The Vacuum Tube

The creation of a vacuum by removing the air from a glass container achieves excellent insulation, a principal that has been known for a century now, and applied in the form of the thermos. By using this type of insulation, the collectors can improve the conversion of solar energy even in between seasons and in the winter period. A special multi-layer metallic paint, made from recyclable products, called CERMET, is applied to make the internal space especially selective to infra-red refraction for the absorption of solar energy. The vacuum protects the selective coating from any outer agent, preserving its long life.

Inside the glass tube lies a copper pipe folded into a U-shape with aluminium thermal conductors, to transfer the solar energy from the inside wall of the glass pipe to the collector case. The heat transfer fluid flows into each copper pipe, then connected in parallel to the upper part of the panel to a single collector.

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The solar collector is formed by a series of borosilicate glass tubes in a double cavity, soldered at the extremes to render the internal cavity a vacuum. The internal cavity is coated with “CERMET” for absorption of solar energy by utilising recycled products. The absorption unit consists of a copper tube, formed into a U-shape and connected to an aluminium support, thereby increasing its absorption surface.

The entire length of the tubing is then encased with a vacuum borosilicate double glass tube, then connected in parallel to the upper part of the panel to a single collector.(the collector is supplied preassembled) The metal frame is electro coated with a layer of coloured aluminium making it corrosion resistant to saline vapour as defined by the current norms.

The unit has been designed so that the entire assembly of the collector can be simply “fitted” together. The interior grooving houses special square headed screws for easy fixing to brackets. A protective aluminium film, which coats the copper connectors, has the same technical characteristics as the frame and is completely insulated with special “ISOPLUS” system, rendering it inflammable class 0 (ISO - DIS 1182.2), water repellent and with low bio-persistency. Reflective, secular aluminium sheeting is fixed underneath the tubing (EN 573/3 – 485/2 – EN 485/4 plus test for anodic oxidation DIN 50943). It has low iridescence, and a total reflective co-efficient higher than 90% using the Compound Parabolic Concentrator system.