Radiation heat collection device

Abstract

This invention relates to a device that comprises at least one collection unit ( 11 ), equipped with a collection tube ( 21 ) placed on supports ( 23 ), which is formed by an inner absorber tube ( 31 ) shaped as a continuous tube and an outer envelope tube ( 33 ). The collection unit ( 11 ) also comprises reflectors ( 15 ) that direct the radiation toward the collection tube ( 21 ). Moreover, the device comprises means ( 41, 43 ) designed to maintain the collection tube ( 21 ) space between the absorber tube ( 31 ) and the envelope tube ( 33 ) at a pressure of between 5·10 −1 -5·10 −2 mbar. The main advantages of the invention include the reduction in the breaking of glass due to the lower stresses to fatigue, an increase in the effective collection surface (97%-98%) and active management of the vacuum, which makes it possible to monitor the evolution thereof at all times.

1 . Radiation heat collection device that comprises at least one collection unit ( 11 ) equipped with a collection tube ( 21 ) placed on supports ( 23 ) and reflectors ( 15 ), wherein the collection tube is formed by an inner absorber tube ( 31 ) and an outer envelope tube ( 33 ), the reflectors ( 15 ) direct the radiation toward the collection tube ( 21 ), and wherein said radiation heat collection device comprises means ( 41 ,  43 ) designed to maintain the collection tube ( 21 ) space between the inner absorber tube ( 31 ) and the outer envelope tube ( 33 ) at a pressure of between 5×10 −1 -5×10 −2  mbar when the device is operative. 
     
     
         2 . Device, as claimed in  claim 1 , wherein the inner absorber tube ( 33 ) is shaped as a continuous tube. 
     
     
         3 . Device, as claimed in  claim 1 , wherein the outer envelope tube ( 33 ) is formed by multiple segments united by joints ( 51 ,  81 ,  95 ,  95 ′) that include support and slide means ( 65 ) for the inner absorber tube ( 31 ). 
     
     
         4 . Device, as claimed in  claim 1 , wherein the collection tube ( 21 ) supports ( 23 ) are shaped as a rigid structure and fixed to a bearing structure of the collection unit ( 11 ). 
     
     
         5 . Device, as claimed in  claim 19 , wherein each collection unit ( 11 ) is formed by two semi-collectors ( 13 ,  13 ′) and are connected by vacuum pumps at a central part ( 41 ) and at an end ( 43 ). 
     
     
         6 . Device, as claimed in  claim 5 , wherein the device further comprises an element ( 45 ) that is connected to the central part of each collection unit ( 11 ), designed for the introduction of a gas that allows to drag the hydrogen present in the collection tube ( 21 ) space between the inner absorber tube and the outer envelope tube ( 33 ), in collaboration with the vacuum pumps ( 43 ) connected to the ends of each collection unit ( 11 ). 
     
     
         7 . Device, as claimed in  claim 3 , wherein said joints ( 51 ) comprise: flanges ( 53 ,  53 ′) with co-operating means ( 55 ,  59 ;  55 ′,  59 ′) with the ends ( 57 ,  57 ′) of each pair of segments of the outer envelope tube ( 33 ); a ring ( 61 ) placed between said flanges ( 53 ,  53 ′), fixed to a support ( 23 ); sealing bands ( 63 ,  63 ′) placed in openings of said ring ( 61 ) adjacent to said ends ( 57 ,  57 ′); an insulation crown ( 62 ) with inner radial teeth ( 64 ) designed for the support and sliding of the inner absorber tube ( 31 ) joined to said ring ( 61 ); and axial tightening means designed to bring said ends ( 57 ,  57 ′) close to the ring ( 61 ). 
     
     
         8 . Device, as claimed in  claim 3 , wherein said joints ( 81 ) comprise: flanges ( 83 ,  83 ′) fixed to a support ( 23 ); an insulation crown ( 85 ) with lateral slots ( 87 ,  87 ′) designed for the reception of each pair of segments ( 35 ,  35 ′) of the outer envelope tube ( 33 ) between pairs of sealing bands ( 89 ,  89 ′); and inner radial teeth ( 86 ) designed for the support and sliding of the inner absorber tube ( 31 ) and radial tightening means for said flanges ( 83 ,  83 ′). 
     
     
         9 . Device, as claimed in  claim 1 , wherein each collection unit is formed by multiple groups of segments ( 36 ,  37 ) of the outer envelope tube ( 33 ), wherein the segments ( 36 ,  37 ) of each group are united by joints ( 95 ) fixed to supports ( 23 ), and the ends of each group are united by pairs of joints ( 95 ′) supported in a displaceable manner on supports ( 23 ) with an intermediate bellows device ( 97 ), said joints ( 95 ,  95 ′) comprising: flanges ( 101 ,  101 ′) with co-operating means ( 105 ,  109 ;  105 ′,  109 ′) with the ends ( 107 ,  107 ′) of each pair of segments ( 36 ,  37 ) of the outer envelope tube ( 33 ); a ring ( 111 ) placed between said flanges ( 101 ,  101 ′); sealing bands ( 113 ,  113 ′) placed in openings of said ring ( 112 ) adjacent to said ends ( 107 ,  107 ′); an insulation crown ( 112 ) with inner radial teeth ( 114 ) designed for the support and sliding of the inner absorber tube ( 31 ) joined to said ring ( 111 ); and means designed to maintain said ends ( 107 ,  107 ′) and the ring ( 111 ) immobilized. 
     
     
         10 . Device, as claimed in  claim 1 , wherein said outer envelope tube ( 33 ) is made of glass, or of polymethylmethacrylate (PMMA). 
     
     
         11 . Device, as claimed in  claim 10 , wherein the outer envelope tube ( 33 ) is made of glass and wherein the thickness of said outer envelope tube is between 2.5 and 3.5 mm. 
     
     
         12 . Device, as claimed in  claim 1 , wherein the inner absorber tube ( 31 ) has a circular cross-section and a diameter of between 70 and 90 mm. 
     
     
         13 . Device, as claimed in  claim 1 , wherein said inner absorber tube ( 31 ) has an oval cross-section. 
     
     
         14 . Device, as claimed in  claim 1 , wherein the useful collection surface of the collection tube ( 21 ) is between 97%-98% of its total length. 
     
     
         15 . Device, as claimed in  claim 1 , wherein the focal length is between 1,700 mm and 1,900 mm. 
     
     
         16 . Device, as claimed in  claim 1 , wherein the length of the segments of the outer envelope tube ( 33 ) united by the joints ( 51 ,  81 ,  95 ,  95 ′) is between 4 and 6 m. 
     
     
         17 . Device, as claimed in  claim 1 , wherein the length of the segments of the inner absorber tube ( 31 ) joined by welds is between 12 and 16 m. 
     
     
         18 . Device, as claimed in  claim 1 , wherein the solar radiation is collected by means of parabolic reflectors. 
     
     
         19 . Device, as claimed in  claim 1 , wherein said means comprise vacuum pumps. 
     
     
         20 . Device, as claimed in  claim 10 , wherein the means designed to maintain said ends ( 107 ,  107 ′) and the ring ( 111 ) immobilized include encapsulated traction springs ( 104 ,  104 ′).