rotation axis at right angles to the sun, the reflected image moves around noon. This is because the earth is rotating at an angle of 23.4 degrees with respect to the revolution axis. During the summer solstice, it moves upward from morning to noon, moves downward from noon to afternoon, and opposite during the winter solstice. It moves downward from morning to noon and upward from noon to afternoon.
Considering the axis X on the earth that is perpendicular to the sun at noon on the summer solstice, the axis X has an inclination of 0 degree with respect to the revolution axis. The axis X is rotated by the rotation of the earth, and the axis X after 1 hour is tilted by about 0.7 degrees with respect to the revolution axis. After about 2 hours, about 2.9 degrees, after 3 hours, about 6.4 degrees, 6 After a time, the slope is 23.4 degrees.
Therefore, a positional shift occurs in the reflected light by the reflecting mirror of the solar collector disposed on the axis X.

FIG. 8 is a diagram in which the moving angle of the reflected image by the reflecting mirror attached to the axis X is displayed with time.
At 9 am, the angle of movement gradually decreases by 6.4 degrees, 0 degrees at noon, and increases again to 6.4 degrees at 3 pm. That is, since it is gradually tilted to 0 degrees toward noon from about 6 degrees at the time of 9:00 am, the reflected light gradually shifts upward, and gradually falls after noon.
In the case of the winter solstice, the angle change is the same, but in the morning, it is the opposite change, upward in the morning and downward in the afternoon.
At the time of spring equinox and autumn equinox, the rotation axis is perpendicular to the revolution axis, so the fluctuation of the inclination of the axis X is eliminated, and the positional deviation of the reflected light does not occur.

From the above consideration, in order to capture sunlight more efficiently, the rotation axis 3 in FIG. 1 is reciprocated in the north-south direction following the change in the position of the sun in the day, and the ground angle of the solar collector 1 is set to 1 It is necessary to make fine adjustments within the range of 0 to about 6 degrees per day for correction.
FIG. 9 is a diagram showing the maximum fine adjustment angle with respect to the change in the position of the sun in the day, and is approximately shown as a straight line corresponding to the seasonal change for one year.
That is, it is 0 degrees for the spring equinox and the autumn equinox, and about 6 degrees for the summer solstice and the winter solstice, during which the maximum fine adjustment angle changes every day as shown in the figure.

FIG. 10 is a diagram showing a fine adjustment angle with respect to a change in the position of the sun in the day, and a fine adjustment angle that changes from 9:00 am to 3:00 pm, which is a time zone with a large amount of solar thermal energy, corresponding to the time change of the day. Is shown.
Before 9 am and after 3 pm, the position of the sun increases rapidly, so it is not suitable for fine-tuning. The point seems to be enough.
Accordingly, the maximum fine adjustment angle may be set in relation to time within a range of 0 to 7 degrees per day. That is, 0 to 6.4 degrees if you want to collect solar heat from 9 am to 3 pm, 0 to 7 degrees if you want a slightly longer time, for example, 9:20 am to 2 pm If it is up to 40 minutes, set it in the range of 0 to 5 degrees.

The fine adjustment for the sun position change of the day is executed by reciprocating the rotation shaft 3 of FIG.
Since the rotation is as small as about 7 degrees per day, the control configuration may be simple.
Specifically, from 9:00 am to 3:00 pm, rotating at a constant time or for a predetermined time, for example, once every hour to rotate up to about 2 degrees, once every 30 minutes, about 1 degree rotation, If it is once in 10 minutes, the rotation may be about 0.3 degrees.

  These controls are executed by software based on the calendar in the same manner as the adjustment of the ground angle for one year, and a sensor for detecting that the sunlight hits the right angle is provided in the heat collector 5 to collect the sunlight. A servo mechanism that always contacts the heater 5 at a right angle may be used.

  As described above, according to the first embodiment, a plurality of solar heat collectors in which a heat collector and a plane reflecting mirror are integrated are arranged in a line in the east-west direction, and the rotation shaft and the rotation shaft that rotate the solar heat collector are rotated. It is equipped with a control device and adjusts the ground angle so that the solar collector is facing the sun throughout the year by rotating the solar heat collector in the north-south direction by reciprocating the rotation axis following the position change of the sun in the year. In addition, since the rotation angle of the rotating shaft is reciprocated by following the position of the sun in the day and the ground angle is finely adjusted, solar heat can be collected very efficiently. The effect is that the installation location is not restricted.

In addition, the correction of the solar collector's ground angle with respect to a change in the position of the sun in the year and a change in the position of the sun in the day can be realized by reciprocating rotation with a small angle of the same rotation axis, so the rotation mechanism and rotation control device can be simplified The solar heat can be collected extremely economically because it can be configured at a low price, and it is easy to maintain with few failures.
Furthermore, since one solar heat collection system may be one rotating shaft and one rotation control device, it is economically incomparable with a system in which a control device is provided for each solar heat collector. In addition, when configuring a plurality of solar heat collection systems, it is only necessary to prepare as many rotation control devices having the same control content as the number of systems, and it is possible to easily cope with a large-scale system.

It is a figure which shows Example 1 of this invention. It is sectional drawing which shows a solar-heat collector. It is a top view of the solar heat collection system of Example 1. FIG. It is a front view of the solar heat collection system of Example 1. It is a figure which shows the example of installation of a solar-heat collector. It is a figure which shows the example of installation of a solar-heat collector. It is a figure which shows the adjustment angle with respect to the position change of the sun of 1 year. It is a figure which shows the movement angle of a reflected image. It is a figure which shows the maximum fine adjustment angle with respect to the position change of the sun of the day. It is a figure which shows the fine adjustment angle with respect to the position change of the sun of the day.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solar collector 2 Support body 3 Rotating shaft 4 Rotation control device 5 Heat collector 6 Reflector 7 Case 8 Glass window 9 Heat collecting plate 10 Pipe

Claims (5)

A solar collector that integrates at least a collector that inputs sunlight from the lower surface and a planar reflector that inputs sunlight by concentrated reflection on the lower surface of the collector is arranged in a row in the east-west direction. A rotating shaft that fixes the solar collector and a rotation control device that rotates the rotating shaft,
By rotating the rotating shaft back and forth within a range of 40 to 65 degrees in one year, the solar collector is rotated in the north-south direction to adjust the ground angle so that the solar collector faces the sun throughout the year, and 1 A solar heat collecting system, wherein the ground angle is finely adjusted by reciprocating the rotating shaft within a range of 0 to 7 degrees per day.   The solar collector is installed so as to face the sun in spring or autumn, and it will be + 23.4 ± 5 degrees in the summer solstice and −23.4 ± 5 degrees in the winter solstice, based on the ground angle of the solar collector at that time The solar heat collection system according to claim 1, wherein the rotation shaft is rotationally controlled in a predetermined direction at 0.2 to 0.4 degrees per day.   3. The rotary shaft is reciprocally rotated in one day with an angle that changes daily to be 0 degree in spring equinox, autumn equinox, about 6 degrees in summer solstice, and winter solstice. Solar heat collection system.   The solar heat collection system according to any one of claims 1 to 3, wherein the rotating shaft is reciprocally rotated within a range of 0 to 7 degrees at least around 3 noon in one day.   5. The solar heat collection system according to claim 4, wherein the rotary shaft is reciprocally rotated so that the maximum fine adjustment angle is reached at 0 degrees at noon, 9 am and 3 pm per day.

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