Numerical study of convective flow with condensation of a pure fluid in capillary regime

Miscevic, Marc; Lavieille, Pascal; Piaud, Benjamin

doi:10.1016/j.ijheatmasstransfer.2009.05.004

Cited by 19 publications

(6 citation statements)

References 21 publications

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“…Also, condensation heat transfer and pressure drop depend on the corresponding structure of the two phase flow (mist flow, annular flow, bubbly flow, or slug/plug flow) as shown by Odaymet et al [7]. Three main condensation flows were identified in a small circular tube: the annular flow, the intermittent or elongated bubbles flow, and the spherical bubbles flow by Louahlia-Gualous and Mecheri [8]. Annular flow is especially found to be one of the dominant condensation flows in microchannelsas shown by Odaymet and Louahlia-Gualous [9] and Quan et al [10].…”

Section: Introductionmentioning

confidence: 91%

“…Louahlia-Gualous and Asbik [3] conducted a numerical model predicting heat transfer for condensation of pure refrigerant and binary mixture in a mini-tube. Miscevic et al [4] developed a stationary condensation capillary flow model based on the separate flow approach by taking into account the coupling between a cylindrical interface and a hemispherical interface. Recently, Ribeiro et al [5] experimentally investigated the thermal-hydraulic performance of microchannel condensers using three different copper metal foams structures with distinct pore densities and porosities (0.893 and 0.947) as enhanced surfaces on the air-side.…”

Section: Introductionmentioning

confidence: 99%

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Condensation Heat Transfer in Horizontal Non-Circular Microchannels

Mghari¹,

Asbik²,

Louahlia-Gualous³

2013

EPE

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This investigation contributes to a better understanding of condensation heat transfer in horizontal non-circular microchannels. For this purpose, the conservation equations of mass, momentum and energy have been numerically solved in both phases (liquid and vapor), and all the more so the film thickness analytical expression has been established. Numerical results relative to variations of the meniscus curvature radius, the condensate film thickness, the condensation length and heat transfer coefficients, are analyzed in terms of the influencing physical and geometrical quantities. The effect of the microchannel shapes on the average Nusselt number is highlighted by studying condensation of steam insquare, rectangular and equilateral triangular microchannels with the same hydraulic diameter of 250 µm.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Condensation Heat Transfer in Horizontal Non-Circular Microchannels

Mghari¹,

Asbik²,

Louahlia-Gualous³

2013

EPE

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“…The average Nusselt number is found to decrease with a decrease in the boiling number (corresponding to an increase of the annular zone length) or with an increase in the capillary number (corresponding, for Fig. 9 Example of the interface shape in the annular zone calculated by Miscevic et al (2009) for low capillary number and two liquid to vapor density ratio instance, to an increase of the mass velocity). So, mean thinning of the liquid film can reduce heat transfer coefficient according to the spatial distribution change of the liquid and vapor phases within the channel when boiling number or capillary number is modified.…”

Section: Annular Regimementioning

confidence: 99%

“…Three main flow regimes were observed in the lowest diameter channel: annular regime, intermittent regime and isolated bubbles regime. Miscevic et al (2009) calculated the phase distribution in the annular regime in the steady state (Fig. 9).…”

Section: Annular Regimementioning

confidence: 99%

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Experimental Investigations on Condensation in the Framework of ENhanced COndensers in Microgravity (ENCOM-2) Project

Bortolin

Achkar

Kostoglou

et al. 2014

Microgravity Sci. Technol.

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We report preliminary results on experimental investigations on condensation in the framework of the European Space Agency funded programme Enhanced Condensers in Microgravity (ENCOM-2) which aims at better understanding underlying phenomena during condensation. The first experiment is a study on condensation of HFE on external curvilinear surface of 15 mm height during reduced gravity experiments. It is found that the local minimum of the film thickness exists at the conjugation area of condensed film and the meniscus at the bottom of the fin; this leads to the local maximum of the heat transfer coefficient, which we also found moves towards the fin tip. The second experiment is a study of falling films hydrodynamics inside a vertical long pipe. In particular, characteristics of wavy falling films produced employing intermittent liquid feed are examined in order to assess wave effects on film condensation. Preliminary results suggest that intermittent feed simply divides the film in two autonomous regions with the wave feature of each one depending only on its flow rate. The processing of registered film thickness data can lead to the estimation of the transverse velocity profile in the film, which is mainly responsible for heat transfer during condensation. The third experiment looks at in-tube convective condensation at low mass fluxes (typical of Loop Heat Pipes and Capillary Pumped Loops) of n-pentane inside a 0.56 mm diameter channel. The results show that the mean heat transfer in the annular zone when it is elongated may be less than the mean heat transfer when it is shorter, due to the interface deformation involved by surface tension effect. When the length of this annular zone reaches a critical value, the interface becomes unstable, and a liquid bridge forms, involving the release of a bubble. The heat transfer due to the phase-change in this isolated bubble zone appears to be very small compared to the sensible heat transfer: the bubbles evolve and collapse in a highly subcooled liquid. The last experiment concerns in-tube condensation of R134a inside a square channel of 1.23 mm hydraulic diameter at mass fluxes of 135 kg m−2 s−1 and 390 kg m−2 s−1 for three different configurations: horizontal, vertical downflow and vertical upflow. For the calculated heat transfer coefficient it is found that gravity has no effect on condensation in downflow configurations at 390 kg m−2 s−1 and in upflow conditions at both values of mass velocity. The effect of gravity on the condensation heat transfer coefficient becomes noteworthy in downflow at mass velocity G = 135 kg m−2 s−1 and vapour quality lower than 0.6

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