A Study of Drying Uniformity in a New Design of Tray Dryer

Abstract

Application of tray dryer is widely used in agricultural drying because of its simple design and capability to dry products at high volume. However, the greatest drawback of the tray dryer is uneven drying because of poor airflow distribution in the drying chamber. This study investigates kenaf core drying uniformity in a tray dryer through Computational Fluid Dynamics (CFD) simulation. The simulation focused on air velocity above the products and was conducted under steady state condition to simplify the analysis. The experimental and simulation data exhibit very good agreement. The drying rate of dried products in each tray predicted based on average air velocity from the simulation. The result shows that, the higher the air velocity, the higher the drying rate of the products. The alternate arrangement of tray position adopted to ensure that all trays are exposed directly to drying air and to improve airflow distribution in drying chamber. There was a variation of final moisture content for product at different columns. However, the uniformity of air flow distribution to each level of product at the same column are acceptable. Drying using semi-continuous mode was recommended to improve drying time and uniformity.