Drying characteristics of Eucalyptus clones with large-diameter

ObjectiveIn the present paper, drying characteristics of Eucalyptus clones with large-diameter were studied, and the drying schedule was predicted, in order to provide scientific basis for the utilization of Eucalyptus big-diameter wood. MethodDrying characteristics of 10-year-old Eucalyptus clones with large-diameter were studied by 100℃ test method. On the basis of drying defects, namely initial crack, internal crack and cross-section deformation during wood drying process, the drying schedule of Eucalyptus big-diameter wood was proposed. ResultThe initial crack was grade 2;internal crack degree was moderate, being grade 3;degree of cross-section deformation was serious, being grade 4. Drying speed was grade 4, which meant the drying speed was slow and Eucalyptus a the wood dried slowly. Volume dry shrinkage rate(19.656%), radial dry shrinkage rate(10.976%) and tangential dry shrinkage rate(9.451%) were large;difference dry shrinkage(0.861) was small. According to the grades of the three defects, the basic conditions of drying schedule were as follows:under the condition of initial temperature 50 ℃, difference between wet and dry bulb temperatures at initial period 2-4℃, temperature at late drying period 75℃, it took 20.75 d to dry Eucalyptus clones with large-diameter with 25-30 mm thickness to 10.00% moisture content. ConclusionThe main defect is section deformation. In order to avoid it, the dry-ing schedule should be initial temperature 50℃, difference between wet and dry bulb temperatures at initial period 2-4℃, temperature at late drying period 75℃in actual production. This schedule can be adjusted based on specific condition.