Reflecting parabolic construction for solar heating systems

Abstract

A reflecting parabolic construction for solar heating systems comprises at least a reflecting parabola for concentrating solar beams on a thermal carrier containing receiver tube, wherein the parabola comprises an aluminum fretted central layer, on the faces thereof two opposite aluminum layers are applied. According to a first embodiment, in the concave part of the reflecting parabolic construction a crystal mirror of minimum thickness is applied. According to a further aspect of the invention, one of the layers is a reflecting aluminum layer made by depositing vapors, and protected by a sol-gel protective layer having a thickness corresponding to few microns.

1 . A parabolic solar radiation reflecting construction for solar energy heating systems, comprising at least a reflecting parabola for concentrating solar beams on a receiver tube containing a thermal carrier fluid therein, characterized in that said parabola comprises a central aluminum fretted layer having opposite faces on each of which is applied a respective aluminum reflecting layer, said parabola having a parabola concave portion coated by a thin crystal mirror. 
     
     
         2 . A reflecting parabolic construction, according to  claim 1 , characterized in that said aluminum layer is made by depositing vapors and is protected by a sol-gel protective layer having a thickness of few microns. 
     
     
         3 . A reflecting parabolic construction, according to  claim 1 , characterized in that said reflecting parabola has a reflecting surface including a colloidal suspension capable of solidifying to a gel form. 
     
     
         4 . A reflecting parabolic construction, according to  claim 2 , characterized in that said vapors are deposited on natural anodized aluminum to a thickness from 0 to 10 microns, to provide said aluminum layer with a reflectivity having a maximum reflectivity loss of 2%. 
     
     
         5 . A reflecting parabolic construction, according to  claim 3 , characterized in that said colloidal suspension is deposited to a very thin colloidal suspension layer with a surface similar to that of a paint or glass material. 
     
     
         6 . A reflecting parabolic construction, according to  claim 4 , characterized in that said natural anodized aluminum is treated by a physical vapor deposition method. 
     
     
         7 . A reflecting parabolic construction, according to  claim 1 , characterized in that said construction comprises a top metal sheet element coated by a reflecting surface and comprising a plurality of holes for compensating thermal expansions.