Drying Kinetics of Poplar (Populus Deltoides) Wood Particles by a Convective Thin Layer Dryer

Abstract

Drying of poplar wood (Populus Deltoides) particles was carried out at different drying conditions using a laboratory convective thin layer dryer. Drying curves were plotted and in order to analyze the drying behavior, the curves were fitted to different semi-theoretical drying kinetics models. The effective moisture diffusivity was also determined from the integrated Fick's second law equation and correlated with temperature using an Arrhenius- type model to calculate activation energy of diffusion. The results showed that Midilli et al. model was found to satisfactorily describe the drying characteristics of poplar wood particles dried at all temperatures and air flow velocities. In general, the drying rate increases with increasing air temperature and air flow velocity. A short constant drying rate period was observed and drying frequently took place at falling rate period in all cases. The effective moisture diffusivity of poplar wood particles increased from 1.01E-10 to 2.53E-10 m2·s-1 as the drying air temperature increased from 65 to 85 °C. The activation energy of diffusion for 1 m·s-1 and 1.5 m·s-1 air flow velocities were calculated as 27.8 kJ·mol-1 and 50.8 kJ·mol-1, respectively.