CN114413486A - A fluid lattice magnetron enhanced absorption solar energy collector - Google Patents

Abstract

The invention discloses a fluid dot matrix type magnetic control enhanced absorption solar heat collection device, which comprises a condenser and a solar energy absorption unit arranged above the condenser, wherein a permanent magnet is arranged at the bottom of the condenser and positioned above a rotating disc, the rotating disc is connected with a controller for controlling the rotating disc to rotate, and the controller and the rotating disc are both connected with a power supply; the solar energy absorption unit comprises a heat collecting tube, a water storage tube and a glass vacuum inner tube, wherein the water storage tube and the glass vacuum inner tube are sequentially sleeved and embedded outside the heat collecting tube, transverse and longitudinal arc-shaped optical fibers are arranged inside the heat collecting tube, and a reinforced dot matrix absorption unit is arranged on the arc-shaped optical fibers. The invention overcomes the problems of poor high temperature resistance and durability of the absorption coating of the traditional solar heat collector, slow heat absorption, long heat transfer time and the like caused by uneven heat absorption of the traditional direct absorption heat collector, and further improves the heat collection efficiency, the energy storage efficiency and the heat transfer efficiency of the heat collector.

Description

A fluid lattice magnetron enhanced absorption solar energy collector

technical field

The invention belongs to the field of solar thermal utilization, and in particular relates to a fluid lattice type magnetron enhanced absorption solar energy heat collection device.

Background technique

As one of the most abundant renewable energy sources, solar energy has become the focus of current scientific research. In particular, the research on solar thermal energy is a hotspot of research. The conventional medium-temperature heat collection method mainly relies on the selective absorption coating on the vacuum coated tube to absorb solar radiation to heat the internal working medium, and transfer the heat to the fluid in the tube by means of heat conduction and convection. This indirect absorption method is difficult to maintain the heat resistance and vacuum degree of the selective absorption coating for a long time, and the large temperature difference causes the heat collector tube to burst easily, resulting in poor system stability, reliability and durability, and the process is complicated and the cost is relatively high high, thus becoming a major obstacle to its application. In view of this, direct absorption heat collectors using nanofluids to directly absorb solar energy have attracted extensive attention. The heat transfer mechanism of nanofluid directly absorbing solar heat collector is to add nanoparticles with strong heat collecting ability to the traditional heat collecting fluid, so that the heat collecting working medium itself has strong solar energy absorption characteristics, and the heat collecting medium collects and absorbs the heat. The three characteristics of heat, heat transfer and heat transfer are integrated, the manufacture is simple, the cost is low, and the heat collection efficiency is greatly improved.

In recent years, with the development of magnetic fluids, researchers have found that although the direct absorption of solar collectors by nanofluids can effectively improve the absorption of solar light and heat, changing the type, size, and shape of nanoparticles can further improve the absorption of solar light. heat absorption efficiency. Magnetic nanofluids not only have the magnetic properties of solid substances, but also have the flow characteristics of liquids. Under the action of an external magnetic field, the magnetic particles in the magnetic nanofluids will aggregate in a small range, and the shape of the aggregates will change, which also enhances heat transfer. effect.

Patent CN110195938A discloses a magnetic field-assisted nanofluid direct absorption type concentrating magnetic fluid solar heat collecting device, including a solar positioning tracking reflection device, a solar energy absorbing device and a heat exchange steam generating device. The efficiency of photothermal absorption and heat transfer is effectively improved by nanofluid, and the nanomagnetic fluid hill-shaped structure is formed in the nanofluid by an external magnetic field to supplement the absorption of solar energy. However, although the device improves the absorption efficiency of solar energy to a certain extent, it generally exhibits the characteristics of rapid heating around and slow heating in the middle, resulting in long heat transfer time and low overall heat absorption efficiency.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above-mentioned technical problems, and to provide a fluid lattice type magnetron enhanced absorption solar energy heat collection device with improved solar energy collection efficiency and heat transfer efficiency, long equipment service life and energy saving.

The present invention solves its technical problem and realizes through the following technical solutions:

A fluid lattice-type magnetron strengthening absorption solar energy heat collection device, comprising a concentrator and a solar energy absorption unit installed above the concentrator, a permanent magnet is arranged at the bottom of the concentrator, and the permanent magnet is located above a rotating disk, The rotating disk is connected with a controller that controls the rotation of the rotating disk, and both the controller and the rotating disk are connected to a power source; the solar energy absorption unit includes a heat collection tube, a water storage tube and a glass vacuum inner tube which are sequentially embedded outside the heat collection tube, The inside of the heat collecting tube is provided with transverse and longitudinal arc-shaped optical fibers, and the arc-shaped optical fibers are provided with reinforced lattice absorption units.

The permanent magnet is embedded in the center of the rotating disk. When the rotating disk rotates, it can rotate with it. The purpose is that the direction of the magnetic field generated by the rotating disk also changes during the rotation process, which can control the optical fiber inside the heat collector tube. The synaptic direction of the enhanced lattice absorption unit on the upper part also changes together, so that it receives the maximum intensity of light at the most suitable angle, which strengthens the light and heat absorption of the part in Figure 3, thereby improving the absorption efficiency of solar energy. Further, the strengthening lattice absorption unit is a magnet particle adsorbed with a magnetic high thermal conductivity composite material. Magnet particles are magnetic steel that has been mechanically pulverized and ground into small magnets, which are adhered to the optical fiber through epoxy glue. Under the action of , a synapse is formed along the direction of the magnetic field, and the direction of the synapse changes with the rotation of the permanent magnet, which is used to capture and conduct solar light, as shown in Figure 4. When sunlight hits these protruding structures, it is continuously absorbed and reflected repeatedly until the sunlight is completely absorbed, so that these synapses can maximize the absorption and storage of solar light and heat at the most suitable angle.

Further, the magnetic high thermal conductivity composite material is a composite nanomaterial of ferric oxide modified carbon nanotubes.

Further, the inside of the heat collecting tube contains an absorbing working medium, and the absorbing working medium is a mixed liquid obtained by adding Fe ₃ O ₄ -graphene composite functional nano-magnetic fluid to the base liquid. The base fluid is heat transfer oil, water or ethylene glycol. Under the action of the dispersant, the nanoparticles can be uniformly and stably distributed in the base liquid. Under the action of the permanent magnet, the evenly distributed nanoparticles begin to aggregate in a small range to form a chain-like heat channel, which can effectively improve the absorption of solar energy. efficiency.

Further, the water storage pipe, the glass vacuum inner pipe and the heat collection pipe are fixed on one side of the fixed baffle, and the other side of the fixed baffle is respectively provided with a water inlet and a water outlet connected to the water storage pipe, and the absorption equipment of the heat collection pipe is connected. Quality import and export.

Further, the controller is connected with a photosensitive sensor, and the power source is a solar panel.

Further, the concentrator includes a metal semi-arc-shaped light reflecting surface, and the surface of the reflecting surface is coated with a high reflectivity film. The solar light around the heat collector tube is focused by the reflective surface and concentrated on the heat collector tube and absorbed by the absorbing working medium in the heat collecting tube. At the same time, some light that has not had time to be absorbed by the absorbing working medium and penetrate the vacuum inner tube can be absorbed by the concentrated light. The reflective surface-13 reflects again to achieve the effect of secondary absorption, thereby improving the absorption of the part farthest from the sun in the ③ part (Fig. 3) of the heat collector.

Further, the solar energy absorbing unit is supported on the concave surface of the light reflecting surface through a bracket.

Further, both ends of the light reflecting surface are fixed on a tripod.

The beneficial effects of the present invention are:

Compared with the prior art, the present invention proposes a fluid lattice-type magnetron enhanced absorption solar heat collector, which overcomes the poor high temperature resistance and durability of the traditional solar collector absorption coating, and the existing direct absorption type heat collector. The problem of slow heat absorption and long heat transfer time caused by uneven heat absorption of the device can be solved by optimizing the structure and material of the device, based on the existing direct absorption solar heat collector, to solve the problem of the internal heat absorption of the absorbing working medium. Slow or relying on the limitation of slow heating speed and long time due to heat conduction, by adding devices in the middle area where the heating temperature is relatively slow, the middle part absorbs light and heat at a synchronous or nearly synchronous speed with other parts, which further improves the heat collection and storage capacity of the collector. energy efficiency and heat transfer efficiency.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the present invention;

Fig. 2 is the structural representation of the solar energy absorption unit in the present invention;

Fig. 3 is the schematic diagram of light reflecting surface reflecting sunlight in the present invention;

FIG. 4 is a schematic diagram of the solar energy absorption of the enlarged enhanced lattice absorption unit in the present invention.

Description of reference numbers:

1-glass vacuum outer tube, 2-water storage tube, 3-heat collector tube, 4-fixed baffle, 5-screw cap, 6-water outlet, 7-anti-corrosion sealing material, 8-absorbing medium inlet and outlet, 9-inlet Nozzle, 10-screw cap, 11-fiber, 12-strengthened lattice absorption unit, 13-light reflecting surface, 14-tripod, 15-fixer, 16-support, 17-permanent magnet, 18-controller, 19- Spin the disc.

Detailed ways

The present invention will be further described in detail below through specific embodiments and accompanying drawings. The following embodiments are only descriptive, not restrictive, and cannot limit the protection scope of the present invention.

Example 1

As shown in Figures 1 and 2, a fluid lattice type magnetron enhanced absorption solar heat collector includes a concentrator and a solar energy absorption unit installed above the concentrator, and a permanent magnet 17 is arranged at the bottom of the concentrator, The permanent magnet 17 is located above the rotating disk 19, the rotating disk 19 is connected with a controller 18 that controls the rotation of the rotating disk 19, and the controller 18 and the rotating disk 19 are both connected to a power source; the solar energy absorption unit includes a heat collection tube 3 and is sequentially nested outside the heat collection tube. The water storage tube 2 (glass material) and the glass vacuum inner tube 1 are provided with horizontal and vertical arc-shaped optical fibers 11 inside the heat-collecting tube, and the arc-shaped optical fibers 11 are provided with reinforced lattice absorption units 12.

The water storage tube 2 , the glass vacuum inner tube 1 and the heat collection tube 3 are fixed on one side of the fixed baffle 4 , and the other side of the fixed baffle 4 is respectively provided with a water inlet 9 and a water outlet 6 connected to the water storage tube 1 , and a water outlet 6 connected to the heat collection tube 3 . Import and export of absorbing working fluid 8. The controller 18 is connected with a photosensitive sensor, and the power source is a solar panel, which is used to store energy and provide energy for the rotation of the rotary disk 19 and the operation of the intelligent controller 18. The power supply device can also be selected according to needs, or a battery, Generators or directly connected to household and industrial circuits.

The concentrator includes a metal semi-arc-shaped light reflecting surface 13, and the surface of the reflecting surface 13 is coated with a high reflectivity film. The solar light around the heat collector tube is focused by the reflective surface and concentrated on the heat collector tube and absorbed by the absorbing working medium in the heat collecting tube. At the same time, some light that has not had time to be absorbed by the absorbing working medium and penetrate the vacuum inner tube can be absorbed by the concentrated light. The reflective surface 13 reflects again to achieve the effect of secondary absorption, thereby improving the absorption of the part farthest from the sun in the third part of the heat collecting tube. The solar energy absorption unit is fixed on the inner concave surface of the light reflection surface 13 by the holder 15 and the bracket 16 . Both ends of the light reflecting surface 13 are fixed on the tripod 14 . Screw caps 5 and 10 are installed on the water inlet 6 and the water outlet 9 for connection and fixation of the water inlet, the water outlet and the water pipe. The absorbing working medium inlet and outlet 8 is provided with a kind of sealing material 7, which can seal the absorbing working medium inside the heat collecting tube 3 to avoid its leakage.

According to the time and radian of the sun from rising to falling, the moving speed of the sun can be reasonably calculated, so as to set the angular speed of the rotation of the rotating disk 19, so that the permanent magnet 17 embedded in the rotating disk 19 is always facing the sun, so that the permanent magnet 17 is always facing the sun. The enhanced lattice absorption unit 12 controlled by the magnet 17 and the nanoparticle aggregates in the absorption working medium can maximize the absorption of the sun's light and heat and the fastest heat transfer along the direction of the sun's rays. At the same time, in different seasons, the sun's The length of the time period from rising to landing is different. Therefore, a photosensitive sensor is set on the surface of the controller as the working switch of the rotary disc 19. When the photosensitive sensor senses sunlight, the rotary disc 19 starts to work. When night falls, the photosensitive When the sensor cannot sense light, the rotating disk 19 stops working. The enhanced lattice absorption unit 12 is a magnet particle adsorbed with a magnetic high thermal conductivity composite material, and the magnetic high thermal conductivity composite material is a composite nanomaterial of ferric oxide modified carbon nanotubes.

The inside of the heat collecting tube 3 contains an absorbing working medium, and the absorbing working medium is a mixed liquid obtained by adding Fe ₃ O ₄ -graphene composite functional nano-magnetic fluid to the base liquid.

The above-mentioned materials can be purchased from the market or prepared by referring to the prior art, and the present invention provides a preparation method for absorbing working medium and strengthening lattice absorption unit.

The preparation of embodiment 2 absorption working medium:

Fe ₃ O ₄ -graphene composite functional nanomagnetic fluid was prepared by a two-step method. A small amount of sodium tripolyphosphate was added to the heat-conducting oil, and the heat-conducting oil solution with a mass concentration of 2g/L of sodium tripolyphosphate was prepared by ultrasonic oscillation for 20 min in a water bath at 50°C. Weigh a certain mass of dry nano _{- Fe3O4} powder and nano-graphene, add it to the sodium tripolyphosphate heat-conducting oil solution, prepare a composite solution with a volume fraction of 5%, stir with a magnetic heating stirrer, heat and stir to 70 ℃, ultrasonically oscillate for 40 min in a water bath at 70 ℃, so that Fe ₃ O ₄ can be completely wrapped on the surface of graphene to form composite magnetic particles, which are uniformly dispersed in the solution under the action of a dispersant. Graphene has good heat absorption and heat conduction properties but no magnetism, Fe ₃ O ₄ is magnetic but not very good in heat absorption, the composite functional nano-magnetic fluid prepared above not only has good heat absorption and heat conduction properties, but also has Magnetism, which can be controlled by a magnetic field, can be aggregated under the action of a magnetic field.

The preparation of embodiment 3 strengthens lattice absorption unit:

Magnetic ferric oxide nanoparticles were prepared by chemical co-precipitation method. Using NH ₃ ·H ₂ O as a precipitant, a certain amount of mixed solution of FeCl ₂ and FeCl ₃ was added to the beaker, and then 28% ammonia water was added to the beaker. in a beaker. Mechanical stirring, constant temperature in a water bath, electric stirring for 45 min, and then stand on a magnet. After the black solid is completely precipitated, the supernatant liquid is poured out. Repeated washing with distilled water until the pH is neutral, drying in a vacuum drying oven at 60° C. for 24 h to obtain magnetic ferric oxide nanoparticles.

Take 1 g of pretreated carbon nanotubes into a 100 mL flask, add 15 mL of concentrated nitric acid and 45 mL of concentrated sulfuric acid in turn, install a reflux condensation and absorption device, and heat under reflux for 0.5 h. After cooling to room temperature, the excess acid was filtered, and the remaining powdery substance was pure carbon nanotubes. The obtained carbon nanotubes were washed with deionized water until the pH value was 7. Finally, the washed carbon nanotubes were placed in an oven to dry for 2 h to obtain pure carbon nanotubes.

The obtained magnetic ferric oxide nanoparticles and pure carbon nanotubes were put into a ball mill, respectively, and ball milled for 3h and 1h, respectively. 80 mg of ball-milled multi-walled carbon nanotubes were weighed and added to 25 mL of triethylene glycol solution, and sonicated for 10 min; then 200 mg of ball-milled magnetic Fe ₃ O ₄ nanoparticles were added while magnetic stirring, and the mixed solution was placed in a collector. Heat to 280°C in a thermal constant-temperature heating magnetic stirrer, keep for 30min, and then naturally cool to room temperature. Dilute with ethanol and separate the product from the aqueous solution through a magnetic adsorption process with a commercial magnet; finally, repeatedly wash with ethanol and dry in a vacuum oven to obtain a composite nanomaterial of ferroferric oxide modified carbon nanotubes.

The strong magnetic steel is crushed and ball-milled for 1 h, and then the ball-milled magnetic steel particles are uniformly adhered to the optical fiber with two-component epoxy glue. The composite nanomaterial is adsorbed on the magnetic steel fixed on the optical fiber, and the two ends of the composite optical fiber are fixed on the tube wall of the heat collecting tube with aerogel to be suspended in the middle position of the heat collecting tube.

Working principle of Example 4

When the photosensitive sensor senses sunlight, the controller 18 sends an instruction to control the rotating disc 19 together with the permanent magnet 17 to start to rotate and turn to the direction facing the sun. At this time, the device starts to work, and the sunlight first passes through the transparent glass vacuum. The outer tube 1 and the glass water storage tube 2 illuminate the water, and a small part of the sunlight is absorbed by the water filled between the glass vacuum inner tube 2 and the collector tube 3, and most of the sunlight that is not absorbed by the water passes through the water and reaches the collector tube 3 Among the absorbing working fluids installed in the absorbing working fluid, the part of the absorbing working fluid closest to the sun begins to collect heat, and at the same time, the sunlight irradiated on the light reflecting surface 13 is collected and reflected by the light reflecting surface 13 and enters the heat collecting tube 3 below. In water, as shown in Figure 3, for the same reason, the part that penetrates the water is absorbed and stored by the part in the absorbing working medium, because the optical fiber 11 and the strengthened lattice absorption unit fixed on the surface of the optical fiber 11 are added to the part of the absorbing working medium. 12. Therefore, part of the light and heat absorption is improved, and part of it absorbs and stores a large amount of light and heat. Since the absorbing working medium absorbs light and heat faster than water, the absorbing working medium transfers the absorbed heat to water, and through heat transfer, The water temperature is increased, cold water is continuously entered from the water inlet 9, and the heated hot water is discharged along with the water outlet 6 for daily household or industrial use. The irradiation angle of sunlight is different in different time periods. The controller-18 controls the rotating disk-19 and the permanent magnet-17 to always follow the direction of the sun to rotate, so as to receive the strongest sunlight to the greatest extent. The solar energy absorbing device part of the device can also be arranged in a large-scale socket to meet the needs of different application occasions.

Embodiment 5 Comparative test photothermal test:

The device described in the present invention and the device obtained in the patent CN110195938A were subjected to photothermal test, under the sun lamp (35A, 300V, the experimental light intensity was 1500W/m ² ), the temperature patrol instrument was used to test, and the test results were as follows: The location is shown in Figure 3, Table 1 is the result obtained from the patent CN110195938A device test, and Table 2 is the device of the present invention. The patent CN110195938A device transfers heat from the outside to the inside of the fluid. From Table 1, it can be found that the temperature gradually decreases from the outside to the inside, and the water contacts the lowest temperature of the fluid, and the heat transfer is slow. In the present invention, heat is transferred from the inside to the outside of the fluid, and the water contacts the place with the highest or higher temperature of the fluid, and the heat transfer is faster. From Table 2, it can be found that the temperature difference between different positions is small, which reduces the heat transfer inside the fluid and accelerates the heat transfer. heat transfer from fluid to water.

Table 1

Table 2

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. a fluid lattice type magnetron strengthening absorption solar energy heat collecting device, comprising a concentrator and a solar energy absorption unit installed above the concentrator, it is characterized in that, be positioned at the bottom of the concentrator and be provided with a permanent magnet, the permanent The magnet is located above the rotating disk, the rotating disk is connected with a controller that controls the rotation of the rotating disk, and both the controller and the rotating disk are connected to a power source; the solar energy absorption unit includes a heat collection tube and a water storage tube sequentially embedded outside the heat collection tube , a glass vacuum inner tube, the heat collecting tube is provided with a horizontal and vertical arc-shaped optical fiber, and the arc-shaped optical fiber is provided with a strengthening lattice absorption unit. 2 . The solar thermal collector according to claim 1 , wherein the enhanced lattice absorption unit is a magnet particle adsorbed with a magnetic high thermal conductivity composite material. 3 . 3 . The solar heat collecting device according to claim 2 , wherein the magnetic high thermal conductivity composite material is a composite nanomaterial of ferric oxide modified carbon nanotubes. 4 . 4 . The solar heat collecting device according to claim 1 , wherein the inside of the heat collecting tube contains an absorbing working medium, and the absorbing working medium is adding Fe ₃ O ₄ -graphene composite functional nano-magnetic fluid to the base. 5 . liquid mixture. 5 . The solar thermal collector according to claim 4 , wherein the base liquid is heat-conducting oil, water or ethylene glycol. 6 . 6 . The solar heat collecting device according to claim 1 , wherein the water storage pipe, the glass vacuum inner pipe and the heat collecting pipe are fixed on one side of the fixed baffle, and the other side of the fixed baffle is respectively provided with a connection. 7 . The water inlet and outlet of the water storage pipe are connected to the inlet and outlet of the absorbing working medium of the heat collecting pipe. 7 . The solar heat collecting device according to claim 1 , wherein the controller is connected with a photosensitive sensor, and the power source is a solar cell panel. 8 . 8 . The solar heat collecting device according to claim 1 , wherein the concentrator comprises a metal semi-arc light reflecting surface, and the surface of the reflecting surface is coated with a high reflectivity film. 9 . 9 . The solar heat collecting device according to claim 8 , wherein the solar energy absorbing unit is supported on the inner concave surface of the light reflecting surface through a bracket. 10 . 10 . The solar heat collecting device according to claim 8 , wherein both ends of the light reflecting surface are fixed on a tripod. 11 .

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