JPH0476355A - Solar heat collecting device - Google Patents

Abstract

PURPOSE:To make a substantial improvement of light collecting and heat collecting amount, collect efficiently and easily a solar energy flow in winter season in particular to make an economic utilization of the solar energy by a method wherein a light transparent plate is placed to cover a fixed reflector floor and a light collecting heat collecting surface and the reflector floor is installed at a lowering gradient of a specified angle in respect to a light collecting and heat collecting surface. CONSTITUTION:A light transparent plate 1 is mounted to cover a fixed reflector floor 2 and a light collecting and heat collecting surface 3. The reflector floor 2 is installed at a decreasing gradient with an angle of a range not exceeding a solar high angle at noon at least in the winter solstice in respect to the light collecting and heat collecting surface 3. Solar light passed through a transparent member 1 such as glass or the like directly impinges against the heat collecting surface 3 to get a direct radiation and another reflection part reflected against the reflector 2 with a decreasing gradient. Light reflected at the gradient reflector floor is reflector again at a rear surface 1' of the transparent member and reaches the reflection of repeated one through the reflection floor, glass rear surface and the reflector floor and the like so as to make a substantial improvement of the light collecting and heat collecting amount.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a solar heat collection device for efficiently concentrating sunlight and extracting a large amount of thermal energy in a system that utilizes solar thermal energy. It is.

[Conventional technology]

In general, as a method for obtaining a high-density thermal energy flow,
There are various types of heat collectors that track and concentrate sunlight, but due to economic reasons, it is difficult to popularize them for consumer use, so considering regional characteristics and solar dependence, the heat collectors are mounted on the roof and oriented towards the south. It is known to be installed as

In this conventional heat collector, a reflector is installed on the heat collector and extended to a sloped roof or installed diagonally with a mounting base, but a reflective floor is installed at an upward slope relative to the heat collection surface. Type heat collectors or vertical heat collectors with horizontal reflective floors and vertical heat collectors in attics with glass roofs are often used.

[Problem to be solved by the invention]

However, with conventional heat collectors, the heat collector is placed near the ridge of the roof and faces south, so if a structure in front of it (for example, a roof) is used as a reflector, the roof surface should face south. However, this is an upward slope when viewed from the direction of the sunlight path, and the incidence rate of reflected light on the heat collecting surface becomes a low value, making it impossible to maintain a high reflectance of the reflector, resulting in poor performance. was insufficient.

In particular, there are still problems, as there is too much adherence to traditional architectural forms and configurations adapted to the winter season, making it impossible to achieve economical solar concentration. In flat plate heat collectors that are arranged on the ground and receive direct sunlight, when a high load (high temperature) is applied to collect hot water and store it in a heat storage tank for winter heating, the net absorbed energy flow on the heat collecting surface is F,
□ is not high, so the flow rate has to be extremely reduced. On the other hand, heat loss is lost regardless of the flow rate, so the heat loss wasted is more than the amount of heat that can actually be obtained and taken into the heat storage tank. The reality is that it has not been put into practical use because it cannot withstand the burden of a large-area heat collector.

The present invention aims to eliminate these conventional drawbacks by significantly increasing the amount of heat collected, efficiently and easily concentrating the fading solar thermal energy flow, especially in the winter, and making it economical for space heating and hot water supply. The objective is to obtain a solar heat collecting device that is useful for buildings, convenient for maintenance of the heat collecting surface, and sufficient for practical use, and that also has excellent practical harmony with buildings, and by achieving harmony, reduces heat loss of the device. The present invention aims to provide a heat collecting device that can reduce costs in an inexpensive form using a component hour wheel.

[Means to solve the problem]

The present invention provides a heat collector having a light-transmitting plate that transmits sunlight, a heat-collecting surface that receives the sunlight that passes through the light-transmitting plate, and an upward-facing surface that can irradiate the heat-collecting surface with reflected light. In a solar heat collection device consisting of a fixed reflective floor, the heat collection surface is installed facing south, and the wall surface other than the heat collection surface is composed of a reflector, and
The solar heat collecting device is characterized in that the reflective floor is arranged at a downward slope with respect to the heat collecting surface at an angle that does not exceed at least the solar altitude angle at noon on the winter solstice.

[For production]

In the solar heat collecting device of the present invention, sunlight passes through the transparent material l such as glass, and is reflected by the direct beam reaching the heat collecting surface 3 and the adjacent downhill reflective floor 2. Adjacent to this, there is a re-reflection portion that is reflected off the downward slope reflective floor and is re-reflected on the back surface 1' of the transmitter and reaches the heat-collecting surface 3. Adjacent to this is a reflective floor,
The glass back surface 2 is connected with the second reflection portion that is repeatedly reflected again, and the reflectance is kept high, the amount of heat collected is greatly improved, and it can be used economically.

〔Example〕

Embodiments of the present invention will be explained with reference to Figures 1 to 12. In Figure 1, it has a transparent plate 1 that transmits sunlight, and a heat collecting surface 3 that receives sunlight that passes through the transparent plate 1. A solar heat collecting device consisting of a heat collector and an upwardly facing fixed reflective floor 2 capable of irradiating reflected light onto the heat collecting surface 3, the heat collecting surface 3 being installed facing south, and the heat collecting surface The other wall surfaces are constructed of reflectors, and the reflective floor 2 is arranged at a downward slope with respect to the heat collecting surface 3 at an angle that does not exceed the solar altitude angle at noon on the winter solstice. .

In this case, the fixed reflective floor 2 is opposed to the heat collecting surface 3 along with the solar light transmitting plate 1 at an open spread angle, and has a slope within twice the reflective floor slope angle from the vertical to the south. It is effective to adopt a configuration including a heat collecting surface 3 having an angle.

In the figure, 4 is a frame room, 5 is a water supply pump, 6.6' is a heel drain, 7 is a drain, and 8 is a building.

That is, looking at the optical path S of the reflection reach, in Figure 2, when the sun's zenith angle is Z (complementary angle of the solar altitude angle), the angle of incidence on the reflecting floor surface has a downward slope of δ (Z + δ) The angle of reflection is also the same, but with respect to the vertical line, it is (Z+2
6).

Now, if the heat collecting surface is tilted south by an angle ν from the vertical line and faces south, the incidence rate of reflected light on the heat collecting surface (expressed as cos θ, where θ is the angle between the light ray and the normal to the surface) μ, becomes p@”cos θ=sin(Z +26-shi), and 26 from 5in(Z-ν) when the reflective floor is horizontal.
The incidence rate improves by the angle of .

Next, the optical path S shown in FIG. 3 is the re-reflected light that is reflected on the reflective floor surface, then reflected again on the back surface of the transparent material such as glass, and reaches the heat collecting surface. If the slope angle of the glass surface to the south is ψ, the angle of incidence of sunlight reflected on the reflective floor surface to the back surface of the glass is (Z + 2 δ + ψ), which is 2 δ angles smaller than (Z + ψ) in the case of a horizontal reflective floor. big.

As shown in Figure 4, the reflectance R9 on the back surface of the glass becomes larger as the angle of incidence becomes wider (indeed, it gets higher, especially as it approaches 90°), and a slight increase in the incidence becomes a marked improvement in the reflectance. come.

Therefore, in order to obtain strong re-reflected light, it is desirable to make the incident angle as large as possible, and moreover, to make it close to 90@.

Since the incident angle is added to the angle of incidence by twice the angle δ of the down-slope reflective floor, the down-slope reflective floor is an effective means for obtaining strong re-reflected light.

Furthermore, in addition to this, the re-reflected optical path reflected by the glass surface is reflected at an angle of (Z + 2 δ + 2 ψ) with respect to the vertical perpendicular, and the incidence rate μlll1g of the inclination angle ν to the heat collecting surface is μl19 = cos θ = sin ( Z + 2δ+
2ψ→−ν).

In this way, the re-reflected light is strongly re-reflected and the heat-collecting surface is suppressed by the downward-sloping reflective floor and the transparent glass surface, which has an open spread angle with respect to the heat-collecting surface. The synergistic effect of increasing the incidence rate works to increase the absorbed energy flow on the heat collecting surface.

To achieve this, it is necessary to realize strong re-reflected light incidence by configuring the down-sloping reflective floor and the solar light transmissive body to face each other at an open angle to the heat collecting surface. However, if the down-sloping reflective floor and the glass or other surface face each other at an open angle to the heat-collecting surface,
The slope of the glass surface up and down is not a particular problem.

However, instead of an open spread angle, parallel or closed pinch angles will reduce the effectiveness of the present invention and should be avoided.

That is, if they are parallel, 1 δ1 = 1 ψ1, the angle of incidence on the back surface of the glass decreases to (Z + 26 - ψ) = (Z + δ), and the incidence rate also decreases to a value of 5 inches (Z + ν). Also, if the angle is closed, 1ψl>lδ1
Therefore, the angle of incidence on the back surface of the glass is (
It becomes even smaller than Z + δ), and the incidence rate is also 5 inches (Z + ν
) will be reduced to an even smaller value.

The above description describes the effects of the reflection beam and the re-reflection beam, but the effects of the re-reflection beam connected to these, the repeat-reflection beam that is reflected twice on the back of the glass, and the slope reflection floor. The same goes for the repeat reflection beam that is reflected once more and reaches the heat collecting surface, and as the number of reflections increases, the rate of incidence on the heat collecting surface itself improves.

Furthermore, since the angle of incidence on the back surface of the glass is much larger the second time than the first time, the reflectance itself also becomes higher.

However, when such repeated reflections occur, the zenith angle Z is small (the sun's altitude is high), so the initial angle of incidence on the back surface of the glass (Z+26
+ψ) stays at a relatively small value, so as can be seen from Figure 4, the reflectance R is a low value, and the long sword is dissipated to the outside, and the input to the heat collection surface is repeatedly reflected on the sloped reflective floor surface. With the addition of attenuation due to this, it cannot help but be slight.

Further, even though the incidence rate is improved, it cannot be as large as shown in the left because Z is small.

Looking at the ebb and flow of each reflection, as the zenith angle Z becomes smaller, as shown in Figure 1, the reflections that follow the direct line of sight gradually stand up and approach each other. As shown in the diagram, the area of repeated reflex deviation increases, and the next reflex, the repeated reflex deviation, appears, and when that area increases sufficiently, the repeat reflex deviation appears.

Conversely, when the zenith angle Z gradually increases, the repeat reflexes first thin out and finally disappear, and the next repeat reflex reflex and then the repeat reflex reflex follow the same path.

For example, in a situation as shown in Figure 1, where the repeat reflection back is thin but still present, the irradiation occupancy rate of the heat collecting surface of the repeat reflection back is not 100%, but it has a small value, and the repeat reflection This shows that there are no reflections and reflections, and the irradiation occupancy rate of reflections and reflections is 100%. Although these analytical values can be derived, they are omitted here.

The phenomenon that stands out among these fluctuations in the reflection angle is that during the period around the winter solstice, when the zenith angle Z is large and the direct reach and reflex reach are mostly occupied, as the sun increases in altitude, the re-reflection reach enters. This is a phenomenon that occurs when

That is, when the re-reflected light appears, the angle of incidence on the back surface of the glass starts from 90''.In other words, the reflectance is 1
Starting from 00%, strong re-reflected light from the top of the heat collecting surface,
It will be irradiated in the form of a combination of direct radiation and reflex radiation.

Therefore, during the winter solstice, the re-reflected light remains strong and flows into the heat collecting surface with an energy inflow distribution that is convenient for heating the heat medium (for example, water). This is a strong factor showing good performance during the period.

Next, regarding the selection of the inclination angle ν of the heat collecting surface, for example, the fifth
If the mounting head angle is increased to 45° as shown in the figure, the Z
When it is small, such as = 15', the incidence rate of the direct beam improves as shown in the figure, but the reflected light can enter the heat collecting surface, reducing the net absorbed energy flow F mbs as a whole. Therefore, it is not a good idea to make the inclination angle too large.

Figure 6 shows the results of an investigation by changing the inclination ν of the heat collecting surface and installing it on a device with a downwardly sloping floor angle δ.

Even at two periods with markedly different solar altitudes, the sea δ
gives one peak value. Although this peak value is gentle, even if the optimum angle of ν is δ, it can be seen that the width of the δ angle before and after it, that is, the range of sea 0 to 2 δ is the preferred mounting inclination angle range.

Next, the slope angle δ is used to install the downward slope reflective floor. Therefore, at least the following requirements must be met.

In other words, the main reflecting surface, which is a downward-sloping reflecting floor, needs to satisfy the condition that it can receive sunlight at a desired time, so it has a downward slope that is at least lower than the zenith angle at noon on the winter solstice in the region. There must be.

Even at times other than noon, it is actually necessary to collect heat, to maintain a good incidence of reflection destinations, to secure an effective reflective floor area, and to prevent rainwater from forming on the surface of the sunlight transmitting plate. In view of the relationship with the required gradient for flow down, the preferred angle is actually 2 or less of the above-mentioned gradient angle. In the example, a good result was obtained by adopting a downward slope angle of 12.5°, which is less than half of the downward slope angle 31'' required to receive sunlight at noon on the winter solstice.

Down-sloping reflective floors are not limited to single-slope reflective floors, and can be applied in a variety of ways.

For example, as shown in FIG. 7, by making the reflective floor 2 a cylindrical surface with a parabola as a conducting wire, the reflected light S! is well concentrated on the heat collecting surface 3. However, as the design point moves away from the 1st time, the tracking system is no longer available, so
The situation changes completely and becomes less efficient.

In particular, if such a curved surface is adopted, it is difficult to maintain the slope of the reflective floor at the foot of the heat collecting surface, and in some cases, it may become upward slope as shown in the figure, and the zenith angle may deviate from the design point. Decrease the incidence of reflex dorsal light in the summer when Z is small.

Since the reflected light irradiates the heat collecting surface over a wide area, optical precision is not required, and the reflective floor 2 can be replaced by a block-like collection of reflective planes as shown in Figure 8. .

In addition, as a convenient measure when the sun's zenith angle becomes smaller in the summer and the angle of incidence of reflected light on the back of the glass decreases, the light reflected from the back of the glass becomes weaker and less expected. A movable reflector (not shown) whose inclination angle can be changed is displaceably provided on the floor surface in the middle of the sloped reflective floor, and the sunlight received by the movable reflector is reflected directly and is effectively applied to the heat collecting surface. It is also possible to make the delivery possible.

In Figure 1, the solar light transmissive body 1, which forms the glass roof, is installed with a gentle slope of 2.5", slanting to the south to serve as a rain cover. Also, the downward sloping reflective floor 2 is installed to collect heat. Since it has a downward slope of 12.5@ with respect to surface 3, the roof glass surface faces the heat collecting surface with an open spread angle of 15 degrees.

Furthermore, since the heat collection surface 3 is installed tilted to the south from the vertical perpendicular at an elevation angle equal to the slope angle of the reflective floor 2, the heat collection surface 3 is arranged at right angles to the sloped reflective floor 2 as shown in the figure. ing.

In order to compare and examine the heat collection performance of such down-sloping reflective floor frame-type heat collectors, we also compared the heat-collecting performance of frame-type heat collectors with horizontal reflective floors that are not down-sloping floors, as shown in Figure 9. When we compare the amount of light received at noon on the winter solstice, when the solar altitude is lowest (Z is largest), as shown in Figure 9, the horizontal floor is better than the downward sloping floor. It is predicted that the number will increase by 33.7%. In other words, more light is received, and the heat collection surface has exactly the same area, so assuming that the light collection efficiency is the same, the horizontal bed will have a higher net absorbed energy flow F mb at the winter solstice.
Although s should be high at 33.7%, the actual result is contrary to this prediction. One of the reasons for this is that due to the presence of the down-sloping reflecting floor δ, the incidence rate of reflected continuous light, re-reflected light, repeat-reflected light, etc. to the heat collecting surface is greatly improved.

For example, at noon on the summer solstice, F abs on the horizontal floor is 1
If this is the case, F abs of the down-sloping floor has a value close to 2, giving a large reversal difference.

Another reason is that the combination of a downwardly sloping floor and a glass surface that transmits sunlight faces the heat collector at an open angle.

Since the incident angle of the re-reflected light on the back surface of the glass is added to the incident angle by an angle of 2δ, which is twice the slope angle of the downwardly sloped floor, the reflectance R9 is significantly improved.

Figure 10 compares the reflectance of re-reflected light on February 7th, and the reflectance of the downward slope floor at noon is more than 2.6 times that of the horizontal floor.

As mentioned earlier, this effect is particularly great during the winter period, when the re-reflected light enters the winter solstice.

Figure 11 shows a comparison of the heat collection flow over the years, with the horizontal axis representing months and the vertical axis representing the net absorbed energy flow Febs (W/rrr) per unit area of the heat collection surface.

In addition to the heat collector A of the embodiment of the present invention, a heat collector B with a horizontal reflective floor of the same shape and a single plate type heat collector C, which is commonly used, are said to be most suitable for collecting heat in winter. The angle of inclination commonly used in the past, i.e. 5 from the horizontal plane.
A 5° raised angle is included for comparison.

Since this heat collector C was placed for the winter season, it is unavoidable that there would be a dip around the summer solstice, but the heat collector C is also F even in the winter season. S cannot exceed 100OW/n.

Heat collector B on the horizontal floor shows an increase in power after peaking at the winter solstice, and the period in which the power exceeds 1500 W/nf continues for over a month. However, on the other hand, the drop around the summer solstice was also severe, resulting in an even lower drop than the drop of the 55@ type when placed alone.

On the contrary, the downward slope method heat collector A according to the embodiment of the present invention has obtained higher values than either of the above two sides for many years.

Wide period of winter (6 months) from the autumnal equinox to the vernal equinox
The practical significance of being able to secure a net absorbed energy flow of 1500 W/J or more over this period is significant.

What is noteworthy is that the net absorbed energy flow reaches its peak from late January to mid-February, which is the severe winter season, reaching approximately 1,650 W/d, making it suitable for both winter heating and hot water supply. ing.

An additional note about the obtained curve is that the content of the absorbed energy flow at the winter solstice is mainly composed of direct radiation and reflex radiation, and is approximately 90'
Of course, the reason why it is higher than that of horizontal bed heat collector B at that point is due to the improvement in the incidence rate of the reflective back, and the reason that the difference is not significant is because the incidence rate is higher due to the large Z. This is because the improvement is not noticeable.

Therefore, as the winter solstice rolls around and Z gradually becomes smaller and the amount of sunlight received increases, the difference gradually becomes apparent.

At the same time, as mentioned above, reflexive transgressions have entered the market strongly, and the two peaks have risen at a relatively high rate.

The slight difference in height between these two mountains is due to seasonal factors, such as the higher atmospheric penetration of sunlight during the colder months of February.

Near the summer solstice, there are many re-reflections, re-reflections, re-reflections, and 5-reflections, but since Z is small, the reflectance on the glass surface is low, and the dissipation to the outside is large, so they are Even when combined, the value remains small.

At this time, the most powerful effect is the reflection from near the foot of the heat collecting surface, and the improvement of the incidence rate due to the downward slope of the floor is very effective.

This is significantly higher than the value for the horizontal floor type, and is 55" for the single arrangement.
This is the main reason why it exceeds its type.

From these facts, it can be said that high heat collecting ability can be demonstrated when the sun's zenith angle Z is large (solar altitude is low), so it can be said that the installation area is suitable for mid-high latitude areas rather than low latitude areas.

Fig. 12 shows an example of the installation in a building 8 of a flat roof building, where the heat collector cover 13 having a heat collecting surface and the glass roof, which is the sunlight transmitting body 1 of the heat collecting device, are slightly exposed. Just,
No piping is exposed outside. In this example, the side wall of the part exposed to the outside connected to the glass roof is also made of a glass transparent material.

Since the piping is connected to a small heat collecting surface indoors, the length of the piping is short, and the heat storage tank can be placed at the shortest distance from the heat collecting surface, which is advantageous in terms of heat loss and cost maintenance.

In addition, when cleaning dirt from roof glass, which is a solar light transmissive material, the posture of the roof glass itself is low, and wiping after rinsing with water is not dangerous and easy, and it does not protrude outdoors or be placed in a location that is exposed to strong wind. Therefore, there is less wind damage from typhoons, etc.
The equipment on the roof is also low-slung, so the building's aesthetics are not outdated.

In the unlikely event that the roof glass breaks and rainwater leaks down,
If an emergency drainage ditch 7 is provided at the end of the down-sloped floor in Figure 1, at the foot of the heat collection surface, and the rainwater is guided to the outside, the down-slope reflective floor 2 will become a second roof for double safety. It can be made into a structure.

C Effects of the Invention] The present invention has a much higher net absorbed energy flow per unit area (r, b, It is possible to maintain a high reflectance of the reflector plate, significantly increasing the amount of heat collection, and it is also economically effective as it efficiently concentrates the solar thermal energy flow that is fading in the winter. It has practical effects such as easy maintenance of the thermal surface, excellent practical harmony with the building, and ability to reduce heat loss from equipment.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, Figs. 2 and 3 are its optical path diagram, Fig. 4 is a reflectance diagram of the glass surface, Fig. 5 is a diagram of the inclined heat collecting surface and optical path, and Fig. 6 is the original diagram of 1lJt angle change and direct energy, Figure 7.8 is an example diagram of a reflective floor that does not have a single slope, and Figure 9
．． Figure 10 is a comparison diagram of light reception 1 reflectance of sloped floor and horizontal floor, 1st
Figure 1 shows the performance curve, and Figure 12 shows how it is installed into a building. 1... Translucent body, 2... Reflective floor, 3... Heat collecting surface, 4
... Frey enters, 5... pump, 6,6'... hengoo, 7... drain.

Claims (2)

[Claims] (1) A light-transmitting plate that transmits sunlight, a heat collector having a heat-collecting surface that receives the sunlight that passes through the light-transmitting plate, and an upward fixed reflective floor that can irradiate the heat-collecting surface with reflected light. A solar heat collection device comprising: installed with the heat collection surface facing south;
The wall surface other than the heat collecting surface is constructed of a reflector, and the reflective floor is arranged at a downward slope with respect to the heat collecting surface at least at an angle not exceeding the solar altitude angle at noon on the winter solstice. Solar heat collector. (2) Claim 1, wherein the fixed reflective floor and the solar light transmitting plate face each other at an open spread angle with respect to the heat collecting surface.
The described solar heat collector.