Abstract:

In order to reveal the coagulation efficiency of fine particles by the combination of seed particles with acoustic wave,a numerical simulation is performed by coupling the population balance model and the Eulerian mul- tiphase model and by introducing the acoustic coagulation kernel function via some user-defined functions.From the simulation at constant particle size and flow velocity,the coagulation efficiency varying with acoustic frequency,sound pressure level,residence time and initial dust concentration is investigated.The results indicate that (1) the total coagulation efficiency of fine particles is greatly influenced by the acoustic frequency; (2) there is an optimum acoustic frequency for coagulation; (3) high acoustic frequency is conducive to the coagulation of small particles,while low acoustic frequency is favorable for the coagulation of large particles; (4) higher sound pressure level may result in greater vibration amplitude and higher coagulation efficiency of fine particles; (5) longer residence time benefits the collision between fine particles and thus promotes the coagulation; and (6) the increase of the initial dust concentration effectively improves the total coagulation efficiency of fine particles,and the maximum coagula- tion efficiency is near the initial peak diameter.All these above-mentioned conclusions are consistent with the ex- perimental ones.

Key words: fine particles, coagulation, seed particles, acoustic wave