基于CFD对小管径粒径比填料床填料结构的优化
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摘要
为探究填料方式即内部结构不同对内部压降影响并得到最优填料结构,利用CFD Fluent 16. 2对管径粒径比D/d=2. 15下不同内部结构的细长填料床进行数值模拟,3种模型局部径向空隙率分布均与实验结果吻合良好。模拟结果表明,细长填料床内局部压力与速度分布存在不均性;单一D/d下,大空隙率的内部结构或中空通道的存在均可有效降低压降,且进口速度越大对压降影响越大;经综合分析,该D/d下存在中空通道的结构性能最佳。根据模拟结果得到低D/d下压降计算公式,与实验值进行比较,平均误差约为11. 2%。
In order to investigate the influence of different internal structures on pressure drop and determine the optimal internal structure,CFD Fluent 16. 2 is used to carry out numerical simulation on slender packed bed with different internal structure under the diameter ratio of tube to particle D/d = 2. 15. The local radial void fraction distribution of three models agrees well with the experimental results.The simulation results show that the local pressure and velocity distribution are inhomogeneity in the slender packed bed.With the same D/d,the internal structure with the large void ratio or the existence of the hollow channel can reduce effectively pressure drop.The higher the inlet velocity,the greater its influences on pressure drop.After comprehensive analysis,the internal structure with hollow channel is the best.The equation for calculating the pressure drop with low D/d is obtained.Compared with the experimental values,the average error is about 11. 2%.
In order to investigate the influence of different internal structures on pressure drop and determine the optimal internal structure,CFD Fluent 16. 2 is used to carry out numerical simulation on slender packed bed with different internal structure under the diameter ratio of tube to particle D/d = 2. 15. The local radial void fraction distribution of three models agrees well with the experimental results.The simulation results show that the local pressure and velocity distribution are inhomogeneity in the slender packed bed.With the same D/d,the internal structure with the large void ratio or the existence of the hollow channel can reduce effectively pressure drop.The higher the inlet velocity,the greater its influences on pressure drop.After comprehensive analysis,the internal structure with hollow channel is the best.The equation for calculating the pressure drop with low D/d is obtained.Compared with the experimental values,the average error is about 11. 2%.
引文
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[14]Guo Z,Sun Z,Zhang N,et al.Experimental characterization of pressure drop in slender packed bed(1
[2]Calis H P A,Nijenhuis J,Paikert B C,et al.CFD modelling and experimental validation of pressure drop and flow profile in a novel structured catalytic reactor packing[J]. Chemical Engineering Science,2001,56(4):1713-1720.
[3]Romkes S J P,Dautzenberg F M,van den Bleek C M,et al.CFD modelling and experimental validation of particle-to-fluid mass and heat transfer in a packed bed at very low channel to particle diameter ratio[J]. Chemical Engineering Journal,2003,96(1/2/3):3-13.
[4]Kuroki M,Ookawara S,Ogawa K. A High-fidelity CFD model of methane steam reforming in a packed bed reactor[J]. Journal of Chemical Engineering of JAPAN,2009,42(S1):73-78.
[5]Bai H,Theuerkauf J,Gillis P A,et al. A coupled DEM and CFD simulation of flow field and pressure drop in fixed bed reactor with randomly packed catalyst particles[J]. Industrial&Engineering Chemistry Research,2009,48(8):4060-4074.
[6]Eppinger T,Seidler K,Kraume M. DEM-CFD simulations of fixed bed reactors with small tube to particle diameter ratios[J].Chemical Engineering Journal,2011,166(1):324-331.
[7]Dixon A G.Correlations for wall and particle shape effects on fixed bed bulk voidage[J].The Canadian Journal of Chemical Engineering,1988,66(5):705-708.
[8]Mueller G E.Radial void fraction distributions in randomly packed tied beds of uniformly sized spheres in cylindrical containers[J].Powder Technology,1992,72:269-275.
[9]De Klerk A.Voidage variation in packed beds at small column to particle diameter ratio[J]. AIChE Journal,2003,49(8):2022-2029.
[10]Guo Z,Sun Z,Zhang N,et al.Pressure drop in slender packed beds with novel packing arrangement[J]. Powder Technology,2017,321:286-292.
[11]Ergun S. Fluid flow through packed column[J]. Chemical Engineering Progress,1952,48(2):89-94.
[12]Carman P C.Fluid flow through granular beds[J].Chemical Engineering Research and Design,1997,75:S32-S48.
[13]Tallmadge J A. Packed bed pressure drop-an extension to higher Reynolds numbers[J].AIChE Journal,1970,16(6):1092-1093.
[14]Guo Z,Sun Z,Zhang N,et al.Experimental characterization of pressure drop in slender packed bed(1