A tower-type solar energy absorber with a load tooth profile absorption layer

Abstract

The present invention provides a tower-type solar energy absorber with a load tooth profile absorption layer, which includes a tubular absorber group with a mesoscopic scale tooth profile absorption layer on its surface, a metal heat conduction screen coated with a heat absorption coating closely attached to the backlight side of the absorber, and a lighting window at the opening of the absorber group. Sunlight is reflected and concentrated onto the surface of the tubular absorber by the mirror field. The solar energy is absorbed by the tooth profile absorption layer and transferred to the working medium in the tube. At high temperatures, part of the thermal radiation flow of the absorber itself is blocked by the tooth profile structure during the emission process and is absorbed again, effectively reducing the dissipation of thermal radiation and improving the conversion efficiency. Part of the sunlight on one side of the lighting window is concentrated by the mirror field onto the lighting opening and enters the cylindrical heat conduction cavity on the backlight side of the absorber tube group. Its energy is absorbed by the heat absorption coating on the surface of the heat conduction screen and transferred to the backlight side of the absorber tube group, improving the uniformity of the heat flow distribution on the light-facing and backlight sides of the tubular absorber and increasing the service life of the solar energy absorber.

Description

Technical Field

[0001] The present invention relates to the field of solar thermal absorbers for tower-type solar concentrating and heat collection systems, and particularly to a tower-type solar energy absorber with a load profile-type absorption layer. Background Art

[0002] With the strong promotion of the utilization of clean energy, the scale of solar thermal utilization technology has gradually expanded. Among them, tower-type solar concentrating and heat collection 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-type solar thermal power generation technology is being vigorously developed.

[0003] The tower-type solar concentrating and heat collection technology arranges absorbers for receiving solar radiation on the absorption tower, and reflects sunlight onto the absorbers through heliostats around the absorption tower to achieve photothermal conversion through the absorbers. Currently, the tower-type solar absorbers in operation mainly adopt vertically arranged multi-tube exposed heat absorber groups, which are arranged in a circle to receive the reflected sunlight from the surrounding concentrating mirror fields. The surface of the heat absorption tubes is sprayed with heat absorption coatings such as high-temperature resistant silicon-based coatings to absorb sunlight and generate high temperatures, and transfer heat to the working medium inside the tubes. However, during the working process, the high-temperature absorber will generate thermal radiation, and the surface of the conventional circular heat absorption tubes will directly dissipate the thermal radiation flux into the surrounding environment, and the thermal radiation loss becomes more serious with the increase of the concentration ratio. In addition, there is a large temperature difference between the light-facing side and the backlight side of the heat absorption tubes at high temperatures, and the uniformity of its heat flux distribution needs to be further improved. Summary of the Invention

[0004] Aiming at the above existing problems, the present invention designs a tower-type solar energy absorber with a load profile-type absorption layer, and proposes a new surface structure of the absorber and an arrangement method of the absorber group to reduce the thermal radiation loss of the tower-type absorber and improve the uniformity of the heat flux distribution of the tubular heat absorber group.

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

[0006] The present invention first provides a tower-type solar energy absorber with a load profile-type absorption layer, which includes an exposed tubular heat absorber group with a load profile-type absorption layer, a daylighting window, and a heat conduction screen;

[0007] The exposed tubular heat absorber group includes multiple heat absorption tubes. Each heat absorption tube is arranged in a circular pattern around the central axis of the tower-type solar absorber, and an opening for arranging a daylighting window is reserved in the circumferential direction of the exposed tubular heat absorber group. An absorption layer with a stepped tooth profile structure is arranged on the surface of each heat absorption tube; the heat conduction screen is cylindrical, and the outer surface of the heat conduction screen is arranged closely against the backlight side of each heat absorption tube of the exposed tubular heat absorber group, and an opening is provided at the opening position of the exposed tubular heat absorber group. An absorption coating is sprayed on the inner side of the heat conduction screen to absorb the sunlight entering the heat conduction screen from the daylighting window; the daylighting window is arranged at the opening of the exposed tubular heat absorber group and the heat conduction screen.

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

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

[0010] Each heat absorption tube of the tower-type solar heat absorber uses the absorption layer with a stepped tooth profile structure to absorb sunlight to achieve photothermal conversion, and then heats the working medium inside the heat absorption tube through the heat conduction plate surface and the heat conduction material; the thermal radiation of the heat absorption tube itself is blocked by the concave structure between the tooth profiles during the dissipation process, and then is recaptured for secondary absorption, reducing the thermal radiation of the heat absorption tube;

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

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

[0013] In the present invention, an endothermic layer with a stepped tooth profile structure at the mesoscopic scale is arranged on the surface of each endothermic tube in the exposed tube type endothermic tube group. The endothermic layer is composed of a stepped tooth profile heat conduction plate surface coated with a coating and a heat conduction material filled inside 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 concave structure between the tooth profile structures during the dissipation process and is recaptured for secondary absorption, reducing the heat radiation of the endothermic tube at high temperatures.

[0014] The present invention is provided with a daylighting window and a heat conduction screen. The sunlight from the daylighting window is absorbed by the absorption coating on the inner surface of the heat conduction screen and transmitted to the backlight side of each endothermic tube, reducing the temperature difference between the light side and the backlight side of the endothermic tube. Brief Description of the Drawings

[0015] Figure 1 It is a schematic diagram of a tower type solar endothermic tube with a tooth profile type absorption layer according to the present invention;

[0016] Figure 2 It is a schematic cross-sectional view of a tube type endothermic tube with a tooth profile structure absorption layer according to the present invention;

[0017] Figure 3 It is a schematic diagram of the surface structure of a stepped tooth profile type absorption layer of a tube type endothermic tube according to the present invention;

[0018] Figure 4 It is a schematic diagram of the specific structure of the absorption layer and the radiation absorption process according to the present invention. Detailed Embodiments

[0019] The following further elaborates and explains the present invention in combination with specific embodiments. The described embodiments are only examples of the disclosed content and do not delimit the scope of limitation. Without conflict, the technical features of each embodiment in the present invention can be combined accordingly.

[0020] As Figure 1 shown, the tower type solar endothermic tube with a tooth profile type absorption layer according to the present invention is composed of an exposed tube type endothermic tube group 1 with a tooth profile type absorption layer, a daylighting window 2, and a cylindrical heat conduction screen 3.

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

[0022] Att Figure 2 gives the structure of the endothermic tube with a tooth profile structure absorption layer; AttFigure 3 shows the surface structure of the stepped tooth profile absorption layer of the heat-absorbing tube. In a specific embodiment of the present invention, as Figure 2 , 3 shown, the outer surfaces of the heat-absorbing tubes of the heat-absorber group 1 are wrapped with heat-conducting plate surfaces 4 with stepped tooth profile structures. The surface of 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-scale size of the heat-absorbing tube diameter, the size of each stepped structure on the plate surface is less than 1 mm. The mesoscopic-scale surface barrier formed by arranging the stepped structures neatly enhances the secondary absorption of the heat-absorbing tube to the emitted thermal radiation. A material 5 with high heat absorption and heat conduction performance, such as black chromium and graphene oxide, is filled in the tiny space between the inner side of the stepped structure and the outer surface of the heat-absorbing tube.

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

[0024] As Figure 4 shown, first, an absorption coating 4-1 with high heat absorption performance is sprayed on the surface of the heat-conducting plate surface 4, which has a solar radiation absorption rate of more than 90%. Then, an anti-reflection coating 4-2 with anti-reflection performance is sprayed to reduce the surface reflectivity and further improve the absorption performance of the absorption layer. Solar radiation irradiates the coating on the heat-conducting plate surface 4 for photothermal conversion, and then heats the working medium of the inner heat-absorbing tube through the heat-conducting plate surface and the heat-conducting material 5. The thermal radiation of the heat-absorbing tube itself is blocked by the concave structure between the stepped surfaces during the dissipation process and then re-captured and absorbed again by the absorption layer. The heat-conducting plate surface is made of high-temperature resistant Haynes 230 alloy. At the same time, the absorption coating 4-1 is an absorption coating mainly composed of a high-temperature resistant resin, which is prepared by high-speed dispersing the high-temperature resistant resin, a dispersant, and a light-absorbing pigment, etc., and through particle screening and high-temperature annealing, and has an absorption rate of more than 90%; the anti-reflection layer is a silicon-rich anti-reflection resin coating or an alumina anti-reflection coating, which is prepared by hydrolysis condensation reaction of a silicon alkyl-containing aqueous solution and a high-temperature annealing process.

[0025] The daylighting window 2 is arranged on the opening of the receiver group 1, which is composed of interconnected secondary reflection rectangular channels and a secondary reflection extended surface. The opening area of the rectangular channel is the same as that of the receiver group opening. Among them, the secondary reflection extended surface is located on the light-facing side, and extended surfaces are arranged on the left and right sides in the circumferential direction of the exposed tube type receiver group. Each reflecting surface of the secondary reflection rectangular channel and the secondary reflection extended surface uses a high reflectivity material, and the material can be selected according to the existing materials in this field. In this embodiment, its material composition is mainly a composite high reflectivity material of a glass matrix and an aluminized emission layer. The included angle of the reverse extension line of the extended surface of the daylighting window 2 is the opening angle of the daylighting window. To ensure that too much solar radiation is not wasted, the receiving angle of a typical secondary reflector, 30°, is used as the opening angle of the daylighting window. The fan-shaped mirror field in the heliostat field with the same central angle and opening angle as the opening angle will reflect light onto the daylighting window, and the radiation is transmitted to the internal heat conduction screen 3 through the window.

[0026] The heat conduction screen 3 is cylindrical, and its outer surface is arranged closely against the light-shielded side of each heat absorption tube of the tube type receiver group 1. The material of the heat conduction screen 3 uses a high-temperature heat-conducting metal, and a high-performance absorption coating is sprayed on the inner side of the heat conduction screen. The sunlight from the daylighting window 2 is absorbed by the absorption coating on the inner surface of the heat conduction screen, and the heat is transferred to the light-shielded side of each heat absorption tube through heat conduction and heat radiation of the heat-conducting metal, so as to improve the thermal uniformity of the heat absorption tube.

[0027] In an embodiment of the present invention, the material of the circular heat conduction screen uses the high-temperature resistant Haynes 230 alloy. Based on the fact that both the thickness of the heat conduction screen and the diameter of the heat absorption tube of the receiver group are at the centimeter level, and the thickness of the heat conduction screen is less than the diameter of the heat absorption tube, the heat conduction screen 3 is convenient for quickly conducting heat.

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

[0029] Each heat absorption tube of the tower-type solar receiver uses the absorption layer with a trapezoidal tooth profile structure to absorb sunlight to achieve photo-thermal conversion, and then heats the working medium of the internal heat absorption tube through the heat conduction plate surface and the heat-conducting material; the thermal radiation of the heat absorption tube itself is blocked by the concave structure between the tooth profile structures during the dissipation process, and then is recaptured for secondary absorption, reducing the thermal radiation of the heat absorption tube;

[0030] The fan-shaped mirror field in the heliostat field with the same central angle and opening angle as the opening angle will reflect light onto the daylighting window, and the radiation is transmitted to the internal heat conduction screen through the window. The sunlight from the daylighting window is absorbed by the absorption coating on the inner surface of the heat conduction screen, and the heat is transferred to the light-shielded side of each heat absorption tube through heat conduction and heat radiation methods, reducing the temperature difference between the light-facing side and the light-shielded side of the heat absorption tube, so as to improve the uniformity of the heat flux distribution of the heat absorption tube.

[0031] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent for the present invention. For those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A tower-type solar energy absorber with a load tooth profile absorption layer, characterized in that: An exposed tubular solar absorber group (1) including a load profile absorbing layer, a daylighting window (2), and a heat conduction screen (3); The exposed tubular solar absorber group (1) includes a plurality of absorber tubes, each absorber tube is arranged in a circumferential pattern around the central axis of the tower solar absorber, and an opening for arranging the daylighting window (2) is reserved in the circumferential direction of the exposed tubular solar absorber group (1). An absorbing layer with a stepped profile structure is arranged on the surface of each absorber tube; The heat conduction screen (3) is cylindrical. The outer surface of the heat conduction screen (3) is arranged close to the backlight side of each absorber tube of the exposed tubular solar absorber group (1), and the heat conduction screen (3) is provided with an opening at the opening position of the exposed tubular solar absorber group (1). An absorbing coating is sprayed on the inner side of the heat conduction screen to absorb the sunlight entering the heat conduction screen (3) from the daylighting window (2); The daylighting window (2) is arranged at the opening of the exposed tubular solar absorber group (1) and the heat conduction screen (3); An absorbing layer with a stepped profile structure at the mesoscopic scale of the load is arranged on the circumferential surface around each absorber tube. The absorbing layer is composed of a stepped profile heat conduction plate surface coated with a coating and a heat conduction material filled inside the stepped profile. Each stepped profile structure is hollowed out and closely arranged. The coating sprayed on the outer surface of the heat conduction plate surface includes an antireflection layer and an absorbing layer. The heat conduction material is filled in the gap between the cylindrical surface of the absorber tube and the heat conduction plate surface; The size of each stepped profile on the stepped profile heat conduction plate surface is less than 1 mm, and a concave structure is formed between the inclined surfaces of the stepped profiles; the stepped profile heat conduction plate surface enhances the secondary absorption of the emitted thermal radiation by the absorber tube.

2. The tower-type solar energy heat absorber with a load tooth profile absorption layer according to claim 1, characterized in that: The stepped profile heat conduction plate surface is first sprayed with a light absorbing coating, and then an antireflection coating with antireflection effect is sprayed on the outermost layer. The heat conduction material uses a material with high thermal conductivity and strong absorption performance; The stepped profile heat conduction plate surface uses a heat-resistant heat conduction metal.

3. The tower solar energy heat absorber with a load tooth profile type absorption layer according to claim 1, characterized in that: The daylighting window (2) is composed of interconnected secondary reflection rectangular channels and secondary reflection outward expansion surfaces. Among them, the secondary reflection outward expansion surfaces are located on the light-facing side, and secondary reflection outward expansion surfaces are arranged on the left and right sides in the circumferential direction of the exposed tubular solar absorber group. The included angle of the reverse extension lines of the secondary reflection outward expansion surfaces is the opening angle of the daylighting window.

4. The tower solar energy heat absorber with a load tooth profile type absorption layer according to claim 3, characterized in that: Reflection materials are arranged on the inner wall surfaces of the secondary reflection rectangular channels and the secondary reflection outward expansion surfaces.

5. The tower solar energy heat absorber with a load tooth profile type absorption layer according to claim 3, characterized in that: The daylighting window (2) is located on the circumference of the exposed tubular solar absorber group and is arranged instead of a small part of the absorber tubes; the opening angle is 30°; the width of the daylighting window is 1 / 20 of the circumference of the exposed solar absorber group (1), and the length is the same as the length of the absorber tube.

6. The tower-type solar energy heat absorber with a load tooth profile absorption layer according to claim 1, characterized in that: The outer diameter of each absorber tube is 10 mm to 50 mm, and the overall diameter range of the exposed tubular solar absorber group (1) is 5 to 10 m.

7. A solar energy utilization method for a tower-type solar energy absorber with a load tooth profile absorption layer according to any one of claims 1-6, characterized in that Including: The external heliostat field focuses sunlight on the tower solar absorber; Each absorber tube of the tower solar absorber uses the absorbing layer with a stepped profile structure to absorb sunlight to achieve photothermal conversion, and then heats the working medium inside the absorber tube through the heat conduction plate surface and the heat conduction material; the thermal radiation of the absorber tube itself is blocked by the concave structure between the stepped profile structures during the dissipation process, and then is recaptured for secondary absorption, reducing the thermal radiation of the absorber tube; In the heliostat field, a sector-shaped mirror field with the same central angle and opening angle reflects light onto the daylighting window. Radiation is transmitted to the internal heat conduction screen through the daylighting window. The sunlight from the daylighting window is absorbed by the absorption coating on the inner surface of the heat conduction screen, and the heat is transferred to the backlight side of each heat absorption tube through heat conduction and thermal radiation, reducing the temperature difference between the light-facing side and the backlight side of the heat absorption tube to improve the uniformity of the heat flux distribution of the heat absorption tube.

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