Cover glass tube metal brazing groove end cover straight through pressure photovoltaic power generation heat collecting vacuum tube

Abstract

The application discloses a cover glass tube metal brazing groove end cover straight-through pressure-bearing photovoltaic power generation heat collecting vacuum tube, which comprises an outer cover glass tube, a high-temperature-resistant photovoltaic cell assembly, a wire, an electrically insulating heat-conducting adhesive, an inner straight-through metal pressure-bearing photovoltaic power generation heat collecting tube, a glass metal brazing sealing electrode, a gas absorber, a metal bellows expansion joint and a glass metal brazing sealing electrode. The inner straight-through metal pressure-bearing photovoltaic power generation heat collecting tube is an inner straight-through metal pressure-bearing photovoltaic power generation heat collecting tube with two open ends. The high-temperature-resistant photovoltaic cell assembly is bonded and combined on the electrically insulating heat-conducting adhesive through the electrically insulating heat-conducting adhesive. The inner straight-through metal pressure-bearing photovoltaic power generation heat collecting tube is positioned and installed in the outer cover glass tube head provided with the glass metal brazing sealing electrode through the metal bellows expansion joint. The high-temperature-resistant photovoltaic cell is connected with the glass metal brazing sealing metal electrode through the wire. The outer cover glass tube opening and the inner straight-through metal pressure-bearing photovoltaic power generation heat collecting tube opening are closed through annular brazing of a brazing metal end cover and the metal bellows expansion joint.

Description

Technical Field

[0001] This invention belongs to the field of solar energy application technology, and specifically relates to a glass tube with a metal brazed groove end cap that is directly connected to a pressure-bearing photovoltaic power generation heat collection vacuum tube. Background Technology

[0002] In the field of solar energy application technology, the sealing technology between borosilicate glass or quartz glass and metal has been widely applied in the manufacturing of solar collector tubes and has become a key technology for medium- and high-temperature solar metal-based pressure vacuum collector tubes. For medium- and high-temperature solar metal-based pressure vacuum collector tubes, the sealing between the borosilicate glass or quartz glass and the metal tube is crucial. This technology must not only ensure a certain vacuum level in the medium- and high-temperature solar metal-based pressure vacuum collector tube, but also meet the quality requirements caused by the large diurnal temperature variations resulting in thermal expansion and contraction. However, sealing borosilicate glass or quartz glass with metal involves sealing dissimilar materials. Due to the significant differences in their physical properties, their connection presents many difficulties, resulting in very limited connection methods.

[0003] Medium- and high-temperature solar metal-pressurized vacuum collector tubes, consisting of a central tube with a selective absorption coating and an outer borosilicate glass or quartz glass sleeve, are the core components of a solar thermal collector system. Their reliability and optical performance largely determine the efficiency of the entire system. To protect the selective absorption coating and reduce heat loss, a vacuum must be evacuated between the central tube and the borosilicate glass or quartz glass sleeve. Furthermore, these tubes are required to have a service life of up to 20 years, which places high demands on the quality of the metal sealing between the borosilicate glass and the quartz glass.

[0004] The structure of a medium- and high-temperature solar metal pressure vacuum collector tube consists of a metal tube coated with a selective absorption coating in the middle, and a high borosilicate glass or quartz glass tube that is concentric with the metal tube and is fitted around the outside of the metal tube. Since the thermal expansion coefficients of the metal tube and the high borosilicate glass or quartz glass tube are very different, a special metal bellows expansion joint is required between the two to buffer the deformation caused by temperature. One end of the metal bellows expansion joint is welded to the metal tube through a metal annular groove end cap, and the other end is welded to a metal ring that is sealed together with the high borosilicate glass or quartz glass at one end through a metal annular groove end cap.

[0005] Traditional sealing processes for borosilicate glass or quartz glass with metal employ flame sealing. This method generally requires a very close match between the expansion coefficients of the metal and the borosilicate glass or quartz glass (error less than 6%), making the sealing process quite challenging. Another approach to flame sealing involves using borosilicate glass or quartz glass with mismatched expansion coefficients and metal. However, the metal needs to be thinned to less than 0.1 mm to release the sealing stress. This sealing method, due to the excessively thin metal, leads to a significant reduction in the mechanical strength of the sealed component, and its reliability requires further verification.

[0006] Besides flame sealing, patent CN1262248A proposes a hot-press sealing process for high borosilicate glass or quartz glass with metal. This process utilizes solid-state welding to seal high borosilicate glass or quartz glass and metal together, achieving a vacuum seal. The key feature is that the welding is performed under heating and pressure, with the welding temperature typically 0.7-0.9 times the melting point of the solder. This method primarily uses lead as the solder, with a maximum operating temperature below 200℃. Therefore, lead-sealed vacuum collector tubes can only be applied to medium-temperature solar thermal utilization. Later attempts to use aluminum as the solder in hot-press sealing technology resulted in high residual stress after sealing and a low yield.

[0007] For example, the utility model title is: Glass-Metal Sealing Component and Solar Vacuum Collector Tube, application number CN201720314163.6, authorization announcement number CN206648325U, and authorization announcement date 20171117. This utility model discloses a glass-metal sealing structure for a solar vacuum collector tube, belonging to the field of glass and metal technology. The sealing method employs a heat-sealing technique, where one end of a metal ring is embedded inside the glass tube and concentric with it. The expansion coefficients of the glass tube and the metal ring are similar, allowing for direct heat sealing. To ensure successful sealing of the glass tube and metal ring, this utility model uses a heat-sealing technique that requires their expansion coefficients to be similar.

[0008] To ensure that the coefficients of thermal expansion of the glass and the metal are similar, the metal ring is made of Kova alloy with a coefficient of thermal expansion ranging from 4.0 to 5.5 × 10⁻⁶ mm / ℃, and its main components are nickel, cobalt, and iron; the glass tube is made of borosilicate glass with a coefficient of thermal expansion ranging from 3.3 to 5.5 × 10⁻⁶ mm / ℃.

[0009] The sealing structure significantly reduces production costs while ensuring sealing strength and resistance to thermal shock. However, it has been proven that the aforementioned patent cannot effectively solve the stress problem caused by the difference in the coefficients of thermal expansion between the two components.

[0010] For example, the invention title is: Vacuum heat collection tube glass-metal sealing process, application number CN00103482.0, authorization announcement number CN1132798C, authorization announcement date 20031231.

[0011] This invention relates to a glass-metal sealing process for vacuum heat collector tubes, comprising the following steps: (1) positioning the Kovar metal to be sealed in contact with the glass; (2) applying high-frequency electromagnetic waves to the Kovar metal to raise its temperature and soften or melt the glass to fuse with the Kovar metal; (3) cooling to solidify the glass, thus completing the sealing of the Kovar metal and the glass. Compared with the prior art, this invention has a simple process, low energy consumption, low cost, and a long service life for the heat collector tubes produced. The glass powder used is brittle glass, with a coefficient of expansion that differs significantly from that of high borosilicate glass, making it extremely prone to cracking and vacuum leakage.

[0012] For example, the invention title is: A Line-Focusing Solar Vacuum Collector Tube, application number CN200610138447.0, authorization announcement number CN101187504B, authorization announcement date 20110316. This invention relates to a linear focusing solar vacuum collector tube, comprising a metal inner tube, a glass outer tube, a glass section tube, a glass sealing end, an iron-nickel-Kovar alloy ring, an internal unloading device bellows, a metal concave end cap, pipe fittings, a high-temperature heat-absorbing coating, an exhaust pipe, and glass sealing material. The invention is characterized in that: the glass sealing end of the linear focusing solar vacuum collector tube is located at one end of the glass section tube; the inner sealing surface of the glass sealing end is fused with the iron-nickel-Kovar alloy ring using low-melting-point microcrystalline glass, forming a connecting component; the glass section tube is fused with the glass outer tube; the iron-nickel-Kovar alloy ring is welded to the metal concave end cap; the iron-nickel-Kovar alloy ring is welded to the internal unloading device bellows; the internal unloading device bellows is argon-arc welded to the metal inner tube via pipe fittings; and the outer interface is argon-arc welded to the metal inner tube. The improved glass tube assembly, the new processing technology for the glass sealing end face, the internal unloading devices on both sides, and the optimized structural design help to improve the connection strength and reliability of the linear focusing solar vacuum collector tube. This also facilitates the use of existing solar vacuum collector tube production technologies and processing equipment. The invention focuses on solving the problems of glass-metal sealing and assembly structure and process optimization in solar vacuum collector tubes. This invention is widely applicable to solar high-temperature collector devices such as trough solar thermal power generation, solar air conditioning, and solar seawater desalination. The inner sealing surface of the glass sealing end is fused with a low-melting-point microcrystalline glass ring using an iron-nickel-Kovar alloy ring, forming a connecting component. Its coefficient of thermal expansion differs significantly from that of high borosilicate glass, making it highly susceptible to cracking and vacuum leakage.

[0013] For example, the invention title is: "A Method for Metal Sealing of Glass in a Medium-Temperature Solar Vacuum Collector Tube," application number CN201510672728.3, authorization announcement number CN105254191B, authorization announcement date 20171226. This invention discloses a method for sealing glass and metal in a medium-temperature solar vacuum collector tube, belonging to the field of glass-metal sealing technology. The sealing method uses Kovar alloy and a glass tube, whose coefficients of thermal expansion differ by no more than 15% within a temperature range from room temperature to 450°C. Glass powder with a coefficient of thermal expansion between the two is used as a transition material to achieve a tight seal between the glass and the metal. This sealing method has high mechanical strength and reliability, is simple to operate, and allows for mass production of Kovar and glass sealing. It is also low-cost and suitable for the field of medium-temperature solar vacuum collector tubes. In this patent, the glass powder used as a transition material is fused with a low-melting-point microcrystalline glass ring at the sealing end of the glass to form a connecting component. The coefficient of thermal expansion differs significantly from that of high borosilicate glass, making it highly susceptible to cracking and vacuum leakage.

[0014] For example, the invention title is: "A Vacuum Brazing Process for Glass and Metal," application number CN200910234678.5, authorization announcement number CN101708964B, and authorization announcement date is August 17, 2011. This invention relates to a vacuum brazing process for glass and metal. This process is simple to manufacture, low in cost, and has good economic benefits. The technical solution of this invention is: a vacuum brazing process for glass and metal, comprising the following steps: 1) surface treatment of the glass and metal workpieces; 2) placing the treated workpieces into a vacuum brazing furnace, evacuating the vacuum furnace, and heating to perform vacuum brazing; characterized in that step 1) includes: roughening and cleaning the glass surface, surface cleaning and smoothing the metal workpieces, and chemical electroplating the glass surface. Step 1.2) chemical electroplating the glass surface to coat the glass workpiece surface with a uniform layer of copper. The treated workpieces are assembled and then placed in a vacuum brazing furnace, evacuated, and heated to perform vacuum brazing: i. the brazing filler metal is pre-placed in the glass-metal welding interface. However, coating the glass workpiece surface with a uniform layer of copper is extremely difficult, and due to the different coefficients of thermal expansion of the metal and glass, durability and reliability are poor.

[0015] Another method on the market uses multiple sections of borosilicate glass or quartz glass as transitions to seal the borosilicate glass or quartz glass with a metal, typically Kovar. The first section of borosilicate glass or quartz glass is matched and sealed with Kovar. The coefficient of thermal expansion of the remaining borosilicate glass or quartz glass decreases sequentially, and after three transition sections, it is finally sealed with a rigid borosilicate glass or quartz glass. This sealing method is relatively complex, and the supply of transition glass is scarce, resulting in higher costs.

[0016] This invention arose from the aforementioned technical background, aiming to achieve low-cost, simple-to-manufacture, and highly reliable glass-metal sealing research. This invention can solve the quality problems of welded joints between high borosilicate glass or quartz glass and metal, is simple to manufacture, low-cost, and can achieve significant economic benefits.

[0017] The metal melting points that can be used in this invention are as follows: (1). The melting point of 100% magnesium is 650℃. (2). The melting point of 100% aluminum is 660.452℃. (3) The melting point of an alloy of 65% aluminum and 35% magnesium is 500℃. (4). The melting point of an alloy of 65% magnesium and 35% aluminum is 437℃. (5) The melting point decreases linearly from 660.452℃ to 500℃ as the magnesium content ranges from 0-35%. (6) The magnesium content ranges from 35% to 65%, and the melting point varies between 500℃ and 437℃. (7) The magnesium content increases linearly from 65% to 100%, and the melting point increases linearly from 437℃ to 650℃. Lead: Melting point 327.46℃; Zinc: Melting point 419.5℃; Copper: Melting point 1083℃; Iron: Melting point 1535℃ Summary of the Invention

[0018] The technical solution adopted by this invention to solve its technical problem is: A glass tube with metal brazed groove end cap and direct-through pressure-bearing photovoltaic heat collection vacuum tube includes an outer glass tube, metal end caps, a metal corrugated pipe expansion joint, metal brazing flux, an inner direct-through pressure-bearing photovoltaic heat collection tube, a high-strength high-temperature resistant electrical insulating adhesive, a high-temperature resistant photovoltaic cell, and a degassing agent. Its characteristic is that the inner direct-through pressure-bearing photovoltaic heat collection tube is open at both ends, and the photovoltaic cell is composited on the surface of the inner direct-through metal tube, forming the inner direct-through pressure-bearing photovoltaic heat collection tube. An inner straight-through metal pressure-bearing photovoltaic heat collector tube and an outer glass tube fitted around the inner straight-through metal pressure-bearing photovoltaic heat collector tube, are installed inside the outer casing glass tube via metal end caps at both ends. Due to the significant difference in thermal expansion coefficients between the metal tube and the high borosilicate glass or quartz glass tube, a dedicated metal bellows expansion joint is required to buffer deformation caused by temperature. Therefore, at least one end of the outer casing glass tube has its metal annular groove end cap opening edge welded to one end of the metal bellows expansion joint, and the other end of the metal bellows expansion joint is metal-welded and sealed to the inner straight-through metal pressure-bearing heat collector tube. The metal pressure-bearing photovoltaic heat collection tube, or equipped with a high thermal resistance elastic clip support, supports the metal corrugated tube expansion joint on the inner wall of the outer glass tube; the metal annular groove end cap is brazed and sealed to the outer glass tube opening through a brazed metal pad; the other end of the outer glass tube opening is brazed and sealed to the metal annular groove end cap through a brazed metal pad; the inner hole of the annular groove thin-walled metal end cap, along the welded metal corrugated tube expansion joint inner hole or tube head, is welded to the opening edge of the metal annular groove end cap through metal welding, and then annularly welded and sealed to the inner straight metal pressure-bearing heat collection tube; The materials used to manufacture the internally straight metal pressure-bearing photovoltaic power generation collector tube are corrosion-resistant, high-temperature resistant, and high-strength metal materials, including copper, carbon steel, and stainless steel. The structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell; or the structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a metal reflective film, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell, such as a gallium arsenide high-temperature resistant photovoltaic cell; the positive and negative electrodes of the high-temperature resistant photovoltaic cell are connected in series, and the electrodes are led out through the glass-metal brazing seal connecting the positive and negative electrodes and then led out through the glass tube wall; The metal end cap is a thin-walled metal end cap with an annular groove. The thin-walled metal end cap is welded to a metal bellows expansion joint. The metal bellows expansion joint has holes or openings for inserting a metal pressure-bearing photovoltaic heat collector tube. The annular groove thin-walled metal end cap is made of corrosion-resistant, high-temperature resistant, and high-strength metal materials, such as stainless steel. The annular groove thin-walled metal end cap is formed by machine tool processing, or by machine tool processing combined with metal welding, or by metal three-dimensional printing. The metal annular groove of the glass-metal brazed seal has the following configurations: one side has a thread that matches the threaded end of a high borosilicate glass tube or a quartz glass tube, and the other side is a smooth annular groove wall, forming a single-sided threaded metal end cap; or the metal annular groove has threads on both sides that match the threaded end of a high borosilicate glass tube or a quartz glass tube, forming a double-sided threaded metal end cap; or the two annular groove walls are smooth annular groove walls, forming a thin-walled metal end cap; or one side of the two annular groove walls is a corrugated annular groove wall, and the other side is a smooth annular groove wall, forming a single-sided corrugated annular groove metal end cap; or both annular groove walls are corrugated annular groove walls, forming a double-sided corrugated annular groove metal end cap. At the bottom of the groove of the annular groove thin-walled metal end cap, there is a brazed metal sealing gasket with a melting point lower than the softening temperature of the high borosilicate glass or quartz outer glass tube and the softening temperature of the annular groove thin-walled metal end cap. The brazed metal inside the annular groove thin-walled metal end cap is a metal that can be liquefied when heated to a set temperature. Low melting point brazed metals include aluminum or aluminum alloys, zinc or zinc alloys, and have a melting point temperature below 720°C, and have good wetting properties with the annular groove thin-walled metal end cap and the high borosilicate glass or quartz outer glass tube head. Kovar metals and alloys; the melting point temperature of the brazing metal is higher than the operating temperature of the heat transfer medium but lower than the softening temperature of the high borosilicate glass tube or quartz glass tube and the annular groove thin-walled metal end cap; the sealing connection glass thread provided on the tube head of the high borosilicate glass tube or quartz glass tube, the brazing metal sealing gasket and the annular groove thin-walled metal end cap are brazed and sealed by heating and melting and then tightening; the annular groove thin-walled metal end cap is brazed by heating with an electromagnetic eddy current heater, or by electric heating, or by heating with an electric heater. When a thin-walled metal end cap with an annular groove is joined to Kovar brazing metal via the threaded opening of a high borosilicate glass tube or a quartz glass tube, and then heated, the Kovar brazing metal melts and is then tightened. During this process, the Kovar brazing metal, the thin-walled metal end cap with an annular groove, and the threaded opening of the high borosilicate glass tube or quartz glass tube will mutually weave and fuse together, becoming a single unit. At the system's normal operating temperature, the threads or corrugations of the groove on the thin-walled metal end cap, combined with the annular groove, effectively absorb the Kovar brazing metal and the high borosilicate glass. The limited thermal expansion and contraction of the threaded end of the outer glass tube or quartz outer glass tube ensures a good seal between the annular groove thin-walled metal end cap and the high borosilicate outer glass tube or quartz outer glass tube through Kovar brazing metal. During the brazing process of Kovar brazing metal such as aluminum with the threaded end of the annular groove thin-walled metal end cap, high borosilicate outer glass tube or quartz outer glass tube, the brazing fusion temperature is below 720℃. At this temperature, the annular groove thin-walled metal end cap, aluminum and high borosilicate outer glass tube or quartz outer glass tube release the dissolved gas at the corresponding temperature. The aluminum at the outer edge of the braze reacts with oxygen in the air to form aluminum oxide. During electrothermal brazing, aluminum conducts electricity and rapidly heats up, becoming liquid aluminum. The high borosilicate glass tube or quartz glass tube brazed with the aluminum end cap reaches its softening temperature (high borosilicate glass begins to soften at approximately 821℃). At 720℃, the main components of the high borosilicate glass tube or quartz glass tube, SiO2 and Al, undergo a chemical reaction: 4Al + 3SiO2 = 2Al2O3 + 3Si. This means that at this point, the interface between the high borosilicate glass tube or quartz glass tube and the aluminum can be firmly bonded due to the chemical reaction. Simultaneously, at 720℃, the stainless steel end cap does not soften (the maximum operating temperature of stainless steel 1Cr18Ni9Ti is 870℃), thus meeting the requirements of the high borosilicate glass tube. The process requirements for brazing glass tubes or quartz outer glass tubes and metals include: A chemical reaction occurs between the metal oxide layer surface of the stainless steel end cap and the aluminum, resulting in a strong bond between the stainless steel end cap and the aluminum interface; The deformation of the metal end cap absorbs the stress caused by thermal expansion and contraction of the aluminum or aluminum alloy, or zinc or zinc alloy brazing material, ensuring the brazing quality between the stainless steel end cap and the high borosilicate outer glass tube or quartz outer glass tube; Due to the "U"-shaped and deep closed-loop metal groove cross-section of the metal end cap, the corresponding closed-loop aluminum or aluminum alloy, or zinc or zinc alloy brazing connection sealing layer is longer, resulting in high brazing strength and good airtight sealing performance between the aluminum or aluminum alloy, or zinc or zinc alloy and the high borosilicate outer glass tube or quartz outer glass tube and the metal end cap. The tube head of the high borosilicate glass tube or the quartz glass tube is connected and sealed by a metal brazing fitting with a thin-walled metal end cap with an annular groove corresponding to its shape and size; or it is threadedly fitted with the corresponding thin-walled metal end cap with an annular groove; and then brazed and sealed with a metal washer to form an annular groove thin-walled metal end cap with a "U"-shaped brazing layer between the outer glass tube head and the annular groove thin-walled metal end cap. The inner hole of the annular groove thin-walled metal end cap is connected to the inner hole of the metal bellows expansion joint or the tube head, and then annularly welded and sealed with the inner straight metal pressure photovoltaic heat collection tube. The high borosilicate glass tube or the quartz glass tube is a conventional outer glass tube, or a solar anti-reflective film is provided on the tube wall of the high borosilicate glass tube or the quartz glass tube, with the solar anti-reflective film laminated on the outer surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on the inner surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on both the inner and outer surfaces of the high borosilicate glass tube or the quartz glass tube. A reflective concentrating mirror is installed on the outer borosilicate glass or quartz glass tube. The reflective concentrating mirror is an internal mirror, which is either a metal reflective concentrating mirror integrated with the outer glass tube wall, or a metal reflective concentrating mirror that is attached to the outer glass tube wall and can slide; or it is a high borosilicate glass or quartz glass reflective concentrating mirror. The cross-section of the reflective concentrating mirror is curved, and the focusing line of the reflective concentrating mirror is an inner straight-through metal pressure-bearing photovoltaic power generation heat collection tube whose surface is a high-temperature resistant photovoltaic cell. The cross-section of the outer borosilicate glass or quartz glass tube is circular, elliptical, or a closed line connecting a curve and an arc. The cross-sections of both ends of the outer borosilicate glass or quartz glass tube gradually change from elliptical or a closed line connecting a curve and an arc to a circle. The tube wall of the high borosilicate glass tube or the quartz glass tube may be equipped with a glass-metal brazed sealed outlet electrode; the electrode output end of the inner straight-through metal pressure-bearing photovoltaic heat collector tube wall is led out through the opening on the brazed sealed end cap of the inner straight-through metal pressure-bearing photovoltaic heat collector tube wall. The end cap is brazed and sealed to the glass threaded nozzle of the inner straight-through metal pressure-bearing photovoltaic heat collector tube wall by brazing metal gasket. After the inner straight-through metal pressure-bearing photovoltaic heat collector tube is connected to the vacuum pump through the brazed electrode end cap, the gap between the electrode and the electrode end cap is sealed by metal welding. This realizes the electrical connection end cap of the inner straight-through metal pressure-bearing photovoltaic heat collector tube, the outlet electrode of the inner straight-through metal pressure-bearing photovoltaic heat collector tube and the metal end cap of the glass nozzle of the outer glass tube, forming an electrical circuit between the positive electrode of the inner straight-through metal pressure-bearing photovoltaic heat collector tube and the negative electrode of the photovoltaic heat collector tube outlet electrode. The inner and outer surfaces of the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube are smooth mounting connection surfaces, or mounting connection surfaces with threads, grooves, or flanges for connection with other devices; after evacuating the annular cavity between the inner and outer tubes through the glass exhaust pipe, the glass is welded closed; or the electrode is sealed by glass-metal brazing, after evacuating the annular cavity between the inner and outer tubes, the electrode is sealed by glass-metal brazing and then welded to the metal end cap; the degassing agent is evaporated to form the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube.

[0019] A pressure-bearing photovoltaic (PV) heat collection vacuum tube with a metal brazed groove end cap and an inner straight-through metal tube includes an outer glass tube, metal end caps, metal brazing flux, an inner straight-through metal pressure-bearing PV heat collection tube, a high-strength, high-temperature resistant electrical insulating adhesive, a high-temperature resistant photovoltaic cell, a degassing agent, and a metal corrugated pipe expansion joint. Its characteristic is that the inner straight-through metal pressure-bearing PV heat collection tube is open at both ends, and the photovoltaic cell is composited on the surface of the inner straight-through metal tube, forming the inner straight-through metal pressure-bearing PV heat collection tube. An inner straight-through metal pressure-bearing photovoltaic heat collector tube and an outer glass tube fitted around the inner straight-through metal pressure-bearing photovoltaic heat collector tube, are installed inside the outer casing glass tube via metal end caps at both ends. Due to the significant difference in thermal expansion coefficients between the metal tube and the high borosilicate glass or quartz glass tube, a dedicated metal bellows expansion joint is required to buffer deformation caused by temperature. Therefore, at least one end of the outer casing glass tube has its metal annular groove end cap opening edge welded to one end of the metal bellows expansion joint, and the other end of the metal bellows expansion joint is metal-welded and sealed to the inner straight-through metal pressure-bearing heat collector tube. The metal pressure-bearing photovoltaic heat collection tube, or equipped with a high thermal resistance elastic clip support, supports the metal corrugated tube expansion joint on the inner wall of the outer glass tube; the metal annular groove end cap is brazed and sealed to the outer glass tube opening through a brazed metal pad; the other end of the outer glass tube opening is brazed and sealed to the metal annular groove end cap through a brazed metal pad; the inner hole of the annular groove thin-walled metal end cap, along the welded metal corrugated tube expansion joint inner hole or tube head, is welded to the opening edge of the metal annular groove end cap through metal welding, and then annularly welded and sealed to the inner straight metal pressure-bearing heat collection tube; The materials used to manufacture the internally straight metal pressure-bearing photovoltaic power generation collector tube are corrosion-resistant, high-temperature resistant, and high-strength metal materials, including copper, carbon steel, and stainless steel. The structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell; or the structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a metal reflective film, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell, such as a gallium arsenide high-temperature resistant photovoltaic cell; the positive and negative electrodes of the high-temperature resistant photovoltaic cell are connected in series, and the electrodes are led out through the glass-metal brazing seal connecting the positive and negative electrodes and then led out through the glass tube wall; The metal end cap is a thin-walled metal end cap with an annular groove. The thin-walled metal end cap is welded to a metal bellows expansion joint. The metal bellows expansion joint has holes or openings for inserting a metal pressure-bearing photovoltaic heat collector tube. The annular groove thin-walled metal end cap is made of corrosion-resistant, high-temperature resistant, and high-strength metal materials, such as stainless steel. The annular groove thin-walled metal end cap is formed by machine tool processing, or by machine tool processing combined with metal welding, or by metal three-dimensional printing. The two ends of the outer glass tube are provided with glass insulation sleeves; the glass insulation sleeves are coaxial corrugated sleeves formed by welding glass between the glass tube openings in sequence, at least one layer, of appropriate length, and coaxially fitted with the outer glass tube; the opening of the corrugated sleeve is provided with an insulation glass sleeve for brazing and sealing connection with the metal end cap; the outer glass tube head of the high borosilicate glass or quartz outer glass tube includes smooth tube head, corrugated tube head, and threaded tube head; the corrugated tube head is corrugated on the outer wall and smooth on the inner wall, or the corrugated tube head is smooth on the outer wall and corrugated on the inner wall, or the corrugated tube head is corrugated on the outer wall and corrugated on the inner wall; or the threaded tube head is threaded on the outer wall and smooth on the inner wall, or the threaded tube head is threaded on the inner wall and smooth on the outer wall, or the tube head is threaded on the outer wall and threaded on the inner wall. A glass tube of appropriate length is formed by hot-melting and pressing glass threads at one end, and then straightening the other end to a fixed length. The threaded glass tube is then annealed. The threaded glass tube is then coaxially fitted and welded to another glass tube, forming at least one layer of glass tube. Glass tube openings are sequentially welded together to form a coaxial insulated glass tube sleeve. Afterwards, an anti-reflective film is either laminated onto the wall of the transparent glass tube, or after laminating the anti-reflective film onto the wall of the transparent glass tube, the glass cover tube is then processed. The end of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is then trimmed and straightened. On the inner wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, there is a composite radial inner tube; the open end or the reducing end and the end trimming of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube; then, the outer tube wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is cleaned and dried; on the outer tube wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, a composite high-temperature resistant photovoltaic cell is tightly bonded; the coaxial heat-insulating glass tube sleeve, the sealing connection glass thread of the coaxial heat-insulating glass tube sleeve is brazed to the metal groove thread end cap with a brazed metal sealing gasket; The metal annular groove of the glass-metal brazed seal has the following configurations: one side has a thread that matches the threaded end of a high borosilicate glass tube or a quartz glass tube, and the other side is a smooth annular groove wall, forming a single-sided threaded metal end cap; or the metal annular groove has threads on both sides that match the threaded end of a high borosilicate glass tube or a quartz glass tube, forming a double-sided threaded metal end cap; or the two annular groove walls are smooth annular groove walls, forming a thin-walled metal end cap; or one side of the two annular groove walls is a corrugated annular groove wall, and the other side is a smooth annular groove wall, forming a single-sided corrugated annular groove metal end cap; or both annular groove walls are corrugated annular groove walls, forming a double-sided corrugated annular groove metal end cap. At the bottom of the groove of the annular groove thin-walled metal end cap, there is a brazed metal sealing gasket with a melting point lower than the softening temperature of the high borosilicate glass or quartz outer glass tube and the softening temperature of the annular groove thin-walled metal end cap. The brazed metal inside the annular groove thin-walled metal end cap is a metal that can be liquefied when heated to a set temperature. Low melting point brazed metals include aluminum or aluminum alloys, zinc or zinc alloys, and have a melting point temperature below 720°C, and have good wetting properties with the annular groove thin-walled metal end cap and the high borosilicate glass or quartz outer glass tube head. Kovar metals and alloys; the melting point temperature of the brazing metal is higher than the operating temperature of the heat transfer medium but lower than the softening temperature of the high borosilicate glass tube or quartz glass tube and the annular groove thin-walled metal end cap; the sealing connection glass thread provided on the tube head of the high borosilicate glass tube or quartz glass tube, the brazing metal sealing gasket and the annular groove thin-walled metal end cap are brazed and sealed by heating and melting and then tightening; the annular groove thin-walled metal end cap is brazed by heating with an electromagnetic eddy current heater, or by electric heating, or by heating with an electric heater. When a thin-walled metal end cap with an annular groove is joined to Kovar brazing metal via the threaded opening of a high borosilicate glass tube or a quartz glass tube, and then heated, the Kovar brazing metal melts and is then tightened. During this process, the Kovar brazing metal, the thin-walled metal end cap with an annular groove, and the threaded opening of the high borosilicate glass tube or quartz glass tube will mutually weave and fuse together, becoming a single unit. At the system's normal operating temperature, the threads or corrugations of the groove on the thin-walled metal end cap, combined with the annular groove, effectively absorb the Kovar brazing metal and the high borosilicate glass. The limited thermal expansion and contraction of the threaded end of the outer glass tube or quartz outer glass tube ensures a good seal between the annular groove thin-walled metal end cap and the high borosilicate outer glass tube or quartz outer glass tube through Kovar brazing metal. During the brazing process of Kovar brazing metal such as aluminum with the threaded end of the annular groove thin-walled metal end cap, high borosilicate outer glass tube or quartz outer glass tube, the brazing fusion temperature is below 720℃. At this temperature, the annular groove thin-walled metal end cap, aluminum and high borosilicate outer glass tube or quartz outer glass tube release the dissolved gas at the corresponding temperature. The aluminum at the outer edge of the braze reacts with oxygen in the air to form aluminum oxide. During electrothermal brazing, aluminum conducts electricity and rapidly heats up, becoming liquid aluminum. The high borosilicate glass tube or quartz glass tube brazed with the aluminum end cap reaches its softening temperature (high borosilicate glass begins to soften at approximately 821℃). At 720℃, the main components of the high borosilicate glass tube or quartz glass tube, SiO2 and Al, undergo a chemical reaction: 4Al + 3SiO2 = 2Al2O3 + 3Si. This means that at this point, the interface between the high borosilicate glass tube or quartz glass tube and the aluminum can be firmly bonded due to the chemical reaction. Simultaneously, at 720℃, the stainless steel end cap does not soften (the maximum operating temperature of stainless steel 1Cr18Ni9Ti is 870℃), thus meeting the requirements of the high borosilicate glass tube. The process requirements for brazing glass tubes or quartz outer glass tubes and metals include: A chemical reaction occurs between the metal oxide layer surface of the stainless steel end cap and the aluminum, resulting in a strong bond between the stainless steel end cap and the aluminum interface; The deformation of the metal end cap absorbs the stress caused by thermal expansion and contraction of the aluminum or aluminum alloy, or zinc or zinc alloy brazing material, ensuring the brazing quality between the stainless steel end cap and the high borosilicate outer glass tube or quartz outer glass tube; Due to the "U"-shaped and deep closed-loop metal groove cross-section of the metal end cap, the corresponding closed-loop aluminum or aluminum alloy, or zinc or zinc alloy brazing connection sealing layer is longer, resulting in high brazing strength and good airtight sealing performance between the aluminum or aluminum alloy, or zinc or zinc alloy and the high borosilicate outer glass tube or quartz outer glass tube and the metal end cap. The tube head of the high borosilicate glass tube or the quartz glass tube is connected and sealed by a metal brazing fitting with a thin-walled metal end cap with an annular groove corresponding to its shape and size; or it is threadedly fitted with the corresponding thin-walled metal end cap with an annular groove; and then brazed and sealed with a metal washer to form an annular groove thin-walled metal end cap with a "U"-shaped brazing layer between the outer glass tube head and the annular groove thin-walled metal end cap. The inner hole of the annular groove thin-walled metal end cap is connected to the inner hole of the metal bellows expansion joint or the tube head, and then annularly welded and sealed with the inner straight metal pressure photovoltaic heat collection tube. The high borosilicate glass tube or the quartz glass tube is a conventional outer glass tube, or a solar anti-reflective film is provided on the tube wall of the high borosilicate glass tube or the quartz glass tube, with the solar anti-reflective film laminated on the outer surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on the inner surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on both the inner and outer surfaces of the high borosilicate glass tube or the quartz glass tube. A reflective concentrating mirror is installed on the outer borosilicate glass or quartz glass tube. The reflective concentrating mirror is an internal mirror, which is either a metal reflective concentrating mirror integrated with the outer glass tube wall, or a metal reflective concentrating mirror that is attached to the outer glass tube wall and can slide; or it is a high borosilicate glass or quartz glass reflective concentrating mirror. The cross-section of the reflective concentrating mirror is curved, and the focusing line of the reflective concentrating mirror is an inner straight-through metal pressure-bearing photovoltaic power generation heat collection tube whose surface is a high-temperature resistant photovoltaic cell. The cross-section of the outer borosilicate glass or quartz glass tube is circular, elliptical, or a closed line connecting a curve and an arc. The cross-sections of both ends of the outer borosilicate glass or quartz glass tube gradually change from elliptical or a closed line connecting a curve and an arc to a circle. The tube wall of the high borosilicate glass tube or the quartz glass tube may be equipped with a glass-metal brazed sealed outlet electrode; the electrode output end of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube wall is led out through the opening on the brazed sealed end cap of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube wall. The end cap is brazed and sealed to the glass threaded nozzle of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube wall through a brazed metal gasket. After the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is connected to a vacuum pump through the brazed electrode end cap, the gap between the electrode and the electrode end cap is sealed by metal welding. This realizes the electrical connection end cap of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, the outlet electrode of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube and the metal end cap of the glass nozzle of the outer glass tube, forming an electrical circuit between the positive electrode of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube and the negative electrode of the outlet electrode of the photovoltaic power generation collector tube. The inner and outer surfaces of the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube are smooth mounting connection surfaces, or mounting connection surfaces with threads, grooves, or flanges for connection with other devices; after evacuating the annular cavity between the inner and outer tubes through the glass exhaust pipe, the glass is welded closed; or the electrode is sealed by glass-metal brazing, after evacuating the annular cavity between the inner and outer tubes, the electrode is sealed by glass-metal brazing and then welded to the metal end cap; the degassing agent is evaporated to form the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube.

[0020] The glass tube with a metal brazed groove end cap is directly connected to a pressurized photovoltaic power generation vacuum tube. The metal reflective film layer of the inner pressurized photovoltaic power generation vacuum tube is generated on the outer surface of the inner pressurized photovoltaic power generation vacuum tube wall through magnetron sputtering, chemical reaction, or vacuum evaporation. The metal reflective film layer can be a single metal reflective film layer or a composite metal reflective film layer of more than one metal. The metal reflective film layer includes copper film layer, silver film layer, chromium film layer, copper and silver composite film layer, and copper and chromium composite film layer.

[0021] The glass tube with a metal brazed grooved end cap is directly connected to a pressurized photovoltaic heat collection vacuum tube. The open end of the inner direct-connection metal pressurized photovoltaic heat collection tube is of equal diameter, or is a reduced diameter, or an expanded diameter. The open end of the inner direct-connection metal pressurized photovoltaic heat collection tube is a smooth tube opening, or a tube opening with threads, grooves, or metal end caps for sealing connection. The tube opening of the glass tube with a metal brazed grooved end cap is provided with a metal positioning nozzle, which has threads or grooves. A pressure-balanced pressure-bearing sealing component is connected to the threads or grooves on the metal positioning nozzle. The pressure-balanced pressure-bearing sealing component is at the root of the tube or support, with threads or grooves. The top of the pressure-balanced pressure-bearing sealing component tube or support has a suction cup or suction cap. The pressure-balanced pressure-bearing sealing component tube or support has inlet and outlet liquid ports. The threads or grooves on the metal positioning nozzle are screwed and bolted to the threads or grooves on the pressure-balanced pressure-bearing sealing component pipe or bracket, or snapped into place; the suction cup or suction cap on the pressure-balanced pressure-bearing sealing component is attracted to the top surface of the manifold; or the metal brazed groove end cap of the glass tube is connected to the port of the pressure-bearing photovoltaic power generation heat collection vacuum tube, and a threaded metal positioning nozzle is provided; the threads on the metal positioning nozzle are connected to the threads of the pipe fittings at both ends through the sealing ring. The metal grooved threaded end cap is welded to the end of the inner straight metal pressure-bearing photovoltaic power generation heat collector pipe. The opening of the metal grooved threaded end cap faces the pipe wall or the pipe end. The opening of the glass tube corrugated sleeve faces the pipe end of the inner straight metal pressure-bearing photovoltaic power generation heat collector pipe or the pipe direction of the inner straight metal pressure-bearing photovoltaic power generation heat collector pipe.

[0022] The inner pressure-bearing photovoltaic (PV) vacuum tube is connected to a metal-brazed grooved end cap. Its high thermal resistance spring clip support is installed between the inner pressure-bearing metal PV collector tube and the outer high borosilicate glass or quartz glass tube. It consists of a section of transparent high borosilicate glass or quartz glass tube and three closed-loop high thermal resistance spring clip supports. These three closed-loop supports are respectively installed in three annular grooves located in the middle and at both ends of the inner and outer walls of the transparent high borosilicate glass or quartz glass tube. The three closed-loop high thermal resistance spring clip supports pass through the three annular grooves on the tube wall. Positioning, it is mounted on a transparent tube support between the inner direct-through metal pressure-bearing photovoltaic heat collection tube and the outer casing high borosilicate glass or quartz glass tube; the three closed-loop high thermal resistance spring clip supports are all welded to reduce their inner and outer diameters. After heating, the weld points can be opened, causing the inner and outer diameters of the closed-loop high thermal resistance spring clip supports to decrease and expand respectively. The closed-loop high thermal resistance spring clip supports are supported by the inner and outer tube walls of the direct-through transparent high borosilicate glass or quartz glass tube on the outer casing high borosilicate glass or quartz glass tube wall and the outer wall of the inner direct-through metal pressure-bearing photovoltaic heat collection tube respectively. The metal brazed groove end cap of the glass tube is directly connected to the pressure-bearing photovoltaic heat collection vacuum tube. The tube head of the high borosilicate glass tube or quartz glass tube is connected and sealed by metal brazing through an annular groove thin-walled metal end cap with a corresponding shape and size to the tube head of the high borosilicate glass tube or quartz glass tube. At least one end of the opening of the grooved metal end cap is connected to the tube wall of the opening of the high-temperature photovoltaic cell heat absorption, heat collection and heat transfer inner direct metal pressure photovoltaic heat collection tube through a metal brazed joint.

[0023] The outer glass tube has a metal brazed grooved end cap that is directly connected to the pressure-bearing photovoltaic power generation heat collection vacuum tube. The open end of the outer glass tube is rounded, and the rounded glass tube head is connected to the grooved metal end cap in a glass-metal brazed seal. The opening of the grooved metal end cap is connected to the opening of the high-temperature resistant photovoltaic cell heat absorption, heat collection and heat transfer inner direct metal pressure-bearing photovoltaic power generation heat collection tube in a ring-shaped glass-metal brazed seal.

[0024] The metal brazed grooved end cap of the outer glass tube is directly connected to the pressurized photovoltaic power generation heat collection vacuum tube. The open end of the outer glass tube is connected to a pre-made glass tube head with one end having the same shape and size as the opening end of the outer glass tube and the other end being rounded. This pre-made glass tube head is glass-welded to the open end of the outer glass tube. The rounded glass tube head is then sealed by metal brazing to the grooved metal end cap. The opening of the grooved metal end cap is sealed by annular metal brazing to the opening of the high-temperature photovoltaic cell heat absorption, heat collection, and heat transfer inner direct metal pressurized photovoltaic power generation heat collection tube.

[0025] The metal brazed groove end cap of the glass tube is directly connected to the pressurized photovoltaic heat collection vacuum tube. On the outer wall of the glass tube, there is a groove that fits against the outer glass tube wall and corresponds to the center of the reflector of the inner pressurized photovoltaic heat collection tube. These grooves are attracted to each other by magnets, allowing for synchronous sliding and rotation against the outer glass tube wall. The bottom surface of this inverted "U"-shaped closed support groove is a strip-shaped condenser lens, which can be a strip-shaped Fresnel lens or a strip-shaped convex lens. The concentrating beam of the condenser lens, through a groove located at the center of the reflector of the inner straight-through metal-bearing photovoltaic heat collector tube, focuses the light onto the back surface of the inner straight-through metal-bearing photovoltaic heat collector tube. This achieves low efficiency due to the weak light intensity of the light illuminating the inner straight-through metal-bearing photovoltaic heat collector tube. At the same time, through the reflection of the reflector, the heat radiated from the high-temperature surface of the inner straight-through metal-bearing photovoltaic heat collector tube is reflected back to the inner straight-through metal-bearing photovoltaic heat collector tube, thereby maximizing the light efficiency and minimizing the amount of light radiation.

[0026] The glass tube with a metal brazed grooved end cap is directly connected to a pressurized photovoltaic heat collection vacuum tube. The inner wall of the metal pressurized heat collection tube is reinforced with a radial inner tube with high thermal conductivity for heat transfer, or reinforced with a longitudinal inner tube with a rifling heat transfer spiral with high thermal conductivity. The inner tube is made of copper or carbon material. Alternatively, the glass tube with a metal brazed grooved end cap is directly connected to a pressurized photovoltaic heat collection vacuum tube and is equipped with a tubular guide with closed ends. The tubular guide is made of high borosilicate glass or metal tube.

[0027] A glass tube with metal brazed groove end cap and direct-through pressure-bearing photovoltaic heat collection vacuum tube includes an outer glass tube, metal end caps, a metal corrugated pipe expansion joint, metal brazing flux, an inner direct-through pressure-bearing photovoltaic heat collection tube, a high-strength high-temperature resistant electrical insulating adhesive, a high-temperature resistant photovoltaic cell, and a degassing agent. Its characteristic is that the inner direct-through pressure-bearing photovoltaic heat collection tube is open at both ends, and the photovoltaic cell is composited on the surface of the inner direct-through metal tube, forming the inner direct-through pressure-bearing photovoltaic heat collection tube. An inner straight-through metal pressure-bearing photovoltaic heat collector tube and an outer glass tube fitted around the inner straight-through metal pressure-bearing photovoltaic heat collector tube, are installed inside the outer casing glass tube via metal end caps at both ends. Due to the significant difference in thermal expansion coefficients between the metal tube and the high borosilicate glass or quartz glass tube, a dedicated metal bellows expansion joint is required to buffer deformation caused by temperature. Therefore, at least one end of the outer casing glass tube has its metal annular groove end cap opening edge welded to one end of the metal bellows expansion joint, and the other end of the metal bellows expansion joint is metal-welded and sealed to the inner straight-through metal pressure-bearing heat collector tube. The metal pressure-bearing photovoltaic heat collection tube, or equipped with a high thermal resistance elastic clip support, supports the metal corrugated tube expansion joint on the inner wall of the outer glass tube; the metal annular groove end cap is brazed and sealed to the outer glass tube opening through a brazed metal pad; the other end of the outer glass tube opening is brazed and sealed to the metal annular groove end cap through a brazed metal pad; the inner hole of the annular groove thin-walled metal end cap, along the welded metal corrugated tube expansion joint inner hole or tube head, is welded to the opening edge of the metal annular groove end cap through metal welding, and then annularly welded and sealed to the inner straight metal pressure-bearing heat collection tube; The materials used to manufacture the internally straight metal pressure-bearing photovoltaic power generation collector tube are corrosion-resistant, high-temperature resistant, and high-strength metal materials, including copper, carbon steel, and stainless steel. The structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell; or the structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a metal reflective film, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell, such as a gallium arsenide high-temperature resistant photovoltaic cell; the positive and negative electrodes of the high-temperature resistant photovoltaic cell are connected in series, and the electrodes are led out through the glass-metal brazing seal connecting the positive and negative electrodes and then led out through the glass tube wall; The metal end cap is a thin-walled metal end cap with an annular groove. The thin-walled metal end cap is welded to a metal bellows expansion joint. The metal bellows expansion joint has holes or openings for inserting a metal pressure-bearing photovoltaic heat collector tube. The annular groove thin-walled metal end cap is made of corrosion-resistant, high-temperature resistant, and high-strength metal materials, such as stainless steel. The annular groove thin-walled metal end cap is formed by machine tool processing, or by machine tool processing combined with metal welding, or by metal three-dimensional printing. The metal annular groove of the glass-metal brazed seal has the following configurations: one side has a thread that matches the threaded end of a high borosilicate glass tube or a quartz glass tube, and the other side is a smooth annular groove wall, forming a single-sided threaded metal end cap; or the metal annular groove has threads on both sides that match the threaded end of a high borosilicate glass tube or a quartz glass tube, forming a double-sided threaded metal end cap; or the two annular groove walls are smooth annular groove walls, forming a thin-walled metal end cap; or one side of the two annular groove walls is a corrugated annular groove wall, and the other side is a smooth annular groove wall, forming a single-sided corrugated annular groove metal end cap; or both annular groove walls are corrugated annular groove walls, forming a double-sided corrugated annular groove metal end cap. At the bottom of the groove of the annular groove thin-walled metal end cap, there is a brazed metal sealing gasket with a melting point lower than the softening temperature of the high borosilicate glass or quartz outer glass tube and the softening temperature of the annular groove thin-walled metal end cap. The brazed metal inside the annular groove thin-walled metal end cap is a metal that can be liquefied when heated to a set temperature. Low melting point brazed metals include aluminum or aluminum alloys, zinc or zinc alloys, and have a melting point temperature below 720°C, and have good wetting properties with the annular groove thin-walled metal end cap and the high borosilicate glass or quartz outer glass tube head. Kovar metals and alloys; the melting point temperature of the brazing metal is higher than the operating temperature of the heat transfer medium but lower than the softening temperature of the high borosilicate glass tube or quartz glass tube and the annular groove thin-walled metal end cap; the sealing connection glass thread provided on the tube head of the high borosilicate glass tube or quartz glass tube, the brazing metal sealing gasket and the annular groove thin-walled metal end cap are brazed and sealed by heating and melting and then tightening; the annular groove thin-walled metal end cap is brazed by heating with an electromagnetic eddy current heater, or by electric heating, or by heating with an electric heater. When a thin-walled metal end cap with an annular groove is joined to Kovar brazing metal via the threaded opening of a high borosilicate glass tube or a quartz glass tube, and then heated, the Kovar brazing metal melts and is then tightened. During this process, the Kovar brazing metal, the thin-walled metal end cap with an annular groove, and the threaded opening of the high borosilicate glass tube or quartz glass tube will mutually weave and fuse together, becoming a single unit. At the system's normal operating temperature, the threads or corrugations of the groove on the thin-walled metal end cap, combined with the annular groove, effectively absorb the Kovar brazing metal and the high borosilicate glass. The limited thermal expansion and contraction of the threaded end of the outer glass tube or quartz outer glass tube ensures a good seal between the annular groove thin-walled metal end cap and the high borosilicate outer glass tube or quartz outer glass tube through Kovar brazing metal. During the brazing process of Kovar brazing metal such as aluminum with the threaded end of the annular groove thin-walled metal end cap, high borosilicate outer glass tube or quartz outer glass tube, the brazing fusion temperature is below 720℃. At this temperature, the annular groove thin-walled metal end cap, aluminum and high borosilicate outer glass tube or quartz outer glass tube release the dissolved gas at the corresponding temperature. The aluminum at the outer edge of the braze reacts with oxygen in the air to form aluminum oxide. During electrothermal brazing, aluminum conducts electricity and rapidly heats up, becoming liquid aluminum. The high borosilicate glass tube or quartz glass tube brazed with the aluminum end cap reaches its softening temperature (high borosilicate glass begins to soften at approximately 821℃). At 720℃, the main components of the high borosilicate glass tube or quartz glass tube, SiO2 and Al, undergo a chemical reaction: 4Al + 3SiO2 = 2Al2O3 + 3Si. This means that at this point, the interface between the high borosilicate glass tube or quartz glass tube and the aluminum can be firmly bonded due to the chemical reaction. Simultaneously, at 720℃, the stainless steel end cap does not soften (the maximum operating temperature of stainless steel 1Cr18Ni9Ti is 870℃), thus meeting the requirements of the high borosilicate glass tube. The process requirements for brazing glass tubes or quartz outer glass tubes and metals include: A chemical reaction occurs between the metal oxide layer surface of the stainless steel end cap and the aluminum, resulting in a strong bond between the stainless steel end cap and the aluminum interface; The deformation of the metal end cap absorbs the stress caused by thermal expansion and contraction of the aluminum or aluminum alloy, or zinc or zinc alloy brazing material, ensuring the brazing quality between the stainless steel end cap and the high borosilicate outer glass tube or quartz outer glass tube; Due to the "U"-shaped and deep closed-loop metal groove cross-section of the metal end cap, the corresponding closed-loop aluminum or aluminum alloy, or zinc or zinc alloy brazing connection sealing layer is longer, resulting in high brazing strength and good airtight sealing performance between the aluminum or aluminum alloy, or zinc or zinc alloy and the high borosilicate outer glass tube or quartz outer glass tube and the metal end cap. The tube head of the high borosilicate glass tube or the quartz glass tube is connected and sealed by a metal brazing fitting with a thin-walled metal end cap with an annular groove corresponding to its shape and size; or it is threadedly fitted with the corresponding thin-walled metal end cap with an annular groove; and then brazed and sealed with a metal washer to form an annular groove thin-walled metal end cap with a "U"-shaped brazing layer between the outer glass tube head and the annular groove thin-walled metal end cap. The inner hole of the annular groove thin-walled metal end cap is connected to the inner hole of the metal bellows expansion joint or the tube head, and then annularly welded and sealed with the inner straight metal pressure photovoltaic heat collection tube. The high borosilicate glass tube or the quartz glass tube is a conventional outer glass tube, or a solar anti-reflective film is provided on the tube wall of the high borosilicate glass tube or the quartz glass tube, with the solar anti-reflective film laminated on the outer surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on the inner surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on both the inner and outer surfaces of the high borosilicate glass tube or the quartz glass tube. A reflective concentrating mirror is installed on the outer borosilicate glass or quartz glass tube. The reflective concentrating mirror is an internal mirror, which is either a metal reflective concentrating mirror integrated with the outer glass tube wall, or a metal reflective concentrating mirror that is attached to the outer glass tube wall and can slide; or it is a high borosilicate glass or quartz glass reflective concentrating mirror. The cross-section of the reflective concentrating mirror is curved, and the focusing line of the reflective concentrating mirror is an inner straight-through metal pressure-bearing photovoltaic power generation heat collection tube whose surface is a high-temperature resistant photovoltaic cell. The cross-section of the outer borosilicate glass or quartz glass tube is circular, elliptical, or a closed line connecting a curve and an arc. The cross-sections of both ends of the outer borosilicate glass or quartz glass tube gradually change from elliptical or a closed line connecting a curve and an arc to a circle. The tube wall of the high borosilicate glass tube or the quartz glass tube may be equipped with a glass-metal brazed sealed outlet electrode; the electrode output end of the inner straight-through metal pressure-bearing photovoltaic heat collector tube wall is led out through the opening on the brazed sealed end cap of the inner straight-through metal pressure-bearing photovoltaic heat collector tube wall. The end cap is brazed and sealed to the glass threaded nozzle of the inner straight-through metal pressure-bearing photovoltaic heat collector tube wall by brazing metal gasket. After the inner straight-through metal pressure-bearing photovoltaic heat collector tube is connected to the vacuum pump through the brazed electrode end cap, the gap between the electrode and the electrode end cap is sealed by metal welding. This realizes the electrical connection end cap of the inner straight-through metal pressure-bearing photovoltaic heat collector tube, the outlet electrode of the inner straight-through metal pressure-bearing photovoltaic heat collector tube and the metal end cap of the glass nozzle of the outer glass tube, forming an electrical circuit between the positive electrode of the inner straight-through metal pressure-bearing photovoltaic heat collector tube and the negative electrode of the photovoltaic heat collector tube outlet electrode. The inner and outer surfaces of the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube are smooth mounting connection surfaces, or mounting connection surfaces with threads, grooves, or flanges for connection with other devices; after evacuating the annular cavity between the inner and outer tubes through the glass exhaust pipe, the glass is welded closed; or the electrode is sealed by glass-metal brazing, after evacuating the annular cavity between the inner and outer tubes, the electrode is sealed by glass-metal brazing and then welded to the metal end cap; the degassing agent is evaporated to form the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube.

[0028] A pressure-bearing photovoltaic (PV) heat collection vacuum tube with a metal brazed groove end cap and an inner straight-through metal tube includes an outer glass tube, metal end caps, metal brazing flux, an inner straight-through metal pressure-bearing PV heat collection tube, a high-strength, high-temperature resistant electrical insulating adhesive, a high-temperature resistant photovoltaic cell, a degassing agent, and a metal corrugated pipe expansion joint. Its characteristic is that the inner straight-through metal pressure-bearing PV heat collection tube is open at both ends, and the photovoltaic cell is composited on the surface of the inner straight-through metal tube, forming the inner straight-through metal pressure-bearing PV heat collection tube. An inner straight-through metal pressure-bearing photovoltaic heat collector tube and an outer glass tube fitted around the inner straight-through metal pressure-bearing photovoltaic heat collector tube, are installed inside the outer casing glass tube via metal end caps at both ends. Due to the significant difference in thermal expansion coefficients between the metal tube and the high borosilicate glass or quartz glass tube, a dedicated metal bellows expansion joint is required to buffer deformation caused by temperature. Therefore, at least one end of the outer casing glass tube has its metal annular groove end cap opening edge welded to one end of the metal bellows expansion joint, and the other end of the metal bellows expansion joint is metal-welded and sealed to the inner straight-through metal pressure-bearing heat collector tube. The metal pressure-bearing photovoltaic heat collection tube, or equipped with a high thermal resistance elastic clip support, supports the metal corrugated tube expansion joint on the inner wall of the outer glass tube; the metal annular groove end cap is brazed and sealed to the outer glass tube opening through a brazed metal pad; the other end of the outer glass tube opening is brazed and sealed to the metal annular groove end cap through a brazed metal pad; the inner hole of the annular groove thin-walled metal end cap, along the welded metal corrugated tube expansion joint inner hole or tube head, is welded to the opening edge of the metal annular groove end cap through metal welding, and then annularly welded and sealed to the inner straight metal pressure-bearing heat collection tube; The materials used to manufacture the internally straight metal pressure-bearing photovoltaic power generation collector tube are corrosion-resistant, high-temperature resistant, and high-strength metal materials, including copper, carbon steel, and stainless steel. The structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell; or the structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a metal reflective film, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell, such as a gallium arsenide high-temperature resistant photovoltaic cell; the positive and negative electrodes of the high-temperature resistant photovoltaic cell are connected in series, and the electrodes are led out through the glass-metal brazing seal connecting the positive and negative electrodes and then led out through the glass tube wall; The metal end cap is a thin-walled metal end cap with an annular groove. The thin-walled metal end cap is welded to a metal bellows expansion joint. The metal bellows expansion joint has holes or openings for inserting a metal pressure-bearing photovoltaic heat collector tube. The annular groove thin-walled metal end cap is made of corrosion-resistant, high-temperature resistant, and high-strength metal materials, such as stainless steel. The annular groove thin-walled metal end cap is formed by machine tool processing, or by machine tool processing combined with metal welding, or by metal three-dimensional printing. The two ends of the outer glass tube are provided with glass insulation sleeves; the glass insulation sleeves are coaxial corrugated sleeves formed by welding glass between the glass tube openings in sequence, at least one layer, of appropriate length, and coaxially fitted with the outer glass tube; the opening of the corrugated sleeve is provided with an insulation glass sleeve for brazing and sealing connection with the metal end cap; the outer glass tube head of the high borosilicate glass or quartz outer glass tube includes smooth tube head, corrugated tube head, and threaded tube head; the corrugated tube head is corrugated on the outer wall and smooth on the inner wall, or the corrugated tube head is smooth on the outer wall and corrugated on the inner wall, or the corrugated tube head is corrugated on the outer wall and corrugated on the inner wall; or the threaded tube head is threaded on the outer wall and smooth on the inner wall, or the threaded tube head is threaded on the inner wall and smooth on the outer wall, or the tube head is threaded on the outer wall and threaded on the inner wall. A glass tube of appropriate length is formed by hot-melting and pressing glass threads at one end, and then straightening the other end to a fixed length. The threaded glass tube is then annealed. The threaded glass tube is then coaxially fitted and welded to another glass tube, forming at least one layer of glass tube. Glass tube openings are sequentially welded together to form a coaxial insulated glass tube sleeve. Afterwards, an anti-reflective film is either laminated onto the wall of the transparent glass tube, or after laminating the anti-reflective film onto the wall of the transparent glass tube, the glass cover tube is then processed. The end of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is then trimmed and straightened. On the inner wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, there is a composite radial inner tube; the open end or the reducing end and the end trimming of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube; then, the outer tube wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is cleaned and dried; on the outer tube wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, a composite high-temperature resistant photovoltaic cell is tightly bonded; the coaxial heat-insulating glass tube sleeve, the sealing connection glass thread of the coaxial heat-insulating glass tube sleeve is brazed to the metal groove thread end cap with a brazed metal sealing gasket; The metal annular groove of the glass-metal brazed seal has the following configurations: one side has a thread that matches the threaded end of a high borosilicate glass tube or a quartz glass tube, and the other side is a smooth annular groove wall, forming a single-sided threaded metal end cap; or the metal annular groove has threads on both sides that match the threaded end of a high borosilicate glass tube or a quartz glass tube, forming a double-sided threaded metal end cap; or the two annular groove walls are smooth annular groove walls, forming a thin-walled metal end cap; or one side of the two annular groove walls is a corrugated annular groove wall, and the other side is a smooth annular groove wall, forming a single-sided corrugated annular groove metal end cap; or both annular groove walls are corrugated annular groove walls, forming a double-sided corrugated annular groove metal end cap. At the bottom of the groove of the annular groove thin-walled metal end cap, there is a brazed metal sealing gasket with a melting point lower than the softening temperature of the high borosilicate glass or quartz outer glass tube and the softening temperature of the annular groove thin-walled metal end cap. The brazed metal inside the annular groove thin-walled metal end cap is a metal that can be liquefied when heated to a set temperature. Low melting point brazed metals include aluminum or aluminum alloys, zinc or zinc alloys, and have a melting point temperature below 720°C, and have good wetting properties with the annular groove thin-walled metal end cap and the high borosilicate glass or quartz outer glass tube head. Kovar metals and alloys; the melting point temperature of the brazing metal is higher than the operating temperature of the heat transfer medium but lower than the softening temperature of the high borosilicate glass tube or quartz glass tube and the annular groove thin-walled metal end cap; the sealing connection glass thread provided on the tube head of the high borosilicate glass tube or quartz glass tube, the brazing metal sealing gasket and the annular groove thin-walled metal end cap are brazed and sealed by heating and melting and then tightening; the annular groove thin-walled metal end cap is brazed by heating with an electromagnetic eddy current heater, or by electric heating, or by heating with an electric heater. When a thin-walled metal end cap with an annular groove is joined to Kovar brazing metal via the threaded opening of a high borosilicate glass tube or a quartz glass tube, and then heated, the Kovar brazing metal melts and is then tightened. During this process, the Kovar brazing metal, the thin-walled metal end cap with an annular groove, and the threaded opening of the high borosilicate glass tube or quartz glass tube will mutually weave and fuse together, becoming a single unit. At the system's normal operating temperature, the threads or corrugations of the groove on the thin-walled metal end cap, combined with the annular groove, effectively absorb the Kovar brazing metal and the high borosilicate glass. The limited thermal expansion and contraction of the threaded end of the outer glass tube or quartz outer glass tube ensures a good seal between the annular groove thin-walled metal end cap and the high borosilicate outer glass tube or quartz outer glass tube through Kovar brazing metal. During the brazing process of Kovar brazing metal such as aluminum with the threaded end of the annular groove thin-walled metal end cap, high borosilicate outer glass tube or quartz outer glass tube, the brazing fusion temperature is below 720℃. At this temperature, the annular groove thin-walled metal end cap, aluminum and high borosilicate outer glass tube or quartz outer glass tube release the dissolved gas at the corresponding temperature. The aluminum at the outer edge of the braze reacts with oxygen in the air to form aluminum oxide. During electrothermal brazing, aluminum conducts electricity and rapidly heats up, becoming liquid aluminum. The high borosilicate glass tube or quartz glass tube brazed with the aluminum end cap reaches its softening temperature (high borosilicate glass begins to soften at approximately 821℃). At 720℃, the main components of the high borosilicate glass tube or quartz glass tube, SiO2 and Al, undergo a chemical reaction: 4Al + 3SiO2 = 2Al2O3 + 3Si. This means that at this point, the interface between the high borosilicate glass tube or quartz glass tube and the aluminum can be firmly bonded due to the chemical reaction. Simultaneously, at 720℃, the stainless steel end cap does not soften (the maximum operating temperature of stainless steel 1Cr18Ni9Ti is 870℃), thus meeting the requirements of the high borosilicate glass tube. The process requirements for brazing glass tubes or quartz outer glass tubes and metals include: A chemical reaction occurs between the metal oxide layer surface of the stainless steel end cap and the aluminum, resulting in a strong bond between the stainless steel end cap and the aluminum interface; The deformation of the metal end cap absorbs the stress caused by thermal expansion and contraction of the aluminum or aluminum alloy, or zinc or zinc alloy brazing material, ensuring the brazing quality between the stainless steel end cap and the high borosilicate outer glass tube or quartz outer glass tube; Due to the "U"-shaped and deep closed-loop metal groove cross-section of the metal end cap, the corresponding closed-loop aluminum or aluminum alloy, or zinc or zinc alloy brazing connection sealing layer is longer, resulting in high brazing strength and good airtight sealing performance between the aluminum or aluminum alloy, or zinc or zinc alloy and the high borosilicate outer glass tube or quartz outer glass tube and the metal end cap. The tube head of the high borosilicate glass tube or the quartz glass tube is connected and sealed by a metal brazing fitting with a thin-walled metal end cap with an annular groove corresponding to its shape and size; or it is threadedly fitted with the corresponding thin-walled metal end cap with an annular groove; and then brazed and sealed with a metal washer to form an annular groove thin-walled metal end cap with a "U"-shaped brazing layer between the outer glass tube head and the annular groove thin-walled metal end cap. The inner hole of the annular groove thin-walled metal end cap is connected to the inner hole of the metal bellows expansion joint or the tube head, and then annularly welded and sealed with the inner straight metal pressure photovoltaic heat collection tube. The high borosilicate glass tube or the quartz glass tube is a conventional outer glass tube, or a solar anti-reflective film is provided on the tube wall of the high borosilicate glass tube or the quartz glass tube, with the solar anti-reflective film laminated on the outer surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on the inner surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on both the inner and outer surfaces of the high borosilicate glass tube or the quartz glass tube. A reflective concentrating mirror is installed on the outer borosilicate glass or quartz glass tube. The reflective concentrating mirror is an internal mirror, which is either a metal reflective concentrating mirror integrated with the outer glass tube wall, or a metal reflective concentrating mirror that is attached to the outer glass tube wall and can slide; or it is a high borosilicate glass or quartz glass reflective concentrating mirror. The cross-section of the reflective concentrating mirror is curved, and the focusing line of the reflective concentrating mirror is an inner straight-through metal pressure-bearing photovoltaic power generation heat collection tube whose surface is a high-temperature resistant photovoltaic cell. The cross-section of the outer borosilicate glass or quartz glass tube is circular, elliptical, or a closed line connecting a curve and an arc. The cross-sections of both ends of the outer borosilicate glass or quartz glass tube gradually change from elliptical or a closed line connecting a curve and an arc to a circle. The tube wall of the high borosilicate glass tube or the quartz glass tube may be equipped with a glass-metal brazed sealed outlet electrode; the electrode output end of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube wall is led out through the opening on the brazed sealed end cap of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube wall. The end cap is brazed and sealed to the glass threaded nozzle of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube wall through a brazed metal gasket. After the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is connected to a vacuum pump through the brazed electrode end cap, the gap between the electrode and the electrode end cap is sealed by metal welding. This realizes the electrical connection end cap of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, the outlet electrode of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube and the metal end cap of the glass nozzle of the outer glass tube, forming an electrical circuit between the positive electrode of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube and the negative electrode of the outlet electrode of the photovoltaic power generation collector tube. The inner and outer surfaces of the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube are smooth mounting connection surfaces, or mounting connection surfaces with threads, grooves, or flanges for connection with other devices; after evacuating the annular cavity between the inner and outer tubes through the glass exhaust pipe, the glass is welded closed; or the electrode is sealed by glass-metal brazing, after evacuating the annular cavity between the inner and outer tubes, the electrode is sealed by glass-metal brazing and then welded to the metal end cap; the degassing agent is evaporated to form the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube.

[0029] The glass tube with a metal brazed groove end cap is directly connected to a pressurized photovoltaic power generation vacuum tube. The metal reflective film layer of the inner pressurized photovoltaic power generation vacuum tube is generated on the outer surface of the inner pressurized photovoltaic power generation vacuum tube wall through magnetron sputtering, chemical reaction, or vacuum evaporation. The metal reflective film layer can be a single metal reflective film layer or a composite metal reflective film layer of more than one metal. The metal reflective film layer includes copper film layer, silver film layer, chromium film layer, copper and silver composite film layer, and copper and chromium composite film layer.

[0030] The glass tube with a metal brazed grooved end cap is directly connected to a pressurized photovoltaic heat collection vacuum tube. The open end of the inner direct-connection metal pressurized photovoltaic heat collection tube is of equal diameter, or is a reduced diameter, or an expanded diameter. The open end of the inner direct-connection metal pressurized photovoltaic heat collection tube is a smooth tube opening, or a tube opening with threads, grooves, or metal end caps for sealing connection. The tube opening of the glass tube with a metal brazed grooved end cap is provided with a metal positioning nozzle, which has threads or grooves. A pressure-balanced pressure-bearing sealing component is connected to the threads or grooves on the metal positioning nozzle. The pressure-balanced pressure-bearing sealing component is at the root of the tube or support, with threads or grooves. The top of the pressure-balanced pressure-bearing sealing component tube or support has a suction cup or suction cap. The pressure-balanced pressure-bearing sealing component tube or support has inlet and outlet liquid ports. The threads or grooves on the metal positioning nozzle are screwed and bolted to the threads or grooves on the pressure-balanced pressure-bearing sealing component pipe or bracket, or snapped into place; the suction cup or suction cap on the pressure-balanced pressure-bearing sealing component is attracted to the top surface of the manifold; or the metal brazed groove end cap of the glass tube is connected to the port of the pressure-bearing photovoltaic power generation heat collection vacuum tube, and a threaded metal positioning nozzle is provided; the threads on the metal positioning nozzle are connected to the threads of the pipe fittings at both ends through the sealing ring. The metal grooved threaded end cap is welded to the end of the inner straight metal pressure-bearing photovoltaic power generation heat collector pipe. The opening of the metal grooved threaded end cap faces the pipe wall or the pipe end. The opening of the glass tube corrugated sleeve faces the pipe end of the inner straight metal pressure-bearing photovoltaic power generation heat collector pipe or the pipe direction of the inner straight metal pressure-bearing photovoltaic power generation heat collector pipe.

[0031] The inner pressure-bearing photovoltaic (PV) vacuum tube is connected to a metal-brazed grooved end cap. Its high thermal resistance spring clip support is installed between the inner pressure-bearing metal PV collector tube and the outer high borosilicate glass or quartz glass tube. It consists of a section of transparent high borosilicate glass or quartz glass tube and three closed-loop high thermal resistance spring clip supports. These three closed-loop supports are respectively installed in three annular grooves located in the middle and at both ends of the inner and outer walls of the transparent high borosilicate glass or quartz glass tube. The three closed-loop high thermal resistance spring clip supports pass through the three annular grooves on the tube wall. Positioning, it is mounted on a transparent tube support between the inner direct-through metal pressure-bearing photovoltaic heat collection tube and the outer casing high borosilicate glass or quartz glass tube; the three closed-loop high thermal resistance spring clip supports are all welded to reduce their inner and outer diameters. After heating, the weld points can be opened, causing the inner and outer diameters of the closed-loop high thermal resistance spring clip supports to decrease and expand respectively. The closed-loop high thermal resistance spring clip supports are supported by the inner and outer tube walls of the direct-through transparent high borosilicate glass or quartz glass tube on the outer casing high borosilicate glass or quartz glass tube wall and the outer wall of the inner direct-through metal pressure-bearing photovoltaic heat collection tube respectively. The metal brazed groove end cap of the glass tube is directly connected to the pressure-bearing photovoltaic heat collection vacuum tube. The tube head of the high borosilicate glass tube or quartz glass tube is connected and sealed by metal brazing through an annular groove thin-walled metal end cap with a corresponding shape and size to the tube head of the high borosilicate glass tube or quartz glass tube. At least one end of the opening of the grooved metal end cap is connected to the tube wall of the opening of the high-temperature photovoltaic cell heat absorption, heat collection and heat transfer inner direct metal pressure photovoltaic heat collection tube through a metal brazed joint.

[0032] The outer glass tube has a metal brazed grooved end cap that is directly connected to the pressure-bearing photovoltaic power generation heat collection vacuum tube. The open end of the outer glass tube is rounded, and the rounded glass tube head is connected to the grooved metal end cap in a glass-metal brazed seal. The opening of the grooved metal end cap is connected to the opening of the high-temperature resistant photovoltaic cell heat absorption, heat collection and heat transfer inner direct metal pressure-bearing photovoltaic power generation heat collection tube in a ring-shaped glass-metal brazed seal.

[0033] The metal brazed grooved end cap of the outer glass tube is directly connected to the pressurized photovoltaic power generation heat collection vacuum tube. The open end of the outer glass tube is connected to a pre-made glass tube head with one end having the same shape and size as the opening end of the outer glass tube and the other end being rounded. This pre-made glass tube head is glass-welded to the open end of the outer glass tube. The rounded glass tube head is then sealed by metal brazing to the grooved metal end cap. The opening of the grooved metal end cap is sealed by annular metal brazing to the opening of the high-temperature photovoltaic cell heat absorption, heat collection, and heat transfer inner direct metal pressurized photovoltaic power generation heat collection tube.

[0034] The metal brazed groove end cap of the glass tube is directly connected to the pressurized photovoltaic heat collection vacuum tube. On the outer wall of the glass tube, there is a groove that fits against the outer glass tube wall and corresponds to the center of the reflector of the inner pressurized photovoltaic heat collection tube. These grooves are attracted to each other by magnets, allowing for synchronous sliding and rotation against the outer glass tube wall. The bottom surface of this inverted "U"-shaped closed support groove is a strip-shaped condenser lens, which can be a strip-shaped Fresnel lens or a strip-shaped convex lens. The concentrating beam of the condenser lens, through a groove located at the center of the reflector of the inner straight-through metal-bearing photovoltaic heat collector tube, focuses the light onto the back surface of the inner straight-through metal-bearing photovoltaic heat collector tube. This achieves low efficiency due to the weak light intensity of the light illuminating the inner straight-through metal-bearing photovoltaic heat collector tube. At the same time, through the reflection of the reflector, the heat radiated from the high-temperature surface of the inner straight-through metal-bearing photovoltaic heat collector tube is reflected back to the inner straight-through metal-bearing photovoltaic heat collector tube, thereby maximizing the light efficiency and minimizing the amount of light radiation.

[0035] The glass tube with a metal brazed grooved end cap is directly connected to a pressurized photovoltaic heat collection vacuum tube. The inner wall of the metal pressurized heat collection tube is reinforced with a radial inner tube with high thermal conductivity for heat transfer, or reinforced with a longitudinal inner tube with a rifling heat transfer spiral with high thermal conductivity. The inner tube is made of copper or carbon material. Alternatively, the glass tube with a metal brazed grooved end cap is directly connected to a pressurized photovoltaic heat collection vacuum tube and is equipped with a tubular guide with closed ends. The tubular guide is made of high borosilicate glass or metal tube.

[0036] The beneficial effects of this invention are as follows: the metal brazed groove end cap of the glass tube, directly connected to the pressure-bearing photovoltaic power generation vacuum tube, improves the quality of glass-metal welding, solves the problem of glass-metal sealing, increases the power generation efficiency of high-temperature photovoltaic cells, and utilizes the heat energy converted from solar energy, with an operating temperature up to 400℃. It can be used as a barbecue grill or as a direct-heating hot liquid collector. It can also be used as a collector for trough, Fresnel, and tower power generation. It possesses high mechanical strength and reliability; the internal direct-connection pressure-bearing photovoltaic power generation collector tube structure enables pressure resistance; the vacuum tube structure has good thermal insulation performance and strong pressure resistance, exhibiting high mechanical strength and reliability. It is simple to manufacture, low in cost, and has a significantly extended lifespan, resulting in excellent economic benefits. It represents the future development direction of solar energy. Attached Figure Description

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0038] Figure 1 The end cap of the metal brazed groove of the glass tube is a brazed end cap with a radial concentric corrugated expansion-absorbing thread, which is the main sectional view of the first embodiment of the present invention. Figure 2The end cap of the metal brazed groove of the glass tube is a metal axial corrugated expansion-absorbing threaded brazed end cap, which is the main sectional view of the second embodiment of the present invention. Figure 3 The end cap of the metal brazed groove of the glass tube is a metal axial corrugated expansion-absorbing threaded brazed end cap. The two ends of the glass tube opening are provided with glass insulation sleeves. This is the main sectional view of the third embodiment of the present invention. Figure 3 The end cap of the metal brazed groove of the glass tube is a metal axial corrugated expansion-absorbing threaded brazed end cap. The two ends of the glass tube opening are provided with glass insulation sleeves. This is the main sectional view of the third embodiment of the present invention. Figure 4 The end cap of the metal brazed groove of the glass tube is a metal axial corrugated expansion-absorbing threaded brazed end cap. The two ends of the glass tube opening are provided with glass insulation sleeves. This is the main sectional view of the fourth embodiment of the present invention. Figure 5 The end cap of the metal brazed groove of the glass tube is a metal axial corrugated expansion-absorbing threaded brazed end cap. The two ends of the glass tube are provided with glass insulation sleeves. The inner wall of the metal pressure collector tube is provided with heat transfer fins. This is the main sectional view of the fifth embodiment of the present invention. Figure 6 The end cap of the metal brazed groove of the glass tube is a metal radial concentric corrugated expansion-absorbing thread brazed end cap. The two ends of the glass tube are provided with glass insulation sleeves. The inner wall of the metal pressure collector tube is provided with heat transfer fins. This is the main sectional view of the sixth embodiment of the present invention. Figure 7 shows the end cap of the metal brazed groove of the glass tube, which is a metal radial concentric corrugated expansion-absorbing thread brazed end cap. The two ends of the outer glass tube are equipped with glass insulation sleeves, and the outer glass tube is equipped with a strip condenser lens. The strip condenser in Figure 8 is a convex lens. Figure 8 is a cross-sectional view of Figure 7. Figures 7 and 8 constitute the seventh embodiment of a metal brazed groove end cap of a glass tube that is directly connected to a pressure-bearing photovoltaic power generation heat collection vacuum tube. Figure 9 The strip condenser lens in the image is a Fresnel lens. Figure 9 This is a cross-sectional view of Figure 7; Figure 7 and Figure 9 The eighth embodiment of a metal brazed groove end cap for a glass tube that is directly connected to a pressure-bearing photovoltaic power generation heat collection vacuum tube; Figure 10 shows the end cap of the metal brazed groove of the glass tube, which is a metal radial concentric corrugated expansion-absorbing thread brazed end cap. The two ends of the outer glass tube are equipped with glass insulation sleeves, and the outer glass tube is equipped with a strip condenser lens. The strip condenser in Figure 11 is a convex lens. Figure 11 is a cross-sectional view of Figure 10. Figures 10 and 11 constitute the ninth embodiment of a metal brazed groove end cap for a glass tube that is directly connected to a pressure-bearing photovoltaic power generation heat collection vacuum tube. Figure 12 The strip condenser lens in the image is a Fresnel lens. Figure 12 This is a cross-sectional view of Figure 10; Figure 10 and Figure 12 The tenth embodiment of a metal brazed groove end cap for a glass tube that forms a direct connection to a pressure-bearing photovoltaic power generation heat collection vacuum tube.

[0039] In the diagram: 1. Brazing flux, 2. Glass positioning nozzle, 3. Outer glass tube, 4. Photovoltaic cell, 5. Inner metal heat collector tube, 6. Vacuum chamber, 7. Exhaust nozzle, 8. Inner metal heat collector tube positioning nozzle, 9. Annular groove thin wall, 10. Concentric corrugated expansion-absorbing threaded brazed end cap, 11. Degassing agent, 12. Electrically insulating adhesive, 13. Reflector, 14. Electrically insulating film, 15. Metal reflective film layer, 16. Lead-out electrode, 17. Glass insulation sleeve, 18. Metal brazed end cap, 19. Heat transfer fins, 20. Strip-shaped condenser lens, 21. Positioning metal strap, 22. Condensing lens support groove wall, 23. Convex lens, 24. Lens focusing light inlet hole, 25. Fresnel lens.

Claims

1. A glass-encased, metal-brazed, grooved end cap, and straight-through pressure-bearing photovoltaic heat-collecting vacuum tube, comprising an outer glass tube, metal end caps, a metal corrugated expansion joint, metal brazing flux, an inner straight-through pressure-bearing photovoltaic heat-collecting tube, a high-strength, high-temperature resistant electrical insulating adhesive, a high-temperature resistant photovoltaic cell, and a degassing agent, characterized by: [The text abruptly ends here, so the translation stops as well.] The inner straight-through metal pressure-bearing photovoltaic power generation collector tube is made with photovoltaic cells composited on the surface of the inner straight-through metal tube and is open at both ends. An inner straight-through metal pressure-bearing photovoltaic heat collector tube and an outer glass tube fitted around the inner straight-through metal pressure-bearing photovoltaic heat collector tube, are installed inside the outer casing glass tube via metal end caps at both ends. Due to the significant difference in thermal expansion coefficients between the metal tube and the high borosilicate glass or quartz glass tube, a dedicated metal bellows expansion joint is required to buffer deformation caused by temperature. Therefore, at least one end of the outer casing glass tube has its metal annular groove end cap opening edge welded to one end of the metal bellows expansion joint, and the other end of the metal bellows expansion joint is metal-welded and sealed to the inner straight-through metal pressure-bearing heat collector tube. The metal pressure-bearing photovoltaic heat collection tube, or equipped with a high thermal resistance elastic clip support, supports the metal corrugated tube expansion joint on the inner wall of the outer glass tube; the metal annular groove end cap is brazed and sealed to the outer glass tube opening through a brazed metal pad; the other end of the outer glass tube opening is brazed and sealed to the metal annular groove end cap through a brazed metal pad; the inner hole of the annular groove thin-walled metal end cap, along the welded metal corrugated tube expansion joint inner hole or tube head, is welded to the opening edge of the metal annular groove end cap through metal welding, and then annularly welded and sealed to the inner straight metal pressure-bearing heat collection tube; The materials used to manufacture the internally straight metal pressure-bearing photovoltaic power generation collector tube are corrosion-resistant, high-temperature resistant, and high-strength metal materials, including copper, carbon steel, and stainless steel. The structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell; or the structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a metal reflective film, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell, such as a gallium arsenide high-temperature resistant photovoltaic cell; the positive and negative electrodes of the high-temperature resistant photovoltaic cell are connected in series, and the electrodes are led out through the glass-metal brazing seal connecting the positive and negative electrodes and then led out through the glass tube wall; The metal end cap is a thin-walled metal end cap with an annular groove. The thin-walled metal end cap is welded to a metal bellows expansion joint. The metal bellows expansion joint has holes or openings for inserting a metal pressure-bearing photovoltaic heat collector tube. The annular groove thin-walled metal end cap is made of corrosion-resistant, high-temperature resistant, and high-strength metal materials, such as stainless steel. The annular groove thin-walled metal end cap is formed by machine tool processing, or by machine tool processing combined with metal welding, or by metal three-dimensional printing. The metal annular groove of the glass-metal brazed seal has the following configurations: one side has a thread that matches the threaded end of a high borosilicate glass tube or a quartz glass tube, and the other side is a smooth annular groove wall, forming a single-sided threaded metal end cap; or the metal annular groove has threads on both sides that match the threaded end of a high borosilicate glass tube or a quartz glass tube, forming a double-sided threaded metal end cap; or the two annular groove walls are smooth annular groove walls, forming a thin-walled metal end cap; or one side of the two annular groove walls is a corrugated annular groove wall, and the other side is a smooth annular groove wall, forming a single-sided corrugated annular groove metal end cap; or both annular groove walls are corrugated annular groove walls, forming a double-sided corrugated annular groove metal end cap. At the bottom of the groove of the annular groove thin-walled metal end cap, there is a brazed metal sealing gasket with a melting point lower than the softening temperature of the high borosilicate glass or quartz outer glass tube and the softening temperature of the annular groove thin-walled metal end cap. The brazed metal inside the annular groove thin-walled metal end cap is a metal that can be liquefied when heated to a set temperature. Low melting point brazed metals include aluminum or aluminum alloys, zinc or zinc alloys, and have a melting point temperature below 720°C, and have good wetting properties with the annular groove thin-walled metal end cap and the high borosilicate glass or quartz outer glass tube head. Kovar metals and alloys; the melting point temperature of the brazing metal is higher than the operating temperature of the heat transfer medium but lower than the softening temperature of the high borosilicate glass tube or quartz glass tube and the annular groove thin-walled metal end cap; the sealing connection glass thread provided on the tube head of the high borosilicate glass tube or quartz glass tube, the brazing metal sealing gasket and the annular groove thin-walled metal end cap are brazed and sealed by heating and melting and then tightening; the annular groove thin-walled metal end cap is brazed by heating with an electromagnetic eddy current heater, or by electric heating, or by heating with an electric heater. When a thin-walled metal end cap with an annular groove is joined to Kovar brazing metal via the threaded opening of a high borosilicate glass tube or a quartz glass tube, and then heated, the Kovar brazing metal melts and is then tightened. During this process, the Kovar brazing metal, the thin-walled metal end cap with an annular groove, and the threaded opening of the high borosilicate glass tube or quartz glass tube will mutually weave and fuse together, becoming a single unit. At the system's normal operating temperature, the threads or corrugations of the groove on the thin-walled metal end cap, combined with the annular groove, effectively absorb the Kovar brazing metal and the high borosilicate glass. The limited thermal expansion and contraction of the threaded end of the outer glass tube or quartz outer glass tube ensures a good seal between the annular groove thin-walled metal end cap and the high borosilicate outer glass tube or quartz outer glass tube through Kovar brazing metal. During the brazing process of Kovar brazing metal such as aluminum with the threaded end of the annular groove thin-walled metal end cap, high borosilicate outer glass tube or quartz outer glass tube, the brazing fusion temperature is below 720℃. At this temperature, the annular groove thin-walled metal end cap, aluminum and high borosilicate outer glass tube or quartz outer glass tube release the dissolved gas at the corresponding temperature. The aluminum at the outer edge of the braze reacts with oxygen in the air to form aluminum oxide. During electrothermal brazing, aluminum conducts electricity and rapidly heats up, becoming liquid aluminum. The high borosilicate glass tube or quartz glass tube brazed with the aluminum end cap reaches its softening temperature (high borosilicate glass begins to soften at approximately 821℃). At 720℃, the main components of the high borosilicate glass tube or quartz glass tube, SiO2 and Al, undergo a chemical reaction: 4Al + 3SiO2 = 2Al2O3 + 3Si. This means that at this point, the interface between the high borosilicate glass tube or quartz glass tube and the aluminum can be firmly bonded due to the chemical reaction. Simultaneously, at 720℃, the stainless steel end cap does not soften (the maximum operating temperature of stainless steel 1Cr18Ni9Ti is 870℃), thus meeting the requirements of the high borosilicate glass tube. The process requirements for brazing glass tubes or quartz outer glass tubes and metals include: A chemical reaction occurs between the metal oxide layer surface of the stainless steel end cap and the aluminum, resulting in a strong bond between the stainless steel end cap and the aluminum interface; The deformation of the metal end cap absorbs the stress caused by thermal expansion and contraction of the aluminum or aluminum alloy, or zinc or zinc alloy brazing material, ensuring the brazing quality between the stainless steel end cap and the high borosilicate outer glass tube or quartz outer glass tube; Due to the "U"-shaped and deep closed-loop metal groove design of the metal end cap, the corresponding closed-loop aluminum or aluminum alloy, or zinc or zinc alloy brazing connection sealing layer is longer, resulting in high brazing strength and good airtight sealing performance between the aluminum or aluminum alloy, or zinc or zinc alloy and the high borosilicate outer glass tube or quartz outer glass tube and the metal end cap. The tube head of the high borosilicate glass tube or the quartz glass tube is connected and sealed by a metal brazing fitting with a thin-walled metal end cap with an annular groove corresponding to its shape and size; or it is threadedly fitted with the corresponding thin-walled metal end cap with an annular groove; and then brazed and sealed with a metal washer to form an annular groove thin-walled metal end cap with a "U"-shaped brazing layer between the outer glass tube head and the annular groove thin-walled metal end cap. The inner hole of the annular groove thin-walled metal end cap is connected to the inner hole of the metal bellows expansion joint or the tube head, and then annularly welded and sealed with the inner straight metal pressure photovoltaic heat collection tube. The high borosilicate glass tube or the quartz glass tube is a conventional outer glass tube, or a solar anti-reflective film is provided on the tube wall of the high borosilicate glass tube or the quartz glass tube, with the solar anti-reflective film laminated on the outer surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on the inner surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on both the inner and outer surfaces of the high borosilicate glass tube or the quartz glass tube. A reflective concentrating mirror is installed on the outer borosilicate glass or quartz glass tube. The reflective concentrating mirror is an internal mirror, which is either a metal reflective concentrating mirror integrated with the outer glass tube wall, or a metal reflective concentrating mirror that is attached to the outer glass tube wall and can slide; or it is a high borosilicate glass or quartz glass reflective concentrating mirror. The cross-section of the reflective concentrating mirror is curved, and the focusing line of the reflective concentrating mirror is an inner straight-through metal pressure-bearing photovoltaic power generation heat collection tube whose surface is a high-temperature resistant photovoltaic cell. The cross-section of the outer borosilicate glass or quartz glass tube is circular, elliptical, or a closed line connecting a curve and an arc. The cross-sections of both ends of the outer borosilicate glass or quartz glass tube gradually change from elliptical or a closed line connecting a curve and an arc to a circle. The tube wall of the high borosilicate glass tube or the quartz glass tube may be equipped with a glass-metal brazed sealed outlet electrode; the electrode output end of the inner straight-through metal pressure-bearing photovoltaic heat collector tube wall is led out through the opening on the brazed sealed end cap of the inner straight-through metal pressure-bearing photovoltaic heat collector tube wall. The end cap is brazed and sealed to the glass threaded nozzle of the inner straight-through metal pressure-bearing photovoltaic heat collector tube wall by brazing metal gasket. After the inner straight-through metal pressure-bearing photovoltaic heat collector tube is connected to the vacuum pump through the brazed electrode end cap, the gap between the electrode and the electrode end cap is sealed by metal welding. This realizes the electrical connection end cap of the inner straight-through metal pressure-bearing photovoltaic heat collector tube, the outlet electrode of the inner straight-through metal pressure-bearing photovoltaic heat collector tube and the metal end cap of the glass nozzle of the outer glass tube, forming an electrical circuit between the positive electrode of the inner straight-through metal pressure-bearing photovoltaic heat collector tube and the negative electrode of the photovoltaic heat collector tube outlet electrode. The inner and outer surfaces of the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube are smooth mounting connection surfaces, or mounting connection surfaces with threads, grooves, or flanges for connection with other devices; after evacuating the annular cavity between the inner and outer tubes through the glass exhaust pipe, the glass is welded closed; or the electrode is sealed by glass-metal brazing, after evacuating the annular cavity between the inner and outer tubes, the electrode is sealed by glass-metal brazing and then welded to the metal end cap; the degassing agent is evaporated to form the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube.

2. A glass-encased tube with a metal brazed grooved end cap and a straight-through pressure-bearing photovoltaic heat-collecting vacuum tube, comprising an outer glass tube, metal end caps, metal brazing flux, an inner straight-through pressure-bearing metal photovoltaic heat-collecting tube, a high-strength, high-temperature resistant electrical insulating adhesive, a high-temperature resistant photovoltaic cell, a degassing agent, and a metal corrugated expansion joint, characterized in that: [The inner...] The inner straight-through metal pressure-bearing photovoltaic power generation collector tube is made with photovoltaic cells composited on the surface of the inner straight-through metal tube and is open at both ends. An inner straight-through metal pressure-bearing photovoltaic heat collector tube and an outer glass tube fitted around the inner straight-through metal pressure-bearing photovoltaic heat collector tube, are installed inside the outer casing glass tube via metal end caps at both ends. Due to the significant difference in thermal expansion coefficients between the metal tube and the high borosilicate glass or quartz glass tube, a dedicated metal bellows expansion joint is required to buffer deformation caused by temperature. Therefore, at least one end of the outer casing glass tube has its metal annular groove end cap opening edge welded to one end of the metal bellows expansion joint, and the other end of the metal bellows expansion joint is metal-welded and sealed to the inner straight-through metal pressure-bearing heat collector tube. The metal pressure-bearing photovoltaic heat collection tube, or equipped with a high thermal resistance elastic clip support, supports the metal corrugated tube expansion joint on the inner wall of the outer glass tube; the metal annular groove end cap is brazed and sealed to the outer glass tube opening through a brazed metal pad; the other end of the outer glass tube opening is brazed and sealed to the metal annular groove end cap through a brazed metal pad; the inner hole of the annular groove thin-walled metal end cap, along the welded metal corrugated tube expansion joint inner hole or tube head, is welded to the opening edge of the metal annular groove end cap through metal welding, and then annularly welded and sealed to the inner straight metal pressure-bearing heat collection tube; The materials used to manufacture the internally straight metal pressure-bearing photovoltaic power generation collector tube are corrosion-resistant, high-temperature resistant, and high-strength metal materials, including copper, carbon steel, and stainless steel. The structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell; or the structure of the internally connected metal pressure-bearing photovoltaic heat collector tube consists of, in sequence, an inner metal pressure-bearing tube outer wall, a metal reflective film, a high-strength high-temperature resistant electrical insulating adhesive, and a high-temperature resistant photovoltaic cell, such as a gallium arsenide high-temperature resistant photovoltaic cell; the positive and negative electrodes of the high-temperature resistant photovoltaic cell are connected in series, and the electrodes are led out through the glass-metal brazing seal connecting the positive and negative electrodes and then led out through the glass tube wall; The metal end cap is a thin-walled metal end cap with an annular groove. The thin-walled metal end cap is welded to a metal bellows expansion joint. The metal bellows expansion joint has holes or openings for inserting a metal pressure-bearing photovoltaic heat collector tube. The annular groove thin-walled metal end cap is made of corrosion-resistant, high-temperature resistant, and high-strength metal materials, such as stainless steel. The annular groove thin-walled metal end cap is formed by machine tool processing, or by machine tool processing combined with metal welding, or by metal three-dimensional printing. The two ends of the outer glass tube are provided with glass insulation sleeves; the glass insulation sleeves are coaxial corrugated sleeves formed by welding glass between the glass tube openings in sequence, at least one layer, of appropriate length, and coaxially fitted with the outer glass tube; the opening of the corrugated sleeve is provided with an insulation glass sleeve for brazing and sealing connection with the metal end cap; the outer glass tube head of the high borosilicate glass or quartz outer glass tube includes smooth tube head, corrugated tube head, and threaded tube head; the corrugated tube head is corrugated on the outer wall and smooth on the inner wall, or the corrugated tube head is smooth on the outer wall and corrugated on the inner wall, or the corrugated tube head is corrugated on the outer wall and corrugated on the inner wall; or the threaded tube head is threaded on the outer wall and smooth on the inner wall, or the threaded tube head is threaded on the inner wall and smooth on the outer wall, or the tube head is threaded on the outer wall and threaded on the inner wall. A glass tube of appropriate length is formed by hot-melting and pressing glass threads at one end, and then straightening the other end to a fixed length. The threaded glass tube is then annealed. The threaded glass tube is then coaxially fitted and welded to another glass tube, forming at least one layer of glass tube. Glass tube openings are sequentially welded together to form a coaxial insulated glass tube sleeve. Afterwards, an anti-reflective film is either laminated onto the wall of the transparent glass tube, or after laminating the anti-reflective film onto the wall of the transparent glass tube, the glass cover tube is then processed. The end of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is then trimmed and straightened. On the inner wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, there is a composite radial inner tube; the open end or the reducing end and the end trimming of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube; then, the outer tube wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is cleaned and dried; on the outer tube wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, a composite high-temperature resistant photovoltaic cell is tightly bonded; the coaxial heat-insulating glass tube sleeve, the sealing connection glass thread of the coaxial heat-insulating glass tube sleeve is brazed to the metal groove thread end cap with a brazed metal sealing gasket; The metal annular groove of the glass-metal brazed seal has the following configurations: one side has a thread that matches the threaded end of a high borosilicate glass tube or a quartz glass tube, and the other side is a smooth annular groove wall, forming a single-sided threaded metal end cap; or the metal annular groove has threads on both sides that match the threaded end of a high borosilicate glass tube or a quartz glass tube, forming a double-sided threaded metal end cap; or the two annular groove walls are smooth annular groove walls, forming a thin-walled metal end cap; or one side of the two annular groove walls is a corrugated annular groove wall, and the other side is a smooth annular groove wall, forming a single-sided corrugated annular groove metal end cap; or both annular groove walls are corrugated annular groove walls, forming a double-sided corrugated annular groove metal end cap. At the bottom of the groove of the annular groove thin-walled metal end cap, there is a brazed metal sealing gasket with a melting point lower than the softening temperature of the high borosilicate glass or quartz outer glass tube and the softening temperature of the annular groove thin-walled metal end cap. The brazed metal inside the annular groove thin-walled metal end cap is a metal that can be liquefied when heated to a set temperature. Low melting point brazed metals include aluminum or aluminum alloys, zinc or zinc alloys, and have a melting point temperature below 720°C, and have good wetting properties with the annular groove thin-walled metal end cap and the high borosilicate glass or quartz outer glass tube head. Kovar metals and alloys; the melting point temperature of the brazing metal is higher than the operating temperature of the heat transfer medium but lower than the softening temperature of the high borosilicate glass tube or quartz glass tube and the annular groove thin-walled metal end cap; the sealing connection glass thread provided on the tube head of the high borosilicate glass tube or quartz glass tube, the brazing metal sealing gasket and the annular groove thin-walled metal end cap are brazed and sealed by heating and melting and then tightening; the annular groove thin-walled metal end cap is brazed by heating with an electromagnetic eddy current heater, or by electric heating, or by heating with an electric heater. When a thin-walled metal end cap with an annular groove is joined to Kovar brazing metal via the threaded opening of a high borosilicate glass tube or a quartz glass tube, and then heated, the Kovar brazing metal melts and is then tightened. During this process, the Kovar brazing metal, the thin-walled metal end cap with an annular groove, and the threaded opening of the high borosilicate glass tube or quartz glass tube will mutually weave and fuse together, becoming a single unit. At the system's normal operating temperature, the threads or corrugations of the groove on the thin-walled metal end cap, combined with the annular groove, effectively absorb the Kovar brazing metal and the high borosilicate glass. The limited thermal expansion and contraction of the threaded end of the outer glass tube or quartz outer glass tube ensures a good seal between the annular groove thin-walled metal end cap and the high borosilicate outer glass tube or quartz outer glass tube through Kovar brazing metal. During the brazing process of Kovar brazing metal such as aluminum with the threaded end of the annular groove thin-walled metal end cap, high borosilicate outer glass tube or quartz outer glass tube, the brazing fusion temperature is below 720℃. At this temperature, the annular groove thin-walled metal end cap, aluminum and high borosilicate outer glass tube or quartz outer glass tube release the dissolved gas at the corresponding temperature. The aluminum at the outer edge of the braze reacts with oxygen in the air to form aluminum oxide. During electrothermal brazing, aluminum conducts electricity and rapidly heats up, becoming liquid aluminum. The high borosilicate glass tube or quartz glass tube brazed with the aluminum end cap reaches its softening temperature (high borosilicate glass begins to soften at approximately 821℃). At 720℃, the main components of the high borosilicate glass tube or quartz glass tube, SiO2 and Al, undergo a chemical reaction: 4Al + 3SiO2 = 2Al2O3 + 3Si. This means that at this point, the interface between the high borosilicate glass tube or quartz glass tube and the aluminum can be firmly bonded due to the chemical reaction. Simultaneously, at 720℃, the stainless steel end cap does not soften (the maximum operating temperature of stainless steel 1Cr18Ni9Ti is 870℃), thus meeting the requirements of the high borosilicate glass tube. The process requirements for brazing glass tubes or quartz outer glass tubes and metals include: A chemical reaction occurs between the metal oxide layer surface of the stainless steel end cap and the aluminum, resulting in a strong bond between the stainless steel end cap and the aluminum interface; The deformation of the metal end cap absorbs the stress caused by thermal expansion and contraction of the aluminum or aluminum alloy, or zinc or zinc alloy brazing material, ensuring the brazing quality between the stainless steel end cap and the high borosilicate outer glass tube or quartz outer glass tube; Due to the "U"-shaped and deep closed-loop metal groove design of the metal end cap, the corresponding closed-loop aluminum or aluminum alloy, or zinc or zinc alloy brazing connection sealing layer is longer, resulting in high brazing strength and good airtight sealing performance between the aluminum or aluminum alloy, or zinc or zinc alloy and the high borosilicate outer glass tube or quartz outer glass tube and the metal end cap. The tube head of the high borosilicate glass tube or the quartz glass tube is connected and sealed by a metal brazing fitting with a thin-walled metal end cap with an annular groove corresponding to its shape and size; or it is threadedly fitted with the corresponding thin-walled metal end cap with an annular groove; and then brazed and sealed with a metal washer to form an annular groove thin-walled metal end cap with a "U"-shaped brazing layer between the outer glass tube head and the annular groove thin-walled metal end cap. The inner hole of the annular groove thin-walled metal end cap is connected to the inner hole of the metal bellows expansion joint or the tube head, and then annularly welded and sealed with the inner straight metal pressure photovoltaic heat collection tube. The high borosilicate glass tube or the quartz glass tube is a conventional outer glass tube, or a solar anti-reflective film is provided on the tube wall of the high borosilicate glass tube or the quartz glass tube, with the solar anti-reflective film laminated on the outer surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on the inner surface of the high borosilicate glass tube or the quartz glass tube; or the solar anti-reflective film is laminated on both the inner and outer surfaces of the high borosilicate glass tube or the quartz glass tube. A reflective concentrating mirror is installed on the outer borosilicate glass or quartz glass tube. The reflective concentrating mirror is an internal mirror, which is either a metal reflective concentrating mirror integrated with the outer glass tube wall, or a metal reflective concentrating mirror that is attached to the outer glass tube wall and can slide; or it is a high borosilicate glass or quartz glass reflective concentrating mirror. The cross-section of the reflective concentrating mirror is curved, and the focusing line of the reflective concentrating mirror is an inner straight-through metal pressure-bearing photovoltaic power generation heat collection tube whose surface is a high-temperature resistant photovoltaic cell. The cross-section of the outer borosilicate glass or quartz glass tube is circular, elliptical, or a closed line connecting a curve and an arc. The cross-sections of both ends of the outer borosilicate glass or quartz glass tube gradually change from elliptical or a closed line connecting a curve and an arc to a circle. The tube wall of the high borosilicate glass tube or the quartz glass tube may be equipped with a glass-metal brazed sealed outlet electrode; the electrode output end of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube wall is led out through the opening on the brazed sealed end cap of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube wall. The end cap is brazed and sealed to the glass threaded nozzle of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube wall through a brazed metal gasket. After the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is connected to a vacuum pump through the brazed electrode end cap, the gap between the electrode and the electrode end cap is sealed by metal welding. This realizes the electrical connection end cap of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, the outlet electrode of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube and the metal end cap of the glass nozzle of the outer glass tube, forming an electrical circuit between the positive electrode of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube and the negative electrode of the outlet electrode of the photovoltaic power generation collector tube. The inner and outer surfaces of the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube are smooth mounting connection surfaces, or mounting connection surfaces with threads, grooves, or flanges for connection with other devices; after evacuating the annular cavity between the inner and outer tubes through the glass exhaust pipe, the glass is welded closed; or the electrode is sealed by glass-metal brazing, after evacuating the annular cavity between the inner and outer tubes, the electrode is sealed by glass-metal brazing and then welded to the metal end cap; the degassing agent is evaporated to form the annular grooved thin-walled metal end cap brazed with glass and the inner straight-through metal pressure-bearing photovoltaic power generation collector tube.

3. The glass tube with brazed grooved end cap and direct connection to the pressure-bearing photovoltaic power generation heat collection vacuum tube according to claim 1 or 2, characterized in that: The metal reflective film layer of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube is generated on the outer surface of the tube wall by magnetron sputtering, chemical reaction, or vacuum evaporation. The metal reflective film layer can be a single metal reflective film layer or a composite metal reflective film layer of more than one metal. The metal reflective film layer includes copper film layer, silver film layer, chromium film layer, copper and silver composite film layer, and copper and chromium composite film layer.

4. The glass tube with brazed groove end cap and direct-connection pressure-bearing photovoltaic power generation heat collection vacuum tube according to claim 1 or 2, characterized in that: The open end of the internally connected metal pressure-bearing photovoltaic heat collection tube is of equal diameter, or is a reduced diameter, or an expanded diameter; the open end of the internally connected metal pressure-bearing photovoltaic heat collection tube is a smooth tube opening, or a tube opening with threads, grooves, or metal end caps for sealing connection; the tube opening of the glass tube with metal brazed groove end cap and the internally connected pressure-bearing photovoltaic heat collection vacuum tube is provided with a metal positioning nozzle, which is provided with threads or grooves; the threads or grooves on the metal positioning nozzle are connected to a pressure-balanced pressure-bearing sealing assembly, which is at the root of the tube or support and is provided with threads or grooves; the top of the tube or support of the pressure-balanced pressure-bearing sealing assembly is provided with a suction cup or suction cap; the tube or support of the pressure-balanced pressure-bearing sealing assembly is provided with inlet and outlet liquid ports; The threads or grooves on the metal positioning nozzle are screwed and bolted to the threads or grooves on the pressure-balanced pressure-bearing sealing component pipe or bracket, or snapped into place; the suction cup or suction cap on the pressure-balanced pressure-bearing sealing component is attracted to the top surface of the manifold; or the metal brazed groove end cap of the glass tube is connected to the port of the pressure-bearing photovoltaic power generation heat collection vacuum tube, and a threaded metal positioning nozzle is provided; the threads on the metal positioning nozzle are connected to the threads of the pipe fittings at both ends through the sealing ring. The metal grooved threaded end cap is welded to the end of the inner straight metal pressure-bearing photovoltaic power generation heat collector pipe. The opening of the metal grooved threaded end cap faces the pipe wall or the pipe end. The opening of the glass tube corrugated sleeve faces the pipe end of the inner straight metal pressure-bearing photovoltaic power generation heat collector pipe or the pipe direction of the inner straight metal pressure-bearing photovoltaic power generation heat collector pipe.

5. The glass tube with brazed groove end cap and direct connection to the pressure-bearing photovoltaic power generation heat collection vacuum tube according to claim 1 or 2, characterized in that: The high thermal resistance spring clip support is installed between the inner straight-through metal pressure-bearing photovoltaic power generation collector tube and the outer casing high borosilicate glass or quartz glass tube. It consists of a straight-through transparent high borosilicate glass or quartz glass tube and three closed-loop high thermal resistance spring clip supports. The three closed-loop supports are respectively installed in three annular grooves located in the middle and at both ends of the inner and outer walls of the straight-through transparent high borosilicate glass or quartz glass tube. The three closed-loop high thermal resistance spring clip supports are positioned by the three annular grooves on the tube wall and are fitted onto the metal pressure-bearing straight-through photovoltaic collector tube. The solar collector tube is supported by a transparent tube between the inner straight-through metal pressure-bearing photovoltaic power generation collector tube and the outer casing high borosilicate glass or quartz glass tube. Three closed-loop high thermal resistance spring clip supports are welded to reduce their inner and outer diameters. Heating allows the welds to open, causing the inner and outer diameters of the closed-loop high thermal resistance spring clip supports to decrease and increase respectively. These supports are then supported by the inner and outer walls of the transparent high borosilicate glass or quartz glass tube on the outer casing high borosilicate glass or quartz glass tube and the outer wall of the inner straight-through metal pressure-bearing photovoltaic power generation collector tube, respectively.

6. The glass tube with brazed grooved end cap and direct connection to the pressure-bearing photovoltaic power generation heat collection vacuum tube according to claim 1 or 2, characterized in that: The tube head of the high borosilicate glass tube or the quartz glass tube is connected and sealed by a metal brazing of a thin-walled metal end cap with an annular groove corresponding to its shape and size to the tube head of the high borosilicate glass tube or the quartz glass tube. At least one end of the opening of the metal end cap with the groove is connected by a metal bellows expansion joint with metal welding to the tube wall of the opening of the high-temperature photovoltaic cell heat absorption, heat collection and heat transfer inner straight metal pressure photovoltaic power generation heat collection tube with an annular metal welding connection.

7. The glass tube with brazed groove end cap and direct connection to the pressure-bearing photovoltaic power generation heat collection vacuum tube according to claim 1 or 2, characterized in that: The opening end of the outer glass tube is rounded, and the rounded glass tube head is connected to the grooved metal end cap by glass-metal brazing. The opening of the grooved metal end cap is connected to the opening of the high-temperature photovoltaic cell heat absorption, heat collection and heat transfer inner straight metal pressure photovoltaic power generation heat collection tube by annular glass-metal brazing.

8. The glass tube with brazed grooved end cap and direct-connection pressure-bearing photovoltaic power generation heat collection vacuum tube according to claim 1 or 2, characterized in that: Alternatively, a pre-made glass tube head with one end having the same shape and size as the opening end of the outer glass tube and the other end rounded is connected to the open end of the outer glass tube. The rounded glass tube head is then brazed to a grooved metal end cap for a sealed glass-metal connection. The opening of the grooved metal end cap is then annularly brazed to the opening of the high-temperature photovoltaic cell heat absorption, heat collection, and heat transfer inner direct metal pressure photovoltaic power generation collector tube for a sealed annular glass-metal connection.

9. The glass tube with metal brazed groove end cap according to claim 1 or 2, directly connected to a pressure-bearing photovoltaic power generation heat collection vacuum tube, characterized in that: in The outer wall of the metal brazed groove end cap of the glass tube is directly connected to the outer wall of the pressure-bearing photovoltaic heat collector vacuum tube. A groove corresponding to the center of the reflector of the inner pressure-bearing photovoltaic heat collector tube is provided, and they are attracted to each other by magnets, achieving synchronous contact with the outer glass tube wall for sliding and rotation. The bottom surface of the inverted "U"-shaped closed support groove is a strip-shaped condenser lens, which can be a strip-shaped Fresnel lens or a strip-shaped convex lens. The focused light from the strip-shaped condenser lens passes through the groove at the center of the reflector of the inner pressure-bearing photovoltaic heat collector tube and is focused onto the back surface of the inner pressure-bearing photovoltaic heat collector tube. This maximizes the light efficiency and minimizes the light radiation by reflecting the heat radiated from the surface of the inner pressure-bearing photovoltaic heat collector tube back to the inner pressure-bearing photovoltaic heat collector tube, which is inefficient due to its weak light intensity.

10. The glass tube with brazed groove end cap and direct-connection pressure-bearing photovoltaic power generation heat collection vacuum tube according to claim 1 or 2, characterized in that: The inner wall of the metal pressure-bearing heat collector tube is reinforced with a radial inner tube with high thermal conductivity for heat transfer, or with a longitudinal inner tube with a rifling heat transfer spiral and high thermal conductivity. The inner tube is made of copper or carbon material. Alternatively, a glass tube with a metal brazed groove end cap is provided, and the pressure-bearing photovoltaic heat collector vacuum tube is equipped with a tubular guide with both ends sealed. The tubular guide is made of high borosilicate glass or metal tube.

Images