WO2020099577A1

WO2020099577A1 - Accumulator system for evacuated tubes and method for fusing, melting and evacuation

Info

Publication number: WO2020099577A1
Application number: PCT/EP2019/081355
Authority: WO
Inventors: Ralf LUXENHOFER
Original assignee: Luxenhofer Ralf
Priority date: 2018-11-16
Filing date: 2019-11-14
Publication date: 2020-05-22

Abstract

An accumulator system for evacuated tubes includes a vacuum tube seal having a glass lid (402, 452) wherein a Kovar sleeve (410) is vacuum-welded on a copper tube (406), passes through the glass lid (402, 452). A seal vacuum-tightly seals the glass to metal connection after a vacuum on an enclosed gas or gas mixture is drawn in the glass tube (404) to a pressure between 10^-5 and 10^-8 bar. The seal is a Kovar sleeve (410), which is welded to a lead glass (412), which is fused to the glass tube (404). This arrangement allows the copper tube (406) to be welded to the Kovar sleeve (410) to ensure a vacuum-tight connection.

Description

ACCUMULATOR SYSTEM FOR EVACUATED TUBES AND METHOD FOR FUSING,

MELTING AND EVACUATION

Cross Reference to Related Applications

This application claims the benefit of U.S. Provisional Application No. _

, filed

_ and U.S. Provisional Application 60/ _ , filed

the content of the entirety of which is explicitly incorporated herein by reference and relied upon to define features for which protection may be sought hereby as it is believed that the entirety thereof contributes to solving the technical problem underlying the invention, some features that may be mentioned hereunder being of particular importance.

Copyright & Legal Notice

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The Applicant has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. Further, no references to third party patents or articles made herein is to be construed as an admission that the present invention is not entitled to antedate such material by virtue of prior invention.

Background of the Invention

This invention relates to evacuated tube solar collectors, which are typically used to collect heat radiated from the sun for space heating, domestic hot water or cooling with an absorption chiller. In a variant, vacuum tube collectors use heat pipes for their core. Thus, the collected heat is transferred via the heat pipes to a transfer fluid in a heat exchanger known in the technical field as "manifold".

In the past, simple solar thermal systems, like flat plate collectors, have been used to produce domestic warm water. Simple evacuated tubes of the prior art, as shown in FIG. 1, have also been installed for this purpose. These collectors have an operating temperature between 90°C and approx. 140°C. Large parabolic trough power plants can reach temperatures of over 400°C to produce steam, but they are used only in large-scale industrial applications due to their colossal size and cost.

What is needed is a collector or a collector system with an operating temperature range between 140°C und approx. 250°C. Such a range is useful, by way of example, for:

the food and drink industry, in particular for sterilization washing, cooking, and baking; the textile industry, in particular for washing, bleaching, and dying;

the wood industry, in particular for drying, and pressing;

the metal industry, in particular for galvanization;

the chemical industry, in particular for distillation, and boiling;

the seawater desalination; and

the electricity production using steam.

So far, collector tubes are mainly made of borosilicate glass with a diameter of typically 100- 120 mm. In so called Direct Flow collectors of the prior art, as shown in FIG. 2A, heat transfer fluid circulates directly in and out through every single collector tube 204 of a system via an absorber tube 202. Such a system may contain an array of tubes 204. The heat transfer occurs directly from the absorber layer 206 which is placed inside the collector tube 204 and reflects the collected energy towards the absorber tube 202 which is part of the system's fluid circulation. This type of collector is typically used for flat roof and facade mounting. In so called Heat Pipe collectors of the prior art, as shown in FIG. 2B, the heat transfer fluid 272 circulates within an evacuated heat pipe 252 where it evaporates and rises to the condensor 262. The condensor 262 is fitted into a tube 264 that carries the system's water 266 and transfers the heat to the water 266 at this point. The fluid in the heat pipe 252 then condenses in the area of the condensor 262, falls to the bottom of the heat pipe tube 252 and the process repeats itself continually. Heat Pipe collector systems must always be mounted at an angle, i.e. not flat for this process to function.

For both types of collectors as described above, a gastight and vacuum-proof passageway at one end of the collector tube 204, 254 is required in order to allow the absorber tube 202 or the heat pipe 252 respectively being positioned inside the evacuated collector tube 204, 254. Prior art methods considered as state of the art propose the so-called "thermo compression" method for sealing in a gastight manner. A cross section view of a collector tube 304, illustrating the "thermo compression" method of the prior art, is shown in FIG. 3 A. The collector tube 304, typically made out of glass, is closed with a metal lid 312 (e.g. Dilaton) at the top. By way of example, the collector tube 304 used in the "thermo compression" method, as schematically shown, is made ofborosilicate glass (e.g. Duran 3.3) with a diameter of 100mm. A metal lid 312 is hit on the tube 304 to seal the tubes 304 on its top. There are two reasons why borosilicate glass must be used for this method. First, the glass collector tube 304 must have the same expansion coefficient as the metal lid 312 and second, the glass collector tube 304 must be extremely stable for the "hit" (conducted with approx. 3 tons). The metal lid 312 consists of a suitable alloy (e.g. Dilalon M24). The passages of the fluid conducting absorber tube 202 or heat tube 252 respectively, and optionally an evacuation pipe (not shown) and/or a test pipe (not shown), must be feed through the metal lid 312 and soldered with it in a vacuum-proof manner, e.g. in a vacuum oven. The lower end (not shown) of the glass tube 304 is formed to a closed glass bottom. The evacuation of the tube happens via the evacuation pipe through the metal lid 312 on top.

Another method for sealing in a gastight manner considered the state of the art is the so-called "houskeeper" method. This method is shown in FIG. 3B. The principle of this glass-metal- compound is well-known. However, it requires great effort to balance the different expansion between glass pipe 354 and metal pipe 362. First, apiece of lead glass 356 is melted on to the glass pipe 354 (customary). The glass pipe 354 may be made of AR-glass. A special ceramic 360 is connected to this lead glass structure 356, which is then connected with the metal pipe 362, In this way, the "houskeeper" method balances the different thermal expansions.

In both methods, the diameter of the nozzle 302, 352 of the metal pipe 322, 362 (used for evacuation) is very small (only about 6 mm). The reason for this is, that after reaching the final pressure inside the collector tube, the metal pipe 322, 362 (on which a vacuum pump is connected) must be vacuum-sealed and cut off. Such a small diameter of the nozzle 302, 352 of the metal pipe 322, 362 in relation to a relative large volume of the collector tubes 304, 354 requires a very long time for evacuation (about 45 minutes) in order to reach the desired pressure. This implicates a high energy expenditure not only for to operate a vacuum pump, but also for heating the collector tube during the evacuation time to about 500°C, so that substantially all gaseous molecules, as e.g. oxygen molecules, can be evacuated.

What is needed is a method of evacuating collector tubes within a substantially shorter time, without the need of heating during the evacuation time and a product where an expensive metal lid can be replaced by a more cost-effective element.

Summary of the Invention

An accumulator system and method/apparatus is provided for evacuated glass tubes includes a vacuum tube seal having a glass lid wherein a vacuum-welded copper tube is sealed with a sleeve made of a specially developed alloy known as’Kovar'. The sleeve is sealed with a lead glass which is fused to the glass lid. The sleeve seals vacuum-tightly the glass to metal connection after a vacuum on an enclosed gas or gas mixture is drawn in the tube to a pressure between 1 O^’5 bar and 10^-8 bar. This arrangement allows the copper tube to be welded to the Kovar sleeve, the Kovar sleeve is sealed to the lead glass, the lead glass is fused to the glass lid. This ensures a vacuum- tight connection.

An object of the invention is to provide a method of evacuating collector tubes within a substantially shorter time, without the need of heating during the evacuation time.

Another object of the invention is to reduce the cost of the metal lid by replacing it with a more cost-effective element.

Brief Description of the Drawings

The attached drawings represent, by way of example, different embodiments of the subject of the invention.

FIG. 1 is a cross-section view of an evacuated tube as used in collectors of the prior art.

FIG. 2A is a schematic view of a Direct Flow collectors of the prior art. FIG. 2B is a schematic view of a Heat Pipe collector of the prior art.

FIG. 3A is a cross section view of a part of a collector tube closed with a metal lid at the top as known in the prior art.

FIG. 3B is a cross section view of a sealing between glass pipe and metal pipe in a gastight manner of the prior art.

FIGs. 4A to 4B are perspective views of a glass tube, an absorber layer, a glass lid, a cooper tube and other elements.

FIG. 4C is a cross section view of a part of a glass tube as shown in FIGs. 4A to 4B, closed at its top end by an inexpensive glass lid of the invention.

FIGs. 5A to 5C are illustrations of the production and evacuation method of the invention, comprising heating, evacuating, fusing and crimping steps.

FIG. 6 is an absorber holding clamp.

FIGS 7A and 7B are illustrating a movable mirror placed inside a glass tube.

FIG. 8 is a cross section view of a Direct Flow collector of the invention.

FIG. 9 is a cross section view of a Heat Pipe collector of the invention.

FIG. 10A and 10B are perspective views of an arrangement of two squared profiles such as used in the collectors shown in FIG. 8 and FIG. 9,

Those skilled in the art will appreciate that elements in the Figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, dimensions may be exaggerated relative to other elements to help improve understanding of the invention and its embodiments. Furthermore, when the terms 'first', 'second', and the like are used herein, their use is intended for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. Moreover, relative terms like 'front', 'back', 'top' and 'bottom', and the like in the Description and/or in the claims are not necessarily used for describing exclusive relative position. Those skilled in the art will therefore understand that such terms may be interchangeable with other terms, and that the embodiments described herein are capable of operating in other orientations than those explicitly illustrated or otherwise described.

Detailed Description of the Preferred Embodiment

The following description is not intended to limit the scope of the invention in any way as it is exemplary in nature, serving to describe the best mode of the invention known to the inventors as of the filing date hereof. Consequently, changes may be made in the arrangement and/or function of any of the elements described in the exemplary embodiments disclosed herein without departing from the spirit and scope of the invention.

Now referring to FIG. 4A, when sealing the copper tube 406 via other elements to the top end of the glass tube 404, it is our innovation to replace the expensive metal lid (as shown in FIG. 3A) of the prior art with an inexpensive glass lid 402. Where the copper tube 406 (as used for Direct Flow Collectors as shown in FIG. 2A and for Heat Pipe Collectors as shown in FIG. 2B) penetrates the glass lid 402, there is a sleeve 410 made of a specially-developed alloy (Kovar) which ensures that there is no leak of the vacuum on the top end of the glass tube 404. The glass tube 404 typically contains an absorber layer 405. Given by the design of the glass tubes 404, the copper tube 406 must be passed through the glass lid 402. The assembly of an assembly group 442 proceeds as follows. The copper tube 406 is welded to a Kovar sleeve 410 to ensure a vacuum- tight connection. The Kovar sleeve 410 is further sealed to a lead glass 412. The lead glass 412 is fused to the glass lid 402. The assembly group 442 is placed on the top end of the glass tube 404, Subsequently, the glass lid 402 and the top end of the glass tube 404 are melted and vacuum-tightly connected. Optionally, as shown in FIG. 4A, it is possible to use one or more further intermediate glasses 413, 414. Intermediate glasses 413, 414 can be made of Emaille 8651, Emaille 8242 or similar materials. Intermediate glasses 413, 414 are not required if lead glass 412 is used as the glass connecting the Kovar sleeve 410 and the glass lid 402.

Now referring to FIG. 4B. A glass lid 452 is positioned on the bottom end of the glass tube 404 and vacuum-tightly connected to the glass tube 404. According to the present invention, the glass tube 404 is evacuated to a pressure of 10^"5 to 10 ⁸ bar via an evacuation nozzle 403 and the evacuation nozzle 403 is subsequently sealed vacuum-tightly by squeezing the evaluation nozzle

403. Evacuation and squeezing take a couple of minutes. Due to pinching and sealing the evacuation nozzle 403 of the glass lid 452, a vacuum-tight closure is established.

In an industrial factory setup, the glass lid 402 is fused to the Kovar sleeve 410. The evacuation nozzle is welded to the glass lid 452. Both glass lid 402 and glass lid 452 may be prefabricated. In an industrial production process, an assembly robot may pick glass lids 402, 452 fully automatically from a mold cavity, cavity, box, blister or the like. Glass lid 402 and glass lid 452 may comprise other elements attached to it, e.g. as shown as assembly group 442 for glass lid 402, or the evacuation nozzle 403 for glass lid 452. One end of the glass tube 404 and the glass lid 402 and/or glass lied 452 are positioned towards each other fully automatically by a machine or a robot and seated by melting the glasses of the glass tube 404 and the glass lid 402 or glass lid 452, which allows to establish a connection allowing a vacuum of 10 ⁵ to 10 ⁸ bar inside the closed glass tube

404. The glass lid 452 comprises the evacuation nozzle 403. In an alternative embodiment, the glass lid 402 comprises the evacuation nozzle 403. The evacuation nozzle 403 establishes a connection to the inside space of the glass tube 404. In a newly developed production and evacuation method, a vacuum pump (not shown) is connected to the evacuation nozzle 403 and is operating continuously (i.e. sucking gas from the inside space of the glass tube 404) during the application of following production steps:

a) the glass tube 404 is heated (heat is applied in order to evacuate sufficient molecules); b) the evacuation nozzle 403 is heated close to its melting point;

c) the evacuation nozzle 403 is squeezed and closed, and a holding time is applied; and d) the evacuation nozzle 403 is cut in the area where it is squeezed, such that that portion of the evacuation nozzle 403 remaining connected with the glass lid 452 is vacuum-tightly closed (able to maintain a vacuum of 10 ⁵ to 10 ⁸ bar inside the glass tube 404).

Optionally, the actual pressure applied by the vacuum pump is regularly/continuously measured. Once a defined threshold value (e.g. 10^‘5 bar, 10 ⁶ bar, 10 ⁷ bar, or 10 ⁸ bar) is reached, above-mentioned production step b) or c) can be released and/or triggered.

In an alternative variant, the glass lid 402 comprises the evacuation nozzle 403 and the above production steps a), b), c) and d) can be applied in the same manner.

The present invention ensures production safety and an exceptionally long-life expectancy.

Now referring to FIGS. 5A to SC, the newly developed production and evacuation method allows for a constriction of the evacuation nozzle 403 after about 35 seconds of evacuation and heating in order to reach a desired level of vacuum (e.g. 10 ^s bar, 10 ⁶ bar, 10 ⁷ bar, or 10 ⁸ bar). FIG. 5A is a cross-section view and schematically illustrating the evacuation nozzle 403 (which has a typical diameter of 50mm) and a ring burner 502. Exemplary the ring burner 502 is realized with two elements, the elements are moveable in the direction of the arrows 504 in order to approach towards the evacuation nozzle 403, and are also movable in the opposition direction of the arrows 504 in order to move away from the evacuation nozzle 403. FIG. 5A illustrates above- mentioned production step b). FIGS. SB and SC are a cross-section views and schematically illustrating the evacuation nozzle 403 as well as squeeze and cut jaws 503. The squeeze and cut jaws 503 are moveable in the direction of the arrows 510 in order to approach towards the evacuation nozzle 403 and as a consequence squeeze (shown in FIG. SB) and finally close and cut (shown in FIG. SC) the evacuation nozzle 403, and are also movable in the opposition direction of the arrows 510 in order to move away from the evacuation nozzle 403. FIGS. SB and SC illustrate above-mentioned production steps c) and d). Production steps c) and d) can be executed on the same production station in a combined manner as described for FIGS. SB and SC, or alternatively be realized on two individual production stations (not shown), one production station for step c), and another production station for step d). The evacuation nozzle 403 can be fused and crimped to ensure a reliable vacuum in one step. In a preferred embodiment, in order to secure the vacuum, the glass tube 404 is warmed and the evacuation nozzle 403 is crimped with a crimping tool after being heated by a ring burner 502 three times in the process step b). Subsequently, in a preferred embodiment, the evacuation nozzle 403 is cut with a strip burner (not shown) in the process step d).

Following gas mixtures have been identified to be suitable for the glass to glass melting process. The squeezing and closing of the evacuation nozzle 403 may be done with natural or petroleum gas at 0.8-1.2 bar, preferably at 1 bar, or with oxygen at about 5.5-7.5bar, preferably at 6.5 bar. Tests have shown that in production about 1.3 Nm³/h (normal cubic meter per hour) of natural or petroleum gas is used, or 2.6 Nm³/h of oxygen is used.

The production method for assembling the assembly group 442 as described above does not need contact agents for glass to metal seal.

Now referring to FIGS. 6A and 6B, an absorber holding clamp 550 with suitable properties is provided to be installed inside the glass tube 404, 604, 704, to hold inside the glass tube 404, 604, 704 the absorber layer 405, and to prevent twist/distortion of the absorber layer 405 during operation and to avoid that the absorber layer 405 may contact the inside surface of the glass tube 404, 604, 704. Such a contact would establish a thermal bridge between the absorber layer 405 and the inside surface of the glass tube 404, 604, 704. The absorber holding clam 550 comprises preferably four arms 552 (also called wings) to position and clamp the absorber holding clam 550 towards the inside surface of the glass tube 404, 604, 704. Each arm 552 comprises in the area of its distal end an elevation point 554 (the elevation is directed towards the inside surface of the glass tube 404, 604, 704), preferably realized as a ceramic drop, in order to avoid scratching of the inside surface of the glass tube 404, 604, 704 at the time of insertion of the absorber holding clamp 550 together with the absorber layer 405. Further, the elevation points 554 are minimizing the surface of contact between the absorber holding clamp 550 and the inside surface of the glass tube 404, 604, 704.

Now referring to FIGS. 7A and 7B, a movable mirror 902 is provided. The ability of a mirror to be moveable is optional in the context of the present invention. The movable mirror 902 is suited inside the glass tube 404 and semicircular shaped. FIG. 7A is a cross sectional view across the diameter of the glass tube 404. FIG. 7B is a cross sectional view along the axis of the glass tube

404. The mirror 902 is pivot-mounted inside the glass tube 404, e.g. by use of rollers 904 in roller conveyors 906. The mirror 902 may be turned via a one or more servomotors 910 with the aim to position the mirror 902 towards the sun. This innovative feature is an optional feature of the present innovation. By turning the mirror 902 towards the maximum radiation of the sun, the maximal yield of energy is attained. Because the mirror 902 is inside the glass tube 404, it does not become soiled as external mirrors would. Thanks to this, the mirror 902 does not lose efficiency over time. The movable mirror 902 can optionally be turned completely around the axis of the glass tube 404 so that it may act as an umbrella, withholding radiation to attain the copper tube 406 of the absorber

405, with the effect to turn the collector 'off when needed.

In operation, temperature ranges of 90°C to 250°C are possible, and 140°C to 250°C is the preferred range.

In an embodiment of a Direct Flow collector as shown in FIG. 8, the absorber tube 602 of the collector tubes 604 (also referred to as glass tube 404) are connected to a system of two squared profiles 606, 610. A perspective view of an arrangement of the two squared profiles, such as squared profiles 606, 610, are shown in FIG. 10A and 10B. The squared profiles 606, 610 function as manifold (similar as in FIG. 2 A) and accommodate heat transfer fluid 612 (as well similar as in FIG. 2A). The manifold system of two squared profiles are in a preferred embodiment made of one U-shaped profile 610, tightly connected to a square-shaped profile 606. Typically, the profiles 606, 610 can be machined (e.g. drilling holes 802) and functional components 804 (e.g. thermowells, stream sheets) can be affixed before the two profiles 606, 610 are connected with each other. The connection can be realized through welding and thanks to the flat/plane surfaces, the weld seam 810 is substantially straight and simple to realize e.g. by means of a welding robot. The manifold, as realized according to the present invention, provides further following advantage: the transfer of the energy from the collector tubes 604 into the heat transfer fluid 612 has an increased degree of efficiency. In an embodiment of a heat pipe collector as shown in FIG. 9, the condensor 762 of the collector tubes 704 (also referred to as glass tube 404) are connected to a system of two squared profiles 706, 710. A perspective view of an arrangement of the two squared profiles, such as squared profiles 706, 710, are shown in FIG. 10A and 10B.

Hereinafter, the functional principle of the Heat Pipe collector based on the two chambers is disclosed in more detail. The lower chamber 712 of the collector is filled with water 716 or another suitable fluid. Such suitable fluids are for example (3 times) distilled water, natrium (or NaK-78), pentane, ammonium, methanol or toluol. The water 716 (or another suitable fluid as mentioned) is flowing continuously through that chamber 712. The lower chamber 712 is optionally connected tightly via connection 720 to another lower chamber of another collector and so on. The water 716 in the lower chamber 712 is heated by the condensors 762. Due to the heating, the lower chamber 712 is pressurized and the water 716 is evaporating at about 1 10°C. Once the pressure exceeds a threshold value, one or more valves 722 are opening and allowing steam (wet steam) to escape from the lower chamber 712 into the upper chamber 714. The one or more valves 722 are situated between the lower chamber 712 and the upper chamber 714, operating to open and close a passage 724 between the lower chamber 712 and the upper chamber 714. When the pressure in the lower chamber 712 drops below a threshold value, the one or more valves 722 close the one or more passages 724. Then again, once the pressure exceeds a threshold value, one or more valves 722 are opening and allowing steam (wet steam) to escape from the lower chamber 712 into the upper chamber 714. During operation, this sequence is continuously repeating.

The wet steam in the upper chamber 714 is then further heated by the tips 764 of the condenser 762. The tips 764 of the condenser 762 have typically a temperature of about 250°C. Thus, saturated steam is generated, which may be understood as an intermediate between wet steam and superheated steam.

Hence, the evaporation of the water 716 happens in two consecutive stages. This is similar to the evaporation in a pressure cooker. Multiple autarkic pressure cooker could be interconnected to work in a system. The present invention comprises an industrial manufacturing facility for the production of evacuated collector tubes according to the present disclosure. The invention comprises as well the evacuated collector tubes which have an operating temperature between 140°C and 250°C. The evacuated tubes can be produced on an automated production line in a cost and energy efficient manner. The automated production guarantees that the collectors will continually be of the highest quality. The evacuated tubes disclosed here are different to the tubes of the prior art in terms of design, production and performance. The tubes of the present invention feature a large diameter of about 100 mm, which provides for the optimal relationship between absorber area and heat conductivity. However, other diameters in the range of 80- 140mm, ranges such as 90- 110mm, 80- 100mm, 100- 120mm, and 120- 140mm, are feasible. This also allows for special modifications to be made for specific applications, such as a bent absorber or a concentrating mirror within the tube. The evacuated tubes of the invention are specially designed solar thermal collectors for high temperature applications. One embodiment of a heat pipe operates at temperatures of over 200°C (working temperature) to circulate thermal oil. Such an operating temperature is required, for example, if a craft engine is supplied with the hot thermal oil in order to produce electricity.

Solar thermal collector systems for to accumulate radiation energy radiated by the sun typically comprise tubes which are evacuated to a pressure of about 10 ⁵ to 10 ⁸ bar. Until now, it was not technically possible to crimp and close large evacuation nozzles in a vacuum-tight manner. The glass tubes can be evacuated via an evacuation nozzle 403 with a diameter of 50 mm within approx. 3 minutes and vacuum-seal and crimp the nozzle after reaching the final pressure (10 ⁵ to 10 ⁸ bar). However, this works as well for other diameters in the range of 30-70mm, ranges such as 30-45mm, 45-55mm, 40-50mm, 50-60mm, and 60-70mm. The evacuation nozzle 403 may be made of Boro 3.3 glass. Due to such a large opening of the evacuation nozzle and the resulting more effective evacuation, it is no longer necessary to heat the tubes during the evacuation process.

Until now, it was not possible to vacuum-seal and cut off an evacuation pipe of the diameters mentioned above. The crimping of a glass nozzle of large diameter can produce bubbles and cracks, which make vacuum-tight sealing of the tube impossible. The herein disclosed new method allows a vacuum-tight closure by means of a specific geometry for the crimping and cutting tool, a special gas mixture (natural gas and dioxygen) during the heating and squeezing phase, and a defined holding time at the crimping point.

The invention comprises methods of production and systems, products and devices thereof.

In several advantages, the invention provides for energy efficient production of the assembled and evacuated collector tubes, increased production safety during the production of the tubes, increased production capacity of the tubes with continuously high quality, more effective manifold for higher efficiency and steam production directly in the manifold. The production method of the present invention is in particular more energy efficient as production methods of the prior art due to the fact that the glass tubes 404 do not have to be heated up to 500°C or even more in order to reach the desired level of vacuum. According to the production method of the present invention, temperatures of about 180°C are sufficient to reach the desired level of vacuum within a reasonable time, i.e. typically within 3 to 5 minutes. In methods of production of the prior art, the temperatures of up to 500°C or even more were required to be maintained during 45min or even more. The production method of the present invention, a temperature of about 180°C is required an needs to be maintained for only about 3 minutes.

In another preferred production method, the glass lid 402 or glass lid 452 is welded onto the glass tube 404 in a vacuum-tight manner by means of a laser. This provides an even more energy efficient production method.

In another advantage, the invention provides an innovative production method that is unique in the field of technology. According to this production method, the production process is faster, more efficient, energy saving, environmentally friendly and adapted to achieve increased quality compared to known production methods in the field of technology. In a further advantage, the ability to effectively vacuum seal and crimp a stem of glass, preferably borosilicate glass, of about 50 mm diameter is novel and inventive. Other diameters in the range of 30-70mm are possible, as mentioned above.

In another advantage, the accumulator systems, produced according to the production method disclosed in the present patent application, provide surprisingly high operational output temperatures of the collectors.

In an advantage, the manifold, as realized according to the present invention, provides further following advantage: the transfer of the energy from the collector tubes 604 into the heat transfer fluid 612 has an increased degree of efficiency.

In another advantage particular to the direct flow collector of FIG. 8, the squared shape of the manifold arrangement allows on the one hand an easy affixable contact insulation 806 and on the other hand an increased degree of the insulation compared to round manifold tubes as provided by state of the art. This results in an increased degree of overall efficiency compared to systems of the prior art. Furthermore, thanks to the squared profile the production cost, the material cost (e.g. aluminum) and at a later stage the cost for assembling of the system are remarkably low compared to the prior art. The flat/plane surfaces provide many advantages in machining, processing and handling compared to round profiles. In the prior art, the manifold is typically produced of copper which is costly compared to aluminum, as proposed by the present invention.

In another advantage of the heat pipe collector system of FIGS. 9, 10A and 10B, by way of contrast with the prior art system which are susceptible to the formation of steam and there have a maximum operating temperature limited in the practice to about 140°C to avoid steam formation and therefore the likelihood of damage to the collector system and in particular to the tubes of the collector system, the herein disclosed heat pipe collector system of the invention provides a mode of operating based on two chambers, which allows a controlled continuous generation of steam. The steam generated in this way is of high quality, also known as saturated steam. This saturated steam is made available for use in other fields of application. The Heat Pipe collector described above can be equipped with high temperature Heat Pipe tubes, the high temperature Heat Pipe tubes are capable of reaching temperatures of approximately 400°C. Such an arrangement is capable to produce superheated steam.

The above heat pipe collector system is suitable to be combined with a steam turbine or a mixed-pressure turbine for the production of electricity and power generation. Thanks to the generation of high-quality steam by the heat pipe collector of the present invention, that high- quality steam leads to a more efficient usability of steam turbines or mixed-pressure turbines.

The invention is summarized by the below feature sets:

1. An accumulator system for evacuated tubes comprising a vacuum tube seal having a glass lid (402, 452) wherein a vacuum-welded copper tube (406) passes through the glass lid (402, 452) and wherein a seal vacuum-tightly seals the glass to metal connection after a vacuum is drawn in the tube to a pressure between 1 O ⁵ and 10^‘8 bar, the seal being a Kovar sleeve (410), thereby allowing the copper tube (406) to be welded to the Kovar sleeve (410) to ensure a vacuum-tight connection.

2. The accumulator system of feature set 1, wherein a stub of the glass lid (402, 452) is connected to the glass tube (404) via a pinched and sealed connection such that it may be tightly seal a vacuum in the tube.

3. The accumulator of any of the above feature sets, wherein the glass tube (404) and the glass lid (402, 452) are positioned fully automatically by a machine and seated by melting the glasses of the glass tube (404) and the glass lid (402, 452) to achieve a vacuum of about 10 ⁵ to 10 ⁸ bar, thereby ensuring production safety and long-life expectancy.

4. The accumulator of feature set 1, wherein the accumulator further includes a movable mirror and a servo motor, the mirror being disposed inside the tube and thus protected from the environment, and is adapted to turn via the servomotor so as to generally follow the sun, so as to maximize the energy yield without losing efficiency over time.

5. The accumulator of feature set 4, wherein the movable mirror, when turned to a certain position, acts as an umbrella, turning the collector 'off when needed.

6. The accumulator system of feature set 1 of the direct flow type, wherein the absorber tube (406, 602) of the glass tubes (404, 604) are connected to a subsystem comprising two squared profiles (606, 610) that function as a manifold (630) and accommodate heat transfer fluid (612).

7. The accumulator system of the above feature set, wherein the manifold of two squared profiles are preferably made of one U-shaped profile (610), tightly connected to a squareshaped profile (606),

8. The accumulator system of the above feature set, wherein the profiles (606, 610) are machined profiles and functional components (804) such as thermowells, or stream sheets, are affixed before the two profiles (606, 610) are connected with each other.

9. The accumulator system of the above feature set, wherein the affixing is realized through seam welding and, thanks to the flat/plane surfaces, a resulting weld seam (810) is substantially straight and simple to realize, optionally by means of a welding robot.

10. The accumulator system of feature set 1 of a heat pipe collator type, further comprising a condensor (762) of the collector tubes (704) connected to a system of two squared profiles (706, 710).

11. The accumulator system of feature set 10 combined with a steam turbine or a mixed- pressure turbine for the production of electricity and power generation.

12. The accumulator system of the above feature set, further comprising an upper chamber (714) and a lower chamber (712) of the collector that is filled with a liquid (716) such as water, the liquid (716) flowing continuously through that chamber (712), wherein the lower chamber (712) is optionally connected tightly via connection (720) to another lower chamber of another collector and so on.

13. The accumulator system of the above feature set, wherein the liquid (716) in the lower chamber (712) is -heated by the condensors (762) whereby the lower chamber (712) is pressurized and the liquid (716) is evaporated, in the case of water, at about 110°C, whereinafter, once the pressure exceeds a threshold value, one or more valves (722) are opened thereby allowing steam (wet steam) to escape from the lower chamber (712) into the upper chamber (714), wherein the one or more valves (722) are situated between the lower chamber (712) and the upper chamber (714), operating to open and close a passage (724) located between the lower chamber (712) and the upper chamber (714) such that when the pressure in the lower chamber (712) drops below a threshold value, the one or more valves (722) close the one or more passages (724) and then again, when the pressure exceeds a threshold value, one or more valves (722) open and allow steam (wet steam) to escape from the lower chamber (712) into the upper chamber (714), wherein, during operation, this sequence is continuously repeated, the wet steam in the upper chamber (714) is then further heated by tips (764) of the condensers (762), the tips (764) typically are at a temperature of about 250°C, thereby generating saturated steam, such that the evaporation of the liquid (716) takes place in two consecutive stages.

14. A method for fabricating an accumulator of feature set 1, the method including the steps of:

a. welding the absorber tube (406) to the absorber layer (405);

b. melting of the glass of the glass lid (402) and crimping and sealing to the glass tube (404);

c. inserting the absorber tube (406) through the glass lid (402);

d. fusing the evacuation tube (403) to the glass tube (404);

e. connecting the Kovar sleeve (410) to the absorber tube (406);

f. connecting a vacuum pump to the evacuation tube (403); g. beginning the evacuation by the vacuum pump via the evacuation nozzle (403) of the glass tube (404);

h. heating of the evacuation tube (403);

i. squeezing the evacuation tube (403) and a holding time applies;

j. closing and cutting the evacuation tube (403);

k. trimming the cut surface of the evacuation tube (403);

l. removing finished vacuum tube; and

m. putting the finished vacuum tube into an oven in order to release tension in the materials.

15. The method of feature set 14, wherein the glass is sealed by fusing and crimping in one step.

16. The method of feature set 14, wherein the glass is heated with a ring burner (502) at least three times.

17. The method of feature set 14, wherein the tube is then cut with a strip burner.

18. The method of feature set 14, wherein the accumulator is of a Heat Pipe collector type, and the method further including the steps of:

a. welding the condensor to the absorber tube (406);

b. filling the absorber tube (406) with a fluid;

c. evacuating the absorber tube (406); and

d. closing the absorber tube (406) in a vacuum-tight manner.

It should be appreciated that the particular implementations shown and herein described are representative of the invention and its best mode and are not intended to limit the scope of the present invention in any way.

As will be appreciated by skilled artisans, the present invention may be embodied as a system, a device, or a method. Moreover, the system contemplates the use, sale and/or distribution of any goods, services or information having similar functionality described herein.

The specification and figures should be considered in an illustrative manner, rather than a restrictive one and all modifications described herein are intended to be included within the scope of the invention claimed. Accordingly, the scope of the invention should be determined by the appended claims (as they currently exist or as later amended or added, and their legal equivalents) rather than by merely the examples described above. Steps recited in any method or process claims, unless otherwise expressly stated, may be executed in any order and are not limited to the specific order presented in any claim. Further, the elements and/or components recited in apparatus claims may be assembled or otherwise functionally configured in a variety of permutations to produce substantially the same result as the present invention. Consequently, the invention should not be interpreted as being limited to the specific configuration recited in the claims.

Benefits, other advantages and solutions mentioned herein are not to be construed as critical, required or essential features or components of any or all the claims.

As used herein, the terms "comprises", "comprising", or variations thereof, are intended to refer to a non-exclusive listing of elements, such that any apparatus, process, method, article, or composition of the invention that comprises a list of elements, that does not include only those elements recited, but may also include other elements such as those described in the instant specification. Unless otherwise explicitly stated, the use of the term“consisting” or“consisting of’ or“consisting essentially of’ is not intended to limit the scope of the invention to the enumerated elements named thereafter, unless otherwise indicated. Other combinations and/or modifications of the above-described elements, materials or structures used in the practice of the present invention may be varied or adapted by the skilled artisan to other designs without departing from the general principles of the invention. The patents and articles mentioned above are hereby incorporated by reference herein, unless otherwise noted, to the extent that the same are not inconsistent with this disclosure.

Other characteristics and modes of execution of the invention are described in the appended claims.

Further, the invention should be considered as comprising all possible combinations of every feature described in the instant specification, appended claims, and/or drawing figures which may be considered new, inventive and industrially applicable.

Copyright may be owned by the Applicant(s) or their assignee and, with respect to express Licensees to third parties of the rights defined in one or more claims herein, no implied license is granted herein to use the invention as defined in the remaining claims. Further, vis-a-vis the public or third parties, no express or implied license is granted to prepare derivative works based on this patent specification, inclusive of the appendix hereto and any computer program comprised therein.

Additional features and functionality of the invention are described in the claims appended hereto and/or in the abstract. Such claims and/or abstract are hereby incorporated in their entirety by reference thereto in this specification and should be considered as part of the application as filed.

Multiple variations and modifications are possible in the embodiments of the invention described here. Although certain illustrative embodiments of the invention have been shown and described here, a wide range of changes, modifications, and substitutions is contemplated in the foregoing disclosure. While the above description contains many specific details, these should not be construed as limitations on the scope of the invention, but rather exemplify one or another preferred embodiment thereof. In some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the foregoing description be construed broadly and understood as being illustrative only, the spirit and scope of the invention being limited only by the claims which ultimately issue in this application.

Claims

Claims What is claimed is:

1. An accumulator system for evacuated tubes comprising a vacuum tube seal having a glass lid (402, 452) wherein a vacuum-welded copper tube (406) passes through the glass lid (402, 452) and wherein a seal vacuum-tightly seals the glass to metal connection after a vacuum is drawn in the tube to a pressure between 10 ⁵ and 10 ⁸ bar, the seal being a Kovar sleeve (410), thereby allowing the copper tube (406) to be welded to the Kovar sleeve (410) to ensure a vacuum-tight connection.

2. The accumulator system of claim 1 , wherein a stub of the glass lid (402, 452) is connected to the glass tube (404) via a pinched and sealed connection such that it may be tightly seal a vacuum in the tube.

3. The accumulator of any of the above claims, wherein the glass tube (404) and the glass lid (402, 452) are positioned fully automatically by a machine and seated by melting the glasses of the glass tube (404) and the glass lid (402, 452) to achieve a vacuum of about 10 ⁵ to 10 ⁸ bar, thereby ensuring production safety and long-life expectancy.

4. The accumulator of claim 1, wherein the accumulator further includes a movable mirror and a servo motor, the mirror being disposed inside the tube and thus protected from the environment, and is adapted to turn via the servomotor so as to generally follow the sun, so as to maximize the energy yield without losing efficiency over time.

5. The accumulator of claim 4, wherein the movable mirror, when turned to a certain position, acts as an umbrella, turning the collector 'off when needed.

6. The accumulator system of claim 1 of the direct flow type, wherein the absorber tube (406, 602) of the glass tubes (404, 604) are connected to a subsystem comprising two squared profiles (606, 610) that function as a manifold (630) and accommodate heat transfer fluid (612).

7. The accumulator system of the above claim, wherein the manifold of two squared profiles are preferably made of one U-shaped profile (610), tightly connected to a square-shaped profile (606).

8. The accumulator system of the above claim, wherein the profiles (606, 610) are machined profiles and functional components (804) such as thermowells, or stream sheets, are affixed before the two profiles (606, 610) are connected with each other.

9. The accumulator system of the above claim, wherein the affixing is realized through seam welding and, thanks to the flat/plane surfaces, a resulting weld seam (810) is substantially straight and simple to realize, optionally by means of a welding robot.

10. The accumulator system of claim 1 of a heat pipe collator type, further comprising a condensor (762) of the collector tubes (704) connected to a system of two squared profiles (706, 710).

11. The accumulator system of claim 10 combined with a steam turbine or a mixed-pressure turbine for the production of electricity and power generation.

12. The accumulator system of the above claim, further comprising an upper chamber (714) and a lower chamber (712) of the collector that is filled with a liquid (716) such as water, the liquid (716) flowing continuously through that chamber (712), wherein the lower chamber (712) is optionally connected tightly via connection (720) to another lower chamber of another collector and so on.

13. The accumulator system of the above claim, wherein the liquid (716) in the lower chamber (712) is heated by the condensors (762) whereby the lower chamber (712) is pressurized and the liquid (716) is evaporated, in the case of water, at about 110°C, whereinafter, once the pressure exceeds a threshold value, one or more valves (722) are opened thereby allowing steam (wet steam) to escape from the lower chamber (712) into the upper chamber (714), wherein the one or more valves (722) are situated between the lower chamber (712) and the upper chamber (714), operating to open and close a passage (724) located between the lower chamber (712) and the upper chamber (714) such that when the pressure in the lower chamber (712) drops below a threshold value, the one or more valves (722) close the one or more passages (724) and then again, when the pressure exceeds a threshold value, one or more valves (722) open and allow steam (wet steam) to escape from the lower chamber (712) into the upper chamber (714), wherein, during operation, this sequence is continuously repeated, the wet steam in the upper chamber (714) is then further heated by tips (764) of the condensers (762), the tips (764) typically are at a temperature of about 250°C, thereby generating saturated steam, such that the evaporation of the liquid (716) takes place in two consecutive stages.

14. A method for fabricating an accumulator of claim 1, the method including the steps of: a. welding the absorber tube (406) to the absorber layer (405);

b. melting of the glass of the glass lid (402) and connecting to the glass tube 404; c. inserting the absorber tube (406) through the glass lid (402);

d. fusing the evacuation tube (403) to the glass tube (404);

e. connecting the Kovar sleeve (410) to the absorber tube (406);

f. connecting a vacuum pump to the evacuation tube (403);

g. beginning the evacuation by the vacuum pump via the evacuation nozzle (403) of the glass tube (404);

h. heating of the evacuation tube (403);

i. squeezing the evacuation tube (403) and a holding time applies;

j. closing and cutting the evacuation tube (403);

k. trimming the cut surface of the evacuation tube (403);

l. removing finished vacuum tube; and m. putting the finished vacuum tube into an oven in order to release tension in the materials.

15. The method of claim 14, wherein the glass is sealed by fusing and crimping in one step.

16. The method of claim 14, wherein the glass is heated with a ring burner (502) at least three times.

17. The method of claim 14, wherein the tube is then cut with a strip burner.

18. The method of claim 14, wherein the accumulator is of a Heat Pipe collector type, and the method further including the steps of:

a. welding the condensor to the absorber tube (406);

b. filling the absorber tube (406) with a fluid;

c. evacuating the absorber tube (406); and

d. closing the absorber tube (406) in a vacuum-tight manner.

19. The system(s) and/or method(s) as described in the instant specification, dependent claims, abstract (herein incorporated by reference), and/or drawing figures.