Factors affecting relative humidity during wood vacuum drying

Abstract

Effects of pressure and temperature in the chamber during vacuum drying on the relative humidity and evaporation of wood surface were investigated by using the vacuum chamber. The setting temperature during vacuum drying included dry-bulb temperature t _d, the wet-bulb temperature t _w and the temperature difference between the air in the vacuum chamber and the cooling water in the condenser. Results indicated that relative humidity during vacuum drying was affected by the dry-bulb temperature t _d, the wet-bulb temperature t _w and the temperature difference between the air in the vacuum chamber and the water in the condenser. Relative humidity of wood decreased with the increase in temperature at the given temperature of the water in the condenser. The relative humidity was affected slightly by pressure in the vacuum chamber p _A, and it decreased from 70% to 65% with p _A increased from 50 kPa to 101 kPa. Moreover, there was nearly no evaporation under the vacuum without external heating.

Keywords

influencing factors / radio frequency / relative humidity / wood vacuum drying

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