Energy Quantification and Mechano-Sorptive Behavior in the Kiln Drying Of 2.5 Cm Thick Red Oak Lumber

Energy consumption was quantified in the drying of 2.5 cm thick red oak lumber in a 1.2 m3 steam heated experimental dry kiln. The aluminum pre-fab kiln is located indoors and was “wrapped” with 5 cm thick extruded polystyrene (R=10) for the experimental drying. Transmission loss accounted for about 80% of the energy/kilogram of water removed from the wood. The maximum value was for the 60°C DBT due to comparatively high transmission loss combined with maximum venting loss. Batch venting reduced average energy consumption per kiln run by over 6% compared to the conventional kiln schedule. Average board shrinkage was over 2% less for drying with a low temperature schedule compared to drying by the conventional schedule for red oak. This was due to less compression set developing in the board interior at low wood temperatures, accompanied by more tension set in the surface layers. The mechano-sorptive results were in full agreement with McMillen’s conclusions from his research on red oak.