Bubble Breakup and Coalescence in Turbulent Gas-Liquid Dispersions

Lee, Chung-Hur; Erickson, Larry E.; Glasgow, Larry A.

doi:10.1080/00986448708911986

Cited by 134 publications

(98 citation statements)

References 12 publications

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“…On the other hand, the bubble RMS velocities calculated using the Liepe and Moeckel's model were much worse. Therefore, the following equation was used to calculate the bubble RMS velocities (Lee et al, 1987):…”

Section: Collision Frequencymentioning

confidence: 99%

Establishment of the Center for Advanced Separation Technologies

Hull¹

2005

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INTRODUCTIONThe U.S. is the largest producer of mining products in the world. In 1999, U.S. mining operations produced $66.7 billion worth of raw materials that contributed a total of $533 billion to the nation's wealth. Despite these contributions, the mining industry has not been well supported with research and development funds as compared to mining industries in other countries. To overcome this problem, the Center for Advanced Separation Technologies (CAST) was established by Virginia Tech and West Virginia University to develop technologies that can be used by the U.S. mining industry to create new products, reduce production costs, and meet environmental regulations. This endeavor is supported through U.S. DOE Cooperative Agreement No. DE-FC26-01NT41091: Establishment of the Center for Advance Separation Technologies.Much of the research to be carried out at CAST will be longer-term, high-risk, basic research, and will be carried out in four broad areas: a) Solid-solid separation b) Solid-liquid separation c) Chemical/Biological extraction, and d) Sensor and control development.Distribution of funds has been handled via competitive solicitation of research proposals through Site Coordinators at the two universities. Two RFP's have been issued to date. The first of these, referred to as the CAST I -Round 1 RFP, was issued on August 17, 2001 and closed October 15, 2001. A total of 12 proposals were received in response to this first RFP. These were first reviewed and ranked by a group of technical reviewers (selected primarily from industry). Based on these reviews, and an assessment of overall program requirements, the CAST Technical Committee made an initial selection/ranking of proposals and forwarded these proposals to the DOE/NETL Project Officer for final review and approval. This process took some 6 months to complete but 8 projects were in place at the constituent universities (5 at Virginia Tech and three at West Virginia University) by May 17, 2002. This was followed, on June 1, 2002 with the CAST I -Round 2 RFP, which closed on July 19, 2002. A total of 12 proposals were received in response to this second RFPfive were selected for funding. These were in place at the constituent universities (2 at Virginia Tech and 3 at West Virginia University) by March 1, 2003.All thirteen of these projects are listed below by category, along with brief abstracts of their aims and objectives. The recovery of coarse particles by flotation is a common problem in the coal and minerals processing industry. The objective of this project is to develop methods of extending the upper particle size limit for flotation. The availability of such a technology will improve processing efficiency and greatly simplify the plant flowsheet. Two different complementary approaches will be used to achieve the project objective. One is to use novel flotation reagents that will help increase the attachment force between air bubbles and coarse particles, and the other is to develop new flotation machines specifically de...

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Section: Collision Frequencymentioning

confidence: 99%

Establishment of the Center for Advanced Separation Technologies

Hull¹

2005

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“…Other coalescence models are used also. The coalescence models of Chesters (1991) and Lee et al (1987a) are used in the work of the discrete bubble model (DBM) introduced by Van Den Hengel et al (2005). In these coalescence models, the coalescence rate is modeled as the product of the collision frequency and the coalescence efficiency.…”

Section: Coalescence Modelingmentioning

confidence: 99%

“…In the model of Lee et al (1987a), the coalescence time is equal to the time required for thinning plus the time of rupture. And the contact time is based on the theory of isotropic turbulence which is calculated by a different relation.…”

Section: Coalescence Modelingmentioning

confidence: 99%

“…By assuming a quasi-steady creeping flow, Chesters (1991) calculated the drainage time for partially mobile interfaces using the following relation: Lee et al (1987a) used the model of Sagert and Quinn (1976) for the partially mobile case By investigating the resisting hydrodynamic force during film drainage, Davis et al (1989) concluded that the relationship between the force F and the drainage velocity dh/dt was given by Where characterizes the interfacial mobility. Based on the Eq.…”

Section: (C) Deformable Particles With Partially Mobile Interfacesmentioning

confidence: 99%

“…That is consistent with the idea of the critical velocity model. Lee et al (1987a) suggested that the inertial thinning is predominant for pure inviscid fluid (mco10mPa s). They applied a different model, which is proposed by Sagert and Quinn (1976) Prince and Blanch (1990) simplified the model of Oolman and Blanch (1986) by neglecting the effect of Hamaker force and got,…”

Section: (D) Deformable Particles With Fully Mobile Interfacesmentioning

confidence: 99%

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Coupled Lagrange-Euler Model for Simulation of Bubbly Flow in Vertical Pipes Considering Turbulent 3d Random Walks Models and Bubbles Interaction Effects

Essa¹

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A novel Two-way coupled Euler-Lagrange mode, including bubble-bubble collision, coalescence, with variable bubble radius, and bubbles breakup was applied to simulate air-water bubbly flow in vertical pipes. This approach uses the Continuous Random Walks CRW models for creating the velocity fluctuations according to the given state of turbulent kinetic energy and Dissipation rate at the location of the bubbles which is solved by the turbulence model. This dissertation i) describes the development of the Euler-Lagrange Approach under study, ii) presents a study for the two-way coupling effect on both the continuous and dispersed phases properties, iii) studies the effect of both the lift force coefficient and bubble induced turbulence BIT relations on the gas void fraction distributions, iv) studies the effect of the bubbles coalescence and breakup on bubble sizes and gas void fraction distributions. And presents the results of the simulations performed under each of these considerations.The two-way coupling process takes the effect of the dispersed phase on the continuous one through inserting source terms in the conservation equations of momentum and Turbulence. Also it modifies the volume of the computational cells in the Euler solver available for the continuous phase according to the void fraction of each cell. During the two-way coupling process, some studies needed to be performed like the adjustment of the lift force coefficient and the relation due to the change of the liquid velocity profiles as a result of the two-way coupling.The bubble-bubble collision was applied in the two-way coupling process. It was found that considering the collision appears on the void fraction distribution only in the high velocity and high gas holdup cases with very small effect. The bubble-bubble coalescence was applied as a complementary part of the collision process using the film drainage model of Chesters (1991). This model compares the film drainage time with the contact time to calculate the coalescence efficiency. The coalescence model was tested first before applying the breakup, so the bubbles size increased only and this affected on the void fraction distribution badly. Then the breakup model of Martínez-Bazán (1999a, b) was applied to perform the equilibrium in the bubble sizes. These two processes of the coalescence and breakup found to consume long computational time, the reason that did not give us a chance for testing many cases with considering both coalescence and breakup.The main investigation point through the development of this work was the BIT kinetic energy term and its effect on the used CRW model. This was considered in nearly every phase of the model development to study the effect of the BIT under the different considerations of the bubbles interaction mechanisms. It could be concluded a final vi expression for the BIT relation that is used successfully with the CRW models under consideration.vii ResumenUna nueva aproximación euleriana-lagarangiana, en su forma de acople en dos vías, para ...

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