ANALYSIS OF INTERFACIAL AND MASS TRANSFER EFFECTS ON FORCED CONVECTION IN GAS-LIQUID ANNULAR TWO-PHASE FLOW

In a gas-liquid annular two-phase flow one of the main factors influencing the determination of heat transfer rates is the average thickness of the liquid film. A model to accurately represent the heat transfer in such situations has to be able of determining the average liquid film thickness to within a reasonable accuracy. A typical physical aspect in gas-liquid annular flows is the appearance of interface waves, which affect heat, mass and momentum transfers. Existing models implicitly consider the wave effects in the momentum transfer by an empirical correlation for the interfacial friction factor. However, this procedure does not point out the difference between interface waves and the natural turbulent effects of the system. In the present work, the wave and mass transfer effects in the theoretical estimation of average liquid film thickness are analyzed, in comparison to a model that does not explicitly include these effects, as applied to the prediction of heat transfer rates in a thermally developing flow situation.

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ANALYSIS OF INTERFACIAL AND MASS TRANSFER EFFECTS ON FORCED CONVECTION IN GAS-LIQUID ANNULAR TWO-PHASE FLOW

Revista de Engenharia Térmica ◽

10.5380/ret.v3i1.3483 ◽

2004 ◽

Vol 3 (1) ◽

Author(s):

E. Nogueira ◽

B. D. Dantas ◽

R. M. Cotta

Keyword(s):

Heat Transfer ◽

Mass Transfer ◽

Film Thickness ◽

Liquid Film ◽

Liquid Film Thickness ◽

Phase Flow ◽

Transfer Effects ◽

Two Phase ◽

Transfer Rates ◽

Interface Waves

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Measurement of Liquid Film Thickness in Micro Tube Annular Flow

2010 14th International Heat Transfer Conference, Volume 6 ◽

10.1115/ihtc14-23176 ◽

2010 ◽

Cited By ~ 1

Author(s):

Hiroshi Kanno ◽

Youngbae Han ◽

Yusuke Saito ◽

Naoki Shikazono

Keyword(s):

Heat Transfer ◽

Film Thickness ◽

Liquid Film ◽

Annular Flow ◽

Liquid Film Thickness ◽

Phase Flow ◽

Two Phase ◽

Micro Scale ◽

Film Model ◽

Annular Film

Heat transfer in micro scale two-phase flow attracts large attention since it can achieve large heat transfer area per density. At high quality, annular flow becomes one of the major flow regimes in micro two-phase flow. Heat is transferred by evaporation or condensation of the liquid film, which are the dominant mechanisms of micro scale heat transfer. Therefore, liquid film thickness is one of the most important parameters in modeling the phenomena. In macro tubes, large numbers of researches have been conducted to investigate the liquid film thickness. However, in micro tubes, quantitative information for the annular liquid film thickness is still limited. In the present study, annular liquid film thickness is measured using a confocal method, which is used in the previous study [1, 2]. Glass tubes with inner diameters of 0.3, 0.5 and 1.0 mm are used. Degassed water and FC40 are used as working fluids, and the total mass flux is varied from G = 100 to 500 kg/m2s. Liquid film thickness is measured by laser confocal displacement meter (LCDM), and the liquid-gas interface profile is observed by a high-speed camera. Mean liquid film thickness is then plotted against quality for different flow rates and tube diameters. Mean thickness data is compared with the smooth annular film model of Revellin et al. [3]. Annular film model predictions overestimated the experimental values especially at low quality. It is considered that this overestimation is attributed to the disturbances caused by the interface ripples.

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Analytical Solutions of Heat Transfer and Film Thickness with Slip Condition Effect in Thin-Film Evaporation for Two-Phase Flow in Microchannel

Mathematical Problems in Engineering ◽

10.1155/2015/369581 ◽

2015 ◽

Vol 2015 ◽

pp. 1-15 ◽

Cited By ~ 2

Author(s):

Ahmed Jassim Shkarah ◽

Mohd Yusoff Bin Sulaiman ◽

Md. Razali bin Hj Ayob

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Film Thickness ◽

Liquid Film ◽

Two Phase Flow ◽

Current Model ◽

Liquid Film Thickness ◽

Phase Flow ◽

Two Phase ◽

Analytical Results

Physical and mathematical model has been developed to predict the two-phase flow and heat transfer in a microchannel with evaporative heat transfer. Sample solutions to the model were obtained for both analytical analysis and numerical analysis. It is assumed that the capillary pressure is neglected (Morris, 2003). Results are provided for liquid film thickness, total heat flux, and evaporating heat flux distribution. In addition to the sample calculations that were used to illustrate the transport characteristics, computations based on the current model were performed to generate results for comparisons with the analytical results of Wang et al. (2008) and Wayner Jr. et al. (1976). The calculated results from the current model match closely with those of analytical results of Wang et al. (2008) and Wayner Jr. et al. (1976). This work will lead to a better understanding of heat transfer and fluid flow occurring in the evaporating film region and develop an analytical equation for evaporating liquid film thickness.

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