Application of radio-frequency heating to utility poles. part 1. radio-frequency/vacuum drying of roundwood

Electromagnetic radiation, such as radio-frequency heating has been shown to rapidly heat wood. Previous research at the University of British Columbia focused on the drying of sawnwood using a radio-frequency/vacuum (RF/V) dryer with flat parallel plates. The study described in this paper examined the potential of RF/V drying to rapidly dry roundwood. The investigation was carried out in a laboratory RF/V dryer at stabilized frequency of 13.65 MHz. During drying, the change in the temperature with time, within each roundwood section, was continuously monitored. Examination of all the experimental runs confirmed that the RF/V unit with a flat electrode design, could dry 165- to 240-mm diameter and 2.0- to 2.4-m-long pole sections, from their initial sapwood moisture content (MC) of over 80 percent, to a final MC of less than 25 percent. This was accomplished with limited loss in quality, in less than 16 hours. Furthermore, RF/V drying produced poles with a uniform final MC.

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