Heat transfer and wood moisture effects in moderate temperature fixation of CCA treated wood
J Chen, M Kaldas, Y T Ung, P A Cooper
Practical aspects of heat transfer and fixation of wood exposed to drying conditions after CCA treatment are considered. The rates of heat transfer and CCA fixation are substantially influenced by the cooling effect of water evaporating from the wood surface when drying occurs during fixation. At least in the early stages of fixation, the wood temperature approaches the wet bulb temperature, rather than the dry bulb temperature of the fixation chamber. Some drying during fixation is acceptable, but the time to complete fixation will be extended significantly, depending on the dry bulb/wet bulb depression. At above ambient temperatures, complete hexavalent chromium reduction can occur relatively quickly in relatively dry wood. However, CCA deposited under these conditions is more easily leached from wood and fixation conditions must be controlled to prevent wood from reaching fibre saturation point moisture content before fixation is complete.
Keywords: CCA; FIXATION; TECHNICAL DRYING
Conference: 94-05-29...06-03, Nusa Dua, Bali, Indonesia