JP2014005958A - Solar heat collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar heat collector having high heat collection efficiency, in which a heat transfer fin is bent by small stress and thereby easiness in insertion and adhesion to a double vacuum tube of the heat transfer fin are improved.SOLUTION: A solar heat collector concentrates solar radiation energy on a heat collection part 1 and warms a heat carrier flowing in the heat collection part. The collector includes: a double vacuum tube 2 made of transparent glass; a selective absorption film 3 coated on an outer peripheral surface of an inner tube 2b in the double vacuum tube 2; a heat transfer fin 10 that can come into surface contact with an inner peripheral surface of the inner tube 2b in the double vacuum tube 2 by elastic force; and a heat carrier pipe 15 coming into surface contact with an inside surface of the heat transfer fin 10. An outside surface of the heat transfer fin 10 is subjected to anode oxidation film treatment, and an outer diameter of the heat transfer fin 10 is formed as the same diameter as an inner diameter X of the inner tube 2b in the double vacuum tube 2 or larger. Furthermore, the heat transfer fin is formed in a cross-sectional circular-arc shape while one side thereof is opened, and a V-shaped bent part 12 is provided which bends in a V-shape toward the inside of a circular arc part such that a tip is positioned at a portion opposite to the opening.

Description

  The present invention relates to a solar heat collector, and more particularly to a heat collector of a CPC (Compound Parabolic Concentrator) that is a solar heat collector.

  Conventionally, many devices using sunlight have been developed. For example, CPC (Compound Parabolic Concentrator) is one of them, and a wide range of incident light can be guided to the heat collecting tube by making the light collector (reflector) a parabolic shape and an involute curve shape. Further, a selective absorption film or the like that absorbs solar radiation energy well and has a low emissivity is deposited on the outer surface of the heat collection tube, and a heat medium flows in the heat collection tube is known (for example, Patent Documents 1 and 2).

  Further, the heat collecting part is formed of a vacuum double glass tube, an arc-shaped heat conductor having a selective absorption film surface on the outer peripheral surface and having a resilient force in the outer peripheral direction, the vacuum double glass tube It is known that the inner pipe of the heat conductor is mounted in surface contact, the conductive pipe serving as a medium is brought into surface contact with the inner peripheral surface of the heat conductor, and the heat medium flows in the conductive pipe (for example, Patent Document 3, 4, 5).

JP 2004-278837 A JP 2008-138899 A Japanese Utility Model Publication No. 62-195044 Japanese Utility Model Publication No. 63-43045 JP 2011-202910 A

  In the heat collecting tube structures described in Patent Documents 1 and 2, in order to improve the heat transfer efficiency to the heat medium flowing in the tube, it is necessary to reduce the outer diameter of the heat collecting tube as much as possible. As a result, there is a concern that the heat collection efficiency is lowered. Moreover, since the material of the heat collecting tube is composed of a copper tube, an aluminum tube or the like, the heat retention property is inferior, and there is a concern that heat loss may occur due to heat radiation.

  On the other hand, in the structure of the heat collection tube described in Patent Documents 3 and 4, a conducting tube through which a heat medium flows is provided inside a vacuum double glass tube (hereinafter referred to as a glass tube) having a high degree of vacuum (heat retention), and a wide collection of tubes. The light collecting surface and high heat retention can be ensured in the heat collecting tube. However, in order to bring the heat conductor made of a metal plate into surface contact with the elastic force in the outer peripheral direction on the inner peripheral surface of the glass tube and fix the heating medium conducting tube in surface contact with the inner peripheral surface of the heat conductor, It is necessary to form the shape so that the glass tube and the heat conductor are in accurate contact. If the glass tube and the heat conductor do not come into precise surface contact, for example, if the outer diameter of the heat conductor is too large relative to the inner diameter of the glass tube, the glass tube will break when the heat conductor is attached to the glass tube. There are concerns. Further, if the outer diameter of the heat conductor is too small with respect to the inner diameter of the glass tube, the heat conductor does not come into surface contact with the glass tube and a gap is formed between them, resulting in an increase in thermal resistance. As a result, the glass tube The heat transfer efficiency from the heat medium to the heat medium is reduced. Furthermore, since the heat conductor is formed of a highly reflective metal plate, there is a risk that radiant heat transfer from the internal glass tube to the heat conductor may be reduced. Thus, in order to improve the heat transfer efficiency from the glass tube to the heat medium, it is necessary to make the shape of the heat conductor accurately and to ensure that the glass tube and the heat conductor are in surface contact.

  On the other hand, as shown in FIG. 10, the heat transfer fin described in Patent Document 5 has a concave curve that bends inwardly to an arcuate base 120 formed in an arcuate cross section with an opening 110 on one side. A section 130 is provided. In the structure of the heat transfer fin 100 described in Patent Document 5 formed as described above, the heat transfer fin 100 is bent in a concave shape toward the inside of the arc-shaped portion of the heat transfer fin 100 formed in an arc shape with an opening 110 on one side. By providing the concave curved portion 130, the contact area and adhesion between the heat transfer fin 100 and the double vacuum tube are improved. By providing the concave curved portion 130, the operation of inserting the heat transfer fins 100 into the double vacuum tube can be easily performed by bending the heat transfer fins 100, and the bent heat transfer fins 100 are about to return. The heat transfer fin 100 and the double vacuum tube are pressure-bonded by the elastic stress. Further, the anodic oxide coating on the outer surface of the heat transfer fin 100 reduces friction when the heat transfer fin 100 is inserted into the double vacuum tube, and the heat transfer fin 100 and the double vacuum tube are pressure-bonded. A buffering action is provided to make the elastic stress acting from the heat transfer fin 100 to the double vacuum tube uniform.

  However, since the double vacuum tube has a relatively long length of, for example, 30 to 100 mm and a length of 1000 to 2000 mm, a smaller stress is required to insert the heat transfer fin into the inner tube of the double vacuum tube. It is indispensable for improving the function of the solar heat collecting apparatus and assembling workability to bend the heat transfer fin and improve the adhesion between the heat transfer fin and the double vacuum tube. Further improvement is desired.

  The present invention has been made by the inventors in earnest research in view of the above circumstances. The heat transfer fin is bent with a small stress so that the heat transfer fin can be easily inserted into the double vacuum tube for assembly work. A solar collector with high heat collection efficiency that efficiently conducts solar radiant energy collected in the heat collection section by the reflector to the heat medium flowing in the heat medium pipe by improving the adhesion. The purpose is to provide.

  In order to solve the above-described problems, the present invention is a solar heat collecting apparatus that concentrates irradiated sunlight on a heat collecting section and heats a heat medium flowing in the heat collecting section. A heavy vacuum tube, a selective absorption film coated on the outer peripheral surface of the inner tube of the double vacuum tube, a heat transfer fin capable of surface contact with the inner peripheral surface of the inner tube of the double vacuum tube by elastic force, and the heat transfer A heat transfer medium tube in surface contact with the inner surface of the heat fin, the outer surface of the heat transfer fin is anodized, and the outer diameter of the heat transfer fin is the inner tube of the double vacuum tube. Further, the heat transfer fin is formed in a circular arc shape having an opening on one side, and is directed inward of the arc-shaped portion so that the tip is located at a portion facing the opening. A V-shaped bent portion that is bent into a V shape is provided.

  With this configuration, when a force is applied to the heat transfer fin from a direction orthogonal to the line connecting the opening of the heat transfer fin and the V-shaped bent portion, stress concentrates on the V-shaped bent portion, The heat transfer fin can be bent with a small stress. This makes it easy to insert heat transfer fins with an outer diameter equal to or greater than the inner diameter of the double vacuum tube into the inner tube of the double vacuum tube. The outer surface of the heat transfer fin can be brought into close contact with the inner peripheral surface of the inner tube by the elastic force.

  In addition to suppressing the reflectance of the outer surface of the heat transfer fin by applying an anodic oxide film treatment to the outer surface of the heat transfer fin, when the heat transfer fin is further inserted into the inner tube of the double vacuum tube Since the friction of the heat transfer fins can be reduced and the buffering action can be provided, the heat transfer fins are inserted into the inner tube of the double vacuum tube in combination with the bending and elastic action of the heat transfer fins. The contact area between the heat transfer fin and the inner tube of the double vacuum tube can be increased, and the adhesion between the heat transfer fin and the inner tube of the double vacuum tube can be improved.

  In the present invention, the heat transfer fin is preferably formed so that the thickness of the V-shaped bent portion is thinner than other portions. By comprising in this way, a heat-transfer fin can be bent with still smaller stress, and the insertion to the inner tube of a double vacuum tube of a heat-transfer fin can be made still easier.

  Moreover, in this invention, it is preferable that the internal angle of a V-shaped bending part shall be 25 degrees-35 degrees. By comprising in this way, it becomes possible to bend a heat-transfer fin with few stresses. However, if the inner angle of the V-shaped bent portion is smaller than 25 °, for example, when the heat transfer fin is formed of an aluminum extruded shape, the defect rate becomes high in terms of processing accuracy and the product cost increases. . Further, when the inner angle of the V-shaped bent portion is larger than 35 °, a sufficient amount of bending cannot be expected.

  In the present invention, the ratio (D / R) of the V-shaped inward length (D) of the V-shaped bent portion and the radius (R) of the heat transfer fin is preferably 4/17 to 10/17, Is preferably 5/17 to 8/17. By comprising in this way, it becomes possible to bend a heat-transfer fin with few stresses. When the ratio (D / R) of the length (D) of the V-shaped bent portion and the radius (R) of the heat transfer fin is smaller than 4/17 or larger than 10/17, sufficient deformation is caused. Since the amount cannot be obtained and the elastic stress is reduced, the adhesion to the double vacuum tube is also lowered.

  By configuring in this manner, the outward elastic stress of the heat transfer fin can be reliably ensured, so that the contact area between the heat transfer fin and the inner tube can be increased, and the adhesion can be further improved.

  Further, in this invention, it is preferable that a fitting groove portion having a narrow opening is provided along the longitudinal direction on the inner side surface of the heat transfer fin, and the heating medium pipe is fitted in the fitting groove portion. Good.

  By configuring in this way, the contact area of the heat transfer tube can be increased on the inner surface of the heat transfer fin and the surface contact can be ensured, so the adhesion between the heat transfer fin and the heat transfer tube is improved. To do.

  Further, the heat transfer fin can be formed of an aluminum extruded profile. By comprising in this way, the heat-transfer fin can ensure favorable thermal conductivity. Aluminum has good recyclability.

  According to the present invention, the heat transfer fins can be bent with a small stress to facilitate the insertion of the heat transfer fins into the double vacuum tube, and the assembly work can be facilitated. Can be improved.

It is a schematic perspective view which shows the solar heat collecting device which concerns on this invention. It is a top view which shows a part of said solar heat collecting device in a cross section. It is a side view which shows a part of said solar heat collecting device in a cross section. It is sectional drawing (a) which shows the principal part of the said solar heat collecting apparatus, and the I section expanded sectional view (b) of (a). It is sectional drawing of the heat collecting part in this invention. It is a section perspective view of the heat collection part in this invention. It is a perspective view of the heat-transfer fin in this invention. It is a schematic sectional drawing (a) which shows the shape of the principal part of the heat-transfer fin in this invention, and a dimension, and the partially expanded view (b) of (a). It is a schematic sectional drawing which shows the experimental example which investigates the relationship between the shape of the heat-transfer fin in this invention, and stress. It is a schematic sectional drawing which shows the conventional heat-transfer fin. It is a graph which shows the relationship between the depth of a V-shaped part and displacement amount (deflection) in case the internal angle of the V-shaped bending part in this invention is 25 degrees.

  Hereinafter, embodiments of a solar heat collecting apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIGS. 1 to 3, the solar heat collecting apparatus according to the present invention includes a rectangular cylindrical main frame 31 into which a water supply pipe 33 and a hot water supply pipe 34 are inserted, and a lower portion of one side wall of the main frame 31. A main body 30 comprising a rectangular base plate 32 extending outward from the base plate, a vacuum tube receiver 36 provided at an end of the base plate 32 and facing the main frame 31, and a side wall of the main frame 31 A plurality of heat collecting portions 1 arranged in parallel above the base plate 32 via side frame members 35 provided along the portions, and a light collecting frame member 40 disposed below each heat collecting portion 1 And a light collecting plate 43 that is attached by a cylindrical connection member 42 (see FIG. 4A) and reflects sunlight incident on the vicinity of the heat collecting section 1 to concentrate it on the heat collecting section 1.

  As shown in FIG. 4A, the light condensing frame member 40 is formed of an extruded shape made of aluminum (including an aluminum alloy), and has a concave fitting portion 41 having a U-shaped cross section at the center. The both sides have a mounting surface formed on a bilaterally symmetric and W-shaped compound paraboloid. In addition, the compound paraboloid which forms the attachment surface is a shape formed by combining an involute curve and a parabolic curve (CPC curve), and is a shape in which incident light is reflected toward the heat collector 1 most efficiently. is there.

  As shown in FIGS. 4 to 6, the heat collecting section 1 covers the outer peripheral surface of the double vacuum tube 2 composed of a transparent glass outer tube 2 a and an inner tube 2 b and the inner tube 2 b of the double vacuum tube 2. The selective absorption film 3 is arranged, the heat transfer fin 10 arranged so as to be in surface contact with the inner peripheral surface of the inner tube 2 b of the double vacuum tube 2, and arranged so as to be in surface contact with the inner side surface of the heat transfer fin 10. A water supply pipe 33 inserted into the main frame 2 and a heat medium pipe 15 connected to the hot water supply pipe 34 are provided. As shown in FIGS. 1 and 2, the distal end portion of the heat collecting portion 1 is held in a state of being inserted into a cap 36 a attached to the vacuum tube receiver 36, and the proximal end portion of the heat collecting portion 1 is The frame member 35 is held via an attachment hole 35a.

  The double vacuum tube 2 uses a vacuum glass tube with a high degree of vacuum, and the outer tube 2a and the inner tube 2b, which are closed at one end surface of the glass tube, are overlapped to form one end surface of the outer tube 2a and the inner tube 2b. Close. And the other end surface side is pressure-reduced with a vacuum pump, and the outer tube | pipe 2a is sealed. By doing so, the vacuum layer 5 is formed. The outer peripheral surface of the inner tube 2b is covered with a selective absorption film 3 described later.

  The selective absorption film 3 that covers the outer surface of the inner tube 2b is, for example, plated with black black chrome or electroless nickel on a thin metal film having a low thermal emissivity that tightly covers the outer peripheral surface of the inner tube 2b. Manganese black paint is painted or vapor-deposited, or a thin film having a large sunlight absorption rate is formed by a conventional method using a copper oxide film or an alumite film. By forming the selective absorption film 3 on the outer surface of the inner tube 2b, it is possible to reduce radiant heat transfer from the selective absorption film 3 to the outer tube 2a while efficiently absorbing solar heat. Further, the vacuum layer 5 between the inner tube 2b and the outer tube 2a prevents heat loss due to convective heat transfer from the selective absorption film 3 to the outer tube 2a.

  The selective absorption film 3 formed as described above is coated on the outer peripheral surface of the inner tube 2b of the double vacuum tube 2 as shown in FIG. Since the selective absorption film 3 is located between the outer tube 2a and the inner tube 2b of the double vacuum tube 2, as described above, the inner tube 2b is coated with the selective absorption film 3, and then the outer tube 2a and the inner tube are covered. 2b are joined together.

  As shown in FIGS. 7 and 8, the heat transfer fin 10 is formed of an extruded shape member made of aluminum (including an aluminum alloy) with high thermal conductivity, and has an opening 11a on one side along the longitudinal direction. The base 11 is formed in a substantially arc shape in cross section and the base 11 is formed in the longitudinal direction of the base 11, and the V is directed inward of the base 11 so that the tip is located at a portion facing the opening 11 a. It is formed from a V-shaped bent portion 12 that is bent in a letter shape, and two fitting groove portions 13 that have a narrow opening in the cross section and are formed at positions facing the inner side of the base portion 11. . In this case, the two sides of the V-shaped portion 12a of the V-shaped bent portion 12 are equal.

  When the heat transfer fin 10 formed as described above is applied with a force P in a direction perpendicular to the line L connecting the opening 11a and the V-shaped bent portion 12, as shown in FIG. It has been found that stress concentrates on the bent portion 12. Thereby, the heat-transfer fin 10 can be bent by a small stress, and a resilience can be given according to the bending.

In this case, it is better to thin the thickness t ₂ of the V-shaped portion 12a of the V-shaped bent portion 12 against the wall thickness t ₁ of the base portion 11 and the fitting groove 13 of the heat transfer fins 10. Although the radius r of the tip of the arc portion 12b of the V-shaped portion 12a of the V-shaped bent portion 12 is arbitrary, here is formed in the same dimension as the thickness t ₁ (see FIG. 8 (b)) .

By thus forming the thin V-shaped section 12a the thickness t ₂ of the V-shaped bent portion 12 against the wall thickness t ₁ of the other parts of it to deflect the heat transfer fins 10 in a smaller stress The heat transfer fin 10 can be easily inserted into the inner tube 2b of the double vacuum tube 2.

  Further, in order to bend the heat transfer fin 10 with a small stress, the internal angle θ of the V-shaped bent portion 12 is set in a range of 25 ° to 35 °. When the internal angle θ of the V-shaped bent portion 12 is smaller than 25 °, the defect rate is high in terms of processing accuracy of the heat transfer fin 10 formed of the aluminum extruded profile, and the product cost increases. Further, when the internal angle θ of the V-shaped bent portion 12 is larger than 35 °, a sufficient amount of bending cannot be expected.

  Further, the heat transfer fins 12 are bent with a small amount of stress to ensure outward elastic stress, and in order to increase the contact area between the heat transfer fins 10 and the inner tube 2b, the V-shaped bent portion 12 has a V-shape. The ratio (D / R) of the inward length (D) {the depth of the V-shaped portion 12a} and the radius (R) of the heat transfer fin 10 is preferably 4/17 to 10/17, more preferably 5 /. It is set to 17-8 / 17. When the ratio (D / R) of the length (D) in the V-shape of the V-shaped bent portion 12 to the radius (R) of the heat transfer fin is smaller than 4/17 or larger than 10/17 Since a sufficient amount of deformation cannot be obtained and the elastic stress is reduced, the adhesion of the double vacuum tube 2 to the inner tube 2b is also lowered.

  By configuring in this way, the outward elastic stress of the heat transfer fin 10 can be reliably ensured, so that the contact area between the heat transfer fin 10 and the inner tube 2b can be increased and the adhesion can be further improved. it can.

  Further, as shown in FIG. 7, the outer surface of the heat transfer fin 10 is subjected to an anodic oxide film treatment (hereinafter referred to as alumite treatment). The alumite treatment is performed by, for example, a method of plugging the pores of the anodized film 14 in hot water at around 90 ° C. after degreasing treatment, etching, and alumite treatment. The film thickness of the anodized film 14 is preferably in the range of 2 μm to 20 μm. The reason is that if it is less than 2 μm, the reflectivity of the substrate is reflected, so that it is preferably 2 μm or more. Conversely, if the film thickness exceeds 20 μm, productivity decreases or the thermal resistance of the anodized film 14 cannot be ignored. This is because heat input to the heat transfer fins 10 may be reduced.

  Since the reflectance of the outer surface of the heat transfer fin 10 can be suppressed by applying the alumite treatment to the outer surface of the heat transfer fin 10, the radiant heat transfer to the heat transfer fin 10 is improved and the heat collection efficiency is improved. . Further, by applying alumite treatment to the outer surface of the heat transfer fin 10, the slip property is improved and the friction at the time of inserting the heat transfer fin 10 into the inner tube 2 b can be reduced. When mounting the heat transfer fin 10 to the inner tube 2b, the breakage rate of the double vacuum tube 2 can be suppressed.

  The outer diameter Y of the heat transfer fin 10 before mounting shown in FIG. 7 is formed to be equal to or larger than the inner diameter X of the inner tube 2b of the double vacuum tube 2 shown in FIG. However, an opening 11a is provided in the longitudinal direction of the base portion 11 of the heat transfer fin 10 and is formed in a substantially arc shape in cross section, and V-shaped toward the inside of the base portion 11 so that the tip is located at a portion facing the opening 11a. By forming the V-shaped bent portion 12 bent in a shape, the heat transfer fin 10 can be bent by a small stress as described above, so that the heat transfer fin 10 can be inserted into the inner tube 2b. It becomes. Further, since the elastic force can be given according to the bending, the inserted heat transfer fin 10 can increase the contact area between the heat transfer fin 10 and the inner tube 2b by the outward elastic stress.

  As shown in FIGS. 4 to 7, the two fitting groove portions 13 are formed on the inner surface of the heat transfer fin 10 at a position where the cross section is a narrow opening and faces the inside of the base portion 11. Are formed along the longitudinal direction of the base portion 11 and the heat medium pipe 15 is fitted into the fitting groove 13, whereby the contact area between the heat transfer fin 10 and the heat medium pipe 15 can be increased. The surface contact can be ensured, and the adhesion between the heat transfer fins 10 and the heat transfer tube 15 is improved.

  In addition, the said heat-medium pipe | tube 15 is formed with the U-shaped pipe body formed from a metal with good heat conductivity, such as copper and aluminum, for example, and a heat medium, for example, water flows.

  The double vacuum tube 2, the selective absorption film 3, the heat transfer fin 10, and the heat medium tube 15 configured as described above can be assembled in the following procedure. First, the inner tube 2b and the outer tube 2a whose outer surfaces are covered with the selective absorption film 3 are overlapped, and one end face of the outer tube 2a and the inner tube 2b is closed. And the other end surface side is pressure-reduced with a vacuum pump, and the outer tube | pipe 2a is sealed. Thereby, the double vacuum tube 2 in which the selective absorption film 3 is coated on the outer peripheral surface of the inner tube 2b is formed. Next, the heat transfer fin 10 is bent from the opening of the inner tube 2b and inserted into the inner tube 2b, and the heat transfer fin 10 is brought into close contact with the inner peripheral surface of the inner tube 2b by the elastic force of the heat transfer fin 10. . Since the outer surface of the heat transfer fin 10 is anodized, the slip property is improved and the friction during insertion of the heat transfer fin 10 into the inner tube 2b can be reduced. When the heat transfer fin 10 is attached to the inner tube 2b of the vacuum tube 2, the damage rate of the double vacuum tube 2 is suppressed.

  Next, the fitting groove 13 of the heat transfer fin 10 inserted into the double vacuum tube 2 as described above is fitted to the heat transfer pipe 15 welded and fixed to the water supply pipe 33 and the hot water supply pipe 34. insert. The elastic force of the heat transfer fin 10 and the insertion of the heat transfer medium tube 15 generate pressure in the outer peripheral direction of the inner tube 2b. However, since the outer surface of the heat transfer fin 10 is anodized, an anodized film Since the pressure from the heat transfer fin 10 to the inner tube 2b can be made uniform by the buffering function 14, the adhesion between the heat transfer fin 10 and the inner tube 2b can be improved.

  Thereafter, the base end portion of the double vacuum tube 2 is fitted into an attachment hole 35 a formed in the side frame member 35, and the distal end portion is held by a cap 36 a attached to the vacuum tube receiver 36.

  According to the solar heat collecting apparatus which concerns on the said embodiment, when force P is applied to the heat-transfer fin 10 from the direction orthogonal to the line L which ties the opening 11a of the heat-transfer fin 10 and the V-shaped bending part 12. Since the stress concentrates on the V-shaped bent portion 12, the heat transfer fin 10 can be bent with a small stress. Thereby, insertion of the heat transfer fin 10 formed with the outer diameter Y equal to or larger than the inner diameter X of the inner tube 2b of the double vacuum tube 2 into the inner tube 2b of the double vacuum tube 2 can be facilitated. The outer surface of the heat transfer fin 10 can be brought into close contact with the inner peripheral surface of the inner tube by the elastic force according to the bending of the heat transfer fin 10.

  Further, by applying the anodic oxide film 14 to the outer surface of the heat transfer fin 10, it is possible to reduce friction when the heat transfer fin 10 is inserted into the inner tube 2 b of the double vacuum tube 2 and to have a buffering action. Therefore, the heat transfer fin 10 can be easily inserted into the inner tube 2b of the double vacuum tube 2 in combination with the action of the heat transfer fin 10 and the elastic force. The contact area between the vacuum tube 2 and the inner tube 2b can be increased, and the adhesion between the heat transfer fin 10 and the inner tube 2b of the double vacuum tube 2 can be improved.

Further, the heat transfer fin 10 is formed with the thickness t ₂ of the V-shaped portion of the V-shaped bent portion 12 thinner than the thickness t ₁ of the other portion, so that the heat transfer fin 10 can be formed with a smaller stress. The heat transfer fin 10 can be bent and inserted into the inner tube 2b of the double vacuum tube 2 more easily.

  Further, by providing the inner groove of the heat transfer fin 10 with the narrow groove-shaped fitting groove 13 along the longitudinal direction, the contact area of the heat transfer tube 15 can be increased on the inner surface of the heat transfer fin 10. In addition, since the surface contact can be ensured, the adhesion between the heat transfer fins 10 and the heat transfer tube 15 is improved.

  Furthermore, since the heat transfer fins 10 can be made of an aluminum extruded profile, the heat transfer fins 10 can ensure good heat conductivity, so that the heat conductivity is improved and the heat collection efficiency is increased. Aluminum has good recyclability.

  In the above embodiment, the case where the two sides of the V-shaped portion 12a of the V-shaped bent portion 12 are the same is described. However, at least the tip of the V-shaped portion 12a of the V-shaped bent portion 12 faces the opening 11a. As long as it is located at the site, the lengths of the two sides of the V-shaped portion 12a are not necessarily equal.

  Next, with respect to the solar heat collecting apparatus according to the present invention, with reference to FIGS. 8 and 9, the V-shaped portion 12 a of the V-shaped bent portion 12 of the heat transfer fin 10 formed of an aluminum extruded profile. In order to investigate the relationship between the shape and the stress, the results of experiments conducted under the following conditions will be described.

<Experimental conditions>
・ Angle θ: Inner angle of V-shaped part ・ Depth D: Linear distance between the tip of V-shaped bent part and the curve of heat transfer fin
(The two sides of the V-shaped part shall be equal)
・ Displacement amount (deflection) δ: Deformation amount of heat transfer fin when 10N stress is applied
(The amount of deformation in the stationary state is 0)
-Radius R of heat transfer fin: 17mm
・ Plate thickness (wall thickness) t _{1 of} heat transfer fin: 0.8 mm
・ V-shaped plate thickness (thickness) t ₂ : 0.66 mm
-Heat transfer fin (sample) thickness (depth): 10 mm
Comparative examples a, b, and c: Samples having a thickness (depth) of 10 mm in which the thickness of the heat transfer fin 100 shown in FIG. 10 is 0.6 mm, 0.7 mm, and 0.8 mm.

<Experiment method>
Heat transfer fin (sample) under the above conditions {depth (D) is 3 mm, 5 mm, 8 mm, but for the product (θ = 26 °) 5.3 mm}, as shown in FIG. On the fixed base F having an arcuate upper surface with a curvature larger than the diameter of the fin 10, the line L connecting the opening 11 a and the V-shaped bent portion 12 is placed in parallel with the fixed base F. In this state, a load 10N is applied from directly above the center point perpendicular to the line L connecting the opening 11a and the V-shaped bent portion 12, and the depth (D) and the amount of displacement (deflection) of the V-shaped portion 12a are applied. When the relationship with (δ) was examined using structural analysis software, the results shown in Table 1 were obtained.

  In the above experiment, when the thickness of the heat transfer fin is 0.6 mm, the extrusion process is impossible (×), and when the thickness is 0.7 mm, there is a possibility of a defect rate (Δ). There is no evaluation result. When the wall thickness was 0.8 mm, the extrusion process was good (◯), and the evaluation results were obtained. As a result of the experiment, it is considered realistic that the angle (θ) is in the range of 25 ° to 35 °.

Next, in order to consider the relationship between the depth (D) and the deflection (δ) of the V-shaped bent portion 12, an experiment was conducted on behalf of the case where the angle (θ) was 25 °. 2 and the results shown in FIG. 11 were obtained.

    As a result of the above experiment, when the depth (D) is in the range of 4 mm to 10 mm, the displacement (deflection) (δ) is 5.76 mm to 5.779 mm {maximum: 6.025 (depth 7 mm)}. When the depth (D) is in the range of 5 mm to 8 mm, the displacement (deflection) (δ) is 5.942 mm to 5.958 mm {maximum: 6.025 (depth 7 mm)}. It was.

    The displacement (deflection) (δ) when the angle (θ) is 30 ° and the depth (D) at 35 ° is 5 mm and 8 mm is also 5.863 mm to 5.975 mm as shown in Table 1. It can be estimated that the angle (θ) is as good as when the angle is 25 °.

    As a result of the above experiment, the inner angle of the V-shaped portion 12a of the V-shaped bent portion 12 provided in the heat transfer fin 10 is 25 ° to 35 °, and the depth of the V-shaped bent portion 12 (the length in the V-shaped inward direction). It has been found that the ratio (D / R) of (D) to the radius (R) of the heat transfer fin 10 is preferably 4/17 to 10/17, more preferably 5/17 to 8/17.

    In addition, although the Example demonstrated the case where the plate | board thickness (thickness) of the V-shaped part 12a was thin with respect to the plate | board thickness (thickness) of the heat-transfer fin 10, the board | plate of the heat-transfer fin 10 and the V-shaped part 12a was demonstrated. Even when the thickness (thickness) is the same, stress is concentrated on the V-shaped portion 12a as compared to the heat transfer fin 100 (comparative example) having the concave curved portion 130 (see FIG. 10). growing.

    As can be seen from Comparative Examples a, b, and c, if the thickness is reduced, the amount of displacement (deflection) is dramatically improved. However, if the thickness is excessively decreased, the defect rate is increased. Therefore, the stress concentration location is V-shaped, and by adjusting the angle (inner angle) and length (depth) of the V-shaped portion as described above, the amount of displacement (deflection) of the thin heat transfer fin can be reduced. You can get closer.

DESCRIPTION OF SYMBOLS 1 Heat collection part 2 Double vacuum tube 2a Outer tube 2b Inner tube 3 Selective absorption film 10 Heat transfer fin 11a Opening 12 V-shaped bending part 12a V-shaped part 13 Fitting groove part 14 Anodized film (anodized film process, anodized process) )
15 Heat transfer tube θ Inner angle D of V-shaped bent portion Length (depth) of V-shaped bent portion in V-shaped direction
R Radius of heat transfer fin δ Deflection (displacement)
X Inner tube inner diameter Y Heat transfer fin outer diameter

Claims (7)

A solar heat collecting apparatus that concentrates solar radiation energy on a heat collecting part and heats a heat medium flowing in the heat collecting part,
A transparent glass double vacuum tube, a selective absorption film coated on the outer peripheral surface of the inner tube of the double vacuum tube, and a transmission capable of surface contact with the inner peripheral surface of the inner tube of the double vacuum tube by elasticity. Comprising a heat fin and a heat transfer tube in surface contact with the inner surface of the heat transfer fin,
The outer surface of the heat transfer fin is subjected to an anodic oxide film treatment, and the outer diameter of the heat transfer fin is formed to be equal to or larger than the inner diameter of the inner tube of the double vacuum tube. A V-shaped bent part that is formed in a circular arc shape with an opening on one side and bent in a V shape toward the inside of the arc-shaped part is provided so that the tip is located at a portion facing the opening. ,
A solar heat collector characterized by that. The solar heat collecting apparatus according to claim 1,
The solar heat collecting apparatus according to claim 1, wherein a thickness of the V-shaped bent portion of the heat transfer fin is thinner than other heat transfer fin portions. In the solar heat collecting apparatus of Claim 1 or 2,
A solar heat collecting apparatus, wherein an inner angle of a V-shaped portion of the V-shaped bent portion provided on the heat transfer fin is 25 ° to 35 °. The solar heat collecting apparatus according to any one of claims 1 to 3,
The ratio (D / R) of the radius (R) of the heat transfer fin and the V-shaped inward direction length (D) of the V-shaped bent portion is 4/17 to 10/17. Light heat collector. The solar heat collecting apparatus according to any one of claims 1 to 3,
The ratio (D / R) of the radius (R) of the heat transfer fin and the V-shaped inward direction length (D) of the V-shaped bent portion is 5/17 to 8/17. Light heat collector. In the solar heat collecting apparatus in any one of Claim 1 thru | or 5,
A fitting groove with a narrow opening is provided along the longitudinal direction on the inner surface of the heat transfer fin, and the heat transfer pipe is fitted in the fitting groove. Solar heat collector. The solar heat collecting apparatus according to any one of claims 1 to 6,
The solar heat collecting apparatus according to claim 1, wherein the heat transfer fin is formed of an aluminum extruded profile.

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