Commercial-scale RF/V drying of softwood lumber. 2. Drying characteristics and lumber quality.
1996
Avramidis S. | Zwick R.L.
The experimental program investigated radio-frequency/vacuum (RF/V) kiln-drying of three commercial softwood species produced on the west coast of British Columbia: Douglas-fir, hem-fir, and western redcedar. Based on earlier research work, the experimental program focused on large sections of wood where there would be improved prospects to demonstrate the viability of RF/V drying. Product sizes that were investigated ranged in thickness from 36 to 152 mm, and in width from 101 to 190 mm. Two electrode designs resulted over the course of the project to try and address electric field uniformity issues. Both designs were tested with lumber of the three species under investigation. The results revealed that with proper schedules, RF/V drying resulted in no lumber staining, reduced surface checking, no internal stresses, and a good final moisture content uniformity when compared to conventional drying. With proper schedules, RF/V drying was found to result in dried lumber that also exhibited less shrinkage. RF/V technology allowed for the drying of lumber sizes that are not dried in conventional kilns due to excessive drying times and degrade.
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