JP6798692B2 - Heat storage device - Google Patents

Description

The present invention relates to a heat storage device that stores the collected heat energy.

Modern life requires a lot of energy. Until now, energy was produced by relying on fossil fuels and nuclear power, but due to the effects of global warming and the nuclear accident, safe and clean renewable energy is attracting attention. Among them, solar energy boasts an enormous amount of energy, and there are high expectations for future technological development. Speaking of solar energy, it is generally known that light is directly converted into electric power and used like photovoltaic power generation, but in recent years, light has been condensed and converted into heat, and the heat has been effectively used. There is growing interest. This concentrating solar heat utilization is being actively researched not only in Japan but also in countries around the world.

This type of condensing type solar condensing device efficiently collects sunlight and converts it into heat energy, and for example, a trough type or tower type solar condensing device is known. When using such a solar concentrating device, it is desired to develop a heat storage device that stores the collected heat energy.

In the United States and Spain, steam turbo power generation using solar heat has already been put into practical use, and the heat storage device in this steam turbine power generation is capable of storing solar heat in steam or molten salt obtained by heating boiling water. .. However, since the critical temperature of water is 374 ° C., which is not suitable for higher temperatures, and the molten salt is thermally decomposed at 500 ° C. or higher, these heat storage materials are not suitable for operation in a high temperature range.

As a solar condensing device capable of generating a high temperature range, a beam-down type solar condensing device as shown in Patent Document 1 is known. According to this device, a high temperature environment of 1,000 ° C or higher can be obtained, and iron oxides such as silica sand and magnetite (Fe ₃ O ₄ ) and particles made of silicon carbide (SiC) are used as the heat storage material. Gas can be circulated and flowed in the heat collecting container, and the condensed sunlight is irradiated from above the heat collecting container to store heat.

According to the heat collection and heat storage device using sunlight of Patent Document 1, a tube is inserted into a heat storage container containing a particulate heat storage material, and air, nitrogen, water vapor, etc. flow in from the tube to form particles. The heat storage material is wound up on an air stream to form a fluid layer of the heat storage material, and the fluid layer of the heat storage material is irradiated with sunlight condensed by a solar condensing means to enable heat storage in the heat storage material. ing.

In addition, there is also known a heat collection and heat storage device in which a particulate heat storage material is allowed to flow down in a curtain shape and is irradiated with sunlight collected by a solar condensing means to store heat.

International Publication No. 2014-038553 (page 14, Fig. 1)

However, since the heat storage device of Patent Document 1 irradiates the flow layer of the heat storage material wound up in the air stream with sunlight, the mass of the heat storage material used for heat storage in the container is limited, and sufficient heat is obtained. Not only is it impossible to extract energy, but the handling of gas in the container is also complicated.

In addition, even in the method of flowing down the particulate heat storage material in a curtain shape, sufficient heat energy cannot be extracted because the heat storage material at the time of flowing down is instantaneously irradiated with sunlight, and the particle-like heat storage material cannot be extracted. Controlling the flow rate of the heat storage material is also complicated.

Therefore, the present invention provides a heat storage device capable of locating a massive heat storage material in a concentrated irradiation region of sunlight for a relatively long time and evenly storing heat in the solid heat storage material to extract sufficient heat energy. The purpose is.

In order to solve the above problems, the heat storage device of the present invention
A heat storage device that irradiates a heat storage surface with sunlight collected by a light condensing means and stores heat on the heat storage surface.
The heat storage device includes a tubular outer peripheral wall surrounding the sunlight irradiation region and a plurality of massive solid heat storage materials housed in the outer peripheral wall, and the inside of the outer peripheral wall is inside. It is characterized in that the inner bottom and the outer outer bottom thereof are arranged so as to be relatively movable with each other via a tubular inner peripheral wall .

According to this feature, by moving the inner bottom and the outer bottom in the outer peripheral wall relative to each other through , for example, a cylindrical inner peripheral wall in the vertical direction, a height difference is generated in the solid heat storage material in the outer peripheral wall, resulting in a lump shape. Solid heat storage material moves as if convective in the outer wall. Therefore, by controlling the relative movement speed of the inner bottom and the outer bottom, it is possible to control the time when a new solid heat storage material appears in the concentrated irradiation area of sunlight, and the heat storage material is relatively placed in the irradiation area of sunlight. By arranging it for a long time, it is possible to store sufficient heat energy evenly in the solid heat storage material.

In the outer peripheral wall, the surface shape of the solid heat storage material is controlled to be substantially tapered-concave by the relative movement of both the lowering movement of the inner bottom and the rising movement of the outer bottom. It is said.
According to this feature, the condensed sunlight spreads outward from the center of the condensing means, so that the height of the solid heat storage material is increased at the outer peripheral portion having a substantially tapered concave shape, so that the tubular outer peripheral wall is formed. Since the light that hits the inner wall of the lamp is reduced, the incident loss is reduced, and the concentrated sunlight can be irradiated to the fixed heat storage material without waste, the heat storage efficiency can be improved.

The total area of the inner bottom and the total area of the outer bottom are substantially the same, and the vertical movement speeds of both are controlled to be substantially the same.
According to this feature, the surface of the heat storage surface in the outer peripheral wall is always kept at a constant height when the inner bottom and the outer bottom move relative to each other, and the heat is stably stored in the solid heat storage material. be able to.

The inner bottom and the outer bottom are characterized in that they move relative to each other in the direction in which the inner bottom descends.
According to this feature, the solid heat storage material in the central part that has been condensed and stored heat is introduced into the inner peripheral wall and concentrated on the bottom surface side of the inner bottom to become dense, so that the stored heat is difficult to escape. The heat retention effect can be improved.

The plurality of massive solid heat storage materials are characterized in that they are formed into substantially spheres.
According to this feature, the substantially spherical solid heat storage material moves while rolling due to the ascending / descending movement of the bottom surface in the housed outer peripheral wall, so that heat can be stored over the front and back of the solid heat storage material.

The plurality of massive solid heat storage materials are characterized in that each is formed in substantially the same shape.
According to this feature, since the solid heat storage materials have substantially the same shape, the solid heat storage material can be uniformly moved, and the shape of the heat storage surface becomes more stable.

The solid heat storage material is characterized by containing at least alumina spheres.
According to this feature, alumina not only has a high melting point of 2,000 ° C. or higher, but also has a spherical shape, so that sufficient heat can be stored by irradiation from a condensing portion. In addition, if a solid heat storage material that is not a sphere is used as it is, when the inner bottom and the outer bottom move relative to each other, there is a risk that the inner bottom and the outer bottom may get caught in the gap between the piston and the cylinder in the reciprocating drive device. Several layers may be laid on the bottom and the outer bottom to store heat together with other solid heat storage materials that are not spherical. As another solid heat storage material, for example, a solid heat storage material having a high absorption rate such as ferronickel slag may be used.

It is the schematic of the beam-down type solar condensing device in Example 1. FIG. It is a top view which shows the heat storage apparatus in Example 1. FIG. It is a top view which shows the heat storage apparatus in Example 1. FIG. It is explanatory drawing which shows the operation state by the passage of time in the heat storage apparatus in Example 1, and the temperature distribution map of a solid heat storage material group. It is explanatory drawing which shows the operation state by the passage of time in the heat storage apparatus in Example 1, and the temperature distribution map of a solid heat storage material group. It is an enlarged view of N part which shows the movement and temperature of the solid heat storage material group in the heat storage apparatus in Example 1. FIG. It is explanatory drawing which shows an example of how to take out heat of the solid heat storage material which stored heat by the heat storage apparatus in Example 1. FIG. It is explanatory drawing which shows the basic specifications of the beam-down type solar condensing apparatus in Example 2. FIG. It is a block diagram of the thin film type heat flux meter used in Example 2. It is explanatory drawing which shows the experimental condition when the heat flux distribution was measured on the plane (z = −150 mm) of the condensing means E in Example 2. FIG. It is explanatory drawing which shows the experimental condition when the position was changed downward by 25 mm from z = −150 mm to z = −250 mm in Example 2. FIG. It is a figure which shows the distribution of the radiative flux Rf when z = −150 mm in Example 2. FIG. It is a figure which shows the heat flux distribution obtained by changing the position downward by 25 mm from z = −150 mm to z = −250 mm in Example 2. FIG. It is the schematic of the mechanical stirring type sensible heat storage apparatus 1 in Example 2. It is explanatory drawing which shows the attachment position of the thermocouple 1 to 16 to the heat storage apparatus 1 in Example 2. FIG. It is explanatory drawing which shows the attachment position of the thermocouple 1 to 16 to the heat storage apparatus 1 in Example 2. FIG. It is explanatory drawing which shows the change of the shape of the solid heat storage material group 2 from the initial state to the steady state which arranged the solid heat storage material group 2 in the heat storage device 1 in Example 2. FIG. It is explanatory drawing which shows the experimental condition of the heating experiment of the heat storage device 1 in the beam-down type solar condensing device A in Example 2. It is explanatory drawing which shows the result of the heating experiment of the heat storage device 1 in the beam-down type solar condensing device in Example 2. The temperature distribution diagram in the inner peripheral wall 12 after the experiment in Example 2 is shown. It is explanatory drawing which shows the positional relationship in the initial state which arranged the solid heat storage material group 2 inside the heat storage tank of the heat storage apparatus 1 in Example 2. FIG.

A mode for carrying out the heat storage device according to the present invention will be described below based on examples.

The heat storage device according to the first embodiment will be described with reference to FIGS. 1 to 7.

In this embodiment, the heat storage device will be described as a device that is installed in, for example, a beam-down type solar concentrator using sunlight and stores the condensed light.

FIG. 1 is a schematic view of a beam-down solar concentrator, in which the beam-down solar concentrator A includes a tower 8 erected on the ground and a plurality of heliostats B, B, which are also arranged on the ground. ... and. The tower 8 has hemispherical reflectors 80 and 80 attached to the upper portion thereof, and has a mounting surface 81 at the center thereof, and a heat storage device 1 is installed on the mounting surface 81. Further, a cylindrical condensing means E is arranged above the heat storage device 1.

The heliostat B is a sun tracking device, which follows the movement of the sun, reflects sunlight with a plane mirror, and sends it in a certain direction. The sunlight reflected by the plurality of heliostats B, B, ... Is collected at a predetermined position (first focus C) between the reflectors 80, 80 of the tower 8 and the heat storage device 1, and is first. The sunlight collected at the focal point C is further reflected by the reflectors 80 and 80 installed at the upper part of the tower 8, and is inside the condensing means E installed at the upper part of the heat storage device 1 (second focal point D). It is designed to irradiate the focused light so that it is focused and directly below.

As shown in FIGS. 2 and 3, the heat storage device 1 has a cylindrical outer peripheral wall 11 made of a highly heat-resistant material, a cylindrical inner peripheral wall 12 made of a similarly heat-resistant material, and a donut shape. It is mainly composed of an outer bottom 13 of the above, a circular inner bottom 14, and a glass lid 15 for preventing convective heat transfer to the outside air. The outer peripheral wall 11 is tubular and has a hollowed-out center, and the bottom portion of the outer peripheral wall 11 is formed by the inner bottom 14 and the outer outer bottom 13. The portion that accommodates the solid heat storage material group 2 surrounded by the outer peripheral wall 11 is also referred to as an outer cylinder, and the portion that accommodates the solid heat storage material group 2 surrounded by the inner peripheral wall 12 is also referred to as an inner cylinder. Note that FIG. 3 shows an MM cross section of the heat storage device 1 shown in FIG.

As shown in FIG. 2, the heat storage device 1 includes an inner bottom 14 and an outer outer bottom 13 inside the outer peripheral wall 11, and the inner bottom 14 and the outer outer bottom 13 have a spherical shape having the same shape. The solid heat storage material group 2 in which a plurality of aluminas formed in the above are assembled can be accommodated. Since the spheres constituting the solid heat storage material group 2 are made of alumina, their melting points are as high as 2,000 ° C. or higher. The shapes of the outer bottom 13 and the inner bottom 14 are provided according to the shapes of the outer peripheral wall 11 and the inner peripheral wall 12.

Since the glass lid 15 is made of quartz glass having a high light transmittance, it functions as a lid of the heat storage device 1 to prevent the solid heat storage material group 2 from dropping in temperature due to the influence of the outside air, and also stores heat. The light emitted from the light collecting means E installed above the device 1 can be transmitted through the outer peripheral wall 11.

The condensing means E shown in FIG. 2 is provided with a CPC (Compound Parabolic Concentrator) that increases the condensing intensity by about four times, enhances the intensity of the sunlight condensed by the second focal point D, and increases the intensity of the sunlight collected by the second focal point D, and the glass of the heat storage device 1. The heat storage surface 21 of the solid heat storage material group 2 is irradiated through the lid 15.

As shown in FIG. 3, a donut-shaped outer bottom 13 that follows the shape of the inner peripheral surface of the outer peripheral wall 11 and the shape of the outer peripheral surface of the inner peripheral wall 12 is fitted between the outer peripheral wall 11 and the inner peripheral wall 12. A circular inner bottom 14 that follows the shape of the inner peripheral surface of the inner peripheral wall 12 is fitted inside the inner peripheral wall 12. The outer bottom 13 and the inner bottom 14 are formed so that the surface area S of the upper surface 70 of the outer bottom 13 and the surface area U of the upper surface 71 of the inner bottom 14 are equal to each other.

Further, as shown in FIG. 2, the outer bottom 13 is moved up and down by a reciprocating drive device 40 arranged below the outer bottom 13. Similarly, the inner bottom 14 is moved up and down by the reciprocating drive device 41 arranged below the inner bottom 14. Further, a plurality of reciprocating drive devices are arranged along the shape of the donut-shaped outer bottom 13 (see FIG. 3).

The reciprocating drive device 40 includes a piston rod 31 and a cylinder 32 that fits outside the piston rod 31, and can move up and down the outer bottom 13 by expanding and contracting with a drive control means (not shown). Similarly, the reciprocating drive device 41 includes a piston rod 33 and a cylinder 34 externally fitted to the piston rod 33, and can move up and down the inner bottom 14 by expanding and contracting by a drive means (not shown). The reciprocating drive device 40 and the reciprocating drive device 41 are controlled by drive control means at the same time so that the amount of movement per predetermined time unit is equally expanded and contracted.

As shown in FIG. 2, when heat is stored from sunlight, the reciprocating drive device 40 and the reciprocating drive device 41 described above are moved up and down, respectively, and the height difference between the outer bottom 13 and the inner bottom 14 is increased. The surface shape of the heat storage surface 21 of the solid heat storage material group 2 composed of a plurality of solid heat storage materials is substantially tapered-concave. The substantially tapered-concave shape means a shape in which the central portion is recessed downward and the diameter is tapered. When the outer peripheral wall 11 and the inner peripheral wall 12 are cylindrical, the shape is recessed in a bowl shape as a whole. To say. The substantially tapered-concave shape includes a shape having a parabolic shape when the surface shape of the heat storage surface 21 is viewed in a vertical cross section as shown in FIG. According to this, since the condensed sunlight spreads outward from the center of the condensing means E, the height of the solid heat storage material is increased at the outer peripheral portion having a substantially tapered concave shape, so that the outer peripheral portion of the cylinder Since the light that hits the inner wall of the wall 11 is reduced, the incident loss is reduced, and the fixed heat storage material can be irradiated with the concentrated sunlight without waste, the surface shape of the heat storage surface 21 is a flat surface. In comparison, the heat storage efficiency can be improved. In particular, if the radiation direction of sunlight and the surface of the heat storage surface 21 are in a directional relationship as shown in FIG. 2, the sunlight can be efficiently applied to the solid heat storage material without waste. It is desirable that the distance between the light collecting means E and the heat storage device 1 in the height direction is as close as possible.

As shown in FIG. 2, the sunlight reflected by the reflecting mirrors 80 and 80 shown in FIG. 1 to the condensing means E is set to be irradiated into the outer peripheral wall 11 of the heat storage device 1 by the condensing means E. The irradiation region that has been focused without waste is defined here as the concentrated irradiation region L. As will be described later, in the drawing, the portion of the highest temperature zone F is shown in the darkest black.

4 and 5 are diagrams showing how the outer bottom 13 and the inner bottom 14 are relatively moved by the reciprocating drive devices 40 and 41 over time, and the high temperature range of the solid heat storage material 2 group. is there. FIG. 4A shows a diagram of the heat storage device 1 in which heat storage is started and 30 minutes have passed. In the solid heat storage material 2 group, the heat storage surface 21 is in the maximum temperature zone F (about) due to the irradiation of sunlight from the condensing means E. It is heated to 1,200 ° C.).

When the operation of the heat storage device 1 is started, the sunlight reflected by the beam-down solar concentrator A to the condensing means E is preliminarily formed in a substantially tapered concave shape, and the heat storage surface 21 of the solid heat storage material group 2 is formed. Is irradiated toward. The outer bottom 13 and the inner bottom 14 start relative movement in opposite directions 30 minutes after the solid heat storage material group 2 arranged on the heat storage surface 21 is sufficiently stored. According to this, as shown in FIG. 4B, in a situation where the inner bottom 14 descends as the outer bottom 13 rises, the height difference between the outer bottom 13 and the inner bottom 14 and the spherical feature thereof. Therefore, when the heat storage surface 21 exceeds the limit capable of maintaining a substantially tapered-concave surface shape, the two groups of solid heat storage materials in which heat is stored up to the high temperature zone F in the end heat storage surface region 22 on the outer bottom 13 are inside. It slides down in the direction of the central heat storage surface area 24 on the bottom 14. (See Fig. 6, black arrow in the enlarged view of part N)

Further, in the solid heat storage material 2 group that slides down to the central heat storage surface area 24, the inner bottom 14 descends, and the solid heat storage material 2 group that is stored and slides down sequentially polymerizes in the central heat storage surface area 24. Therefore, it is settled in the central middle layer region 25 on the inner bottom 14.

FIG. 4B shows a diagram in which the outer bottom 13 and the inner bottom 14 start relative movement by the reciprocating drive devices 40 and 41, and 5 minutes (35 minutes after the start of operation) have passed. The outer bottom 13 is controlled to rise and the inner bottom 14 is controlled to fall with the passage of time. In particular, as shown in FIG. 6 in the enlarged view of the N portion shown in 7 and 4, the solid heat storage material 2 groups stored in the end heat storage surface area 22 on the outer bottom 13 slipped down, and as a result, the solid heat storage immediately below. The material 2 group formed a new substantially tapered-concave heat storage surface, and then the solid heat storage material 2 group located in the end middle layer region 23 on the outer bottom 13 was endped by the rise of the outer bottom 13. By being pushed up to the heat storage surface area 22 and appearing on the surface layer, a new substantially tapered-concave heat storage surface is formed and heat is stored. Therefore, the solid heat storage material group 2 moves as if convected in the outer peripheral wall 11, and a new solid heat storage material group 2 appears in the concentrated irradiation region L from the condensing means E. As a result, sufficient heat can be sufficiently stored in the contained solid heat storage material group 2 by sensible heat.

FIG. 5A shows a diagram in which the outer bottom 13 and the inner bottom 14 have started relative movement by the reciprocating drive devices 40 and 41, and 15 minutes (45 minutes after the start of operation) have passed. Initially, the solid heat storage material group 2 located on the heat storage surface 21 has settled in the maximum temperature zone F (about 1,200 ° C.) with the drooping of the inner bottom 14. On the other hand, above that, the solid heat storage material group 2 that slides down while storing heat up to the substantially tapered concave central portion 18 of the heat storage surface 21 is next to the high temperature zone G (about 1,000 ° C to 1,100 ° C). It is hot. In addition, the adjacent medium temperature zone H also stores heat from about 900 ° C. to 1,000 ° C. In particular, as described above, the reciprocating drive device 40 and the reciprocating drive device 41 are controlled by the drive control means at the same time so that the amount of movement per predetermined time unit is equally expanded and contracted. Here, the relative movement between the reciprocating drive device 40 and the reciprocating drive device 41, that is, the speeds of the outer bottom 13 and the inner bottom 14 is controlled by the drive control means described above, and a new solid heat storage is stored in the concentrated irradiation region L of sunlight. By controlling the time when the material group 2 appears, the heat storage material can be positioned in the concentrated irradiation region L of sunlight for a relatively long time, and sufficient heat energy can be evenly stored in the solid heat storage material group 2. ing.

FIG. 5B shows a diagram in which the outer bottom 13 and the inner bottom 14 start relative movement by the reciprocating drive devices 40 and 41, and heat storage is completed after 23 minutes (53 minutes after the start of operation). ing. The maximum temperature zone F, which has settled to the lower part due to the descent of the inner bottom 14, is shielded from heat dissipation by the surrounding high temperature zone G, and a heat retention effect is generated, so that the heat retention effect is enhanced.

Further, since the outer bottom 13 and the inner bottom 14 have the same area, when the outer bottom 13 and the inner bottom 14 move relative to each other at the same speed while the two groups of solid heat storage materials are housed in the heat storage device 1. Since the movement is controlled so that the height of the heat storage surface 21 is substantially flush with each other, the surface of the heat storage surface 21 in the outer peripheral wall 11 is always maintained at a constant height, and is solid. It is possible to stably store heat in the heat storage material group 2.

Further, the relative movement of the outer bottom 13 and the inner bottom 14 by the piston can be appropriately changed in consideration of the heat storage condition of the solid heat storage material 2 group.

Various modes of taking out can be considered. For example, as shown in FIG. 7, when the inner bottom 14 is further lowered after the heat storage is completed, the solid heat storage material group 2 can move to another heat storage tank 90 through the connecting pipe 9. The heat storage tank 90 is capable of extracting air and steam heated by the solid heat storage material group 2 from the upper pipe 92 by sending air and water from the lower pipe 91, and dissipates heat from the solid heat storage material group. 2 is returned to the heat storage device 1 so that it can be reheated. Further, a small hole may be formed in the inner bottom 14 of the inner piston 41 so that particles do not pass through. After the heating of the solid heat storage material group 2 is completed, the outside air is taken in from the inner bottom 14 of the inner piston 41, and the heated air passing through the particles of the solid heat storage material group 2 is taken out from the outer cylinder separately provided on the upper stage of the outer peripheral wall 11. You may do so. By passing between the particles of the solid heat storage material group 2, the contact area with air becomes large, and high-temperature air can be efficiently obtained.

The heat storage device and the beam-down solar condensing device according to the second embodiment will be described with reference to FIGS. 8 to 21.

In the second embodiment, the beam-down type solar concentrator actually used in the experiment and the heat storage device that stores the condensed light will be specifically described. The basic configuration is the same as that of the first embodiment unless otherwise specified, and will be described with the same reference numerals.

Japan's largest beam-down solar concentrator is installed at Miyazaki University, and demonstration experiments on solar heat are underway. FIG. 8 shows the basic specifications of the beam-down solar concentrator. The configuration and the focusing principle of the beam-down type solar condensing device are the same as those of the beam-down type solar condensing device A in the first embodiment. In the second embodiment, in the beam-down type solar concentrator A, 88 heliostats B are arranged in an area where the height of the tower is 16 m and the land area is 60 m × 60 m. In this case, the arrangement area of the beam-down type solar concentrator A is 176 m ² , and the capacity is 100 kW. Each heliostat B is provided with 10 concave mirrors, and the orientation of the concave mirrors is adjusted in order to reflect sunlight and send it in the direction of a predetermined position (first focal point C). The beam-down type solar condensing device A reflects the light reflected by each heliostat B again by the reflecting mirror 80 having the rotating elliptical surface at the upper part of the tower 8, and makes it the second focal point D in the condensing means E. It is a method of collecting sunlight downward. Compared to a normal tower type solar concentrator, there is one more reflection by the mirror, so the loss due to reflection increases slightly, but since the condensing part is close to the ground, the cooling loss can be reduced and the device can be installed easily. To be equipped with. Further, in the beam-down type solar concentrator A, a condensing means E equipped with a CPC (Compound Parabolic Concentrator) is installed in order to increase the condensing intensity by about four times, and the upper entrance of the condensing means E is the second. Located in focus.

The radiation flux distribution at the outlet of the condensing means E was measured using the beam-down solar condensing device A having the above basic specifications. A thin-film heat flux meter 112 shown in FIG. 9 was used for the measurement. The sensor portion of the thin film type heat flux meter shown in FIG. 9 is a T having a copper thin film (plated copper film) 101 having a diameter of 3.2 mm and a thickness of 10 μm and a probe body 103 made of constantan bonded at a surface bond 102 portion. A type thermocouple is used. This sensor unit is built in an insulator 104 made of glass wool, and an insulated copper wire 105 as a measurement wire and a constantan wire 106 are connected to each other. The thin-film heat flux meter 112 is capable of capturing temperature changes at sampling intervals of 50 μs. When the thin film type heat flux meter 112 is moved on the condensing surface, the radiative flux distribution along the path is obtained.

FIG. 10 shows experimental conditions when the heat flux distribution was measured by traversing a thin film type heat flux meter so as to pass through the central axis of the condensing means E on a plane (z = -150 mm) of the condensing means E. .. Here, z indicates the distance in the vertical direction from the reference plane (outlet plane) of the light collecting means E. As shown in FIG. 10, the measurement was started at 10:44 am on December 25, 2015. The experimental conditions in this case were a direct solar normal incident rate (DNI) of 733 W / m ² , the number of heliostats involved in condensing at this time, 74 units, and a swing arm rotation speed of 4.19 rad / S. A low-pass filter with a data collection interval of 50 μs and a radio wave filter of 1 kHz is used. The distribution of the radiative flux Rf when z = −150 mm is shown in FIG. In FIG. 12, x is the distance in the east-west direction from the central axis of the second focal point D (0 mm) of the condensing means E, the positive direction indicates the eastward direction, and y is the second focal point D (0 mm) of the condensing means E. The distance in the north-south direction from the central axis of (0 mm), the positive direction indicates the north direction, the radiation flux Rf at the position determined by these X and Y is shown on the vertical axis, and the contour line of the radiation flux Rf is XY. It is shown on the plane.

Further, FIG. 13 shows the heat flux distribution obtained by changing the focal plane position downward by 25 mm from z = -150 mm to z = -250 mm. FIG. 11 shows the experimental conditions when the position was changed downward by 25 mm from z = -150 mm to z = -250 mm. Since the angular velocity of the traverse and the data recording conditions on the experiment day are the same as those in FIG. 10, other measurement conditions are shown in FIG.

In FIG. 13, the vertical axis represents the focusing magnification Cm per heliostat, the horizontal axis represents the distance from the central axis of the focusing means E at the center of the thin film heat flux meter, and the positive direction indicates the eastward direction. Since the direct solar radiation amount DNI and the radix of the heliostats involved in light collection change from moment to moment, the direct solar radiation amount Cm is the radiative flux Rf obtained by the thin film type heat flux meter as shown in Equation 1. It is defined as the value divided by the radix N of DNI and heliostat.
[Number 1]
Cm = Rf / (DNI ・ N)

From FIG. 13, the radiative flux distribution on the horizontal plane at the height positions z = -150 mm and z = -175 mm has a high central portion and a low toward the periphery, and the absolute values are almost the same. However, due to the characteristics of the condensing means E, as the height position becomes lower, the shape in which the central portion is recessed becomes remarkable.

FIG. 14 shows a schematic view of the mechanically agitated sensible heat storage device 1 that was actually designed and manufactured. As described in the first embodiment, the heat storage device 1 directly exposes the surface of the fixed heat storage material to the sun as shown in FIG. 14 in order to realize high temperature heat storage in consideration of the light collection direction of the beam-down type solar concentrator. It is a heat storage device equipped with a receiver function that heats with light. As shown in the dimensions of the heat storage tank, there are two reciprocating drive devices (hereinafter, "pistons") in which the inner and outer outer peripheral walls 11, the inner peripheral wall 12, and the outer bottom 13 and the inner bottom 14 have the same area. That is, the inner circular piston, the outer donut-shaped piston, and the quartz glass lid 15 and the solid heat storage material having a transmittance of σ = 0.9 to prevent convective heat transfer to the outside air. It consists of group 2. Both pistons move in the vertical direction (z-axis direction) in opposite directions and at the same speed to agitate the solid heat storage material group 2 of the heat storage material.

For the solid heat storage material group 2, alumina spheres having a high melting point and easily available having various particle sizes were used. The particle size of the heat storage material should be smaller because it is heated quickly to the center of the particles, but it was set to φ5 mm in consideration of the clearance between the piston and the cylinder.

The heat storage device 1 has the following features.
(1) Since heat is stored in the solid heat storage material group 2 by sensible heat, it is possible to store heat at a high temperature.
(2) Since the solid heat storage material group 2 is directly heated by sunlight, the heat loss is smaller than that of the indirect heating method in which heat exchange is performed.
(3) The heating temperature of the solid heat storage material group 2 can be easily controlled by changing the moving speed of the piston. Further, by controlling the piston speed according to the radiant intensity, it is possible to keep the temperature of the solid heat storage material group 2 at the set temperature.

When the heat storage device 1 as shown in FIG. 14 is used, the surface shape of the light receiving surface of the solid heat storage material group 2 changes depending on the moving direction of the piston. For the following reasons, the heat storage surface 21 of the solid heat storage material group 2 The experiment was conducted in the direction in which the inner piston of the piston descends so that the surface shape of the piston becomes a substantially tapered-concave shape that is convex downward.
(1) Since the condensed sunlight spreads outward from the center of the condensing means E, the higher the height of the solid heat storage material group 2 in the z direction at the outer peripheral portion, the less the light that hits the inner wall of the outer cylinder. Incident loss is reduced.
(2) The irradiation intensity on the surface of the solid heat storage material group 2 approaches uniform, and the temperature unevenness inside the solid heat storage material group 2 becomes small.
(3) After the heating is completed, the heat storage particles gather in the inner cylinder, and the outer cylinder serves as a heat insulating layer for air, so that the heat retention effect is enhanced.

FIG. 21 shows the positional relationship in the initial state in which the solid heat storage material group 2 is arranged inside the heat storage tank of the heat storage device 1. Further, FIG. 17 shows a change in the shape of the solid heat storage material group 2 from the initial state in which the solid heat storage material group 2 is arranged in the heat storage device 1 to the steady state. In FIG. 21, the distance from the central axis of the condensing means E is shown on the horizontal axis, the vertical distance from the bottom surface of the condensing means E is shown on the vertical axis, and the position of the thermocouple described later is also shown. It is described. In FIG. 17, the horizontal axis represents the distance from the center position of the heat storage surface 21, and the vertical axis represents the vertical distance from the bottom surface of the light collecting means E.

As shown in FIG. 21, in the initial state in which the solid heat storage material group 2 is arranged in the heat storage device 1, the surface of the heat storage particles is formed on a flat surface at z = -210 mm. The shape of the heat storage surface 21, which is the light receiving surface of the solid heat storage material group 2, changes from the initial state in which the solid heat storage material group 2 is arranged in the heat storage device 1 due to the movement of the piston, as shown in FIGS. 21 and 17. It was found that the steady state was reached in about 2 minutes.

Considering the shape of the heat storage surface 21 of the solid heat storage material group 2, 16 thermocouples were attached and the temperature was measured. The mounting positions of the K-shaped sheath tube thermocouples 1 to 16 in the AA cross section shown in FIG. 14 are shown in FIGS. 15 and 16. 15 (a) and 16 (a) show attachment positions of thermocouples fixed to the outer peripheral wall 11 and the inner peripheral wall 12 for performing fixed point measurement, and the height position is z = -270 mm. Further, FIGS. 15 (b) and 16 (b) show attachment positions of thermocouples that move together with the outer bottom 13 and inner bottom 14 of the piston, and the measurement position is 20 mm above the upper surface of each piston, and the initial position is the initial position. The inner piston has z = -270 mm, and the outer piston has z = -390 mm. Further, FIGS. 16A and 16B show the coordinates of the tip of the thermocouple, which is the temperature measurement position, the x coordinate indicates the east-west direction, and the y coordinate indicates the north-south direction. In this specification, the circled numbers in the figure are indicated by numbers corresponding to the numbers.

A heating experiment was conducted in which a thermocouple was installed at the above-mentioned position, sunlight was collected by a beam-down type solar concentrator, and heat was stored in the heat storage device 1.

In the heating experiment of the heat storage tank of the heat storage device 1 in the beam-down type solar concentrator A, sunlight was irradiated with the piston stationary for 30 minutes from the start, and then the piston was moved 160 mm in the z direction in 23 minutes. I made it move at a constant velocity. The experimental conditions are as shown in FIG. As shown in FIG. 18, the measurement was started at 12:00 noon on January 20, 2016. The experimental conditions in this case are that the average direct solar normal incidence (DNI) when the piston is stopped is 953 W / m ² , and the average direct normal normal incidence (DNI) when the piston is moving is 962 W / m ² . At this time, the number of heliostats involved in light collection is 79 units, the piston speed is 0.116 mm / S, and the data collection interval is 1 s.

FIG. 19 shows the results of a heating experiment of the heat storage device 1 in the beam-down type solar concentrator performed under such conditions. FIG. 19A shows the measurement result by the thermocouple fixed to the outer peripheral wall 11 and the inner peripheral wall 12 described above, and FIG. 19B shows the measurement result by the thermocouple attached to the inner bottom 14. c) is a measurement result by a thermocouple attached to the outer bottom 13 of the outer piston. The alternate long and short dash line in FIG. 19 (a) indicates DNI. From FIG. 19, it was found that the maximum temperature was 1070 ° C. only at the 1st position, which is the central position of the inner bottom 14, and reached the target of 1000 ° C.

19 from (a), the variation of the DNI is small, 942~963kW / ^{m 2} at the time of the piston stop may be considered to be substantially during the experiment constant during piston driven by 953~969kW / ^{m 2.} In addition, the result of measurement with a thermocouple fixed at the position of z = -270 mm of the outer peripheral wall 11 and the inner peripheral wall 12 shows that the temperature rises as it approaches the center, and the piston starts moving 30 minutes after the start of the experiment. Therefore, the difference becomes large. This is because the solid heat storage material group 2 has a substantially tapered-concave surface shape as shown in FIG. 17 after 2 minutes from the start due to the movement of the piston, and the closer to the center, the light receiving surface of the solid heat storage material group 2. This is because the distance from the thermocouple to the thermocouple in the z direction is shortened. 30 to 40 minutes after the start of the experiment, the heat storage particles of the solid heat storage material group 2 that were on the surface in the stationary state move and come into contact with the thermocouple, so the temperature rises sharply, and 40 minutes after the start of the experiment, the maximum temperature is 1070. Although the temperature reaches ℃, the temperature starts to decrease because the amount of heat to the heat storage particles on the surface of the solid heat storage material group 2 approaches a constant value.

From FIG. 19B, since the 5th position is almost the same as the 1st position until 30 minutes after the start, the same temperature progress is shown, but the rate of temperature rise decreases after the start of the movement. This is because the piston descends, the distance from the heat storage particles on the surface becomes longer, and the amount of conducted heat decreases. The thermocouple attached to the inner piston has a higher temperature at the same time as it is closer to the center, but shows the same temperature passage as in the 5th position. On the other hand, in the outer piston of FIG. 19C, the temperature rise is small because the distance from the heat storage particles on the surface layer that receives the incident light to the thermocouple mounting position is long. The slight increase in the temperature rise rate from 45 minutes after the start of the experiment is considered to be due to the effect of heat conduction from the x direction by the high-temperature heat storage particles inside.

From the above experimental results, it can be seen that in the solid heat storage material group 2, the amount of heat transfer due to heat conduction is small, and the temperature change is mainly caused by direct heating by sunlight. Further, since the surface position of the solid heat storage material group 2 in the stationary state of the energy Qin incident on the heat storage tank is z = -210 mm, the light collection magnification can be obtained by referring to the value of z = -200 mm in FIG. The area average value of Cm is 2.6. Further, when the time average value of DNI shown in FIG. 18 is 957 W / m ² , the transmittance of quartz glass is σ = 0.9, and the number of heliostats is N = 79, the average incident flux is 177 kW / m ² . When this is multiplied by the heating time of 53 minutes and the cross-sectional area A = 0.126 m ² of the heat storage tank, the incident energy becomes Qin = 71 MJ. The time average value of DNI, 957 W / m ^2, is the average DNI during the experiment, and the average value is obtained from the DNI during the time of irradiation with sunlight, including 23 minutes when the piston is stopped and 30 minutes when the piston is moving. It is a thing.

In order to obtain the temperature inside the inner peripheral wall 12 after the end of the experiment shown in FIG. 19, the temperature at a time of 30 to 53 minutes measured by a thermocouple fixed to the outer peripheral wall 11 and the inner peripheral wall 12 is z in the heat storage tank. = -Assuming that the temperature is at the position of 430 to -270 mm, the temperature distribution shown in FIG. 20 was obtained by the simulation by linear interpolation. FIG. 20 shows a temperature distribution map in the inner peripheral wall 12, where the horizontal axis shows the distance of the condensing means E from the central axis of the CPC, and the vertical axis z is the reference plane (second focal point D) of the condensing means E. ) Is shown in the vertical direction, and the temperature distribution at each position is shown. The amount of heat stored was 12 MJ, and it was found that 17% of the incident energy was stored. The temperature distribution shown in FIG. 20 also corresponds to the schematic diagram shown in FIG. 5 (b) 53 minutes after the start of the experiment. As a calculation method, assuming that the temperature is the same at the same radius position, the calculation is based on the thermocouple 1st to 4th positions fixed at the position of z = -270mm, and the heat storage particles in contact with the thermocouple move with the piston. However, the temperature distribution in the downward direction (z direction) was obtained from the thermocouple assuming that the temperature did not change. The temperature above the thermocouple is set to the same temperature as the thermocouple position, and the temperature distribution is obtained by linearly interpolating in the radial direction.

As a result of the experiment in Example 2 as described above, the following conclusions could be obtained.
(1) When an alumina sphere having a diameter of 5 mm is used as the solid heat storage material group 2 and the piston is stopped for 30 minutes and then irradiated with sunlight under the condition of moving at a speed of 160 mm in 23 minutes, the maximum temperature is reached at the center of the heat storage tank. Was 1070 ° C.
(2) The amount of heat transfer due to heat conduction between the heat storage particles is small, and the temperature changes mainly due to direct heating by sunlight.
(3) Under the experimental conditions this time, 17% of the incident energy could be stored.

According to Examples 1 and 2, by moving the inner bottom and the outer bottom in the outer peripheral wall relative to each other in the vertical direction, a height difference is generated in the solid heat storage material in the outer peripheral wall, and the solid heat storage material in the form of a lump. Moves as if convection in the outer wall, so by controlling the relative movement speed of the inner bottom and outer bottom, it is possible to control the time when a new solid heat storage material appears in the concentrated irradiation area of sunlight. Therefore, the heat storage material can be placed in the sunlight irradiation region for a relatively long time, and sufficient heat energy can be evenly stored in the solid heat storage material.

Further, in Examples 1 and 2 above, the case where alumina spheres are used as the solid heat storage material is shown, but other solid heat storage materials having a high absorption rate may be used. As another solid heat storage material, for example, ferronickel slag can be used. When a non-spherical solid heat storage material such as ferronickel slag is used as it is, when the inner bottom and the outer bottom move relative to each other, they may get caught in the gap between the piston and the cylinder in the reciprocating drive device. Therefore, several layers of alumina spheres may be laid on the inner bottom and the outer bottom, and other solid heat storage materials other than spheres may be laid on the layers to store heat.

Although examples of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these examples, and any changes or additions within the scope of the gist of the present invention are included in the present invention. Is done.

For example, in the above embodiment, the outer peripheral wall 11 and the inner peripheral wall 12 are arranged in the outer peripheral wall 12, but the present invention is not limited to this, and three or four bottoms may be provided so as to move relative to each other. ..

Further, in the above embodiment, the outer peripheral wall 11 and the inner peripheral wall 12 have a cylindrical shape, but the present invention is not limited to this, and a square tubular shape may be used. In this case, the shapes of the outer bottom 13 and the inner bottom 14 are not limited to a circle, and may be an ellipse, a triangle, a square, a rectangle, or the like depending on the shapes of the outer peripheral wall 11 and the inner peripheral wall 12.

1 Heat storage device 2 Solid heat storage material (group)
8 Tower 9 Connecting pipe 11 Outer wall 12 Inner bottom 14 Outer bottom 14 Inner bottom 15 Glass lid 21 Heat storage surface 31, 33 Piston rod 32, 34 Cylinder 40, 41 Piston 70 Upper surface of outer bottom 13 71 Upper surface of inner bottom 14 80 Reflection Mirror 81 Mounting surface 90 Heat storage tank 91 Lower pipe 92 Upper pipe 101 Copper thin film (plated copper film)
102 Surface bond 103 Probe body (Constantan)
104 Insulator (glass wool)
105 Insulated copper wire 106 Constantan wire 112 Thin-film heat flux meter A Beam-down solar concentrator B Heliostat C First focus D Second focus E Condensing means F Highest temperature zone G High temperature zone H Medium temperature zone L Concentration Irradiation area S Surface area of the upper surface 70 of the outer bottom 13 U Surface area of the upper surface 71 of the inner bottom 14

Claims (7)

A heat storage device that irradiates a heat storage surface with sunlight collected by a light condensing means and stores heat on the heat storage surface.
The heat storage device includes a tubular outer peripheral wall surrounding the sunlight irradiation region and a plurality of massive solid heat storage materials housed in the outer peripheral wall, and the inside of the outer peripheral wall is inside. A heat storage device characterized in that the inner bottom and the outer outer bottom thereof are arranged so as to be relatively movable with each other via a tubular inner peripheral wall . In the outer peripheral wall, the surface shape of the solid heat storage material is controlled to be substantially tapered-concave by the relative movement of both the lowering movement of the inner bottom and the rising movement of the outer bottom. The heat storage device according to claim 1. The heat storage device according to claim 1 or 2, wherein the total area of the inner bottom and the total area of the outer bottom are substantially the same, and the vertical movement speeds of both are controlled to be substantially the same. The heat storage device according to any one of claims 1 to 3, wherein the inner bottom and the outer bottom move relative to each other in a direction in which the inner bottom descends. The heat storage device according to any one of claims 1 to 4, wherein the plurality of massive solid heat storage materials are formed in a substantially spherical shape. The heat storage device according to any one of claims 1 to 5, wherein each of the plurality of massive solid heat storage materials is formed in substantially the same shape. The heat storage device according to any one of claims 1 to 6, wherein the solid heat storage material contains at least alumina spheres.

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