Simulation of bubbly flows with special numerical treatments of the semi-conservative and fully conservative two-fluid model

Li, Dongyue; Hasse, Christian

doi:10.1016/j.ces.2017.08.030

Cited by 43 publications

(11 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…And then, the velocity is modified by the pressure, so the convergent velocity field and pressure field can be obtained. The discretization procedure was reported in other works [37,38].…”

Section: Coupling and Numerical Dispersionmentioning

confidence: 99%

Investigation on Bubble Diameter Distribution in Upward Flow by the Two-Fluid and Multi-Fluid Models

Zeng

2021

Energies

View full text Add to dashboard Cite

Bubble flow can be simulated by the two-fluid model and the multi-fluid model based on the Eulerian method. In this paper, the gas phase was further divided into several groups of dispersed phases according to the diameter by using the Eulerian-Eulerian (E-E) multi-fluid model. The diameters of bubbles in each group were considered to be the same, and their distributions were reorganized according to a specific probability density function. The experimental data of two kinds of bubble flow with different characteristics were used to verify the model. With the help of the open-source CFD software, OpenFOAM-7.x (OpenFOAM-7.0, produced by OpenFOAM foundation, Reading, England), the influences of the group number, the probability distribution function, and the parameters of different bubble diameters on the calculation results were studied. Meanwhile, the numerical simulation results were compared with the two-fluid model and the experimental data. The results show that for the bubble flow with the unimodal distribution, both the multi-fluid model and the two-fluid model can obtain the distribution of gas volume fraction along the pipe radius. The calculation results of the multi-fluid model agree with the experimental data, while those of the two-fluid model differ greatly from the experimental data, which verifies the advantage of the multi-fluid model in calculating the distribution of gas volume fraction in the polydisperse bubble flow. Meanwhile, the multi-fluid model can be used to accurately predict the distribution of the parameters of each phase of the bubble flow if the reasonable bubble diameter distribution is provided and the appropriate interphase force calculation model is determined.

show abstract

“…And then, the velocity is modified by the pressure, so the convergent velocity field and pressure field can be obtained. The discretization procedure was reported in other works [37,38].…”

Section: Coupling and Numerical Dispersionmentioning

confidence: 99%

Investigation on Bubble Diameter Distribution in Upward Flow by the Two-Fluid and Multi-Fluid Models

Zeng

2021

Energies

View full text Add to dashboard Cite

show abstract

“…A similar phenomenon is present in the thermochemical recycling of PW due to the presence of impurities in the waste streams [285]. Besides, due to the same reason, it is possible that the flow regime changes in some areas of the reactor, and the dispersed phase changes from the solid/liquid phase to the gas phase, and vice versa [286]. This is while the application of some models such as the drag model is valid based on a fixed dispersed phase, such as the Gidaspow drag model [246].…”

Section: Multi-phase Flow Modelingmentioning

confidence: 67%

“…For example, the drag coefficient correlations are usually reported for, e.g., a single bubble in a bulk of liquid while in some reactor zones, this could be changed into a single liquid droplet in a continuous gas phase. Other than the closure models, another related problem is that the volume fraction that is occupied by each phase can change the dominant dispersed phase and this can cause singular problems [286]. This is more problematic in the E-E simulations in which the phases are considered continuum.…”

Section: Regime Transitionmentioning

confidence: 99%

Multi-Scale Modeling of Plastic Waste Gasification: Opportunities and Challenges

et al. 2022

View full text Add to dashboard Cite

Among the different thermo-chemical recycling routes for plastic waste valorization, gasification is one of the most promising, converting plastic waste into syngas (H2+CO) and energy in the presence of an oxygen-rich gas. Plastic waste gasification is associated with many different complexities due to the multi-scale nature of the process, the feedstock complexity (mixed polyolefins with different contaminations), intricate reaction mechanisms, plastic properties (melting behavior and molecular weight distribution), and complex transport phenomena in a multi-phase flow system. Hence, creating a reliable model calls for an extensive understanding of the phenomena at all scales, and more advanced modeling approaches than those applied today are required. Indeed, modeling of plastic waste gasification (PWG) is still in its infancy today. Our review paper shows that the thermophysical properties are rarely properly defined. Challenges in this regard together with possible methodologies to decently define these properties have been elaborated. The complexities regarding the kinetic modeling of gasification are numerous, compared to, e.g., plastic waste pyrolysis, or coal and biomass gasification, which are elaborated in this work along with the possible solutions to overcome them. Moreover, transport limitations and phase transformations, which affect the apparent kinetics of the process, are not usually considered, while it is demonstrated in this review that they are crucial in the robust prediction of the outcome. Hence, possible approaches in implementing available models to consider these limitations are suggested. Finally, the reactor-scale phenomena of PWG, which are more intricate than the similar processes—due to the presence of molten plastic—are usually simplified to the gas-solid systems, which can result in unreliable modeling frameworks. In this regard, an opportunity lies in the increased computational power that helps improve the model’s precision and allows us to include those complexities within the multi-scale PWG modeling. Using the more accurate modeling methodologies in combination with multi-scale modeling approaches will, in a decade, allow us to perform a rigorous optimization of the PWG process, improve existing and develop new gasifiers, and avoid fouling issues caused by tar.

show abstract

“…In recent years, a number of computational studies have assessed different inter‐phase closure relations by means of qualitative comparison of model predictions of local gas hold‐up and velocity profile against limited experimental data . While the aforementioned studies have provided significant insight into the sensitivity of Euler–Euler model results to closure relations, they have not provided a definitive test of the ability of this model to predict the overall gas hold‐up.…”

Section: Introductionmentioning

confidence: 99%

On the prediction of gas hold‐up in two‐phase flow systems using an Euler–Euler model

et al. 2020

View full text Add to dashboard Cite

We quantify the ability of the two-fluid Euler-Euler model to predict the overall gas hold-up during two-phase flow in vertical columns using a combination of experiments and simulations. Gas hold-up in a bubble column and gas hold-up in the less-frequently studied co-current flow are investigated. For homogeneous flow characterized by nearly uniform bubble size, Euler-Euler model predictions are within 10% of the experimental values for both modes of operation, if the bubble diameter supplied as input to the model is the average bubble diameter in the physical system. This also holds true for heterogeneous flow in bubble columns despite the presence of a broad distribution of bubble sizes, if turbulence and bubble swarm effects on momentum exchange between phases are properly accounted for. Swarm corrections adequate for bubble columns, are less successful for co-current heterogeneous flow, for which gas hold-up predictions are least accurate (average error of 22%). K E Y W O R D S churn-turbulent flow regime, dispersed flow regime, experimental validation, gas-liquid flow, two-fluid Euler-Euler model

show abstract

Simulation of bubbly flows with special numerical treatments of the semi-conservative and fully conservative two-fluid model

Cited by 43 publications

References 65 publications

Investigation on Bubble Diameter Distribution in Upward Flow by the Two-Fluid and Multi-Fluid Models

Investigation on Bubble Diameter Distribution in Upward Flow by the Two-Fluid and Multi-Fluid Models

Multi-Scale Modeling of Plastic Waste Gasification: Opportunities and Challenges

On the prediction of gas hold‐up in two‐phase flow systems using an Euler–Euler model

Contact Info

Product

Resources

About