The Refractance Window Drying Concept

When water is placed over a heating source, infrared energy is transferred throughout the water by convection. The heat energy then radiates from the water, primarily through evaporation.




AFA-Algen When water is covered by a transparent membrane such as plastic and placed over a heating source, evaporation and its associated heat loss are blocked or "refracted", and only conduction occurs. The plastic membrane acts like a mirror reflecting the infrared energy back into the water.
But when a moist raw material is placed on the plastic membrane's surface, the water in the material creates a "window" that allows for the passage of infrared energy through the material. Heat behaves as if there were no membrane in that location, and is directly transferred to the water present in the material. AFAalge
Gefriertrocknung In a matter of a few moments, the water in the material on the plastic membrane's surface evaporates, and the "window" of infrared energy closes and "refracts" back into the heated water source, no longer exposing the material to heat.



R-W-Drying Concept