Evaporation of an isolated liquid plug moving inside a capillary tube

Srinivasan, Vyas; Marty-Jourjon, Victor; Khandekar, Sameer; Lefèvre, Frédéric; Bonjour, Jocelyn

doi:10.1016/j.ijheatmasstransfer.2015.05.039

Cited by 15 publications

(12 citation statements)

References 30 publications

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“…To our knowledge, the first film observation has been made in the U-turn (two branch) water PHP [6]. Several film observations have been carried out since then [7][8][9]. The film length has been measured in the single branch PHP [8].…”

Section: Methodsmentioning

confidence: 99%

“…The film profile direct measurements in the capillaries of the circular section are very difficult. For instance, it is impossible to use the confocal microscopy [9] in the cylindrical tubes, although such a method was successful for the capillary HP case. The film profile reconstruction based on the measurements of the spatial temperature distribution with the infra-red camera lacks precision either [10].…”

Section: Methodsmentioning

confidence: 99%

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In situ investigation of liquid films in pulsating heat pipe

Fourgeaud

Nikolayev

Ercolani

et al. 2017

Applied Thermal Engineering

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International audienceTo understand functioning of the pulsating (or oscillating) heat pipe (PHP), a liquid film deposited by an oscillating meniscus is studied experimentally inside the simplest, single branch PHP, which is a straight capillary sealed from one end. The PHP capillary is of rectangular section of high aspect ratio. The evaporator is transparent so that the films can be studied by two complementary optical methods: grid deflection method and interferometry. We were able to measure the dynamic film profile during the self induced meniscus oscillations. It has been shown that the PHP films have the same origin as those of the Taylor bubbles; their thickness right after deposition is well described by the classical formulas. The film shape in PHPs differs from the classical wedge-shaped film observed in capillary heat pipes because both of the larger thickness and of the receding triple liquid-vapor-solid contact line. The film slope is very weak, with a growing in time ridge adjacent to the contact line. It is shown that this ridge is the dewetting ridge. Its dynamics is defined mainly by the capillary effects. Such results can be generalized to the conventional multi-branch PHP

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

In situ investigation of liquid films in pulsating heat pipe

Fourgeaud

Nikolayev

Ercolani

et al. 2017

Applied Thermal Engineering

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show abstract

“…1(d To determine the contact angle evolution, it is necessary to reconstruct the whole film shape. Recently, two vain attempts [30,31] to measure the dynamic profile of the evaporating liquid film were reported, which shows both the importance and difficulty of this task.…”

mentioning

confidence: 99%

Evaporation-driven dewetting of a liquid film

et al. 2016

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International audienceWe study the dynamics of evaporating ethanol films deposited by a receding liquidmeniscus. The films are surrounded by pure vapor in a capillary heated above the saturationtemperature. We observe the substrate dewetting with the dewetting ridge in spite of thecomplete wetting at equilibrium. The dewetting is caused by a high contact angle (∼30◦)induced by evaporation. The obtained values agree with a theory proposed earlier. The filmshape is measured with both grid deflection technique and interferometry. The phenomenonis convenient to observe inside a capillary with an axial thermal gradient. When the capillaryis closed at one end and open at another to a constant pressure reservoir, the meniscusoscillations are known to appear spontaneously. Such a system is the simplest version ofan industrial device called a pulsating heat pipe. The effect is general and can be used inany system to control the wetting propertie

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“…The second line of Eq. (10) corresponds to the Landau-Levich film deposition characteristic to the Taylor bubble motion [2,12] and its evaporation. Such an expression assumes a constant film thickness d. It will be shown in the following that the film parameters (shape, thickness) have no incidence on the PHP start-up.…”

Section: Film Evaporation-condensation Model In the Presence Of The Tmentioning

confidence: 99%

“…The most important feature of the analysis concerns Eq. (12). The linearization of the integral results in ðDx sat À Dx f Þ½ T s ð x sat Þ À T sat , which vanishes because of the conditions (18,19).…”

Section: Linearizationmentioning

confidence: 99%

Effect of tube heat conduction on the single branch pulsating heat pipe start-up

Nikolayev

2016

International Journal of Heat and Mass Transfer

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International audienceThe oscillation inception in the single-branch pulsating heat pipe (PHP, called also oscillating heat pipe)has been studied in the presence of the heat conduction along the PHP tube, with the imposed both evaporatorheat power and condenser temperature. A start-up regime caused rather by the meniscus/filmevaporation than boiling has been considered. The dynamic equilibrium system state has been analyzed,where the liquid film is absent and the meniscus is located at a position where the tube temperaturecorresponds to the saturation temperature. The temporal evolution of the system responding to an initialfluctuation shows a non-linear response even for small fluctuations. The stability of the equilibrium statehas been analyzed. The stability threshold corresponds to the start-up criterion. The main result ofthe above analysis is the independence of the start-up criterion of the liquid film properties (film shapeand thickness). This result applies to the multi-branch PHP too. Due to the large tube thermal inertia,influence of the temporal variation of the tube temperature on the threshold can be neglected; onlythe equilibrium spatial temperature distribution along the tube matters. The start-up threshold valueis determined for the temperature gradient along the tube, more specifically, its equilibrium value atthe equilibrium meniscus location. It depends only weakly on other system parameters like condensertemperature or adiabatic section length. An analytical expression for the threshold has been obtained.The start-up power scales like square root of the tube heat conductivity. The liquid viscous dissipationis found to be much less important than the energy dissipation via the fluid and solid heat transfer

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Evaporation of an isolated liquid plug moving inside a capillary tube

Cited by 15 publications

References 30 publications

In situ investigation of liquid films in pulsating heat pipe

In situ investigation of liquid films in pulsating heat pipe

Evaporation-driven dewetting of a liquid film

Effect of tube heat conduction on the single branch pulsating heat pipe start-up

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