Hot Air Drying Characteristics and Dynamics Model of Ficus hirta Vahl.

In order to measure hot air drying characteristics and dynamics model of Ficus hirta Vahl. slices, Ficus hirta Vahl. segments and Ficus hirta Vahl. fibrous roots, the moisture content of dry basis and drying rate at different times were measured at 40, 50, 60 and 70 ℃, respectively. Combined with the empirical drying model, Fick's second law and Arrhenius equation, the water diffusion coefficient, activation energy Ea and the regression equation of drying characteristics were calculated. The results showed that the water diffusion coefficients of Ficus hirta Vahl. slices, segments and fibrous roots were 0.4863×10⁻⁹～1.6228×10⁻⁹, 2.0285×10⁻⁹～4.0570×10⁻⁹ and 0.1521×10⁻⁹～0.2536×10⁻⁹ m²/s, respectively, during 40～70 ℃. Apparent activation energies of Ficus hirta Vahl. slices, segments and fibrous roots were 31.93, 35.34 and 17.34 kJ/mol, respectively. In this article, three drying models were compared, all of which had good fitting degree, and the index model was selected to describe the drying characteristics of Ficus hirta Vahl.. Under the hot air drying condition of 40～70 ℃, the drying model expressions were M_R（slice）=exp−(−0.057T²−1.697T−5×10⁻⁵)t, (R²=0.992); M_{R（segment）}=exp−(−4.050×10⁻⁵T²+0.063T+5.750×10⁻⁵) t, (R²=0.979); M_{R（fibrous root）}=exp−(−8.504×10⁻⁵T²−0.058T+6.750×10⁻⁵) t, (R²=0.998). it will provides technical guidance for drying process in practice.