Characteristics and Mathematical Models for Hot-air-dried Rapeseed(Brassica napus)

Drying and storage of rapeseed directly affects its physiological characteristics, potential for breeding, as well as processing characteristics and quality of rapeseed oil produced. In order to provide a technical basis for designing equipment and optimization of process control for hot-air drying of rapeseed, the characteristics of hot-air-dried rapeseed(Brassica napus) under different conditions of moisture content, hot air temperature, and air velocities were investigated, and the applicability of 10 mathematical models for the process of hot air-drying rapeseed was compared. The results showed that there was no apparent constant-rate drying period in the hot-air-drying process, and moisture removal mainly occurred in the falling-rate drying period. Of the various models tested, the page model was found to be the best mathematical model for describing the drying characteristics of rapeseed and the predicted drying characteristic curves fitted well with results obtained. Hot air temperature was the main factor that affected the drying process of rapeseed. With the increase of temperature, the effective moisture diffusion coefficient of rapeseed increased. When the hot air temperature increased from 45 ℃ to 65 ℃, the coefficient increased from 3.835 × 10-10 m2/s to 7.666×10-10 m2/s and the activation energy for rapeseed drying was 29.26 kJ/mol.