Solar collectors receiver tubes

Abstract

Improved solar collectors receiver tubes are described. The improved solar collectors receiver tubes have a getter system containing one or more getter materials in the form of pills housed a single line in a suitable holder.

1 . A solar collectors receiver tube containing a getter system comprising:
 a mechanical support, and   pills consisting of compressed powders of a getter material,   wherein said mechanical support comprises a holder consisting in a base and two lateral shoulders, and   wherein said pills do not comprise any binder, have a diameter equal to or higher than 15 mm, a diameter/height ratio comprised between 2 and 5, and are housed within said holder on said base in a single line.   
     
     
         2 . The solar collectors receiver tube according to  claim 1 , wherein the diameter of the pills is equal to or less than 35 mm. 
     
     
         3 . The solar collectors receiver tube according to  claim 2 , wherein said diameter is comprised between 18 mm and 25 mm. 
     
     
         4 . The solar collectors receiver tube according to  claim 1 , wherein said diameter/height ratio is comprised between 3 and 4. 
     
     
         5 . The solar collectors receiver tube according to  claim 1 , wherein said holder contains also one or more elastic elements in contact with one or more of said pills and said one or more elastic elements present flat or rounded parts for contacting the pills. 
     
     
         6 . The solar collectors receiver tube according to  claim 5 , wherein said one or more elastic elements exert a compression force onto said pills comprised between 50N and 150N. 
     
     
         7 . The solar collectors receiver tube according to  claim 1 , wherein said holder is partially wrapped by a metallic net. 
     
     
         8 . The solar collectors receiver tube according to  claim 7 , wherein said metallic net has openings with a diameter comprised between 10 μm and 500 μm. 
     
     
         9 . The solar collectors receiver tube according to  claim 8 , wherein said diameter is comprised between 20 μm and 50 μm. 
     
     
         10 . The solar collectors receiver tube according to one of  claim 7 , wherein said metallic net is fixed onto lateral shoulders of the holder. 
     
     
         11 . The solar collectors receiver tube according to  claim 7 , wherein said metallic net is fixed on a holder base, on its external. 
     
     
         12 . The solar collectors receiver tube according to  claim 7 , wherein said metallic net partly overlaps and is fixed on a holder base, on its external side, in its overlapping region. 
     
     
         13 . The solar collectors receiver tube according to  claim 1 , wherein said holder has a width greater than a diameter of the pills, and a difference between a holder width and the diameter is comprised between 1 mm and 3 mm. 
     
     
         14 . The solar collectors receiver tube according to  claim 1 , wherein a height of the two lateral shoulders of the holder is less than a height of the pills, and a difference between the height of the two lateral shoulders and the height of the pills is comprised between 0.5 mm and 1 mm. 
     
     
         15 . The solar collectors receiver tube according to  claim 1 , wherein said holder is closed by means of a perforated cover having a metallic net in cover openings and a height of the two lateral shoulders is 1 mm-3 mm more than the height of the pills. 
     
     
         16 . The solar collectors receiver tube according to  claim 15 , wherein said metallic net has openings with a diameter comprised between 10 μm and 500 μm. 
     
     
         17 . The solar collectors receiver tube according to  claim 15 , wherein said perforated cover presents one or more depressions achieving a distributed contact with the pills.