Direct numerical simulation study of end effects and D/d ratio on mass transfer in packed beds

TY - JOUR

T1 - Direct numerical simulation study of end effects and D/d ratio on mass transfer in packed beds

AU - Bale, Shivkumar

AU - Tiwari, Shashank

AU - Sathe, Mayur

AU - Berrouk, Abdallah S.

AU - Nandakumar, Krishnaswamy

AU - Joshi, Jyeshtharaj

N1 - Publisher Copyright: © 2018 Elsevier Ltd

PY - 2018/12

Y1 - 2018/12

N2 - Direct Numerical Simulation (DNS) was performed to investigate the end effects on mass transfer in a packed bed for Reynolds number (Re) ≤ 100. The system considered in this study was naphthalene-air with a Schmidt number (Sc) ∼ 2.52. The location of the spheres’ centers in a randomly packed bed were obtained from Discrete Element Method – Computational Fluid Dynamics (DEM-CFD) simulations. The influence of the confining wall on how packed bed ends affect mass transfer was studied by examining the axial void fraction profile with varying ratio of the column diameter to the particle sphere diameter (D/d). Overall, it was found that the confining wall has a significant impact. The ‘local’ mass transfer coefficient was calculated based on the obtained DNS results and the probability distribution curve and the spatial distribution of the computed ‘local’ Sherwood numbers as function of the ratio X/L (ratio of the height of the active part of the bed to the total height of the bed) were developed to quantify the end effects on mass transfer within packed beds. For a packed bed with no wall effects (D/d = 11), it was found that the end effects can be eliminated by replacing the active particles located at ∼2 sphere diameters from the entrance and ∼1 sphere diameter from the exit by inert particles.

AB - Direct Numerical Simulation (DNS) was performed to investigate the end effects on mass transfer in a packed bed for Reynolds number (Re) ≤ 100. The system considered in this study was naphthalene-air with a Schmidt number (Sc) ∼ 2.52. The location of the spheres’ centers in a randomly packed bed were obtained from Discrete Element Method – Computational Fluid Dynamics (DEM-CFD) simulations. The influence of the confining wall on how packed bed ends affect mass transfer was studied by examining the axial void fraction profile with varying ratio of the column diameter to the particle sphere diameter (D/d). Overall, it was found that the confining wall has a significant impact. The ‘local’ mass transfer coefficient was calculated based on the obtained DNS results and the probability distribution curve and the spatial distribution of the computed ‘local’ Sherwood numbers as function of the ratio X/L (ratio of the height of the active part of the bed to the total height of the bed) were developed to quantify the end effects on mass transfer within packed beds. For a packed bed with no wall effects (D/d = 11), it was found that the end effects can be eliminated by replacing the active particles located at ∼2 sphere diameters from the entrance and ∼1 sphere diameter from the exit by inert particles.

KW - Direct numerical simulation (DNS)

KW - End effects

KW - Mass transfer

KW - Packed bed

UR - http://www.scopus.com/inward/record.url?scp=85050561877&partnerID=8YFLogxK

U2 - 10.1016/j.ijheatmasstransfer.2018.07.100

DO - 10.1016/j.ijheatmasstransfer.2018.07.100

M3 - 文章

AN - SCOPUS:85050561877

SN - 0017-9310

VL - 127

SP - 234

EP - 244

JO - International Journal of Heat and Mass Transfer

JF - International Journal of Heat and Mass Transfer

ER -