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Simulation of Three-dimensional Vibrated Fluidized Bed Dryer using Distinct Element Method

Name: ศุภฤกษ์ วงศ์ศิริวรรณ

Organization : มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

Name: Supalerk Wongsiriwan

keyword: Vibrated Fluidized Bed

; Distinct Element Method (DEM)

; Computational

; Fluid Dynamic (CFD)

Abstract: The particle motion, temperature behavior, and drying rate of particle inside a vibrated fluidized bed dryer were numerically investigated in this work. In the simulation, the Distinct Element Method (DEM) based on the Newton’s second law of motion was used to solve the particle motion. The physical aspects of fluid motion and heat transfer were obtained by applying Computational Fluid Dynamics (CFD) technique. Heat transfer between fluid and particles was estimated using Ranz-Marshall correlation (1952). For the drying of particle, only the constant rate period was considered because very long computational time must be taken to observe drying in the falling rate period. Programming was developed in Standard-C language and using MATLABTM to visualize the results. In the simulation 2,000 particles with stiffness 800 N m-1 were simulated in a rectangular bed with cross-section 50 mm ?50 mm. The time step used to keep the simulation stable was between 5?10-5 and 6.5?10-5 sec.After the model was developed, it was validated with an experimental result of Gupta et al. [23]. The simulation results agreed well with the experiment. The developed program was then used to study the effect of superficial gas velocity (U0), frequency of vibration (f) and amplitude of vibration (a) in fluidized bed dryer. Superficial gas velocities were 0.6, 1.2 and 1.8 m/s while the frequencies of vibration were 37.5 and 75 s-1 and the concerned amplitudes of vibration were 1.6, 2.7 and 4.25 mm. At low velocities (0.6 m/s) and no vibration of bed, particles in the bed were not fluidized but smoothly circulated. Thus, the particles cannot be mixed well and the heat transfer occurred only near the orifice. When increased superficial gas velocity to 1.2 and 1.8 m/s, the fluidization of the particles was observed. The mixing of particles was improved as well as the heat transfer and drying rate. The effect of superficial gas velocity on vibrated fluidized bed was the same as that of stationary bed. The fluidization and drying rate improved with increased in superficial velocity. With introducing of vibration, the fluidization behavior of the particle was improved. The particles in the bed were well mixed and the particle temperature was highly distributed and also increased the drying rate. From the simulation results, increasing of frequency and amplitude could not significantly improve rate of drying.

มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

Address: กรุงเทพมหานคร (Bangkok)

Email: info.lib@mail.kmutt.ac.th

Name: Assoc.Prof. Thongchai Srinophakun

Role: Supervisor

Created: 2546

Issued: 2005-09-19

Modified: 2006-05-09

วิทยานิพนธ์/Thesis

ISBN: 9741832567

CallNumber: CHE1411

tha

DegreeName: Master of Engineering

Level: Master's Degree

Descipline: Chemical Engineering

Grantor: King Mongkut's University of Technology Thonburi

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