Thin-layer modelling of black tea drying process

摘要: Abstract An experimental dryer was developed for determining the kinetics of black tea drying. Drying characteristics were examined using heated ambient air temperature range 80–120°C and flow velocity 0.25–0.65 m/s. The data sample weight, dry- wet-bulb temperatures drying recorded continuously during each test. then fitted to different semi-theoretical models such as Lewis, Page, modified two-term Henderson Pabis models, based on ratios difference between initial final moisture contents equilibrium content. Lewis model gave better predictions than other satisfactorily described thin-layer particles. effective diffusivity varied from 1.14×10 −11 2.98×10 m 2 /s over range. dependence coefficient by Arrhenius-type relationship. activation energy diffusion found be 406.02 kJ/mol. Temperature constant Power-type relationships. coefficients determination above 0.996 both used predict acceptable at conditions understand influence variables rate constant. results illustrate that in spite high content, particles takes place only falling period. This single-layer equation can simulation deep-bed tea.