Radio frequency (RF) energy can heat a wet substrate throughout its entire thickness with zero lag-time for thermal conductivity from the exterior surface. By adding an RF preheat stage to a convection-heated drying line, sensible heat, up to the vaporization temperature, can be imparted immediately throughout the thickness of the web. This allows the convection dryer’s length to be used for evaporation, which increases line speeds and productivity. Additionally, the heat transfer is accomplished without the need for excessively high temperatures as the RF energy is generated by the polar water molecules in their liquid phase below 212°F (100°C).
Radio Frequency Co. Inc.