Grain intermittent drying characteristics analyzed by a simplified model

Intermittent drying experiments for wheat (cv. Tohoku206), long- (cv. L201) and short-grain (cv. Akitakomachi) rough rice were performed and analyzed by a sphere drying model. The sphere drying model consists of three parameters: surface mass transfer coefficient H, dynamic equilibrium moisture content Me, and drying constant K. The first parameter of the model is novel, allowing simulation of every type of drying including intermittent drying simply and precisely. With this model, drying computation was performed using a similar method for both drying and tempering periods, setting H = 0 for the tempering period. The wheat and rough rice samples were dried at 40 °C, 60% relative humidity and tempered at 30, 40, and 50 °C, respectively. There was good agreement between the calculated and experimental values with a standard error of less than 0.47% db for the different initial moisture contents and tempering temperatures. The tempering temperature had a significant effect on rate of internal moisture equilibration.