Influence of vibration characteristics on mixing in a vibrated bed containing spherical particles

The uniform mixing is necessary in many processes such as those used in food, pharmaceutical, chemical and petrochemical industries. The present work numerically studies the influence of vibration characteristics on mixing of binary mixtures produced in vibrationally fluidized bed. Discrete element method was used to model the fluidized granular bed contained two types of spherical particles.Solid-like flow pattern was observed in low frequencies and amplitudes, while as the vibration got stronger the particlesmotion behaved fluid-like, and convection rolls were generated within the bed. As the vibration strength increased, it was seen that the convection rolls became fully developed. The generation and movement of convection rolls played a fundamental role in mixing within vertically vibrated beds. It was realized that mixing of particles was generally improved by increasing the vibration amplitude.In contrast, an optimal frequency was found in each amplitude, by which the best mixing occurred. The average velocity of particles always increased by amplitude at a fixed frequency, while the mixing was not necessarily improved. It was also observed that frequency had no specific effect on mixing time, although increasing the amplitude significantly decreased the mixing time. It was found that the results were in qualitative agreement with some previous experimental studies

کلیدواژه ها:

Discrete element modeling ، Fluidization ، Granular media ، Mixing ، Vibration