Computational flow modelling and design of bubble column reactors

Joshi, Jyeshtharaj B.

doi:10.1016/s0009-2509(01)00273-1

Cited by 347 publications

(231 citation statements)

References 130 publications

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“…The most important characteristics of a multiphase flow are the existence of an interface separating the phases and the associated discontinuities of properties across the phase interface (Joshi, 2001). Modeling of the two phases flow includes the set of momentum and mass equations and interaction between them by considering the empirical exchange momentum.…”

Section: Two Fluid Modelmentioning

confidence: 99%

Investigation of hydrodynamics and transition regime in an internal loop airlift reactor using CFD

Ghasemi

Hosseini

2012

Braz. J. Chem. Eng.

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-CFD modeling for an internal loop airlift reactor is developed for different superficial gas velocities, ranging from 0.015 to 0.073 m/s. Based on the presence of gas bubbles in the downcomer, three regimes can be generally classified as: no gas bubbles (I), stagnation of gas bubbles (II), and recirculation of gas bubbles into the riser (III). The aim of the study is to carefully investigate the regime transition from II to III by considering the gas distribution. In regime II, the CFD simulation results show that the gas holdup difference between the riser and the downcomer remains constant. Due to the transition from regime II to III, the gas holdup difference sharply increases and the ratio of gas holdup in the downcomer and riser changes between the two regimes. At a superficial gas velocity slightly lower than that of the transitional regime, a small amount of gas is dragged to the riser, while the behavior of the regime is similar to regime II. The computational results show that CFD can be used as an effective tool to provide information on the details of the transition regime in internal loop airlift reactors.

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Section: Two Fluid Modelmentioning

confidence: 99%

Investigation of hydrodynamics and transition regime in an internal loop airlift reactor using CFD

Ghasemi

Hosseini

2012

Braz. J. Chem. Eng.

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“…Flow inside an airlift PBR is usually modeled as a multiphase flow system which consists of single phase regions bounded by moving interfaces (Manninen et al, 1996); specifically, it is considered as a two-phase flow, with a dispersed flow regime. Transport phenomena in dispersed phase (gas) flows depend upon the collective dynamics of bubbles interacting with each other and with the surrounding continuous phase (liquid) (Joshi, 2001). For developing these models, experimental investigations and numerical simulations have been used.…”

Section: Introductionmentioning

confidence: 99%

CFD simulation of multiphase flow in an airlift column photobioreactor

Freites¹

2014

Issue 6

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A Computational Fluid Dynamics (CFD) simulation using CFX, ANSYS 11.0, has been carried out using a multiphase flow model with an Eulerian-Eulerian approach for an airlift column photobioreactors (PBR). Transient simulations were performed for three inlet air flow, 2, 3 and 5 l min . The contours for gas holdup, air and water velocity showed that the presence of gas phase (air bubbles) is lower in the downcomer but larger in the riser, which leads to require a vigorous mixing in the riser that will be sufficient for a continuous flow. For air, velocity vectors show that they are smaller in the downcomer than in the riser. Nevertheless, water velocity vectors are organized, pointing down in the downcomer and up in the riser. Water shear stress rate contours analysis showed that, shear stress rate regions are considerably larger in the riser, but lower in the downcomer. Due to fewer restrictions to the liquid phase in the riser, a large amount of energy is dissipated by gas liquid interactions. In the downcomer region, gas phase is almost inexistent, and so are the bubble collisions. Finally, the kinetic energy is larger at the top region of the riser, meanwhile is lower at the downcomer. Similar results are observed for energy dissipation rate.

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“…Amongst the such as limited range of applicability of the empirical aforementioned approaches, the two-fluid approach is correlations so developed, difficulty in extrapolating the widely used. Although there are several studies in inferences to other geometries or even scaled-up versions context of turbulent bubbly flows, a large number of of the same equipment, and overall cost and time frame these studies are found on gas-liquid systems (Friberg 1) ; limitations have led to more attention being focused on Thakre and Joshi 2) ; Joshi 3) ; Sokolichin et al 4) ; Deen et numerical approaches such as computational fluid al. 5) ; Dhotre and Joshi 6) ).…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Oil Dispersions in Vertical Pipe Flow

Parvini¹,

Dabir²,

Mohtashami³

2010

J. Jpn. Petrol. Inst.

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Immiscible liquid dispersions are widely used in chemical process, petroleum industries, polymerization, heterogeneous chemical synthesis, etc. In most of these chemical processes, the rate of inter-phase heat and mass transfer is known to strongly affect the overall performance and depends on the interfacial contact area between the phases. This study at CFD simulations of immiscible liquid dispersion has been performed on a vertical pipe. With specific reference to dispersed liquid-liquid flows, it was seen that the two-fluid approach (Eulerian-Eulerian approach) was extensively used for multiphase modeling, especially when detailed predictions are desirable over a range of holdups in exchange for a reasonable amount of computation power. The results of CFD predictions for water as a continuous and kerosene as a dispersed phase have been compared with the experiments of Farrar and Bruun and Al-Deen and Bruun. These simulations have also been done to understand the effect of various significant forces in turbulent liquid dispersions (drag, lift, turbulent dispersion and added mass). Several expressions for these forces were tested in order to choose the best combination. Further, the problem has been simulated using two different turbulence models. It has been found that lift force is more important than turbulent dispersion and added mass. Inter-phase closure guidelines for liquid-liquid bubbly flows were developed based on simulation results that yielded the best agreement with experimental data.

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Computational flow modelling and design of bubble column reactors

Cited by 347 publications

References 130 publications

Investigation of hydrodynamics and transition regime in an internal loop airlift reactor using CFD

Investigation of hydrodynamics and transition regime in an internal loop airlift reactor using CFD

CFD simulation of multiphase flow in an airlift column photobioreactor

Numerical Simulation of Oil Dispersions in Vertical Pipe Flow

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