Chemical Engineering Research & Design, Vol.74, No.8, 882-892, 1996
Influence of Local Variations of Air Velocity and Flow Direction Reversals on the Drying of Stacked Timber Boards in Kilns
The drying of stacked Pinus radiata boards has been investigated by the use of a kiln model which incorporated airflow reversals, Only one reversal is needed to significantly reduce both the drying time and variations in the extent of drying through the stack. Variations in moisture content of the boards are caused by the progressive humidification of air and the maldistribution of airflow, These variations are predicted for two existing kilns for which their respective flow distributions are known from kiln audits. The use of airflow reversals is more effective than increasing the air flowrate in reducing the moisture variations caused by air humidification. However, flowrate increases reduce moisture variations caused by airflow maldistribution more significantly than reversals, The calculations illustrate the effect of air bypassing the stack in limiting the drying process.