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

Authors
M. Sadeghi
M. H. Khoshtaghaza
Department of Agricultural Machinery Engineering, Tarbiat Modares University, P. O. B: 14115-336, Tehran, Islamic Republic of Iran.
Abstract
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 100, 115 and 130°C and fluidization condition at five vibration intensity levels of 0 (no vibration), 0.063, 0.189, 0.395 and 1.184. 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 (13×10-3 kgv m-2 s-1) was at the vibration intensity of 1.184 and inlet air temperature of 130°C. Also the minimum specific energy consumption (4953.785 kJ kgv-1) was observed at 1.184 vibration intensity and 100°C inlet air temperature condition. Based on lower minimum fluidization velocity and specific energy consumption, the vibration intensity of 1.184 and inlet air temperature of 100°C were recommended for drying black tea particles.

Keywords

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Journal of Agricultural Science and Technology
Volume 14, Issue 4
July and August 2012
Pages 781-788