Vibration Effect on Particle Bed Aerodynamic Behavior and Thermal Performance of Black Tea in Fluidized Bed Dryers

Black tea sample was dried by a vibro-fluidized bed dryer to find its aerodynamic behavior and thermal performance during drying. The drying experiments were conducted at three different inlet air temperatures of ۱۰۰, ۱۱۵ and ۱۳۰°C and fluidization condition at five vibration intensity levels of ۰ (no vibration), ۰.۰۶۳, ۰.۱۸۹, ۰.۳۹۵ and ۱.۱۸۴. The results showed that bed channeling and defluidization problems were decreased in vibration condition. The vibration system decreased the requirement of minimum fluidization velocity of tea particles and this velocity reduced by increasing the vibration intensity. In the experiments, the maximum evaporation rate (۱۳×۱۰-۳ kgv m-۲ s-۱) was at the vibration intensity of ۱.۱۸۴ and inlet air temperature of ۱۳۰°C. Also the minimum specific energy consumption (۴۹۵۳.۷۸۵ kJ kgv-۱) was observed at ۱.۱۸۴ vibration intensity and ۱۰۰°C inlet air temperature condition. Based on lower minimum fluidization velocity and specific energy consumption, the vibration intensity of ۱.۱۸۴ and inlet air temperature of ۱۰۰°C were recommended for drying black tea particles.

Keywords:

Evaporation rate , Minimum fluidization , Specific energy consumption , Vibration intensity