Vacuum enhancing system or non-evaporable getter

Abstract

Vacuum enhancing system or non-evaporable getter of the type used en solar-receptor vacuum tubes which comprises a series of non-evaporable getter material pads the geometry of which is that of a prism with rounded corners and said pads are drilled through the centre thereof and linked by means of a cable ending in a quick-fit closure that allows the fitting thereof to be automated. This system is placed downstream of the expansion-compensating device in the form of non-radial bellows in the longitudinal direction and in the void defined by the vessel that is the interface part between the absorber tube and the expansion-compensating device. A getter system is placed in a radial arrangement, at each of the two ends of the receptor tube, resulting in a receptor tube of completely symmetrical geometry.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention describes a vacuum enhancing system or non-evaporable getter for solar power receptor tubes.BACKGROUND OF THE INVENTION[0002]The getters are solid materials, alloys of different metals, able to chemically absorb gas molecules on their surface. They are widely used for a variety of applications such as in particle accelerators, vacuum tubes, inert gas purification systems, etc.[0003]The non-evaporable getter of the invention will be used in a vacuum tube of the type of those that are used as solar receptors. In general, these receptors consist of two concentric tubes between which the vacuum is generated. The inner tube, through which the fluid that is heated flows, is made of metal and the outer tube is made of glass, usually borosilicate.[0004]Between both tubes is placed an expansion-compensating device in the form of bellows, such that it allows the relative movement between the absorber tube and the glass tube, absorbin...

AI Technical Summary

Benefits of technology

[0016]With respect to the geometry, the getter systems of the invention are formed based on square-shaped pads with rounded edges and with a central drill, all of them joined by means of a cable that is introduced by said drills. This composition avoids the need to have a sheath and a protective mesh wherein the pads are housed, as it is the case in the state of the art.

[0018]In addition, in that location, the diameter of the getters ring will be smaller. The lower rope where the pads are arranged is compensated with the use of the two ends of the tube in such way that a sufficient mass of non-evaporable getter is ensured and the symmetry in the tube is achieved, since the two ends will be identical.

[0019]This symmetry (non-existent in the current solutions) entails a thermal and manufacturing advantage, thanks to the unification of components and because it allows the optimization of the tube (the void of the vessel is used at both sides of the tube and not just at one side as in the current solution).

[0020]This new arrangement also means that if you want to increase the amount of getter it is only required to increase the width of the pads, because in that respect there is enough space, without having to increase the diameter of the glass tube to add more pads, representing a saving of costs and increased efficiency by not increasing the losses.

Problems solved by technology

These molecules end up passing through the metal tube and entering the vacuum area, increasing the thermal losses and, accordingly, significantly reducing the efficiency of the system.

This arrangement has a number of drawbacks such as: increase in the necessary minimum diameter of glass tube to house all those elements in its interior, subjecting the getter to mechanical stresses suffered by the expansion compensation bellows, the need to introduce the getter round pads in a sheath and with a protective mesh touching the expansion-compensating device and, in the case of needing a greater amount of material to increase the absorption, the only choice left is to increase the size or the number of pads of the getter, which implies increasing the diameter of the glass tube.

Furthermore, as it is only installed on one of the two ends of the tube, it means that the tube has different geometry on both sides.

Therefore, the assembly is very traditional and there is no way to automate it because in addition the pads that form the getter are thin and very fragile.

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