Marangoni effect and heat pipe dry-out

Savino, Raffaele; Paterna, D.

doi:10.1063/1.2397586

Cited by 61 publications

(29 citation statements)

References 14 publications

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“…Thus far, to the best of author's knowledge, very few studies (Yang and Homsy 2006;Savino and Paterna 2006;Savino et al 2007) addressed the effects of surface-tension gradients on the performance of micro-grooved heat pipes. The studies (Yang and Homsy 2006;Savino and Paterna 2006) concentrate on a dry-out effect.…”

Section: Introductionmentioning

confidence: 98%

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Effects of a surface-tension gradient on the performance of a micro-grooved heat pipe: an analytical study

Suman

2008

Microfluid Nanofluid

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We investigate effects of surface-tension gradients on the performance of a micro-grooved heat pipe in this work. The surface-tension gradient force is accounted for in the present model, and expressions for radius of curvature, liquid pressure, liquid velocity, and maximum heat throughput are found analytically using a regular perturbation technique. With a favorable surface-tension gradient, the liquid pressure drop across the heat pipe can be decreased by *90%, and the maximum heat throughput can be increased by *20%. In contrast, using an unfavorable surface-tension gradient, the liquid pressure drop increases by *150%, and the maximum heat throughput decreases by *15%. For the same values of the favorable and unfavorable surface-tension gradients, the unfavorable effect is more pronounced than the favorable one. The effects of the surface-tension gradients are found to be increasing with the corner angle of a polygonal heat pipe. Adverse effects of the surface-tension gradient could be due to the variations in the liquid temperature and/or surfactant concentration. Nevertheless, a favorable situation where the surface-tension gradient can facilitate the liquid flow in a heat pipe can also be obtained using a suitable surfactant, surface charge, etc., and then the performance of a micro heat pipe can be improved.List of symbols a smaller side length/side length of a heat pipe polygon, m b larger side length of a heat pipe polygon, m A l liquid flow cross-section area,

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Section: Introductionmentioning

confidence: 98%

“…The studies (Yang and Homsy 2006;Savino and Paterna 2006) concentrate on a dry-out effect. The study (Savino et al 2007) performs an experimental investigation and details the effect of a surface-tension gradient on heat pipes and also on two-phase heat transfer.…”

Section: Introductionmentioning

confidence: 99%

Effects of a surface-tension gradient on the performance of a micro-grooved heat pipe: an analytical study

Suman

2008

Microfluid Nanofluid

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“…Previous studies have shown that different heat transfer profiles were reported depending on various experimental conditions such as gravitational forces [6,32,34], channel geometry [40][41][42], working liquid [36,38,39], applied heat flux [43,44] or mass flux [40,43], etc.…”

Section: Introductionmentioning

confidence: 99%

“…These binary alcohol fluids have recently been investigated and proposed as new operating fluids for advanced heat transfer applications, e.g. column reactors, heat pipes or heat spreaders for terrestrial and space devices [30][31][32][33][34][35][36]. In such non-azeotropic solutions for dilute concentrations, the alcohol-rich component preferentially evaporates in the course of liquid/vapour phase change, which results in a concentration gradient in the liquid/vapour interface.…”

Section: Introductionmentioning

confidence: 99%

Bubble rise in a non-isothermal self-rewetting fluid and the role of thermocapillarity

Mamalis

Koutsos

Sefiane

2017

International Journal of Thermal Sciences

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We report on the motion of a buoyancy-driven bubble in a vertical micro-channel and the significant role of thermocapillarity. A series of experiments have been carried out using a circular micro-channel filled with pure liquids (pure water and pure 1-butanol) and a selfrewetting fluid (water -1-butanol 5% vol.) under isothermal and non-isothermal controlled conditions. In both cases, different mass fluxes and heat fluxes were applied on the microchannel within the same temperature gradient field (18 o C to 75 o C) which was increasing linearly in the same direction with the liquid flow. We have shown that the behaviour of the bubbles in a self-rewetting fluid departed considerably from that of pure liquids. The anomalous property of the alcohol mixture, i.e. the quasi-parabolic dependence of the surface tension with the temperature, drastically modified the movement (promoted or inhibited) and the shape (spherical or deformed) of the migrating bubbles. These phenomena were explained in terms of the location of the bubble associated with the well-defined surface tension 2 minimum, and as a function of dimensionless numbers. Heat transfer coefficient calculations in the single and two-phase flows were acquired for all the liquids used. We demonstrated that the presence of Marangoni stresses resulted in the enhancement of the heat transfer distribution in the self-rewetting fluid flows compared to the pure liquids.

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“…Theoretical studies have shown that if enough Marangoni stress is generated in a heat pipe, it should lead to dry out of the hot end and the device will reach its capillary limit earlier [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Condensation on Highly Superheated Surfaces: Unstable Thin Films in a Wickless Heat Pipe

et al. 2017

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A wickless heat pipe was operated on the International Space Station to provide a better understanding of how the microgravity environment might alter the physical and interfacial forces driving evaporation and condensation. Traditional heat pipes are divided into three zones: evaporation at the heated end, condensation at the cooled end, and intermediate/adiabatic in between. The microgravity experiments reported herein show the situation may be dramatically more complicated. Beyond a threshold heat input, there was a transition from evaporation at the heated end to large-scale condensation, even as surface temperatures exceeded the boiling point by 160 K. The hotter the surface, the more vapor was condensed onto it. The condensation process at the heated end is initiated by thickness and temperature disturbances in the thin liquid film that wet the solid surface. Those disturbances effectively leave the vapor "superheated" in that region. Condensation is amplified and sustained by the high Marangoni stresses that exist near the heater and that drive liquid to cooler regions of the device.

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Marangoni effect and heat pipe dry-out

Cited by 61 publications

References 14 publications

Effects of a surface-tension gradient on the performance of a micro-grooved heat pipe: an analytical study

Effects of a surface-tension gradient on the performance of a micro-grooved heat pipe: an analytical study

Bubble rise in a non-isothermal self-rewetting fluid and the role of thermocapillarity

Condensation on Highly Superheated Surfaces: Unstable Thin Films in a Wickless Heat Pipe

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