Solar collector using linear Fresnel lenses

Abstract

The present invention provides a solar collector using a linear Fresnel lens, which relates to the technical field of solar collectors. The solar collector comprises an outer frame, a plurality of heat collecting tubes in the outer frame, a first container and a second container connected to the heat collecting tubes, and a thermal insulation layer. The linear Fresnel lens has a plurality of focusing areas, each focusing area focuses sunlight, and the heat collecting tube is located within the irradiation range of the focused sunlight. The present invention retains the configuration of a flat-plate solar collector, and replaces the lens with a linear Fresnel lens, so that sunlight is focused on the heat collecting tube, thereby increasing the temperature of the medium in the tube.

Description

Technical Field

[0001] The invention relates to the technical field of solar thermal collectors, in particular to a solar thermal collector using a linear Fresnel lens. Background Art

[0002] Flat-plate solar collector is a basic type of solar collector, which has the advantages of simple structure, reliable operation, reasonable cost, strong pressure bearing capacity, large heat absorption area, and strong ability to integrate with buildings. Of course, as a typical representative of non-concentrating solar collector, it has disadvantages such as low collection temperature. The problem is that solar radiation is directly projected onto the heat-absorbing plate, and it is difficult to further increase the temperature due to the inevitable conduction, convection and radiation. Therefore, it is widely used in heating and has few high-heat application scenarios. However, the biggest advantage of flat-plate solar collector is its ability to integrate with buildings. Therefore, this paper takes flat-plate solar collector as a model and uses linear Fresnel lens to focus sunlight. It proposes a solar collector with high collection temperature, strong ability to integrate with buildings and can be used as a heat source for lithium bromide air-conditioning units. Summary of the invention

[0003] The object of the present invention is to provide a solar thermal collector using a linear Fresnel lens to solve the above technical problems.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A solar collector using a linear Fresnel lens includes an outer frame, a plurality of heat collecting tubes located in the outer frame, a first container and a second container connected to the heat collecting tubes, and a thermal insulation layer. The linear Fresnel lens has a plurality of focusing areas, each focusing area focuses sunlight, the heat collecting tubes are located within the irradiation range of the focused sunlight, and the heat collecting tubes are also equipped with fins for increasing the heating time of the heat collecting tubes.

[0006] Preferably, the fins are fixedly combined with the heat collecting tubes.

[0007] Preferably, the fins are mounted on the outside of the heat collecting tube, wherein the angle of the fins is adjustable relative to the heat collecting tube, and the contact area between the fins and the heat collecting tube changes with the angle adjustment.

[0008] Preferably, it also includes an adjusting structure, which is connected to the heat collecting tube, and the adjusting structure drives the fins to move by the driving force generated by the flow of the medium.

[0009] Preferably, it also includes a ring gear that traps the heat collecting pipe and a first gear that meshes with the ring gear, and the first gear is driven by the adjusting structure.

[0010] Preferably, the fin includes a connecting section connected to the non-meshing area of ​​the ring gear, the connecting section has two extensions, one of which is a bending section and the other is a reflecting section;

[0011] The insulation layer inside the outer frame has a groove adapted to the reflective section, wherein when the reflective section is horizontally laid in the groove, there is a distance between the bent section and the heat collecting tube, and when the reflective section is screwed out of the groove, the bent section is supported by the groove and pushed to the surface of the heat collecting tube.

[0012] Preferably, the curved section has a plurality of reflective strips on its surface, and bare metal is provided between the reflective strips. When the curved section is irradiated with focused sunlight, it generates heat and reflects the focused sunlight to the heat collecting tube.

[0013] Preferably, the regulating structure includes a sleeve as an intermediate structure for connecting the first container and the heat collecting tube, the sleeve has a blocking portion inside, and the end of the blocking portion has a through hole for the medium to pass through;

[0014] There are also a plurality of strip grooves on the periphery of the blocking part, wherein each strip groove has a spring, and each strip groove has a limit block that is slidably matched with the strip groove, and the limit block is combined with the sleeve and serves as a fixing point of the spring;

[0015] The blocking part also has a tooth groove, in which a second gear is arranged, and the second gear is equipped with a shaft, which extends outward through the sleeve. When the blocking part moves relative to the sleeve, the second gear meshes with the tooth groove, so that the shaft equipped with the second gear rotates axially;

[0016] The regulating structure also includes a switching member connected to the first gear, and the switching member is connected to a shaft configured with the second gear to transmit kinetic energy to the first gear.

[0017] Preferably, the diameter of the blocking portion is smaller than the diameter of the connection between the sleeve and the first container, so that the medium entering the sleeve pushes the blocking portion to move relative to the sleeve when entering the heat collecting tube.

[0018] Preferably, there is an inner frame inside the outer frame, and the inner frame is a fixing part of the linear Fresnel lens.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention retains the configuration of a flat-plate solar collector and replaces the lens with a linear Fresnel lens to focus sunlight onto the heat collecting tube and increase the temperature of the medium in the tube.

[0021] 2. The present invention fully considers the change of the sun's altitude and uses two different methods to combine the fins with the heat collecting tube at the location of the heat collecting tube. Therefore, when the focused sunlight deviates from the location of the heat collecting tube, the focused sunlight can still be fully utilized to heat the heat collecting tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a plan view of a solar collector using a linear Fresnel lens;

[0023] Figure 2 An internal diagram of a solar thermal collector using a linear Fresnel lens as proposed in Example 1;

[0024] Figure 3 An internal diagram of a solar thermal collector using a linear Fresnel lens proposed in Example 2;

[0025] Figure 4 for Figure 3 The schematic diagram of the structure of the solar collector when the sunlight is focused onto the collector tube is shown;

[0026] Figure 5 for Figure 3 The schematic diagram of the structure of the solar collector shown is when the sunlight is not focused onto the collector tube;

[0027] Figure 6 for Figure 4 and Figure 5 Schematic diagram of the structure of the middle insulation layer;

[0028] Figure 7 for Figure 3 The plane combination diagram of the middle fin, the ring gear and the collector tube;

[0029] Figure 8 for Figure 7 A partial perspective view of the combined structure shown;

[0030] Fig. 9 for Figure 3 A schematic diagram of the structure of the first gear and the adjustment structure;

[0031] Fig.10 for Fig. 9 Internal cross-sectional view of the middle regulating structure;

[0032] Fig.11 The application diagram of solar thermal collector using linear Fresnel lens;

[0033] Figure numerals: 1. outer frame; 2. linear Fresnel lens; 3. pipe joint; 4. inner frame; 5. first container; 6. second container; 7. heat collecting tube; 8. first fin; 9. insulation layer; 10. second fin; 101. bending section; 102. connecting section; 103. reflecting section; 11. ring gear; 12. adjusting structure; 121. sleeve extension; 122. sleeve; 123. blocking part; 124. through port; 125. tooth groove; 126. limit block; 127. spring; 128. second gear; 129. reversing member; 13. first gear; 14. groove. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0036] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0037] Example 1

[0038] In this embodiment, a solar collector using a linear Fresnel lens is proposed, see Figure 1 and Figure 2 The solar collector using a linear Fresnel lens includes an outer frame 1, which is a rectangular frame with multiple heat collecting tubes 7 inside. The outer frame 1 also includes a first container 5 and a second container 6, which are respectively arranged at both ends of the heat collecting tube 7, and the first container 5 and the second container 6 are connected to the heat collecting tube 7.

[0039] See also Figure 2 The first container 5 and the second container 6 are provided with a pipe joint 3, and the pipe joint 3 is connected with the first container 5 and the second container 6. It should be supplemented that the pipe joint 3 can be a receiving pipe or a valve with blocking and connecting functions.

[0040] Please continue reading Figure 2 A plurality of heat collecting tubes 7 are arrayed in the outer frame 1 along the short side of the outer frame 1 , and the axis of the heat collecting tube 7 is parallel to the long side of the outer frame. In addition, there is a spacing between the heat collecting tubes 7 that is adapted to the focusing range of the linear Fresnel lens 2 .

[0041] See also Figure 2 A partial enlarged view, in which it can be seen that a heat-insulating layer 9 is provided inside the outer frame 1, and an inner frame 4 is also provided inside the outer frame 1. Figure 1 The fixing part of the linear Fresnel lens 2 is shown.

[0042] In this embodiment, Figure 1 The linear Fresnel lens 2 shown has a plurality of focusing areas, each focusing area focuses the sunlight into a line segment, and the above-mentioned heat collecting tube 7 is located within the irradiation range of the focused sunlight.

[0043] It is further explained that the angle between the sunlight and the horizon is variable. During the day, when the solar altitude angle is 90°, that is, at noon, the solar radiation intensity is the largest. On the contrary, when the sun is obliquely shining on the ground, the solar radiation intensity decreases. Combined with the above description, the linear Fresnel lens 2 in this embodiment can project the focused sunlight vertically to the heat collecting tube 7 at noon. Of course, during specific periods in the morning and afternoon, the sunlight focused by the linear Fresnel lens 2 will deviate from the heat collecting tube 7.

[0044] To further illustrate, the thicker the heat collecting tube 7, the shorter the time period that the sunlight focused by the linear Fresnel lens 2 deviates from the heat collecting tube 7. Of course, the thicker the heat collecting tube 7, the worse the heating efficiency of the medium in the tube. Therefore, as a balance, a first fin 8 is provided at the lateral position of the heat collecting tube 7. When the sunlight focused by the linear Fresnel lens 2 deviates from the heat collecting tube 7, the first fin 8 can replace the heat collecting tube 7 to be irradiated, so that the heat collecting tube 7 can still fully heat the medium in the tube during specific periods in the morning and afternoon.

[0045] Example 2

[0046] In this embodiment, a solar collector using a linear Fresnel lens is proposed, see Figure 3-Figure 11 The solar collector using a linear Fresnel lens includes an outer frame 1, which is a rectangular frame with multiple heat collecting tubes 7 inside. The outer frame 1 contains a first container 5 and a second container 6. In the embodiment, one end of the heat collecting tube 7 is connected to the second container 6, and the other end of the heat collecting tube 7 is connected to the first container 5 by means of an adjustment structure 12.

[0047] See also Figure 3 The first container 5 and the second container 6 are provided with a pipe joint 3, and the pipe joint 3 is connected with the first container 5 and the second container 6. It should be supplemented that the pipe joint 3 can be a receiving pipe or a valve with blocking and connecting functions.

[0048] Please continue reading Figure 3 A plurality of heat collecting tubes 7 are arrayed in the outer frame 1 along the short side of the outer frame 1 , and the axis of the heat collecting tube 7 is parallel to the long side of the outer frame 1 . In addition, there is a spacing between the heat collecting tubes 7 that is adapted to the focusing range of the linear Fresnel lens 2 .

[0049] See also Figure 3 A partial enlarged view, in which it can be seen that a heat-insulating layer 9 is provided inside the outer frame 1, and an inner frame 4 is also provided inside the outer frame 1. Figure 3 The fixing part of the linear Fresnel lens 2 is shown.

[0050] In this embodiment, Figure 3 The linear Fresnel lens 2 shown has a plurality of focusing areas, each focusing area focuses the sunlight into a line segment, and the above-mentioned heat collecting tube 7 is located within the irradiation range of the focused sunlight.

[0051] It is further explained that the angle between the sunlight and the horizon is variable. During the day, when the solar altitude angle is 90°, that is, at noon, the solar radiation intensity is the largest. On the contrary, when the sun is obliquely shining on the ground, the solar radiation intensity decreases. Combined with the above description, the linear Fresnel lens 2 in this embodiment can project the focused sunlight vertically to the heat collecting tube 7 at noon. Of course, during specific periods in the morning and afternoon, the sunlight focused by the linear Fresnel lens 2 will deviate from the heat collecting tube 7.

[0052] To further illustrate, the thicker the heat collecting tube 7, the shorter the time period that the sunlight focused by the linear Fresnel lens 2 deviates from the heat collecting tube 7. Of course, the thicker the heat collecting tube 7, the worse the heating efficiency of the medium in the tube. Therefore, as a balance, a second fin 10 is provided on the outside of the heat collecting tube 7. Different from the fixed fin used in Example 1, in this embodiment, the angle of the second fin 10 is adjustable relative to the heat collecting tube 7. In addition, the contact area between the second fin 10 and the heat collecting tube 7 changes with the angle adjustment.

[0053] The first fin 8 in Example 1 is fixedly combined with the heat collecting tube 7. Although the first fin 8 can replace the heat collecting tube 7 to be irradiated when the sunlight focused by the linear Fresnel lens 2 deviates from the heat collecting tube 7, this combination method still has limitations. First, in order to obtain sufficient irradiation time, the first fin 8 must be wide enough, but the spacing between the heat collecting tubes 7 may not be enough to arrange the wider first fin 8; second, after the illumination ends, the first fin 8, as a part of the heat collecting tube 7, will quickly consume the residual heat of the medium in the heat collecting tube 7. Accordingly, this embodiment adjusts the combination method of the second fin 10 and the heat collecting tube 7. After the adjustment, when the sunlight focused by the linear Fresnel lens 2 deviates from the heat collecting tube 7, the second fin 10 will be irradiated instead of the heat collecting tube 7, and the reflected light generated during the irradiation will be projected onto the heat collecting tube 7. In addition, when the second fin 10 is irradiated, the second fin 10 is made to be as close to the backlight surface of the heat collecting tube 7 as possible, and the heat generated when the second fin 10 is irradiated is transferred to the backlight surface of the heat collecting tube 7 evenly. On the contrary, when the second fin 10 and the heat collecting tube 7 cannot be irradiated, the second fin 10 is separated from the heat collecting tube 7 to delay the residual heat radiation time, thereby further improving the utilization efficiency of the medium heat.

[0054] In order to achieve the effects described in the above description, this embodiment also provides Figure 3 The regulating structure 12 shown is connected to the heat collecting tube 7 , and the regulating structure 12 drives the second fin 10 to move under the driving force generated by the flow of the medium.

[0055] To further explain, a ring gear 11 is provided on one side of the heat collecting tube 7 located in the first container 5, and the ring gear 11 encircles the heat collecting tube 7, and the axis of the ring gear 11 coincides with the axis of the heat collecting tube 7. It should be noted that the ring gear 11 is heat-insulated. In addition, for the sake of aesthetics and to reduce light obstruction, a groove is provided in the first container 5 (the groove is not connected to the storage space in the container), and the above-mentioned ring gear 11 is located in the groove. For cooperation, a first gear 13 is also provided in the groove, and the first gear 13 is meshed with the ring gear 11. Most importantly, the first gear 13 is driven by the adjustment structure 12.

[0056] For further explanation, see Figure 7 and Figure 8 The second fin 10 includes a connecting section 102 connected to the non-meshing area of ​​the ring gear 11, preferably connected to the lateral position of the ring gear 11, and the connecting section 102 has two extensions, one of which is a bending section 101, and the other is a reflecting section 103.

[0057] It should be added that there is a ring sleeve (not shown in the drawings) at the other end of the connecting section 102 , which surrounds the heat collecting tube 7 and also has a heat insulation function. Its function is to cooperate with the ring gear 11 to hang the second fin 10 on the outside of the heat collecting tube 7 .

[0058] Different from Example 1, in this embodiment, the insulation layer 9 located in the outer frame 1 has a groove 14 that adapts to the reflecting section 103. When the reflecting section 103 is laid horizontally in the groove 14, the bent section 101 is spaced apart from the heat collecting tube 7. On the contrary, when the adjusting structure 12 drives the first gear 13 to engage with the ring gear 11 so that the reflecting section 103 is rotated out of the groove 14, the bent section 101 is supported by the groove 14 and is pushed to the surface of the heat collecting tube 7.

[0059] To further explain, there are several reflective strips on the surface of the curved section 101, and there is bare metal between the reflective strips (the above description is not shown in the figure). In this way, the curved section 101 can generate heat when irradiated by focused sunlight and can reflect the focused sunlight to the collector tube 7.

[0060] See also Fig. 9 and Fig.10 The regulating structure 12 includes a sleeve 122 as an intermediate structure for connecting the first container 5 and the heat collecting tube 7. A blocking portion 123 is provided inside the sleeve 122. A through hole 124 is provided at the end of the blocking portion 123 for medium to pass through. There are three strip grooves on the periphery of the blocking portion 123, wherein each strip groove has a spring 127, and each strip groove has a limit block 126 that slides with the strip groove. The limit block 126 is combined with the sleeve 122, and the limit block 126 is also a fixing point of the spring 127.

[0061] Please continue reading Fig. 9 and Fig.10 The blocking part 123 also has a tooth groove 125 in the same direction as the strip groove. There is only one relatively long groove wall in the tooth groove 125 with a plurality of teeth. A second gear 128 is arranged in the tooth groove 125. The second gear 128 is provided with a shaft, which extends outward through the sleeve 122. When the blocking part 123 moves relative to the sleeve 122, the second gear 128 meshes with the tooth groove 125, so that the shaft configured by the second gear 128 rotates axially. The adjustment structure 12 also includes a reversing member 129 connected to the first gear 13. The outer periphery of the reversing member 129 is the sleeve extension 121. The reversing member 129 is connected to the shaft configured by the second gear 128, and transmits kinetic energy to the first gear 13.

[0062] In this embodiment, the reversing member 129 includes two helical teeth meshing at an angle of 90°, one of which is connected to the shaft, and the other is connected to the first gear 13. Thus, when the shaft to which the second gear 128 is configured rotates axially, the first gear 13 will rotate accordingly.

[0063] Regarding the adjustment structure 12 , it should also be noted that the diameter of the blocking portion 123 is smaller than the diameter of the connection between the sleeve 122 and the first container 5 , so that the medium entering the sleeve 122 will push the blocking portion 123 to move relative to the sleeve 122 when entering the heat collecting tube 7 .

[0064] The solar collector using linear Fresnel lenses proposed in this embodiment is mainly used in lithium bromide air-conditioning units. The pump configured for the lithium bromide air-conditioning unit pumps heavy oil (heat transfer medium) into the solar collector using linear Fresnel lenses. The adjustment structure 12 in this embodiment uses the kinetic energy generated by the heavy oil in the flow to adjust the second fin 10. It is further explained that after the temperature of the heavy oil drops, the lithium bromide air-conditioning unit will gradually reduce the power of the pump until the temperature cannot be used, and then the pump group is shut down.

[0065] The use process of the solar thermal collector using linear Fresnel lens proposed in this embodiment when used in combination with a lithium bromide air conditioning unit is as follows:

[0066] First, in the morning when the sunlight is good, the pump group is started, and the pump group pumps the heavy oil to flow. The flowing heavy oil enters the sleeve 122 through the first container 5, and enters the heat collecting tube 7 through the opening 124 set by the blocking part 123. During this period, because the opening 124 is obviously smaller than the diameter of the entrance of the blocking part 123, the blocking part 123 will move relative to the sleeve 122 to the position of the heat collecting tube 7. During the movement, the tooth groove 125 is meshed with the second gear 128. After the reversing member 129 is reversed, the first gear 13 is meshed with the ring gear 11, so that the second fin 10 is rotated out of the groove 14, and the bottom of the groove 14 is used as a support to squeeze the curved section 101 in the second fin 10 to the surface of the heat collecting tube 7; the reflecting section 103 in the second fin 10 is obliquely set behind the heat collecting tube 7;

[0067] Second, from morning to noon, the sun's altitude gradually rises, and the sunlight focused by the linear Fresnel lens 2 first irradiates the reflective section 103, and then directly irradiates the heat collecting tube 7 at noon;

[0068] Third, from noon to dusk, the height of the sun gradually decreases, and the light focused by the linear Fresnel lens 2 first illuminates the heat collecting tube 7 and then illuminates the reflecting section 103 until the sun sets. The operating power of the pump group is reduced, making it difficult for the heavy oil flowing in the casing 122 to further maintain the position of the blocking part 123. Combined with the pulling force of the spring 127, the blocking part 123 is reset. After resetting, the second fin 10 rotates back to the groove 14, and the curved section 101 in the second fin 10 is separated from the heat collecting tube 7, thereby blocking the heat conduction between the second fin 10 and the heat collecting tube 7 and making full use of the residual heat energy of the heavy oil.

[0069] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A solar thermal collector using a linear Fresnel lens, comprising an outer frame, a plurality of heat collecting tubes located in the outer frame, a first container and a second container connected to the heat collecting tubes, and a thermal insulation layer, characterized in that: It also includes a linear Fresnel lens, which has multiple focusing areas, each focusing area focuses sunlight, and the heat collecting tube is located within the irradiation range of the focused sunlight. The heat collecting tube is also equipped with fins, which are used to increase the heating time of the heat collecting tube. The fins are installed on the outside of the heat collecting tube, wherein the angle of the fins is adjustable relative to the heat collecting tube, and the contact area between the fins and the heat collecting tube changes with the angle adjustment; The regulating structure is connected to the heat collecting tube, and the regulating structure drives the fins to move due to the driving force generated by the flow of the medium; It also includes a ring gear for entrapping the heat collecting pipe and a first gear meshed with the ring gear, wherein the first gear is driven by the adjusting structure; The fin includes a connecting section connected to the non-meshing area of ​​the ring gear, the connecting section has two extensions, one of which is a bent section, and the other is a reflecting section; the insulation layer located inside the outer frame has a groove adapted to the reflecting section, wherein when the reflecting section is horizontally laid in the groove, there is a distance between the bent section and the heat collecting tube, and when the reflecting section is screwed out of the groove, the bent section is supported by the groove and is pushed to the surface of the heat collecting tube.

2. The solar collector using a linear Fresnel lens according to claim 1, characterized in that: There are several reflective strips on the surface of the curved section, and bare metal is between the reflective strips. When the curved section is irradiated with focused sunlight, it generates heat and reflects the focused sunlight to the collector tube.

3. The solar thermal collector using a linear Fresnel lens according to claim 1, characterized in that: The adjustment structure includes a sleeve as an intermediate structure for connecting the first container and the heat collecting tube, a blocking part is provided inside the sleeve, and a through hole for medium to pass through is provided at the end of the blocking part; there are also multiple strip grooves on the periphery of the blocking part, wherein each strip groove has a spring, and each strip groove has a limit block that slides with the strip groove, the limit block is combined with the sleeve and serves as a fixing point for the spring; the blocking part also has a tooth groove, and the tooth groove has a second gear, and the second gear is equipped with a shaft, which extends outward through the sleeve, and when the blocking part moves relative to the sleeve, the second gear meshes with the tooth groove, so that the shaft configured by the second gear rotates axially; the adjustment structure also includes a reversing member connected to the first gear, and the reversing member is connected to the shaft configured by the second gear, so as to transmit kinetic energy to the first gear.

4. The solar thermal collector using a linear Fresnel lens according to claim 3, characterized in that: The diameter of the blocking part is smaller than the diameter of the connection between the sleeve and the first container, so that the medium entering the sleeve pushes the blocking part to move relative to the sleeve when entering the heat collecting tube.

5. The solar collector using a linear Fresnel lens according to claim 1, characterized in that: There is an inner frame inside the outer frame, and the inner frame is a fixing part of the linear Fresnel lens.

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