Solar medium-high temperature evacuated collector tube sealed by glass and metal in high-temperature hot melting mode

Abstract

The invention discloses a solar medium-high temperature vacuum heat collecting tube sealed by glass and metal in a high-temperature hot melting mode, and belongs to the technical field of solar vacuum heat collecting tubes, the solar medium-high temperature vacuum heat collecting tube comprises a high borosilicate glass tube body, and a metal heat conduction tube is arranged in the high borosilicate glass tube body. The copper connecting piece is processed into a cutting edge shape, then glass beads are fully hung in a glass high-temperature molten state, the glass bead hanging copper connecting piece and the outer cover glass tube are sealed in a melting mode at high temperature, and then double holes in the top of the glass bead hanging copper connecting piece and the heat conduction tube in the tube are sealed in a high-temperature brazing mode. Residual gas in the vacuum interlayer and gas released in the operation process can be absorbed through the non-evaporable getter arranged at the tail of the heat conduction pipe, the vacuum degree is maintained, convection heat loss is reduced, the high borosilicate glass pipe body and the hanging bead copper connecting piece are directly sealed at high temperature, transition glass is not needed, the production cost is reduced, the vacuum degree can be kept all the time, and the service life is prolonged. The service life is greatly prolonged, and market popularization is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of solar vacuum heat collecting tubes, and in particular relates to a solar medium- and high-temperature vacuum heat collecting tube sealed by high-temperature heat fusion of glass and metal. Background Art

[0002] As global energy supply issues become increasingly prominent and sustainable development strategies are actively promoted, solar energy, as a clean and renewable energy source, is increasingly used in the energy field.

[0003] Solar high-temperature collector tubes are the core components of solar thermal utilization systems, and their performance directly affects the efficiency and stability of solar thermal utilization. Currently, there are two sealing methods for solar vacuum high-temperature collector tubes on the market: the first is glass-metal cobalt high-temperature sealing technology. Due to the different expansion coefficients of high borosilicate glass and metal cobalt, they cannot be directly sealed with metal cobalt. 3 to 5 transition glasses are required for transition, and then they are butt-sealed with high borosilicate glass. However, transition glass is expensive and has high manufacturing costs, which is not conducive to market promotion. Moreover, transition glass is brittle and easily breaks on windy days. The second is high-temperature hot pressing sealing technology. High borosilicate glass and metal cobalt are sealed with aluminum wire or lead wire. High temperature and high pressure are used to seal the glass flange of high borosilicate glass and metal cobalt into one. However, due to the low melting point of aluminum wire and lead wire, air leakage is easy to occur during high-temperature operation (the operating temperature of high-temperature solar collector tubes is 300℃~500℃), and the vacuum state cannot be maintained, thereby reducing the service life and heat collection efficiency.

[0004] In order to solve the above problems, after research and through technical improvements, we have designed a solar high-temperature collector tube with high heat collection efficiency, low production cost, long service life, and an operating temperature range of 300℃ to 500℃. This collector tube can generate great social benefits and can be promoted and applied on a large scale. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a solar medium- and high-temperature vacuum heat collecting tube using glass and metal high-temperature heat sealing, comprising a high borosilicate glass tube body, a metal heat conducting tube disposed within the high borosilicate glass tube body, and a vacuum layer disposed between the high borosilicate glass tube body and the metal heat conducting tube; The head end of the metal heat pipe is brazed with a copper connector with a hanging bead, one end of which is processed into a knife edge shape, and the inner and outer walls of the copper connector blade edge are hung with glass beads in a high-temperature molten state, and then directly sealed with the head of the high-borosilicate glass body at a high temperature; A U-shaped tube is provided at one end of the metal heat-conducting tube, and the U-shaped tube and the metal heat-conducting tube are welded together in a one-to-one correspondence. The outer wall of the metal heat-conducting tube is provided with a wave heat-collecting surface 1, and the outer wall of the metal heat-conducting tube is provided with a heat-collecting surface plated with a heat-absorbing film. The absorption ratio of the heat-collecting surface plated with the heat-absorbing film is 94%, and the emission ratio is 6%. The vacuum degree in the vacuum layer is 3×10 -6 pa, the two conduits of the metal heat-conducting pipe pass through the copper connector and are sealed by brazing, and the tail ends of the metal heat-conducting pipe are respectively provided with an evaporable getter and a non-evaporable getter.

[0006] The innovative technical solution adopted to solve the above technical problems is: abandoning the traditional metal and transition glass structure, and using high borosilicate glass and hanging bead copper parts for direct sealing. One end of the hanging bead copper connector is processed into a blade edge shape, and the flexibility of the pure copper thin wall offsets the thermal expansion stress of the glass and copper. No transition glass is required. The material cost of a small copper tube connector is much lower than that of 5 transition glasses, and multiple transition glass sealing processes are eliminated, which reduces production costs. The shortcomings of transition glass being brittle and easy to break in windy weather are abandoned. The blade structure shape can convert linear expansion stress into local elastic deformation, thereby improving the thermal shock resistance of the interface. A non-evaporable getter is set at the tail end of the metal heat pipe to continuously absorb residual gas in the vacuum layer and gas released during operation to maintain the vacuum degree. The brazing temperature is higher than the operating temperature, which can ensure that the sealing contact surface is stable at high temperatures.

[0007] Furthermore, the blade edge of the copper connector has a shape length of 3mm to 5mm, and the blade edge of the copper connector is wrapped with glass.

[0008] Through the above technical solution, the glass-wrapped structure forms a glass-copper-glass composite sealing interface, which improves the airtightness of the device and enables it to withstand thermal cycles.

[0009] Furthermore, the outer surface of the metal heat-conducting pipe is in a wave shape, and the metal heat-conducting pipe is formed by extruding an aluminum ingot through an open mold at high temperature.

[0010] Furthermore, the length of the U-shaped tube is 5 cm to 7 cm, and the outer surface of the wavy metal heat-conducting tube of the high borosilicate glass tube body is coated with a heat-absorbing film.

[0011] Furthermore, an exhaust pipe is provided at the tail of the high borosilicate glass tube body, and a fixing piece is provided on the side surface of the metal heat conducting tube, and the side surface of the fixing piece is in contact with the inner wall of the high borosilicate glass tube body.

[0012] Through the above technical solution, the exhaust pipe at the tail of the high borosilicate glass tube body can accurately control the exhaust process of the vacuum interlayer.

[0013] Furthermore, a metal spring sheet is provided on the side surface of the metal heat pipe, on which evaporable getter and non-evaporable getter are placed, and the side surface of the metal spring sheet contacts the inner wall of the high borosilicate glass tube body.

[0014] The beneficial effects of the present invention are as follows: (1) By processing the copper pipe connector into a knife-edge shape and then evenly covering it with liquid glass beads in a high-temperature molten state, and then brazing it with other components after cooling, the thin-walled flexibility of the pure copper parts is fully utilized to offset the stress generated by the different thermal expansion coefficients of glass and copper, greatly extending the service life of the device; (2) The metal heat pipe head end and the beaded copper pipe fitting, and the upper end of the borosilicate glass tube body and the beaded copper pipe connector are sealed by brazing, and a non-evaporable getter is set at the tail end of the metal heat pipe to absorb the residual gas inside the vacuum interlayer and the gas released during operation, maintain the vacuum degree, and prevent air convection in the vacuum interlayer of the high-temperature heat collecting tube, thereby preventing heat loss; (3) The borosilicate glass tank body and the copper connector are directly sealed without the need for transition glass, which reduces production costs, is conducive to market promotion, and eliminates the disadvantage of transition glass being brittle and easy to break. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a first-view structural diagram of a solar medium- and high-temperature vacuum heat collecting tube sealed with glass and metal at high temperature according to the present invention; Figure 2 This is a diagram showing the structure of a borosilicate glass tube body of a solar medium- and high-temperature vacuum heat collecting tube that uses glass and metal high-temperature heat sealing according to the present invention; Figure 3 This is a partial structural diagram of a solar medium- and high-temperature vacuum heat collecting tube sealed with glass and metal at high temperature according to the present invention; Figure 4 This is a schematic diagram of a metal spring piece of a solar medium- and high-temperature vacuum heat collecting tube sealed with glass and metal at high temperature heat; Figure 5 yes Figure 1 Schematic diagram of the middle BB; Figure 6 This is another structural diagram of a solar medium- and high-temperature vacuum heat collecting tube sealed with glass and metal at high temperature according to the present invention; Figure 7 It is a cross-sectional view of a solar medium- and high-temperature vacuum heat collecting tube sealed by high-temperature heat fusion of glass and metal according to the present invention.

[0016] Figure numerals: 1. borosilicate glass tube body; 2-1. wave heat collecting surface 1; 2-2. heat collecting surface coated with heat absorbing film; 3. vacuum layer; 4. metal heat conducting pipe; 5. copper connector; 6. U-shaped tube; 7. fixing piece; 8. metal spring sheet. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] like Figure 1-Figure 7 As shown, the present embodiment is a solar medium- and high-temperature vacuum collector tube that adopts high-temperature heat sealing of glass and metal, including a high-borosilicate glass tube body 1, a metal heat-conducting pipe 4 is arranged in the high-borosilicate glass tube body 1, a vacuum layer 3 is arranged between the high-borosilicate glass tube body 1 and the metal heat-conducting pipe 4, and an exhaust pipe is arranged at the tail of the high-borosilicate glass tube body 1. The vacuum layer 3 can be evacuated through the exhaust pipe and the vacuum pumping equipment. After the vacuum is evacuated, the exhaust tail pipe is sealed at high temperature to ensure that the vacuum degree of the vacuum layer 3 is stable for a long time.

[0019] The head end of the metal heat pipe 4 is brazed with a copper connector 5. One end of the copper connector 5 is processed into a knife-edge shape. The inner and outer walls of the knife-edge of the copper connector 5 are directly sealed with the high borosilicate glass tube body 1. The length of the knife-edge shape of the copper connector 5 is 3mm to 5mm. The knife-edge of the copper connector 5 is wrapped by glass. The glass-wrapped structure forms a "glass-metal-glass" composite sealing interface, which improves the airtightness of the device and enables it to withstand multiple thermal cycles. Two copper tubes of the same diameter are brazed at the head end of the metal heat pipe 4, which is convenient for brazing and sealing with the glass bead copper connector 5.

[0020] Abandoning the traditional structure of metal and transition glass, high borosilicate glass and copper are directly sealed. One end of the copper connector 5 is processed into a knife-edge shape. The thermal expansion stress of glass and copper is offset by the flexibility of the thin wall. No transition glass is required. The cost of copper material is much lower than that of transition glass, and multiple transition glass sealing processes are eliminated, which reduces production costs and breaks through the expansion coefficient matching limitation of traditional metal-glass sealing. The copper connector 5 is a knife-edge circular tubular structure with a thin edge and a thick end. Under high temperature conditions, when the high borosilicate glass is in a molten state, the high-temperature red copper connector 5 is infiltrated so that it is evenly covered inside and outside the copper connector 5. It is then slowly cooled naturally and used. This process is called the glass bead hanging process.

[0021] A U-shaped tube 6 is provided at one end of the metal heat-conducting tube 4. The blade structure can convert the linear expansion stress into local elastic deformation, thereby improving the thermal shock resistance of the interface. The blade edge design realizes the dual functions of "flexible sealing + stress unloading" to avoid cracking caused by the lack of stress unloading structure. The length of the U-shaped tube 6 is 5 cm to 7 cm. The U-shaped tube 6 is welded to the metal heat-conducting tube 4 in a one-to-one correspondence. The outer wall of the metal heat-conducting tube 4 is provided with a wavy heat-collecting surface 2-1. The outer wall of the metal heat-conducting tube 4 is provided with a heat-collecting surface plated heat-absorbing film 2-2. The absorption ratio of the heat-collecting surface plated heat-absorbing film 2-2 is 94%, the emission ratio is 6%, and the emission ratio is 6%. The vacuum degree in the vacuum layer 3 is 3×10 -6 pa, the head end of the high borosilicate glass tube body 1 and the beaded copper connector 5 are sealed by brazing, and the two conduits of the metal heat pipe 4 pass through the copper connector 5 and are sealed by brazing. The tail end of the metal heat pipe 4 is respectively provided with an evaporable getter and a non-evaporable getter, which continuously absorb the residual gas in the vacuum layer 3 and the gas released during operation to maintain the vacuum degree. The brazing temperature of 600℃-700℃ is higher than the operating temperature, which can ensure that the sealing contact surface is stable at high temperature and avoid the low melting point of aluminum and lead wire in other technologies, which leads to sealing failure during high-temperature operation.

[0022] The outer surface of the metal heat-conducting pipe 4 is wavy. The metal heat-conducting pipe 4 is formed by high-temperature extrusion of an aluminum ingot through an open mold. A fixing part 7 is provided on the side surface of the metal heat-conducting pipe 4. The side surface of the fixing part 7 contacts the inner wall of the high borosilicate glass tube body 1. The outer diameter of the fixing part 7 holds the inner wall of the high borosilicate glass tube body 1 tightly, limiting the axial movement of the metal heat-conducting pipe 4, ensuring that the metal heat-conducting pipe 4 and the U-shaped pipe 6 maintain a stable stress unloading state during the thermal cycle, avoiding sealing failure caused by displacement deviation. The outer surface of the wavy metal heat-conducting pipe 4 of the high borosilicate glass tube body 1 is coated with a heat-absorbing film. The heat-absorbing film layer determines the medium and high temperature heat collection capacity. The absorption ratio is ≥94%, and the reflectance is ≤6%. An exhaust pipe is provided at the tail of the high borosilicate glass tube body 1, and the exhaust pipe is connected to the exhaust equipment. When the vacuum is fully evacuated and the vacuum degree reaches 3*10Pa, the tail pipe is sealed in a high-temperature molten state to make the high borosilicate glass tube body 1 in a vacuum state, and finally baked for mirror finish treatment. A fixing part 7 is provided on the side surface of the metal heat-conducting pipe 4, and the side surface of the fixing part 7 is in contact with the inner wall of the side of the high borosilicate glass tube body 1. A metal spring piece 8 is provided on the side surface of the metal heat-conducting pipe 4, and a getter is placed on it. The side surface of the metal spring piece 8 is in contact with the inner wall of the side of the high borosilicate glass tube body 1.

[0023] The working principle of this embodiment is as follows: when solar radiation shines on the device, sunlight first shines on the high borosilicate glass tube body 1. The heat-absorbing film absorbs the light, causing the temperature of the metal heat pipe 4 to rise. The vacuum layer 3 reduces heat loss by blocking the air. The beaded copper connector 5 is processed into a 3-5mm long blade edge and is directly sealed with the high borosilicate glass tube body 1. The flexibility of the thin copper wall offsets the stress caused by the difference in thermal expansion coefficient between glass and copper, avoiding cracking at the sealed interface. The metal spring sheet 8 restricts the movement of the metal heat pipe 4 to ensure structural stability.

[0024] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A solar medium- and high-temperature vacuum heat collecting tube using glass and metal high-temperature heat sealing, characterized by: It comprises a high borosilicate glass tube body (1), a metal heat conducting pipe (4) is arranged in the high borosilicate glass tube body (1), and a vacuum layer (3) is arranged between the high borosilicate glass tube body (1) and the metal heat conducting pipe (4); The head end of the metal heat conducting pipe (4) is brazed and connected to a copper connector (5) with a hanging bead, one end of the copper connector (5) is processed into a knife edge shape, and the inner and outer walls of the knife edge of the copper connector (5) are hung with glass beads in a high-temperature molten state, and then directly sealed with the head of the high-borosilicate glass body (1) at a high temperature; A U-shaped tube (6) is provided at one end of the metal heat conducting tube (4), and the U-shaped tube (6) and the metal heat conducting tube (4) are welded together in a one-to-one correspondence. The outer wall of the metal heat conducting tube (4) is provided with a wave heat collecting surface (2-1), and the outer wall of the metal heat conducting tube (4) is provided with a heat collecting surface plated heat absorbing film (2-2). The absorption ratio of the heat collecting surface plated heat absorbing film (2-2) is 94%, and the emission ratio is 6%. The vacuum degree in the vacuum layer (3) is 3×10 -6 pa, the two conduits of the metal heat-conducting pipe (4) pass through the copper connector (5) and are sealed by brazing, and the tail end of the metal heat-conducting pipe (4) is welded with a metal spring sheet (8).

2. The solar medium- and high-temperature vacuum heat collecting tube using glass and metal high-temperature heat sealing according to claim 1, characterized in that: The copper connector (5) has a blade edge shape with a length of 3 mm to 5 mm, and the blade edge of the copper connector (5) is wrapped with glass.

3. The solar medium- and high-temperature vacuum heat collecting tube using glass or metal high-temperature heat sealing according to claim 1, characterized in that: The outer surface of the metal heat-conducting pipe (4) is in a wave shape, and the metal heat-conducting pipe (4) is formed by extruding an aluminum ingot through an open mold at high temperature.

4. The solar medium- and high-temperature vacuum heat collecting tube using glass and metal high-temperature heat sealing according to claim 1, characterized in that: The length of the U-shaped tube (6) is 5 cm to 7 cm, and the outer surface of the wavy metal heat-conducting tube of the high borosilicate glass tube body (1) is coated with a heat-absorbing film.

5. The solar medium- and high-temperature vacuum heat collecting tube using glass or metal high-temperature heat sealing according to claim 1, characterized in that: An exhaust pipe is provided at the tail of the high borosilicate glass tube body (1), and a fixing piece (7) is provided on the side surface of the metal heat conducting tube (4), wherein the side surface of the fixing piece (7) contacts the inner wall of the high borosilicate glass tube body (1).

6. The solar medium- and high-temperature vacuum heat collecting tube using glass or metal high-temperature heat sealing according to claim 1, characterized in that: The side surface of the metal heat conducting pipe (4) is provided with a metal spring sheet (8), on which an evaporable getter and a non-evaporable getter are placed, and the side surface of the metal spring sheet (8) is in contact with the inner wall of the high borosilicate glass tube body (1).

Images