Moisture and thermal diffusivity of lentil seed under convective infrared-microwave: Modelling with and without shrinkage

Abstract

The effect of infrared radiation and microwave radiation on the moisture and thermal diffusivity characteristics of lentil seeds during infrared and microwave drying was investigated. Using mathematical equations, values and curves, moisture and thermal diffusivity were obtained. This study was to determine the moisture and thermal diffusivity of seed lentil with and without shrinkage at input temperatures 40°C and 60°C, infrared powers 1,000 W and 2,000 W and microwave power 270 W and 450 W, when the moisture content was reduced from 60 to 9% (d.b.). Drying rate was increased with increased air temperature, infrared radiation and microwave powers. Also drying rate decreased continuously with decreasing moisture content. The calculated values of moisture diffusivity by considering shrinkage were smaller than the values of moisture diffusivity without considering shrinkage. Moisture diffusivity with and without shrinkage decreased with decrease in moisture content of lentil seeds and thermal diffusivity with and without shrinkage decreased with increased moisture content. Both moisture and thermal diffusivity values decreased with increase in temperature.