Numerical On Flow Properties Of Heat Transfer In Vibrated Fluidized Bed

Vibration fluidized bed has been widely used in sugar, chemical, food, pharmaceutical and other industries. It’s a retrofit fluidized bed to which the source of vibration is applied, thereby improving quality and eliminate the some undesired fluidized phenomenon in the fluidized processes, such as non-uniform mixture, channeling, etc. With the development of science and technology, computational fluid dynamics (CFD) numerical simulation has been widely used in dense gas-solid flows, the simulation results can reappeared the actual particle motion. The Eulerian-Eulerian two-fluid and the kinetic theory of granular flow model are applied to simulate gas and particle of Geldart B and D flow and particle convective heat transfer in two-dimensional vibration fluidized, meanwhile the UDF code of vibrating grid and heat transfer model is written by C language. The influences of different parameter on the gas-solid fluidization characteristics and heat transfer characteristics are discussed.In the research of hydrodynamics, In the single nozzle fluidized bed, it analyzed that the bulks formation, grow and break in the cycle process. Then it is found that the bulks are inhibited by vibration, but the merge frequency of bulks is increased at the same time. In the uniform fluidized bed, Effects of vibration amplitude and frequency on the distribution of particle concentration, bed pressure drop, are discussed. Simulation results show that vibrated distributor results in a periodic low concentration region of particles on the surface of the distributor. The appearance of the vibration gap brings the generation of the big bulk in the bed. There are three regions along the bed height:a low concentration with a gap nearby the distributor, high concentration in the middle of the bed and transition region on the bed surface. It is influenced concentration most nearby the distributor, and the periodicity of change in void fraction is equal to the vibration frequency. With the increase of the vibration amplitude and frequency, the radial distribution of average concentration and velocity of particles tend to uniform. With the vibration of the distributor, the pressure drop is also a periodic oscillation. It is found that the vibrate force is occurred in the period of0to1/8by the study of the average kinetic energy.In the research of heat transfer in both fluidized bed model, it analyzed the effect of heat transfer on the various operating parameter. The simulation results showed that:with increasing gas velocity, the heat transfer coefficient go up at first and then decline; Under low gas velocity, the heat transfer coefficient go up at first and then decline with increasing amplitude and frequency; Higher amplitudes and frequency of vibration results in lower heat transfer coefficient under high gas velocities.