Tower type solar heat absorber loaded with tooth profile type absorbing layer

Abstract

The invention provides a tower type solar heat absorber loaded with a tooth profile type absorption layer. The tower type solar heat absorber comprises a tubular heat absorber set loaded with a mesoscale tooth profile type absorption layer on the surface, a metal heat conduction screen tightly attached to the shady face of the heat absorber and coated with a heat absorption coating, and a lighting window at an opening of the heat absorber set. Sunlight is reflected and converged to the surface of the tubular heat absorber through a mirror field, solar energy is absorbed by the tooth profile type absorption layer and transmitted to a working medium in the tube, part of heat radiation flow of the heat absorber is blocked by the tooth profile type structure in the emission process at high temperature and then is secondarily absorbed, dissipation of heat radiation is effectively reduced, and the conversion efficiency is improved; part of sunlight on one side of the lighting window is converged to the lighting opening by the mirror field and enters the cylindrical heat conduction cavity of the backlight face of the heat absorption pipe set, energy of the sunlight is absorbed by the heat absorption coating on the surface of the heat conduction screen and transmitted to the backlight face of the heat absorption pipe set, and the uniformity of heat flow distribution of the tubular heat absorber towards light and the backlight side is improved. And the service life of the solar heat absorber is prolonged.

Description

Technical Field

[0001] The invention relates to the field of photothermal absorbers of tower-type solar energy concentrating and heat collecting systems, and in particular to a tower-type solar energy heat absorber with a loaded toothed profile type absorption layer. Background Art

[0002] With the vigorous promotion of clean energy utilization, the scale of solar thermal utilization technology has gradually expanded. Among them, tower solar concentrating thermal technology can bring higher power generation efficiency due to its high concentration ratio and high cycle temperature. For areas rich in solar energy resources, tower solar thermal power generation technology is being vigorously developed.

[0003] The tower solar concentrating technology arranges an absorber that receives solar radiation on the absorption tower, and reflects sunlight to the absorber through the heliostats around the absorption tower, and realizes light-heat conversion through the absorber. The tower solar absorber currently in operation mainly adopts a vertically arranged multi-tube exposed absorber group, which is arranged in a circle to receive reflected sunlight from the surrounding concentrator field. The surface of the heat absorbing tube is sprayed with heat-absorbing coatings such as high-temperature resistant silicon-based coatings to absorb sunlight to generate high temperature and transfer heat to the working fluid in the tube. However, during the working process, the high-temperature absorber will generate thermal radiation. The surface of the conventional circular heat absorbing tube will cause the heat radiation flow to be directly dissipated into the surrounding environment. As the concentration ratio increases, the heat radiation loss becomes more serious. In addition, there is a large temperature difference between the light-facing side and the backlight side of the heat absorbing tube at high temperature, and the uniformity of its heat flow distribution needs to be further improved. Summary of the invention

[0004] In view of the above existing problems, the present invention designs a tower solar absorber with a load-toothed profile absorption layer. The present invention proposes a new absorber surface structure and absorber group arrangement method to reduce the thermal radiation loss of the tower absorber and improve the uniformity of the heat flux distribution of the tube absorber group.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention first provides a tower solar thermal absorber with a toothed profile absorbing layer, which comprises an exposed tube thermal absorber group with a toothed profile absorbing layer, a daylighting window and a heat conductive screen;

[0007] The exposed tube heat absorber group includes a plurality of heat absorbing tubes, each of which is arranged in a circle around the central axis of the tower solar absorber, and an opening for arranging a lighting window is reserved in the circumferential direction of the exposed tube heat absorber group, and an absorption layer with a stepped tooth profile structure is arranged on the surface of each heat absorbing tube; the thermal conductive screen is cylindrical, and the outer surface of the thermal conductive screen is arranged close to the backlight side of each heat absorbing tube of the exposed tube heat absorber group, and an opening is provided at the opening position of the exposed tube heat absorber group, and an absorption coating is sprayed on the inner side of the thermal conductive screen to absorb sunlight entering the thermal conductive screen from the lighting window; the lighting window is arranged at the opening of the exposed tube heat absorber group and the thermal conductive screen.

[0008] According to a preferred embodiment of the present invention, a heat absorption layer with a terraced tooth profile structure that carries a mesoscopic scale load is arranged on the surrounding surfaces of each heat absorption tube, and the heat absorption layer is composed of a terraced tooth profile heat conductive plate surface coated with a coating and a heat conductive material filled inside the terraced tooth profile; each terraced tooth profile structure is hollowed out inside and arranged closely, and the coating sprayed on the surface of the terraced plate surface includes an anti-reflection layer and an absorption layer, and the heat conductive material is filled in the gap between the cylindrical surface of the tubular heat absorber and the terraced plate surface.

[0009] The present invention also provides a solar energy utilization method based on the tower-type solar thermal absorber, which specifically comprises: an external heliostat field focuses sunlight on the tower-type solar thermal absorber;

[0010] Each heat absorbing tube of the tower solar thermal absorber uses the absorption layer of the terrace tooth profile structure to absorb sunlight to achieve light-heat conversion, and then heats the internal heat absorbing tube working fluid through the heat conductive plate surface and the heat conductive material; the heat radiation of the heat absorbing tube itself is blocked by the concave structure between the tooth profile structure during the dissipation process, and then is recaptured for secondary absorption, reducing the heat radiation of the heat absorbing tube;

[0011] The fan-shaped mirror field with the same central angle and opening angle in the heliostat field irradiates the reflected light to the lighting window, and transmits the radiation to the internal thermal screen through the window. The sunlight from the lighting window is absorbed by the absorption coating on the inner surface of the thermal screen, and the heat is transferred to the backlight side of each heat absorber tube through heat conduction and heat radiation, reducing the temperature difference between the light-facing side and the backlight side of the heat absorber tube, so as to improve the uniformity of the heat flux distribution of the heat absorber tube.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The present invention arranges a mesoscopic-scale stepped tooth profile structure heat absorption layer on the surface of each heat absorption tube of the exposed tube type heat absorber group, and the heat absorption layer is composed of a stepped tooth profile heat conduction plate surface coated with a coating and a heat conductive material filled in the stepped tooth profile; when sunlight irradiates the heat conduction plate surface, it can efficiently absorb sunlight; in addition, the heat radiation of the stepped tooth profile heat conduction plate surface itself is blocked by the recessed structure between the tooth profile structure during the dissipation process, and is recaptured for secondary absorption, thereby reducing the heat radiation of the heat absorber tube at high temperature.

[0014] The present invention is provided with a lighting window and a heat conductive screen. The sunlight from the lighting window is absorbed by the absorption coating on the inner surface of the heat conductive screen and transmitted to the backlight side of each heat absorbing tube, thereby reducing the temperature difference between the light-facing side and the backlight side of the heat absorbing tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of a tower solar thermal absorber loaded with a toothed profile absorption layer according to the present invention;

[0016] Figure 2 2. It is a schematic cross-sectional view of a tubular heat absorber with a toothed structure absorption layer according to the present invention;

[0017] Figure 3 It is a schematic diagram of the surface structure of the stepped tooth profile absorption layer of the tubular heat absorber of the present invention;

[0018] Figure 4 It is a schematic diagram of the specific structure of the absorption layer and the radiation absorption process of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0020] like Figure 1 As shown, the tower solar thermal absorber with a toothed profile absorbing layer of the present invention is composed of an exposed tube thermal absorber group 1 with a toothed profile absorbing layer, a lighting window 2 and a cylindrical heat conductive screen 3.

[0021] The exposed tube heat absorber group 1 includes a plurality of heat absorber tubes with a loaded toothed profile absorption layer, each heat absorber tube is arranged in a circle around the central axis of the absorber to form a conventional cylindrical absorber, leaving only a small rectangular opening, the length of the opening is the same as the length of the heat absorber tube, the width is 1 / 20 of the circumference of the exposed tube heat absorber group 1, and the opening is used to arrange the lighting window 2. The surface of each heat absorber tube in the heat absorber group is arranged with an absorption layer with a small-sized terrace toothed structure to enhance the secondary absorption of the dissipated heat radiation.

[0022] Attached Figure 2 The heat absorbing tube structure with toothed structure absorbing layer is given; Figure 3 The surface structure of the heat absorbing tube terrace tooth profile absorption layer is given. In a specific embodiment of the present invention, Figure 2 , 3 As shown, the outer surface of each heat absorbing tube of the heat absorber group 1 is wrapped with a heat conducting plate surface 4 with a stepped tooth profile structure, and the tooth profile structure on the plate surface is sprayed with an absorption coating and an anti-reflection coating. The inside of each stepped structure is hollowed out and closely arranged, and a concave structure is formed between the stepped slopes. Based on the centimeter-level size of the heat absorbing tube diameter, the size of each terrace on the plate surface is less than 1 mm. The secondary absorption of the emitted thermal radiation by the heat absorbing tube is enhanced by neatly arranging the mesoscopic scale surface barrier of the stepped structure. The tiny space between the inner side of the terrace and the outer surface of the heat absorbing tube is filled with a material 5 with high heat absorption and thermal conductivity, such as black chromium and graphene oxide.

[0023] In a specific embodiment of the present invention, the outer diameter of each heat absorbing tube in the exposed tube heat absorber group 1 is 40mm, and the metal plate surface of the heat absorbing tube is closely arranged with stepped tooth profile structures of the same size, and 200 rows of tooth profile structures are arranged around the circumference of the heat absorbing tube. The bottom surface of each stepped platform is 0.62mm long and 0.7mm high. The lower layer of the plate surface is sprayed with an efficient light absorption coating. The light absorption coating is used to efficiently absorb sunlight, and the material selection can be based on commercially available materials. In this embodiment, the light absorption coating is mainly composed of high temperature resistant resin, dispersant and light absorbing pigment; an anti-reflection coating is sprayed on the light absorption coating. The anti-reflection coating is used to reduce the reflection of sunlight and can be selected based on commercially available materials. In this embodiment, its material composition is mainly silicon-rich anti-reflection resin coating or aluminum oxide anti-reflection coating to further improve the absorption of sunlight by the heat absorber.

[0024] like Figure 4 As shown, the surface of the heat-conducting plate surface 4 is first sprayed with an absorbing coating 4-1 with high heat absorption performance, which has a solar radiation absorption rate of more than 90%, and then an anti-reflective coating 4-2 with anti-reflective performance is sprayed to reduce the surface reflectivity and further improve the absorption performance of the absorption layer. The solar radiation is irradiated on the coating on the heat-conducting plate surface 4 for light-heat conversion, and then the internal heat-absorbing tube working fluid is heated by the heat-conducting plate surface and the heat-conducting material 5. The heat radiation of the heat-absorbing tube itself is blocked by the concave structure between the terraces during the dissipation process, and then is recaptured and enters the absorption layer for secondary absorption. The heat-conducting plate surface adopts a high-temperature resistant Haynes 230 alloy, and the heat-absorbing coating 4-1 adopts an absorbing coating whose main component is a high-temperature resistant resin, which is prepared by high-speed dispersion of the high-temperature resistant resin with a dispersant and a light-absorbing pigment, and is prepared by particle screening and high-temperature annealing, and has an absorption rate of more than 90%; the anti-reflective layer adopts a silicon-rich anti-reflective resin coating or an aluminum oxide anti-reflective coating, which is prepared by a hydrolysis condensation reaction of a silane-containing aqueous solution and a high-temperature annealing process.

[0025] The lighting window 2 is arranged on the opening of the absorber group 1, and is composed of a secondary reflection rectangular channel and a secondary reflection outer expansion surface that are interconnected. The opening area of ​​the rectangular channel is consistent with the opening of the absorber group, wherein the secondary reflection outer expansion surface is located on the light-facing side, and the outer expansion surface is set on the left and right sides of the circumferential direction of the exposed tube absorber group. The secondary reflection rectangular channel and each reflective surface of the secondary reflection outer expansion surface are made of high reflectivity materials, and the materials can be selected according to the existing materials in the field. In this embodiment, its material composition is mainly a glass matrix and an aluminum-plated emission layer composite high reflective material. The angle between the reverse extension line of the outer expansion surface of the lighting window 2 is the opening angle of the lighting window. In order to ensure that too much solar radiation is not wasted, the receiving angle of the typical secondary reflector is 30° as the opening angle of the lighting window. The fan-shaped mirror field with the same central angle as the opening angle in the heliostat field irradiates the reflected light to the lighting window, and transmits the radiation to the internal thermal conductive screen 3 through the window.

[0026] The heat conductive shield 3 is cylindrical, and its outer surface is arranged close to the backlight side of each heat absorbing tube of the tubular heat absorber group 1. The heat conductive shield 3 is made of high temperature resistant heat conductive metal, and a high performance absorption coating is sprayed on the inner side of the heat conductive shield. The sunlight from the lighting window 2 is absorbed by the absorption coating on the inner surface of the heat conductive shield, and the heat is transferred to the backlight side of each heat absorbing tube through heat conduction and heat radiation of the heat conductive metal, so as to improve the thermal uniformity of the heat absorbing tube.

[0027] In one embodiment of the present invention, the circular heat conductive screen material is made of high temperature resistant Haynes 230 alloy. Since the thickness of the heat conductive screen and the diameter of the heat absorbing tube of the heat absorber group are both in the centimeter level, and the thickness of the heat conductive screen is smaller than the diameter of the heat absorbing tube, the heat conductive screen 3 is convenient for fast heat conduction.

[0028] The tower solar thermal absorber of the present invention is arranged in a heliostat field for use, and the heliostat field focuses sunlight on the tower solar thermal absorber;

[0029] Each heat absorbing tube of the tower solar thermal absorber uses the absorption layer of the terrace tooth profile structure to absorb sunlight to achieve light-heat conversion, and then heats the internal heat absorbing tube working fluid through the heat conductive plate surface and the heat conductive material; the heat radiation of the heat absorbing tube itself is blocked by the concave structure between the tooth profile structure during the dissipation process, and then is recaptured for secondary absorption, reducing the heat radiation of the heat absorbing tube;

[0030] The fan-shaped mirror field with the same central angle and opening angle in the heliostat field irradiates the reflected light to the lighting window, and transmits the radiation to the internal thermal screen through the window. The sunlight from the lighting window is absorbed by the absorption coating on the inner surface of the thermal screen, and the heat is transferred to the backlight side of each heat absorber tube through heat conduction and heat radiation, reducing the temperature difference between the light-facing side and the backlight side of the heat absorber tube, so as to improve the uniformity of the heat flux distribution of the heat absorber tube.

[0031] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A tower solar thermal absorber with a toothed profile absorbing layer, characterized in that: It comprises an exposed tube heat absorber group (1) loaded with a toothed profile absorption layer, a lighting window (2) and a heat conductive screen (3); The exposed tube heat absorber group (1) comprises a plurality of heat absorbing tubes, each heat absorbing tube is arranged in a circle around the central axis of the tower solar absorber, and an opening for arranging a lighting window (2) is reserved in the circumferential direction of the exposed tube heat absorber group (1), and an absorption layer with a stepped tooth profile structure is arranged on the surface of each heat absorbing tube; The heat conductive screen (3) is cylindrical, and the outer surface of the heat conductive screen (3) is arranged in close contact with the backlight side of each heat absorbing tube of the exposed tube type heat absorber group (1), and an opening is provided at the opening position of the exposed tube type heat absorber group (1), and an absorption coating is sprayed on the inner side of the heat conductive screen to absorb sunlight entering the heat conductive screen (3) from the lighting window (2); The lighting window (2) is arranged at the opening of the exposed tube heat absorber group (1) and the heat conductive screen (3).

2. The tower solar thermal absorber with a toothed profile absorbing layer according to claim 1, characterized in that: The surrounding surfaces of each heat absorbing tube are arranged with a mesoscopic scale stepped tooth profile structure heat absorbing layer, which is composed of a stepped tooth profile heat conducting plate surface coated with a coating and a heat conducting material filled inside the stepped tooth profile; each stepped tooth profile structure is hollowed out inside and arranged closely, and the coating sprayed on the surface of the stepped plate surface includes an anti-reflection layer and an absorption layer, and the heat conducting material is filled in the gap between the cylindrical surface of the tubular heat absorber and the stepped plate surface.

3. The tower solar thermal absorber with a toothed profile absorbing layer according to claim 2 is characterized in that: The surface of the terraced tooth profile heat conducting plate is first sprayed with a light absorbing coating, and then an anti-reflective coating with an anti-reflective effect is sprayed on the top layer. The heat conducting material is a material with high thermal conductivity and strong absorption performance; The surface of the stepped tooth profile heat conducting plate is made of high temperature resistant heat conducting metal.

4. The tower solar thermal absorber with a toothed profile absorbing layer according to claim 3 is characterized in that: The size of each stepped tooth profile on the stepped tooth profile heat conduction plate surface is less than 1 mm, and a concave structure is formed between the inclined surfaces of the stepped tooth profile; the stepped tooth profile heat conduction plate surface enhances the secondary absorption of the emitted thermal radiation by the heat absorbing tube.

5. The tower solar thermal absorber with a toothed profile absorbing layer according to claim 2, characterized in that: The light-collecting window (2) is composed of interconnected secondary reflection rectangular channels and secondary reflection external expansion surfaces, wherein the secondary reflection external expansion surface is located on the light-facing side, and external expansion surfaces are arranged on the left and right sides of the circumferential direction of the exposed tube heat absorber group, and the angle between the reverse extension lines of the secondary external expansion surfaces is the opening angle of the light-collecting window.

6. The tower solar thermal absorber with a toothed profile absorbing layer according to claim 5, characterized in that: Reflective materials are arranged on the inner wall surfaces of the secondary reflection rectangular channel and the secondary reflection outer expansion surface.

7. The tower solar thermal absorber with a toothed profile absorbing layer according to claim 5, characterized in that: The light-transmitting window (2) is located on the circumference of the exposed-tube heat absorber group, and is arranged to replace a small portion of the heat-absorbing tubes; the opening angle is 30°; the width of the light-transmitting window is 1 / 20 of the circumference of the exposed-tube heat absorber group (1), and the length is the same as the length of the heat-absorbing tubes.

8. The tower solar thermal absorber with a toothed profile absorbing layer according to claim 1, characterized in that: The outer diameter of each heat absorbing tube is 10 mm to 50 mm, and the overall diameter of the exposed tube heat absorber group (1) is in the range of 5 to 10 m.

9. A method for utilizing solar energy based on the tower solar thermal absorber according to any one of claims 2 to 7, characterized in that include: An external heliostat field focuses sunlight onto the tower solar thermal receiver; Each heat absorbing tube of the tower solar thermal absorber uses the absorption layer of the terrace tooth profile structure to absorb sunlight to achieve light-heat conversion, and then heats the internal heat absorbing tube working fluid through the heat conductive plate surface and the heat conductive material; the heat radiation of the heat absorbing tube itself is blocked by the concave structure between the tooth profile structure during the dissipation process, and then is recaptured for secondary absorption, reducing the heat radiation of the heat absorbing tube; The fan-shaped mirror field with the same central angle and opening angle in the heliostat field irradiates the reflected light to the lighting window, and transmits the radiation to the internal thermal screen through the window. The sunlight from the lighting window is absorbed by the absorption coating on the inner surface of the thermal screen, and the heat is transferred to the backlight side of each heat absorber tube through heat conduction and heat radiation, reducing the temperature difference between the light-facing side and the backlight side of the heat absorber tube, so as to improve the uniformity of the heat flux distribution of the heat absorber tube.

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