A composite heat exchange tube for a solar heat collection device

Abstract

The present invention belongs to the technical field of compound heat exchange tubes, and discloses a compound heat exchange tube for a solar heat collection device, which includes a double-layer glass vacuum tube, a metal tube and end caps. The double-layer glass vacuum tube and the metal tube are fixed through the end caps. A heat collection mechanism is arranged on the outer side of the double-layer glass vacuum tube. The heat collection mechanism includes two fixing rings fixedly arranged on the double-layer glass vacuum tube, and the structures on the two fixing rings are the same; an annular plate is rotatably arranged in an annular groove on the fixing ring, a connecting plate is fixedly arranged on the annular plate, an arc-shaped plate is fixedly arranged on the connecting plate, and arc-shaped outer grooves are symmetrically arranged on the outer wall of the arc-shaped plate. In the present invention, through the arranged heat collection mechanism, when there is light during the day, the light collecting film can be automatically unfolded to gather light, so that heat conversion can also be carried out on the side of the compound heat exchange tube opposite to the light, thereby improving the heating efficiency of the compound heat exchange tube.

Description

Technical Field

[0001] The invention belongs to the technical field of composite heat exchange tubes, and in particular relates to a composite heat exchange tube for a solar heat collection device. Background Art

[0002] The composite heat exchange tube is an important component of the solar thermal collection device. It converts light into heat by using solar energy to heat the water in the water tank so that users can use hot water at night. However, since the composite heat exchange tube is generally tilted and placed facing south after installation, during daytime use, light can only irradiate the front of the composite heat exchange tube but not the back of the composite heat exchange tube. Therefore, the thermal conductive coating on the back of the composite heat exchange tube cannot be fully utilized, resulting in the heating efficiency of the composite heat exchange tube to be improved. Summary of the invention

[0003] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a composite heat exchange tube for a solar thermal collector, which effectively solves the problems raised by the background technology.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a composite heat exchange tube for a solar thermal collector, comprising a double-layer glass vacuum tube, a metal tube and an end cap, wherein the double-layer glass vacuum tube is fixed to the metal tube by the end cap, and a heat collection mechanism is arranged on the outer side of the double-layer glass vacuum tube, and the heat collection mechanism comprises two fixing rings fixedly arranged on the double-layer glass vacuum tube, and the structures on the two fixing rings are the same; an annular plate is rotatably arranged in an annular groove on the fixing ring, a connecting plate is fixedly arranged on the annular plate, an arc plate is fixedly arranged on the connecting plate, and an outer wall of the arc plate is symmetrically provided with an arc outer groove; the two corresponding arc outer grooves on the two fixing rings are rotatably arranged between each other A reel is dynamically arranged, and a vortex spring is also arranged at the connection between the reel and the arc-shaped outer groove. A focusing film is wound on the reel, and an external magnetic block is symmetrically fixed on the free end of the focusing film. The structures at both ends of the arc plate are the same, wherein an arc-shaped inner groove and a through hole are opened at one end of the arc plate, and the arc-shaped inner groove is connected with the outside through the through hole, and a magnetic driving component and a liquid are arranged inside the arc-shaped inner groove; during the day, the liquid in the arc-shaped inner groove evaporates due to heat to form a high pressure that pushes the magnetic driving component to move in the arc-shaped inner groove, so that the magnetic driving component drives the focusing film to unfold and gather heat through the external magnetic block through magnetic adsorption, and at night, after the temperature of the liquid in the arc-shaped inner groove drops, the focusing film is rolled up.

[0005] Preferably, the magnetic driving component includes an inner magnetic block and a telescopic spring; wherein the inner magnetic block is slidably disposed inside the arc-shaped inner groove and is magnetically connected to the outer magnetic block in the arc-shaped outer groove, the telescopic spring is located at one end of the arc-shaped inner groove close to the through hole, and the liquid is located at one end of the arc-shaped inner groove away from the through hole.

[0006] Preferably, an automatic adjusting member is symmetrically and movably arranged between the fixed ring and the arc-shaped plate, and the inside of the automatic adjusting member is communicated with the inside of the arc-shaped inner groove through a connecting pipe.

[0007] Preferably, the automatic adjusting member includes a cylinder body, a sliding rod is slidably arranged inside the cylinder body, the shape of the sliding rod is an inverted T shape, a support spring is wound around the part of the sliding rod located inside the cylinder body, an upper support is fixedly arranged on the sliding rod, the upper support is hinged to the fixed ring, a lower support is fixedly arranged on the cylinder body, and the lower support is hinged to the arc-shaped plate; the space between the sliding rod and the inner bottom wall of the cylinder body is communicated with the arc-shaped inner groove through a connecting pipe.

[0008] Preferably, self-cleaning members are arranged at positions close to the reel on both arc-shaped plates; the self-cleaning members include two telescopic rods, the two telescopic rods are respectively fixed on the two arc-shaped plates, and the ends of the two telescopic rods are both fixedly connected to a cleaning brush plate, and the cleaning brush plate abuts against the light-concentrating film on the reel.

[0009] Preferably, the surface of the light-concentrating film in contact with the cleaning brush plate is a light-concentrating surface, and the reel is of a hollow structure, and the arc-shaped inner grooves corresponding to the two arc-shaped plates are communicated through the hollow reel.

[0010] Preferably, the arc-shaped plate is made of a light-transmitting material, and convex lenses are embedded at both ends of the arc-shaped plate.

[0011] Preferably, an annular cavity is formed inside the end cover, and a self-cleaning mechanism for automatically cleaning the metal pipe is arranged inside the annular cavity.

[0012] Preferably, the self-cleaning mechanism includes a floating ring slidably arranged inside the annular cavity, rod bodies are symmetrically and fixedly connected to the floating ring, a return spring is wound around each rod body inside the annular cavity, and a plurality of annular scraping blades are fixedly arranged together at one ends of the two rod bodies passing through the rod holes on the end cover.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] 1) During operation, through the set heat collection mechanism, when there is light during the day, the light-concentrating film can be automatically unfolded to concentrate the light, so that heat conversion can also be carried out on the side of the composite heat exchange tube opposite to the light, thereby improving the heating efficiency of the composite heat exchange tube;

[0015] 2) During operation, through the set automatic adjusting member, when the light obliquely irradiates the composite heat exchange tube, the automatic adjusting member can automatically extend to adjust the angle of the arc-shaped plate, so that the light-concentrating film between the two arc-shaped plates faces the light, thereby increasing the effective light-concentrating area of the light-concentrating film and improving the heating efficiency of the composite heat exchange tube;

[0016] 3) During operation, the self-cleaning component can clean the dust on the condenser film during the coiling process of the condenser film, thus ensuring the light-condensing effect of the condenser film.

[0017] 4) During operation, the self-cleaning mechanism can utilize the different temperatures of the metal tube during the day and night, so that the floating ring drives the annular scraper to move, and the annular scraper cleans the scale on the exposed end of the metal tube, thus ensuring the heating effect of the exposed end of the metal tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention.

[0019] In the drawings:

[0020] Figure 1 is a schematic structural diagram of a composite heat exchange tube of the prior art of the present invention;

[0021] Figure 2 is a schematic structural diagram of a composite heat exchange tube for a solar heat collection device of the present invention;

[0022] Figure 3 is a schematic diagram of the heat collection mechanism of the present invention;

[0023] Figure 4 of the present invention Figure 3 is an enlarged structural diagram at position A in the present invention;

[0024] Figure 5 is a schematic diagram of the internal structure of the arc-shaped plate of the present invention;

[0025] Figure 6 is a schematic installation diagram of the automatic adjustment component of the present invention;

[0026] Figure 7 is a schematic composition diagram of the automatic adjustment component of the present invention;

[0027] Figure 8 is a schematic installation diagram of the self-cleaning mechanism of the present invention;

[0028] Figure 9 is a schematic composition diagram of the self-cleaning mechanism of the present invention.

[0029] In the figure: 1. Double-layer glass vacuum tube; 2. Metal tube; 3. End cap; 301. Annular cavity; 4. Heat collection mechanism; 5. Fixed ring; 6. Annular plate; 7. Connecting plate; 8. Arc-shaped plate; 9. Arc-shaped outer groove; 10. Reel; 11. Condensing film; 12. Outer magnet; 13. Arc-shaped inner groove; 14. Through hole; 15. Inner magnet; 16. Automatic adjusting part; 1601. Cylinder body; 1602. Slide bar; 1603. Support spring; 1604. Upper support; 1605. Lower support; 17. Connecting pipe; 18. Self-cleaning part; 1801. Telescopic rod; 1802. Cleaning brush; 19. Convex lens; 20. Self-cleaning mechanism; 2001. Floating ring; 2002. Rod body; 2003. Return spring; 2004. Annular scraper; 21. Telescopic spring. Specific implementation mode

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection scope of the present invention.

[0031] Refer to Figure 1 , the composite heat exchange tube includes a double-layer glass vacuum tube 1, a metal tube 2 and an end cap 3. After the metal tube 2 is inserted into the double-layer glass vacuum tube 1, it is fixed to the double-layer glass vacuum tube 1 through the end cap 3; a vacuum cavity is formed between the inner and outer layers of glass of the double-layer glass vacuum tube 1 to facilitate heat storage, and a heat conduction coating is provided on the outer wall of the metal tube 2 to facilitate the acceleration of heat conversion. A fluid such as alcohol or water is injected into the metal tube 2.

[0032] During use, the composite heat exchange tube is installed on the solar water tank through the end cap 3. When light passes through the double-layer glass vacuum tube 1 and is absorbed by the heat conduction coating on the metal tube 2 and converted into heat, the liquid in the metal tube 2 is heated. After reaching the boiling point of the liquid, the liquid absorbs heat and evaporates and moves towards the end cap 3. Since the exposed end of the metal tube 2 is located inside the water tank, the temperature here is relatively low. After the evaporated liquid touches the exposed end of the metal tube 2, it cools and releases heat to form a liquid, thereby heating the exposed end of the metal tube 2 through the released heat, and then heating the water in the water tank through the exposed end of the metal tube 2. The cooled liquid falls again under its own weight, and so on continuously, thereby realizing the process of heating the water in the water tank by using light.

[0033] However, since the compound heat exchange tubes are generally placed obliquely and facing south after installation, during the day, light can only irradiate the front of the compound heat exchange tubes and cannot irradiate the back of the compound heat exchange tubes. Therefore, the heat conduction coating on the back inside the compound heat exchange tubes cannot be fully utilized, resulting in the heating efficiency of the compound heat exchange tubes needing to be improved.

[0034] As shown by Figures 1-9 :

[0035] Referring to Figures 2-4 , the present invention relates to a compound heat exchange tube for a solar heat collection device, including a double-layer glass vacuum tube 1, a metal tube 2, and an end cap 3. The double-layer glass vacuum tube 1 and the metal tube 2 are fixed through the end cap 3. To solve the problem that during the day, light can only irradiate the front of the compound heat exchange tube and cannot fully utilize the back of the compound heat exchange tube, resulting in the heating efficiency needing to be improved, a heat collection mechanism 4 is provided on the outer side of the double-layer glass vacuum tube 1. The heat collection mechanism 4 includes two fixing rings 5 fixedly arranged on the double-layer glass vacuum tube 1, and the structures on the two fixing rings 5 are the same; an annular plate 6 is rotatably arranged in the annular groove on the fixing ring 5, a connecting plate 7 is fixedly arranged on the annular plate 6, an arc-shaped plate 8 is fixedly arranged on the connecting plate 7, and arc-shaped outer grooves 9 are symmetrically arranged on the outer wall of the arc-shaped plate 8; a scroll 10 is rotatably arranged between the two corresponding arc-shaped outer grooves 9 on the two fixing rings 5, a scroll spring is also arranged at the connection of the scroll 10 and the arc-shaped outer groove 9, a light-concentrating film 11 is wound around the scroll 10, outer magnetic blocks 12 are symmetrically fixedly arranged at the free ends of the light-concentrating film 11, and the two ends of the arc-shaped plate 8 have the same structure. Among them, an arc-shaped inner groove 13 and a through hole 14 are arranged at one end of the arc-shaped plate 8, the arc-shaped inner groove 13 communicates with the outside through the through hole 14, and a magnetic driving member and a liquid are arranged inside the arc-shaped inner groove 13; in the daytime state, the liquid in the arc-shaped inner groove 13 is heated and evaporated to form high pressure to push the magnetic driving member to move in the arc-shaped inner groove 13, so that the magnetic driving member drives the light-concentrating film 11 to unfold and collect heat through magnetic adsorption of the outer magnetic blocks 12. In the night state, after the temperature of the liquid in the arc-shaped inner groove 13 drops, the light-concentrating film 11 is wound up;

[0036] With such a design, since the compound heat exchange tubes are generally obliquely arranged after installation, when there is light, the liquid in the arc-shaped inner groove 13 of the arc-shaped plate 8 made of a light-transmitting material at the edge is first irradiated by the light. After reaching the boiling point of the liquid, the liquid evaporates. At this time, under the action of the evaporation of the liquid, the magnetic driving member moves towards the fixing ring 5. The magnetic driving member drives the light-concentrating film 11 to unfold through the outer magnetic blocks 12. At this time, the scroll spring is in a tensioned state. The light is reflected to the corresponding position of the double-layer glass vacuum tube 1 through the light-concentrating film 11, so that the position on the double-layer glass vacuum tube 1 opposite to the light can also utilize the light, thereby improving the heat collection effect of the compound heat exchange tube and improving the heating efficiency;

[0037] At night, due to the relatively low temperature, after the liquid cools, the pressure in the arc-shaped inner groove 13 decreases. Under the action of the scroll spring, the scroll 10 rotates to wind up the condenser film 11, thereby protecting the condenser film 11 when not in use and preventing dust and the like from adhering to the surface of the condenser film 11 after long-term accumulation, so as to ensure the use effect of the condenser film 11.

[0038] Refer to Figure 5 , specifically, the magnetic driving member includes an inner magnetic block 15 and a telescopic spring 21; the inner magnetic block 15 is slidably disposed inside the arc-shaped inner groove 13 and is magnetically connected to the outer magnetic block 12 in the arc-shaped outer groove 9. The telescopic spring 21 is located at one end of the arc-shaped inner groove 13 close to the through hole 14, and the liquid is located at one end of the arc-shaped inner groove 13 far from the through hole 14;

[0039] With this design, when the liquid evaporates due to heat, the air pressure in the space where the liquid is located will increase, thereby pushing the inner magnetic block 15 to slide inside the arc-shaped inner groove 13, causing the telescopic spring 21 to be compressed. At the same time, the inner magnetic block 15 drives the outer magnetic block 12 to slide inside the arc-shaped outer groove 9 by magnetic force, and the condenser film 11 is automatically unwound through the outer magnetic block 12.

[0040] Considering the actual use process, it takes a relatively long time for the liquid to change only through direct sunlight. Therefore, convex lenses 19 are embedded at both ends of the arc-shaped plate 8, so that the convex lenses 19 can produce a focusing effect to further reduce the time required for the liquid to change.

[0041] Refer to Figures 6-7 , an automatic adjusting member 16 is symmetrically and movably disposed between the fixed ring 5 and the arc-shaped plate 8, and the inside of the automatic adjusting member 16 is communicated with the inside of the arc-shaped inner groove 13 through a connecting pipe 17;

[0042] The automatic adjusting member 16 includes a cylinder body 1601. A sliding rod 1602 is slidably disposed inside the cylinder body 1601. The shape of the sliding rod 1602 is an inverted T shape. A support spring 1603 is wound around the part of the sliding rod 1602 located inside the cylinder body 1601. An upper support 1604 is fixedly disposed on the sliding rod 1602, and the upper support 1604 is hinged to the fixed ring 5. A lower support 1605 is fixedly disposed on the cylinder body 1601, and the lower support 1605 is hinged to the arc-shaped plate 8; the space between the sliding rod 1602 and the inner bottom wall of the cylinder body 1601 is communicated with the arc-shaped inner groove 13 through the connecting pipe 17;

[0043] With such a design, for example, in the morning, since the light can only irradiate one side of the compound heat exchange tube, after the liquid in the arc-shaped inner groove 13 in the irradiated direction evaporates, the pressure in the space where the liquid is located is transmitted to the inside of the cylinder body 1601 through the connecting pipe 17, causing the support spring 1603 to be compressed. As the air pressure in the cylinder body 1601 increases, the length of the sliding rod 1602 extending out of the cylinder body 1601 expands, that is, the overall length of the automatic adjusting member 16 expands. Under the action of the automatic adjusting member 16, the arc-shaped plate 8 rotates around the fixed ring 5, making the light-concentrating film 11 on the other side of the compound heat exchange tube that is not irradiated more directly facing the direction of the light, so that the area of the light-concentrating film 11 that can be irradiated by the light is larger, in order to improve the light-concentrating effect of the light-concentrating film 11.

[0044] Refer to Figure 4 , considering that after the light-concentrating film 11 has been used for a long time, dust will accumulate on its surface, which will reduce the light-concentrating effect of the light-concentrating film 11. To solve this problem, self-cleaning members 18 are provided at positions close to the reel 10 on both arc-shaped plates 8; the self-cleaning member 18 includes two telescopic rods 1801, the two telescopic rods 1801 are respectively fixed on the two arc-shaped plates 8, and the ends of the two telescopic rods 1801 are both fixed to the cleaning brush 1802, and the cleaning brush 1802 abuts against the light-concentrating film 11 on the reel 10;

[0045] With such a design, when the light-concentrating film 11 is either unrolled or wound up, the light-concentrating film 11 itself will also undergo bending deformation during the winding process to reduce the adhesion force of dust. At the same time, the light-concentrating film 11 will have relative movement with the cleaning brush 1802, and the dust on the light-concentrating film 11 is cleaned by the cleaning brush 1802 to ensure the use effect of the light-concentrating film 11.

[0046] Furthermore, the surface of the light-concentrating film 11 that contacts the cleaning brush 1802 is the light-concentrating surface, and the reel 10 is of a hollow structure, and the corresponding arc-shaped inner grooves 13 on the two arc-shaped plates 8 are connected through the hollow reel 10;

[0047] With such a design, when the liquid evaporates, the pressures in the two corresponding arc-shaped inner grooves 13 are equal after being connected, so that the two arc-shaped plates 8 can move synchronously. Whether the above content is added or not can be selected according to actual needs.

[0048] Refer to Figures 8-9 , considering that after the exposed end of the metal tube 2 in the compound heat exchange tube has been heating water for a long time, scale will form on its surface, which will reduce the heating effect of the metal tube 2. To solve this problem, an annular cavity 301 is formed inside the end cover 3, and a self-cleaning mechanism 20 for automatically cleaning the metal tube 2 is provided inside the annular cavity 301;

[0049] The self-cleaning mechanism 20 includes a floating ring 2001 slidably arranged in the annular cavity 301. Rod bodies 2002 are symmetrically and fixedly connected to the floating ring 2001. A return spring 2003 is wound around each rod body 2002 inside the annular cavity 301. One ends of the two rod bodies 2002 passing through the rod holes in the end cover 3 are commonly and fixedly provided with a plurality of annular scrapers 2004;

[0050] With such a design, during the day, since the temperature of the metal tube 2 is relatively high, the air pressure in the lower half of the annular cavity 301 in the end cover 3 becomes larger, thereby pushing the floating ring 2001 to move and compress the return spring 2003. The floating ring 2001 drives the annular scraper 2004 to move through the rod body 2002, and the annular scraper 2004 removes scale from the exposed end of the metal tube 2. At night, the temperature of the metal tube 2 is relatively low. At this time, under the action of the return spring 2003, the floating ring 2001 returns to its original position. At this time, the annular scraper 2004 processes the scale on the surface of the metal tube 2 again, so as to ensure the use effect of the metal tube 2. At the same time, the annular scraper 2004 is made of a heat-conducting material. When it contacts the water in the water tank, it can also increase the heating area of the metal tube 2, thereby improving the heating efficiency.

[0051] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0052] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A composite heat exchange tube for a solar heat collection device, comprising a double-layer glass vacuum tube (1), a metal tube (2) and an end cover (3), wherein the double-layer glass vacuum tube (1) and the metal tube (2) are fixed via the end cover (3), and a heat collection mechanism (4) is arranged on the outer side of the double-layer glass vacuum tube (1), characterized in that: The heat collecting mechanism (4) comprises two fixing rings (5) fixedly arranged on the double-layer glass vacuum tube (1), and the structures of the two fixing rings (5) are the same; an annular plate (6) is rotatably arranged in an annular groove on the fixing ring (5), a connecting plate (7) is fixedly arranged on the annular plate (6), an arc plate (8) is fixedly arranged on the connecting plate (7), and an outer wall of the arc plate (8) is symmetrically provided with an arc outer groove (9); a reel (10) is rotatably arranged between two corresponding arc outer grooves (9) on the two fixing rings (5), a spiral spring is further arranged at the connection between the reel (10) and the arc outer groove (9), a focusing film (11) is wound on the reel (10), and the focusing film (11) is An external magnetic block (12) is symmetrically fixedly arranged at the free end, and the two ends of the arc plate (8) have the same structure, wherein an arc-shaped inner groove (13) and a through hole (14) are opened at one end of the arc plate (8), and the arc-shaped inner groove (13) is connected to the outside through the through hole (14), and a magnetic driving component and liquid are arranged inside the arc-shaped inner groove (13); in the daytime state, the liquid in the arc-shaped inner groove (13) evaporates due to heat to form a high pressure to push the magnetic driving component to move in the arc-shaped inner groove (13), so that the magnetic driving component drives the focusing film (11) to expand and collect heat through the external magnetic block (12) through magnetic attraction, and in the night state, the focusing film (11) is rolled up after the temperature of the liquid in the arc-shaped inner groove (13) decreases.

2. The composite heat exchange tube for a solar thermal collector according to claim 1, characterized in that: The magnetic driving component comprises an inner magnetic block (15) and a telescopic spring (21); wherein the inner magnetic block (15) is slidably disposed inside the arc-shaped inner groove (13) and is magnetically connected to the outer magnetic block (12) inside the arc-shaped outer groove (9); the telescopic spring (21) is located at one end of the arc-shaped inner groove (13) close to the through hole (14); and the liquid is located at one end of the arc-shaped inner groove (13) away from the through hole (14).

3. The composite heat exchange tube for a solar thermal collector according to claim 2, characterized in that: An automatic adjustment member (16) is symmetrically and movably arranged between the fixed ring (5) and the arc-shaped plate (8), and the interior of the automatic adjustment member (16) is connected to the interior of the arc-shaped inner groove (13) via a connecting pipe (17).

4. The composite heat exchange tube for a solar thermal collector according to claim 3, characterized in that: The automatic adjustment member (16) comprises a cylinder (1601), a slide rod (1602) is slidably arranged inside the cylinder (1601), the slide rod (1602) is in the shape of an inverted T, a portion of the slide rod (1602) located on the cylinder (1601) is surrounded by a support spring (1603), an upper support (1604) is fixedly arranged on the slide rod (1602), the upper support (1604) is hingedly arranged with a fixing ring (5), and a lower support (1605) is fixedly arranged on the cylinder (1601), and the lower support (1605) is hingedly arranged with an arc plate (8); wherein the space between the slide rod (1602) and the inner bottom wall of the cylinder (1601) is connected to the arc inner groove (13) via a connecting pipe (17).

5. The composite heat exchange tube for a solar thermal collector according to claim 1, characterized in that: A self-cleaning member (18) is provided at a position close to the reel (10) on the two arc-shaped plates (8); the self-cleaning member (18) comprises two telescopic rods (1801), the two telescopic rods (1801) are respectively fixed on the two arc-shaped plates (8), the ends of the two telescopic rods (1801) are fixed to a cleaning brush (1802), and the cleaning brush (1802) abuts against the focusing film (11) on the reel (10).

6. The composite heat exchange tube for a solar thermal collector according to claim 5, characterized in that: The side of the light-concentrating film (11) that contacts the cleaning brush (1802) is a light-concentrating surface, and the reel (10) is a hollow structure, and the corresponding arc-shaped inner grooves (13) on the two arc-shaped plates (8) are connected through the hollow reel (10).

7. The composite heat exchange tube for a solar thermal collector according to claim 1, characterized in that: The arc-shaped plate (8) is made of a light-transmitting material, and convex lenses (19) are embedded at both end portions of the arc-shaped plate (8).

8. The composite heat exchange tube for a solar thermal collector according to claim 1, characterized in that: An annular cavity (301) is formed inside the end cover (3), and a self-cleaning mechanism (20) for automatically cleaning the metal tube (2) is provided inside the annular cavity (301).

9. The composite heat exchange tube for a solar thermal collector according to claim 8, characterized in that: The self-cleaning mechanism (20) comprises a floating ring (2001) slidably arranged in an annular cavity (301), rod bodies (2002) are symmetrically fixedly connected to the floating ring (2001), a return spring (2003) surrounds each rod body (2002) located inside the annular cavity (301), and a plurality of annular scrapers (2004) are fixedly arranged on one end of the two rod bodies (2002) passing through the rod holes on the end cover (3).

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