Numerical Simulation Of Fluid Dynamics Of Packed Bed Based On CFD

The particles in the random packed bed with large tube to particle diameter ratios are random accumulation,resulting in high pressure drop and low heat and mass transfer efficiency.The slender packed bed can effectively reduce the pressure drop,improve the heat and mass transfer efficiency of the fluid flow,and enhance the heat dissipation inside the tube.Now it is widely used in the industry.In order to explore the influence of different particle arrangement structure in the slender packed beds on the local void fraction distribution,local velocity distribution and pressure drop,find the optimum packing structure under the single D/d,the CFD Fluent 16.2 is used.Simulate the three kinds of slender packed beds with different tube to particle diameter ratios of D/d=2.1547,D/d=2.40 and D/d=2.4142.This paper can further deepen the understanding of the fluid flow phenomenon in the slender packed bed,lay a foundation for the subsequent experiments,it also contributes to the design and optimization of the slender packed bed in industrial applications.1.Establish three possible particle arrangement geometry models under D/d=2.1547,then used the CFD to calculate.The results suggest that with the single D/d,internal radial void fraction distribution,the local velocity distribution and the pressure drop of the fluid under different internal structures were different.In the same packed bed,the larger apparent inlet velocity,the greater pressure drop.The presence of special structure and large void ratio can effectively reduce the internal pressure drop.In another words,the slight change of the internal structure will strongly affecting the pressure drop.the internal pressure of the packed bed.According to the CFD calculation results,the optimal packing structure at D/d=2.1547 is determined which the model A with the hollow structure.The formula for calculating the pressure drop under low D/d is obtained.Compared with the Guo’s experimental values,the average error is about 11.2%.2.Establish four particle arrangement geometry model under D/d=2.40 and used the CFD to calculate.The results suggest that if the hollow structure is wide enough,it will play a leading role in reducing the pressure drop.The model A with the structure is the optimal packing structure at the D/d.The pressure drop in the slender packing bed cannot be determined simply according to the global void ratio.3.Establish three geometric model of the particle arrangement structure under D/d=2.414.Appropriately enlarge the tube to particle diameter ratios so that more packing particles can be accommodated on the single layer.The results suggest that the results obtained by the above simulation calculations are universal,the difference in internal structure affects the fluid flow characteristics in the slender packed bed.