Vacuum press drying studies on two fast-growing Indian wood species

摘要

Two fast-growing Indian species,Melia composita Benth.and Eucalyptus tereticornis Sm.,which have different sets of physical properties,were dried together in a vacuum press dryer (VPD) under two drying conditions,i.e.,above boiling point (ABP) and below boiling point (BBP).The ABP and BBP conditions were maintained by keeping the temperature constant at 75 ℃ and maintaining two pressure levels:300 mm of Hg (ABP) and 450 mm of Hg (BBP).In order to understand pressure conditions at the core during vacuum drying,a cylindrical brass pipe was inserted in both wood cores and attached with pressure gauges placed outside of the VPD.The results indicate that the Melia wood core attained equilibrium pressure immediately with the pressure of VPD,while Eucalyptus attained it very slowly,reaching equilibrium at later stages of drying when cracks and checks advanced to the core.The drying rate was higher for Melia than Eucalyptus under both drying conditions.The drying rate of Melia (ABP) was higher than Melia (BBP),however,the drying rate for Eucalyptus (ABP) was not significantly different from the BBP drying rate.