CONVECTIVE THIN-LAYER DRYING AND REWETTING CHARACTERISTICS OF SESAME SEED

Abstract

Fundamental information on drying and re-wetting characteristics of agricultural seeds is required in the design and aeration systems as well as in the prediction of drying rate using various mathematical models. Thin-layer drying experiments were conducted using air-ventilated oven to simulate the artificial drying and rewetting processes of sesame seed (6.9 to 18.2% w.b) at three drying temperatures of 40, 50 and 60^oC. Five drying models were applied to the thin-layer data. The Page equation fitted the data best after comparing the determination of coefficient (R²), the standard error of moisture content (SEM) and mean relative percent error (e) between the experimental and predicted values. The drying rate of sesame seed under drying and rewetting conditions increased with increased temperature of drying( 40 to 60^oC) and initial moisture content of seed( 6.9, 11.5 and 18.2% w.b).  The parameters K and n of the page model was related to the drying temperature and moisture content by two empirical expressions of Page equation for predicting moisture ratio. The coefficient of determination (R²) for parameters K and n were 0.95 and 0.87 respectively.  The effective diffusivity was found to be 2.32 x 10-11 m²s^-1.