Conventional drying system for wood strands operates now at high drying temperatures.
The high temperatures result in high volatile organic compounds (VOCs) emission. By
reducing drying temperatures and transferring energy directly into the moist wood without
wasting heat of the surrounding environments, microwave drying reduces energy required
and decreases thermal degradation of the wood material, thereby reducing VOCs emission. In
this work, the temperature and moisture content changes under different microwave drying
conditions were investigated. The effects of microwave drying on emission of VOCs were
evaluated. Extractives were analyzed using Gas Chromatography / Mass Spectrometry
(GC/MS). The result showed that increasing the microwave power input or decreasing
sample weight results in high drying temperature, high drying rate, and short drying time.
Different strand geometry and initial moisture content resulted in different warm-up curves,
but did not affect final moisture content. Comparing with conventional drying, microwave
drying resulted in low VOC emissions. Effect of microwave drying on the strand surface
energy was investigated as well.