Surface tension effects on adiabatic gas–liquid flow across micro pillars

Krishnamurthy, Santosh; Peles, Yoav

doi:10.1016/j.ijmultiphaseflow.2008.08.001

Cited by 16 publications

(12 citation statements)

References 26 publications

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“…This is known as churn flow, which at the same time is associated with the largest interfacial areas. 17 Our results are analogous to those of Krishnamurthy and Peles 22 on their gas and liquid flow across micro-pillars. For u G < 1 m s −1 they observed bubbly slug flow.…”

Section: Designsupporting

confidence: 85%

“…The different modeling strategies for the multiscale phenomena in these systems have been reviewed by Ge et al 18 As in large-scale systems, flow regime maps have been constructed for micro-packed beds that map flow patterns in a 2D domain of liquid and gas velocities. [19][20][21] However, by only using velocities, the effect of other parameters that can influence flow patterns, such as physical fluid properties 22 and inlet section design 23,24 are not reflected. The study of flow in porous media, relevant in oil recovery, has several common characteristics with the multiphase flow in micropacked beds.…”

Section: Introductionmentioning

confidence: 99%

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Tailoring the multiphase flow pattern of gas and liquid through micro-packed bed of pillars

et al. 2019

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Section: Designsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Tailoring the multiphase flow pattern of gas and liquid through micro-packed bed of pillars

et al. 2019

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“…Alternatively, micro packed-beds can be used to increase the catalytic surface area (Losey et al 2001;Ajmera et al 2006;Hotz et al 2008); this however increases the pressure drop over the channel significantly. Alternatively, micro pillars in micro channels can be used (Losey et al 2002;Krishnamurthy and Peles 2007;Krishnamurthy and Peles 2009). These pillars increase the catalytic specific surface area, have an open structure, and are well-defined, whereas micro packed-beds have a more random distribution over the channel.…”

Section: List Of Symbolsmentioning

confidence: 99%

Gas–liquid dynamics at low Reynolds numbers in pillared rectangular micro channels

Loos

Schaaf

Tiggelaar

et al. 2009

Microfluid Nanofluid

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Most heterogeneously catalyzed gas-liquid reactions in micro channels are chemically/kinetically limited because of the high gas-liquid and liquid-solid mass transfer rates that can be achieved. This motivates the design of systems with a larger surface area, which can be expected to offer higher reaction rates per unit volume of reactor. This increase in surface area can be realized by using structured micro channels. In this work, rectangular micro channels containing round pillars of 3 lm in diameter and 50 lm in height are studied. The flow regimes, gas hold-up, and pressure drop are determined for pillar pitches of 7, 12, 17, and 27 lm. Flow maps are presented and compared with flow maps of rectangular and round micro channels without pillars. The Armand correlation predicts the gas hold-up in the pillared micro channel within 3% error. Three models are derived which give the single-phase and the two-phase pressure drop as a function of the gas and liquid superficial velocities and the pillar pitches. For a pillar pitch of 27 lm, the Darcy-Brinkman equation predicts the single-phase pressure drop within 2% error. For pillar pitches of 7, 12, and 17 lm, the Blake-Kozeny equation predicts the single-phase pressure drop within 20%. The two-phase pressure drop model predicts the experimental data within 30% error for channels containing pillars with a pitch of 17 lm, whereas the Lockhart-Martinelli correlation is proven to be nonapplicable for the system used in this work. The open structure and the higher production rate per unit of reactor volume make the pillared micro channel an efficient system for performing heterogeneously catalyzed gas-liquid reactions.

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“…The data were correlated in terms of an 'equilibrium' heat transfer coefficient and the exit gas-mass fraction. Krishnamurthy and Peles (2009) reported on an adiabatic study of nitrogen-ethanol flows across a staggered array of circular pin fins. The test piece was 1.5 mm wide and 10 mm long and contained 68 rows of fins in either 9 or 10 columns.…”

Section: Introductionmentioning

confidence: 99%

A comparison of flow boiling heat-transfer in in-line mini pin fin and plane channel flows

McNeil

Raeisi

Kew

et al. 2010

Applied Thermal Engineering

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The use of a boiling fluid as a coolant is an attractive option for electronic devices as electrical power densities increase. However, for systems working at the micro-scale, design methods developed for evaluating heat transfer in macro-scale evaporators are not appropriate for passages with hydraulic diameter of the order of 1mm and below. Heat-transfer coefficients and pressure drops are reported for two surfaces, a pin-fin and a plate surface, each with 50 mm square base area. The pin-fin surface was comprised of 1 mm square pin-fins that were 1mm high and located on a 2 mm square pitch array covering the base. The channel was 1 mm high and had a glass top plate. The data were produced while boiling R113 at atmospheric pressure. For both surfaces, the mass flux range was 50-250 kg/m 2 s and the heat flux range of 5-140 kW/m 2. The results obtained have been compared with a standard correlation for tube bundles. The measured heat transfer coefficients for the pin-fin surface are slightly higher than those for the plate surface. Both are dependent on heat flux and reasonably independent of mass flux and vapour quality. Thus, heat transfer is probably dominated by nucleate-boiling and is increased by the pin-fins due to the increase in area and heat-transfer coefficient. The pin-fin pressure drops were typically 7 times larger than the plate values. The pin-fin heat-transfer coefficients and pressure drops are compared to macro-scale tube bundle correlations. At low vapour qualities the heat-transfer coefficients are in reasonable agreement with the correlations, but, as the vapour quality increases, they do not show the convective enhancement which would be expected for a conventionally-sized tube bundle. Measured two-phase pressure drops are in reasonable agreement with the tube bundle correlation.

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Surface tension effects on adiabatic gas–liquid flow across micro pillars

Cited by 16 publications

References 26 publications

Tailoring the multiphase flow pattern of gas and liquid through micro-packed bed of pillars

Tailoring the multiphase flow pattern of gas and liquid through micro-packed bed of pillars

Gas–liquid dynamics at low Reynolds numbers in pillared rectangular micro channels

A comparison of flow boiling heat-transfer in in-line mini pin fin and plane channel flows

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