The demonstration of increased lumber value using optimized lumber sorting and radio frequency vacuum drying.

摘要

This paper presents an experimental evaluation of the first commercial scale dry/sort/re-dry (Q-SiftReg.) strategy for drying of 2 by 4 Pacific Coast hemlock [Tsuga] lumber using combined conventional and radio frequency vacuum drying technologies. The strategy was evaluated through six experimental tests in which lumber loads were dried to different final average moisture content in an industrial heat-and-vent conventional kiln, and measured for initial and final moisture content distribution, shrinkage, and drying degrade. Additionally, a stochastic model especially developed for this strategy was calibrated with the measured data and used to simulate the results of the strategy under different drying conditions within the calibration range. The study demonstrated that the implementation of the Q-Sift strategy decreases the process drying time, and reduces shrinkage and kiln-drying degrade in comparison with a single conventional pass. An economic model was also developed in order to determined the industrial viability of the method, and for the studied industrial case it was demonstrated that the revenues of the new strategy allow an investment payback in less than 1.5 years..