Experiments and modelling of the microwave assisted convective drying of canola seeds

Abstract

The heat and mass transfer that occurred during the drying of a 1:1 mixture of two canola seed varieties using combined microwave (MW) and convective drying was studied. A coupled mathematical model was adapted to simulate the physical process. The product was re-wetted to an initial moisture content (IMC) of 18% w.b. and then dried in a microwave oven under MW density of 0.5 W g−1, 1 W g−1 and 2 W g−1. Results show that the maximum drying rate increased from 4.3 × 10−5to 6.8 × 10−5kg [water] kg−1 [grain w.b.] s−1 in the convective drying as the temperature of the inlet air increased from 40 to 60 °C, but it remained constant when MW was combined with convective hot-air. The use of microwave energy during drying of canola seeds resulted in faster drying when coupled with convective drying at low relative humidity.