The Study On Rational Matching Of Hot Air Combined With High Frequency Drying In Larch Boxed-heart Square Timber

In this study, the cross section of 120mm boxed-heart larch lumber was dried under the interaction of radio-frequency convection and conventional drying. The effect of wood bar thickness, radio frequency applied periods and time on the drying quality, drying rate and energy consumption was investigated, respectively. On this basis, the appropriate periods to apply radio frequency were explored. The findings are as follows:1)The effect of radio frequency heating on water migration was also discussed. It is observed that the drying rate of radio-frequency convection drying was faster than conventional drying. The promoting effect of radio-frequency on moisture migration were various at different moisture content; above fiber saturation point, it increased with decreasing moisture content; below the fiber saturation point, it decreased with decreasing moisture content.2) The wood bars with three different thickness (15mm,20mm,25mm) divided into three piles are dried under two electrode plate, two repeated experiment needed. The suitable wood bar thickness was determined in this study. The consumption of radio frequency and convection drying, the distribution of temperature and moisture content and drying quality were investigated and analyzed, ensuring that the wood bar with 20mm thickness is the most suitable.3) The suitable match between radio-frequency convection drying and conventional drying was discussed. Three piles of boxed-heart larch lumber with the wood bars of 20mm thickness were dried under radio-frequency convection and conventional drying. The drying consumption, the distribution of temperature and moisture content, drying quality was assessed comprehensively. When the moisture content is 20% to 10% and high-frequency heating can be applied to achieve fast and efficient drying; continuous high-frequency heating ("HF ON") 5min after the temperature difference between the surface of the core reached 6℃, stop ("H F OFF") about 60 min after stabilization of 1℃, that is, under he experim ental conditions "H F oN" 5min, "HF OFF" 60 min, to maintain the temperature difference between the surface of the core material in the heap of wood 1～6℃. The actual production process, for the wood that wood character and density was basically the same,the required energy consumption could be estimated by formula:P=n×2.4 (kW)...