Mechanism of heat transfer in bubbly liquid and liquid‐solid systems: Single bubble injection

Kumar, Samir; Kusakabe, Ken Takeshi; Raghunathan, K.; Fan, Liang‐Shih

doi:10.1002/aic.690380510

Cited by 53 publications

(41 citation statements)

References 16 publications

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“…Furthermore, within the range of their study ( p / = 1-39 cp), they speculated that this decrease may be caused by the increase in bubble size and rise velocity due to enhanced bubble coalescence with the increase of liquid viscosity which results in decreasing gas holdup and, thereby, heat transfer. However, this explanation is highly suspect as the increased bubble size and rise velocity are reported to increase the local heat transfer (Kumar et al, 1992). Bubble motion and the associated wake flows are believed to be responsible for the above-mentioned transport phenomena in multiphase systems (Fan and Tsuchiya, 1990).…”

Section: Aiche Journalmentioning

confidence: 96%

Heat‐transfer characteristics in viscous gas‐liquid and gas‐liquid‐solid systems

Kumar

Fan

1994

AIChE Journal

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Section: Aiche Journalmentioning

confidence: 96%

Heat‐transfer characteristics in viscous gas‐liquid and gas‐liquid‐solid systems

Kumar

Fan

1994

AIChE Journal

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“…Two acrylic columns having internal diameters of 25 and 140 mm are used. A rigid borescope [22][23][24][25][26][27][28][29][30][31] (Olympus) with a 60 o field of view and 0 o direction of view is used to obtain particle images in a dynamic system. The borescope has a diameter of 6 mm and length of 250 mm.…”

Section: Methodsmentioning

confidence: 99%

Determination of Actual Object Size Distribution from Direct Imaging

Hossain¹,

Chen²,

Yang³

et al. 2009

Ind. Eng. Chem. Res.

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Direct imaging is a technique commonly used in the study of particle, bubble, and droplet size distribution in a dynamic system. Objects such as particles, bubbles, and droplets can be present at various distances from the imaging device when images are captured. Hence, the location of the object will need to be known in order to determine the actual size of an individual object. However, the location of the object cannot be determined from a single image. A single calibration scale defined at the focusing plane is normally used for the determination of all the object sizes from images. When the focus is close to the imaging device, the change in magnification with location is large. The size distribution obtained from the use of a single calibration scale would thus give a considerable deviation from the actual size distribution. In this study, a statistical method is proposed to reconstruct the actual object size distribution from the experimental object size distribution obtained from images using a single calibration scale defined at the focusing plane. Experiments are performed to validate the accuracy of the proposed method on the particle size distribution determination in a settling system. The stability of the proposed method is also analyzed theoretically for imaging devices with different depth-of-field (DOF), focusing location, and change in magnification with distance.

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“…Kumar et al (1992) found that the injection of a single bubble into liquids or liquid-solid suspensions enhances the heat transfer rate via bubble wake. Since the wake size is proportional to bubble size, a larger bubble would have a larger wake and stronger vortices associated with the wake, thereby enhancing the rate of heat transfer.…”

Section: Effect Of Pressurementioning

confidence: 99%

Engineering Development of Slurry Bubble Column Reactor (Sbcr) Technology

Toseland¹

2002

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Project ObjectivesThe major technical objectives of this program are threefold: 1) to develop the design tools and a fundamental understanding of the fluid dynamics of a slurry bubble column reactor to maximize reactor productivity, 2) to develop the mathematical reactor design models and gain an understanding of the hydrodynamic fundamentals under industrially relevant process conditions, and 3) to develop an understanding of the hydrodynamics and their interaction with the chemistries occurring in the bubble column reactor. Successful completion of these objectives will permit more efficient usage of the reactor column and tighter design criteria, increase overall reactor efficiency, and ensure a design that leads to stable reactor behavior when scaling up to large diameter reactors. AbstractThis report summarizes the results of a Department of Energy-funded study on slurry bubble column reactors (SBCR). Alternate fuels projects need high reactor throughput for competitive economics so that reactors must operate in the churn-turbulent region of flow. Little data in this flow regime, especially at the conditions of high pressure and temperature for organic fluids found in an industrial reactor, existed at the inception of this project. This report summarizes the large body of fundamental data that was developed on these flows. It covers both the local liquid turbulence and large-scale liquid internal circulation aspects of flow in the SBCR. Where understood, the underlying mechanisms, which result in the macro-scale phenomena, are elucidated and modeled. Finally, new models for reactor design are also presented. Executive SummaryThe state of the art in design and modeling of bubble columns before the initiation of this project relied solely on the use of ideal flow patterns (e.g., perfectly mixed liquid and plug flow of gas) or on the use of the axial dispersion model (ADM). The use of ideal flow patterns can lead to serious over design, and the uncertainty in the values of the axial dispersion coefficients precludes a more accurate design based on the ADM. Since these models represent crude descriptions of the flow pattern in bubble columns and do not account for input from the fluid dynamics of the system, the scaleup of SCBR has been uncertain.The need for rapid scaleup and optimal commercialization for gas conversion processes necessitated an improved understanding and quantification of fluid dynamics and transport in slurry bubble column reactors. This report presents the results of an extensive experimental and theoretical program on SBCR.This program was conducted by a team comprising Air Products (APCI), Washington University in St. Louis (WU), The Ohio State University (OSU), Iowa State University (ISU) and Sandia National Laboratory (SNL). SNL participated as an active team member, but was supported by separate DOE funds; therefore, SNL's work will not be reported here.Bubble columns are complex. The complexity can be simplified in breaking up the phenomena occurring in bubble columns according to sc...

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Mechanism of heat transfer in bubbly liquid and liquid‐solid systems: Single bubble injection

Abstract: Local instantaneous changes in heat-

Cited by 53 publications

References 16 publications

Heat‐transfer characteristics in viscous gas‐liquid and gas‐liquid‐solid systems

Heat‐transfer characteristics in viscous gas‐liquid and gas‐liquid‐solid systems

Determination of Actual Object Size Distribution from Direct Imaging

Engineering Development of Slurry Bubble Column Reactor (Sbcr) Technology

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