Characteristics of sunflower seed drying and microwave energy consumption

The effect of the microwave-convective drying technique on the moisture ratio, drying rate, drying time, effective moisture diffusivity, microwave specific energy consumption, and energy efficiency of sunflower seeds were investigated. Drying took place in the falling rate period. Increasing the microwave power caused a significant decrease in the drying time. The drying data were fitted to four thin-layer drying models. The performance of these models was compared using the coefficient of determination, reduced chi-square and root mean square error between the observed and predicted moisture ratios. The results showed that the Page model was found to satisfactorily describe the microwave-convective drying curves of sunflower seeds. The effective moisture diffusivity values were estimated from Fick diffusion model and varied from 1.73 10(-7) to 4.76 10(-7) m(2) s(-1). Increasing the microwave power resulted in a considerable increase in drying efficiency and a significant decrease in microwave specific energy consumption. The highest energy efficiency and the lowest microwave specific energy consumption were obtained at the microwave power of 300 W.