WO2009000129A1

WO2009000129A1 - A solar vacuum heat-collecting tube

Info

Publication number: WO2009000129A1
Application number: PCT/CN2007/070202
Authority: WO
Inventors: Xinian Jiang; Hongchuan Ge; Hansan Gao; Xiaobo Zhou
Original assignee: Beijing Eurocon Solar Energy Tech.Co., Ltd.
Priority date: 2007-06-28
Filing date: 2007-06-28
Publication date: 2008-12-31

Abstract

A solar vacuum heat-collecting tube includes a vacuum glass tube (1) and a metal heat absorber (2) provided inside the vacuum glass tube (1). The metal heat absorber (2) includes a metal heat-absorbing tube bundle with two or more metal heat-absorbing tubes (22) and a tubular metal heat-absorbing fin (23). The metal heat-absorbing fin (23) is thermally connected with the metal heat-absorbing tubes (22).

Description

Solar vacuum collector tube

Foot or

[1] The present invention relates to a heat collecting tube in the field of solar thermal utilization, and more particularly to a medium and high temperature solar vacuum heat collecting tube for a solar thermal power generation system.

[2] The trough collector is one of the main methods of solar collectors for solar thermal power generation systems. The trough type concentrating heat collecting device comprises a trough type parabolic concentrator, a receiver and a tracking mechanism, wherein the receiver is a key component for obtaining high temperature heat energy, generally a medium-high temperature (300-400 ° C) concentrating solar vacuum heat collecting tube Composition. The conventional concentrating solar vacuum heat collecting tube is generally a two-head vacuum collecting tube. For example, the two-head vacuum collecting tube of the Chinese utility model patent patrol with the patent number 99230587, the solar energy of the Chinese utility model patent gong of the patent number 200420091 975.1 Vacuum collector tubes, etc. The conventional solar vacuum heat collecting tube generally comprises a double-type metal tube coated with a heat absorbing film on the outer surface and a vacuum glass tube disposed outside the metal tube, the metal tube is disposed concentrically with the vacuum glass tube, wherein the metal tube is Both ends protrude from the outside of the glass tube and are sealed with the glass tube at the glass tube port. The vacuum interlayer between the metal tube and the glass tube of the two-head vacuum heat collecting tube not only protects the coating on the surface of the metal tube, but also reduces the heat collecting loss, and has a better solar heat collecting effect. However, the two-head vacuum heat collecting tube has the following defects in actual use:

[3] 1. The traditional two-head vacuum collector tube mainly collects heat through the heat absorbing coating on the outer surface of the metal tube.

If the heat collecting efficiency is to be increased, the diameter of the heat collecting tube needs to be increased. However, the increase in the diameter of the metal tube must increase the diameter of the sealing port, which leads to an increase in sealing difficulty, which is almost impossible to achieve. The increase in heat collection efficiency is limited.

[4] 2. The heat exchange medium in the vacuum heat collecting tube mainly obtains heat by heat exchange with the tube wall of the metal tube, and the conventional two-head vacuum collecting tube has a relatively small heat exchange area because of only one metal tube. Therefore, the heat exchange efficiency is relatively low. Moreover, if the diameter of the metal pipe is increased, the capacity of the heat exchange medium is increased, thereby affecting the heat exchange efficiency.

[5] 3. Due to the weather and day and night, the metal heat absorbing tube undergoes a huge temperature change, and the thermal expansion coefficient of the metal tube and the glass tube is different, so that it is prone to hot bending and thermal fatigue, and the metal tube is deviated. The focal line, which affects the heat collecting efficiency, causes the vacuum tube to rupture, so it is difficult to make the vacuum heat absorbing tube very long, generally within 2m. Moreover, increasing the diameter of the metal pipe will increase the temperature difference between the upper and lower sides of the metal pipe, causing the metal pipe to deform and causing the glass tube to be damaged.

[6] 4. Since the traditional solar vacuum tube uses a single-tube metal tube, the capacity of the heat exchange medium is large, and it is affected by its own weight. It is necessary to use a high-strength metal tube, such as a stainless steel tube, which not only receives a large amount of material. Restricted, and the stainless steel tube has a low thermal conductivity, which is prone to upper and lower temperature differences and cause deformation.

[7] Therefore, it is necessary to provide a new type of concentrating solar vacuum heat collecting tube to overcome the defects of the existing conventional solar heat collecting tubes. [8] The technical problem to be solved by the present invention is to provide a solar vacuum heat collecting tube which can increase the diameter of the metal heat absorbing body and reduce the capacity of the heat exchange medium, thereby improving the heat collecting efficiency and the heat exchange efficiency.

[9] The technical problem to be solved by the present invention is to provide a solar vacuum heat collecting tube, which can reduce the sealing interface diameter of the metal heat absorbing body and the glass tube port, thereby making the sealing more reliable, improving the yield and the service life.

[10] The above technical problem of the present invention can be solved by the following technical solution, a solar vacuum heat collecting tube comprising a vacuum glass tube and a metal heat absorbing body sleeved in the vacuum glass tube, wherein The metal heat absorber comprises:

[11] a metal heat absorbing tube bundle having two or more metal heat absorbing tubes parallel to the axis of the glass tube;

[12] The metal heat absorbing fin is formed into a cylindrical shape extending in the axial direction of the vacuum glass tube, and is heat-exchanged with the metal heat absorbing tube.

[13] In the present invention, the metal heat absorbing fin is bent from the outside to the inside to form a groove, and the metal heat absorbing tube is embedded in the groove to form heat exchange with the metal heat absorbing fin. connection.

[14] In the present invention, the shape of the groove coincides with the outer contour of the metal heat absorbing tube, so that the metal heat absorbing tube can closely fit with the groove groove to form a better heat exchange effect.

[15] In the present invention, the metal heat absorbing tube is tightly crimped or welded into the groove of the metal heat absorbing fin.

[16] In the present invention, the metal heat absorbing fin is formed in a cylindrical shape substantially coaxial with the glass tube.

[17] In the present invention, the two ends of the metal heat absorbing tube bundle are respectively connected to a metal outlet tube, and the metal outlet tube extends from the glass tube to the two ports of the glass tube, so that the metal outlet tube at both ends and the metal suction tube The heat pipe bundles together form a heat exchange medium passage opening at both ends. The diameter of the metal outlet pipe is larger than the diameter of the single metal heat pipe, but is much smaller than the diameter of the metal heat absorbing fin.

[18] In the present invention, the glass tube port is sealed with a metal koving cover, and a metal bellows is respectively disposed outside the metal outlet tube at the two ends, and a port and a metal outlet tube of the metal bellows are respectively disposed. The seals are welded together and the other port is welded to the metal slab.

[19] In the invention, the metal bellows described above is located in the glass tube.

[20] In the present invention, the metal heat absorbing fins are made of aluminum or copper.

[21] In the present invention, an anti-reflection film is prepared on the inner surface and/or the outer surface of the associated vacuum glass tube to enhance the transmittance of sunlight and improve the heat collection efficiency.

[22] In the present invention, the surface of the metal heat absorbing body is plated with a solar selective absorbing coating.

With the above structure of the present invention, the effect of the solar vacuum heat collecting tube of the present invention is remarkable: 1) the metal heat absorbing body is formed by the cylindrical metal heat absorbing fin and the metal heat absorbing tube bundle, and the metal heat absorbing body The diameter of the cylinder can be prevented from being limited by the fluid capacity, and can be made as large as possible, thereby contributing to the concentrating and concentrating efficiency of the concentrating solar energy receiving device, and improving the heat collecting efficiency of the solar vacuum heat collecting tube. 2) Since the heat exchange medium is only accommodated in each metal heat absorbing tube of the metal heat absorbing tube bundle, the capacity of the heat exchange medium is greatly reduced, thereby improving the heat exchange efficiency of the heat exchange medium. 3) Since the overall capacity of the heat exchange medium is greatly reduced, the diameter of the corresponding metal outlet tube that is connected to both ends of the metal heat absorbing tube bundle can be much smaller than the diameter of the metal heat absorbing fin, thereby having a smaller outlet diameter. Make glass sealing more reliable, improve yield and service life. 4) Since the cylindrical metal heat absorbing fin does not need to displace the heat medium, the required strength is greatly reduced, so that the metal heat absorbing fin can be made of a metal material having high heat conductivity, such as aluminum or copper, thereby Metal The temperature difference between the upper and lower sides of the heat absorbing body is reduced, and the influence of the deformation is greatly eliminated or reduced, so that the length of the solar vacuum heat collecting tube can be increased as needed, and the temperature of the heated heat exchange medium can be increased.

Country deletion

[24] FIG. 1 is a schematic longitudinal sectional structural view of a solar vacuum heat collecting tube of the present invention;

[25] FIG. 2 is a schematic cross-sectional structural view of a solar vacuum heat collecting tube of the present invention;

[26] FIG. 3 is an enlarged view of a portion A of FIG. 2 of the present invention;

[27] FIG. 4 is another schematic cross-sectional structural view of the solar vacuum heat collecting tube of the present invention;

[28] FIG. 5 is a schematic cross-sectional structural view of a solar vacuum heat collecting tube of the present invention.

difficult

As shown in FIG. 1 to 5, the basic structure of the solar vacuum heat collecting tube of the present invention is the same as that of the existing solar vacuum tube, and includes a vacuum glass tube 1 and a metal heat absorbing body disposed inside the vacuum glass tube 1. 2. The outer surface of the metal heat absorbing body 2 is plated with a solar selective absorbing coating 21. The key point of the present invention is that, in the present invention, the metal heat absorbing body 2 comprises: a metal heat absorbing tube bundle having two or more metal heat absorbing tubes 22 disposed in parallel with the axis of the glass tube 1; The heat absorbing fins 23 are formed in a cylindrical shape extending in the axial direction of the vacuum glass tube 1, and are heat-exchanged with the metal heat absorbing tubes 22. Thus, it is only necessary to replace the heat medium in each of the metal heat absorbing tubes 22, and the diameter of the metal heat absorbing fins 23 can be prevented from being limited by the fluid capacity of the heat exchange medium, and can be made as large as possible, thereby greatly improving the solar vacuum set. The heat collecting efficiency of the heat pipe. And for the same diameter solar vacuum heat collecting tube, the sum of the capacities of the heat exchange medium in all the metal heat absorbing tubes 22 of the present invention is far less than the heat exchange medium capacity of the conventional single-tube metal heat absorbing body, thereby greatly improving The heat exchange efficiency.

As shown in FIG. 2, FIG. 4 and FIG. 5, in the present invention, the metal heat absorbing fins 23 can be bent inwardly from the outside to form a groove 231, and the metal heat absorbing tube 22 is embedded. The recess 231 is disposed in the recess 231 to form a heat exchange connection with the metal heat absorbing fins 23.

As shown in FIG. 2, FIG. 4 and FIG. 5, as a preferred manner, the shape of the groove 231 can be consistent with the outer contour of the metal heat absorbing tube 22, so that the metal heat absorbing tube 22 is formed. It can be closely adhered to the groove 231 to form a better heat exchange effect. In the present invention, the metal heat absorbing tube 22 can be engaged with the groove 231 by any heat exchange connection, and the specific connection manner can be unrestricted as long as the heat exchange effect between them can be ensured. For example, the metal heat absorbing tube 22 can be tightly crimped or welded into the recess 231 of the metal heat absorbing fin 23 to form a heat exchange connection with the outer wall of the recess 231. Of course, the metal heat absorbing tube 22 can also be bonded to the groove 231 by a high temperature thermal conductive adhesive to form a heat exchange connection with the outer wall of the recess 231.

As a preferred embodiment, as shown in Fig. 2, the metal heat absorbing fins 23 may be formed in a cylindrical shape substantially coaxial with the glass tube 1.

[33] In the present invention, as shown in FIG. 1, the two ends of the metal heat absorbing tube bundle can be respectively connected to a metal outlet tube 24, and the metal outlet tube 24 extends from the glass tube 1 to the glass tube 1. The two ports, so that the metal outlet tube 24 at the two ends together with the metal heat absorbing tube bundle constitute a heat exchange medium passage opening at both ends, and the heat exchange medium can enter the heat exchange medium passage from one end thereof for heat exchange, and after being heated Output from the other end. The diameter of the metal outlet tube 24 and the total amount of the heat exchange medium in the entire metal heat absorbing tube 22 of the metal heat absorbing tube bundle The flow is adapted. Since the total capacity of the heat exchange medium in the entire metal heat absorption tube 22 is much smaller than the internal capacity of the cylindrical metal heat absorption fins, the diameter of the metal outlet tube 24 will be larger than the diameter of the single metal heat absorption tube 22. However, it is much smaller than the diameter of the metal heat absorbing fin 23. Thus, compared with the conventional solar vacuum heat collecting tube having a single metal heat absorbing tube, the metal outlet tube of the present invention has a smaller sealing interface diameter, thereby making the glass sealing more reliable and improving the solar vacuum heat collecting tube. Yield and service life.

[34] In the present invention, as shown in FIG. 1, the glass tube 1 port is sealed with a metal koving cover 3, and a metal bellows 4 is respectively disposed outside the metal outlet tube 24 at the two ends. One port 41 of the metal bellows 4 is sealingly welded to the metal outlet tube 24, and the other port 42 is welded to the metal koving cover 3 to form a sealed environment within the glass tube 1. The glass tube 1 is evacuated and placed in a getter to maintain the degree of vacuum in the glass tube 1 to prevent heat loss. The metal kovar cover 3 can be sealed and sealed with the glass tube 1 by a molten metal or heat sealing method. Since the metal bellows 4 has a certain degree of flexibility, it can absorb the expansion deformation well, thereby eliminating the adverse effects between the glass tube 1 and the metal heat absorbing body 2 due to the difference in temperature and material expansion characteristics.

As shown in Fig. 1, in the present invention, the above-described metal bellows 4 is located in the glass tube 1.

[36] In the present invention, since the cylindrical metal heat absorbing fins 23 do not need to displace the heat medium, the required strength is greatly reduced, so that the metal heat absorbing fins 23 can be made of a metal material having high heat conductivity. For example, aluminum or copper, so that the temperature difference between the upper and lower sides of the metal heat absorbing body 2 is reduced, the influence of deformation is greatly eliminated or weakened, and the length of the solar vacuum heat collecting tube can be increased as needed to increase the temperature of the heat exchange medium heated. The solar vacuum heat collecting tube of the present invention may have a length of 4 m, 6 m or more.

[37] In the present invention, as shown in FIG. 2, an anti-reflection film 11 may be prepared on the inner surface and/or the outer surface of the associated vacuum glass tube 1 to enhance the transmittance of sunlight and improve the heat collection efficiency. . Fig. 2 shows an example in which an anti-reflection film is prepared on both the inner surface and the outer surface of the vacuum glass tube 1.

[38] In the present invention, the number of metal heat absorbing tubes 22 of the metal heat absorbing tube bundle can be determined according to actual needs, as shown in FIG. 5, which is an example of having two metal heat absorbing tubes 22; 3 and FIG. 4 are examples of having four metal heat absorbing tubes 22.

[39] In the present invention, the plurality of metal heat absorbing tubes 22 may be evenly distributed on the outer surface of the cylindrical metal heat absorbing fins 23, as shown in FIGS. 2 and 5; or, according to sunlight The plurality of metal heat absorbing tubes 22 may be unevenly distributed on the outer circumference of the cylindrical metal heat absorbing fins 23 to achieve a better heat collecting effect, depending on the irradiation angle and the condensing area of the concentrator.

The above-described embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.

Claims

[I] i, a solar vacuum heat collecting tube, comprising: a vacuum glass tube and a metal heat absorbing body disposed in the vacuum glass tube, wherein the metal heat absorbing body comprises: a metal heat absorbing tube bundle , having two or more metal heat absorbing tubes parallel to the axis of the glass tube; the metal heat absorbing fins are formed into a cylindrical shape extending along the axial direction of the vacuum glass tube, and are heat-exchanged with the metal heat absorbing tube.

[2] 2. The solar vacuum heat collecting tube according to claim 1, wherein the metal heat absorbing fin is bent inwardly from the outer side to form a groove, and the metal heat absorbing tube is embedded in the In the groove, a heat exchange connection is formed with the metal heat absorbing fin.

[3] 3. The solar vacuum heat collecting tube according to claim 2, wherein the shape of the groove coincides with an outer contour of the metal heat absorbing tube.

[4] 4. The solar vacuum heat collecting tube according to claim 2, wherein the metal heat absorbing tube is tightly crimped or welded into the groove of the metal heat absorbing fin.

[5] The solar vacuum heat collecting tube according to claim 1, wherein the metal heat absorbing fin is formed in a cylindrical shape substantially coaxial with the glass tube.

[6] 6. The solar vacuum heat collecting tube according to claim 1, wherein the two ends of the metal heat absorbing tube bundle are respectively connected to a metal outlet tube, and the metal outlet tube extends from the glass tube to the glass tube. The two ports, so that the metal outlet tubes at both ends together with the metal heat absorbing tube bundle constitute a heat exchange medium passage opening at both ends.

[7] 7. The solar vacuum heat collecting tube according to claim 6, wherein the diameter of the metal outlet tube is larger than the diameter of the single metal heat absorbing tube, and smaller than the diameter of the metal heat absorbing fin.

[8] 8. The solar vacuum heat collecting tube according to claim 6, wherein the glass tube port is sealed with a metal koving cover, and metal corrugations are respectively disposed outside the metal outlet tubes at the two ends. In the tube, one port of the metal bellows is sealed and welded to the metal outlet tube, and the other port is welded to the metal cantilever cover.

[9] 9. The solar vacuum heat collecting tube according to claim 8, wherein said metal bellows is located in said glass tube.

[10] The solar vacuum heat collecting tube according to claim 1, wherein the metal heat absorbing fins are made of aluminum or copper.

[I I] 11. The solar vacuum heat collecting tube according to claim 1, wherein an anti-reflection film is prepared on an inner surface and/or an outer surface of the associated vacuum glass tube.

[12] 12. The solar vacuum heat collecting tube according to claim 1, wherein a surface of the metal heat absorbing body is coated with a solar selective absorbing coating.