Applications

Lubi – Applications

Efficiency curves of the LubiTM solar air collector

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The LubiTM solar air collector reaches its maximum efficiency at 80,7% which is the highest figure ever reached by a single?pane solar air heater. The biggest benefit, however, is that this high performance is maintained over a very wide range of air flow rates. Whereas traditional solair air collectors, glazed or not, suffer from a loss in performance with air flows lower than 5 cfm/ft2 (100 m3/h/m2), the LubiTM solar air collector curve remains as high as 55% with air flows as low as 2 cfm/ft2 (40 m3/h/m2).

This allows for a substantial temperature increase as high as 45oC (81oF) above ambient, which makes the LubiTM solar air collector ideally suited for all solar air heating applications such as building space heating, coupling to heat pumps, industrial or drying processes and, of course, preheating of outside air.

How does the LubiTM solar air collector work to attain high efficiencies

The basic principle of the LubiTM system is to reduce the heat losses to the environment, which are a common feature of all glazed solar air collectors. This is attained by means of the multiple perforations spread across the entire glazing surface through which incoming outside air is admitted. The underlying operating principles governing the transformation of incoming solar rays into useful thermal energy are as follows:

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  1. Solar radiation passes through the highly transmissive polycarbonate and reaches the absorber, which may happen to be the wall or the roof of the building.
  2. Solar radiation is transformed into heat by contact through the panel and in front of the absorber. This heat is then trapped as hot air within the plenum between the panels and the absorber.
  3. On sunny days, some of the plenum heat is transferred by conduction through the wall, thereby contributing to space heating of the building.
  4. The solar?heated air is mechanically drawn into the ventilation system of the building or process.
  5. The influx of outside air through the LubiTM panel perforations cools the panels down continuously, preventing them from ever warming up. In this way, heat losses to the environment are reduced to an absolute minimum. Therefore, the only place where the solar heat can go is into the building or the process to be heated.
  6. Since all outward heat losses are practically eliminated with the LubiTM, even absorbers of light colour (light brown, grey or white, so common on industrial buildings) maintain a very reasonable thermal efficiency of over 50%.

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