Visualization of bubble detachment and coalescence under the influence of a nonuniform electric field

Liu, Z.; Herman, Čila; Mewes, Dieter

doi:10.1016/j.expthermflusci.2006.03.025

Cited by 25 publications

(9 citation statements)

References 17 publications

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“…This work has been summarized in a recent paper by Iacona et al [37] and extended to the coalescence of bubbles from adjacent nozzles by Liu et al [38]. Herman and Iacona [39] Chaddock model requires as input an experimental "contact angle" remote from the wall, beyond the region of necking, so it is an artefact of the local flow field and not a material property.…”

Section: Studies Of a Single Bubble In An Electric Fieldmentioning

confidence: 99%

“…In the approximately uniform field generated by a plane electrode above a plane wall, Herman and Iacona [39] observed the predicted elongation of the bubbles in the direction of the field. In the non-uniform field created by a small spherical electrode placed off-axis from the orifice, which might simulate the distortion of the field by detached bubbles in boiling, bubbles were elongated and tilted [37,38]. Di Marco et al [43] Son et al [13] for vapour bubbles in a gravitational field.…”

Section: Studies Of a Single Bubble In An Electric Fieldmentioning

confidence: 99%

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A study of nucleate boiling and critical heat flux with EHD enhancement

et al. 2007

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Abstract. The paper describes results from an experimental and theoretical study of the effect of an electric field on nucleate boiling and the critical heat flux (CHF) in pool boiling of R123 at atmospheric pressure on a horizontal wall with a smooth surface.Two designs of electrode (parallel rods and wire mesh) were used.The experimental data exhibit some differences from the data obtained by other researchers in similar experiments on a wall with a different surface finish and with a slightly different design of wire mesh electrode. The hydrodynamic model for EHD enhancement of CHF cannot reconcile the differences.A theoretical model has been developed for the growth of a single vapour bubble on a superheated wall in an electric field, leading to a numerical simulation based on the level-set method. The model includes matching of sub-models for the micro-and macroregions, conduction in the wall, distortion of the electric field by the bubble, the temperature dependence of electrical properties and free-charge generation. In the present form of the model, some of these effects are realised in an approximate form. The capability to investigate dry-spot formation and wall temperature changes that might lead to CHF has been demonstrated.

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Section: Studies Of a Single Bubble In An Electric Fieldmentioning

confidence: 99%

Section: Studies Of a Single Bubble In An Electric Fieldmentioning

confidence: 99%

A study of nucleate boiling and critical heat flux with EHD enhancement

et al. 2007

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“…For surface boiling with a large number of nucleation sites on a natural surface, Kweon and Kim [14] observed smaller detachment sizes. This is also generally the case for isolated bubbles growing in non-uniform electric fields [8,15]. However, for single bubble events in axisymmetric or uniform electric fields, the detachment volume of the bubble has been observed to in some cases increase, decrease or remains unchanged [11,12,15].…”

Section: Introductionmentioning

confidence: 90%

Electric field effects during nucleate boiling from an artificial nucleation site

Siedel

Cioulachtjian

Robinson

et al. 2011

Experimental Thermal and Fluid Science

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“…Liu et al 15 studied the effects of a nonuniform electric field on the formation, coalescence, and detachment of both single bubbles and pairs of air bubbles to identify characteristic bubble behaviors. It was observed that the nonuniform electric field prevented the bubble pair from coalescing: bubbles repelled each other at lowvolume flow rates.…”

Section: Andmentioning

confidence: 99%

“…The bubble was elongated and detached faster with a decreased volume with increasing electric field magnitude, whereas regular bubble detachment is typically absent in microgravity with no applied electric field. Herman et al 14 and Liu et al 15 studied the effects of a nonuniform electric field on the formation, coalescence, and detachment of both single bubbles and pairs of air bubbles to identify characteristic bubble behaviors. It was observed that the nonuniform electric field prevented the bubble pair from coalescing: bubbles repelled each other at low‐volume flow rates.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer and Bubble Detachment in Subcooled Pool Boiling from a Downward‐Facing Microheater Array in a Nonuniform Electric Field

Liu

Herman

Kim

2009

Annals of the New York Academy of Sciences

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The effects of a nonuniform electric field on vapor bubble detachment and heat transfer in subcooled pool boiling from a microheater array are investigated. The heater array faced downward to simulate a -1 g gravity condition and to eliminate the dominant masking effect of the buoyancy force. Experiments were conducted at different subcooling levels for various wall temperatures and electric field magnitudes. A dielectric fluid, FC-72, was used as the working fluid at ambient pressure. The array of 3 x 3 independently controlled microheaters was maintained at constant temperature and the rate of heat transfer from each heater was measured. Bubble images were recorded using a high-speed camera. The electric field was applied between the horizontal downward-facing microheater array, which was grounded, and a spherical, off-axis electrode beneath it. Boiling heat transfer results with and without the electric field are presented in this study. In the absence of the nonuniform electric field, compared to the same bulk fluid temperature and wall superheat settings in the +1 g situation, a much larger primary bubble was formed on the heater array, due to the coalescence of the secondary bubbles that nucleated on the heater array. The vapor bubble remained on the heater array surface and no bubble detachment was observed. With the nonuniform electric field applied, bubbles were lifted and sheared off from the heater array surface. The electric field was able to break up the primary bubble into several smaller bubbles--considerably greater heat transfer enhancement was measured than under similar conditions in +1 g.

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Visualization of bubble detachment and coalescence under the influence of a nonuniform electric field

Cited by 25 publications

References 17 publications

A study of nucleate boiling and critical heat flux with EHD enhancement

A study of nucleate boiling and critical heat flux with EHD enhancement

Electric field effects during nucleate boiling from an artificial nucleation site

Heat Transfer and Bubble Detachment in Subcooled Pool Boiling from a Downward‐Facing Microheater Array in a Nonuniform Electric Field

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