CFD Simulation Research Of Smoke Flow And Particle Of Harmful Ingredients Interception In Filter

Cigarette filter can effectively filter many harmful ingredients in mainstream smoke, which can reduce the health hazards of cigarettes to the smokers. Therefore, it is very important to improve the performance of cigarettes. Currently, the research on cigarette filter mainly relied on experimental means, which not only invested huge and several results could not be obtained from the experiment. However it can greatly reduce the cost and obtain some results and parameters which is unable to get from experiment through CFD simulation method.Based on the theory of porous media and volume average method, a physical model of the whole size of filter was built. The algorithm of particle interception in the whole size of filter media was obtained by calculating. According to the principle of mass conservation and momentum conservation, a computational fluid dynamics model of smoke flow and particle interception in an acetate filter which fiber size is Y-shape was developed. UDF(User Defined Function) was applied to describe the variation of smoke speed in single suction(within 2 seconds) and kinds of filtering mechanism of particle in smoke in filter media, which was added to the Fluent default function as source term and then been solved. The inertial resistance of the filter was taken into consideration, which provided a more precise measurement of the smoke flow and the particle interception in the filter under higher smoke speed conditions. The commercial software, FLUENT 6.3, was used to simulate the smoke flow and particle interception in the filter in single suction.The velocity and pressure profiles of smoke or nicotine particle in the filter, as well as nicotine particle volume fraction profile were well simulated. Finally, the comparisons of nicotine particle filtration efficiency between Fluent simulation results in this work and experimental results, as well as the model prediction in the literature were made to validate the simulation model, which including smoke velocity, filter porosity and thickness. The comparisons showed that the particle entrapment model from simulation results was in good agreement with that from the experimental results. In addition, the Fluent simulation results are more close to reality at both the beginning and the end of the smoke process comparing with the model predicted results in the literature.The profile of the smoke velocity, pressure and nicotine particle volume fraction in the whole process of the single suction at different time in the cavity filter were obtained by using the model built in the above. The nicotine particle filtration efficiency in single suction in the cavity filter was computed and the results were compared with that of ordinary filter. The comparison showed that the nicotine particle filtration efficiency of the cavity filter is lower than that of ordinary filter.