Numerical simulation of gas-solid coupling in moistening cylinder of tobacco based on CFD
Aiming at the study of the problem of'black box'inside the moistening cylinder,we used the computational fluid dynamics(CFD)and proposed a numerical simulation of gas-solid two-way coupling.By establishing a visual flow field and temperature field model,the influencing factors and influencing mechanism of the blade process were investigated.The results showed that the existence of particles in the flow field simulation could effectively improve the gas flow form and the contact between gas and solid.The overall gas phase velocity decreased from 1.0 m/s to 0.3 m/s and strengthened the heat transfer between the two phases.In temperature field simulation,temperature change showed a stage-like change,and the heat transfer between the gas and solid in the first half of the moistening cylinder was significant,the average temperature of the gas phase decreased from 81.0℃ to 68.8℃,while the average temperature of the particles rapidly increased from 25.0℃ to 64.8℃.The temperature in the second half was relatively stable.The heat flux density of gas-solid heat transfer showed a trend of gradually decreasing and then stabilizing with axial position.The relative errors between the simulated values and the experimental values of the gas phase and particle temperature were 0.7％and-2.5％respectively,and the simulated values were in good agreement with the experimental values on the whole,indicating that the model was reasonable and effective.Further study found that with the increase of cylinder inclination and rotation speed,the heat transfer effect between the two phases decreased.To meet the requirements of the lubrication process,the inclination angle of the cylinder should be less than 8°.Considering the production rate and energy consumption,the rotational speed should be selected as 15 r/min.
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