Drying Kinetics of Oil Palm Frond Particles in an Agitated Fluidized Bed Dryer

Abstract

The drying kinetics of oil palm frond particles in a laboratory-scale agitated fluidized bed dryer were investigated under various operating conditions: inlet air temperature (50–80°C), superficial air velocity (0.6–1.0 m/s), bed load (200–300 g), and agitation speed (300–500 rpm). To study the effects of these variables on the drying time and drying rate, an experimental design using Taguchi orthogonal array was employed. Based on analysis of variance (ANOVA), the results indicated that inlet air temperature greatly affected the drying rate, followed by superficial air velocity and bed load. The effect of agitation speed on the drying rate was found to be small. The experimental drying kinetics data were compared with the values obtained from three different models, namely, the Page model, modified quasi-stationary method (MQSM), and a new composite model. It was found that the proposed new model could satisfactorily predict the complete drying rate curve for the drying of oil palm fronds.

Keywords:

• Agitated fluidized bed
• Composite model
• Drying characteristics
• Falling rate period
• Fluidization
• Stirred fluidized bed

ACKNOWLEDGMENT

The authors are grateful for the support provided by the Malaysian Ministry of Science and Technology through the Science Fund research grant number 03-01-02-SF0396.