Surface tension-driven flow in wickless heat pipes with self-rewetting fluids

Savino, Raffaele; Cecere, Anselmo; Paola, Roberto Di

doi:10.1016/j.ijheatfluidflow.2009.01.009

Cited by 91 publications

(53 citation statements)

References 7 publications

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“…In the present paper, we are interested in the thermocapillary migration of a deformable bubble inside a cylindrical tube filled with liquids that exhibit a non-monotonic dependence of the surface tension on temperature. In particular, these so-called "self-rewetting" fluids (Vochten & Petre 1973;Petre & Azouni 1984;Limbourgfontaine et al 1986;Savino et al 2009Savino et al , 2013, which are non-azeotropic, high carbon alcohol solutions, have quasi parabolic surface tensiontemperature curves with well-defined minima; the parabolicity of these curves increases with alcohol concentration. These fluids were first studied by Vochten & Petre (1973) who observed the occurrence of the minimum in surface tension with temperature in high carbon alcohol solutions.…”

Section: Introductionmentioning

confidence: 99%

“…Ahmed & Carey 1999). Savino et al (2009) illustrated the anomalous behaviour of self-rewetting fluids by performing experiments to visualise the behaviour of vapour slugs inside wickless heat pipes made of pyrex borosilicate glass capillaries. They found that the size of the slugs was considerably smaller than that associated with fluids such as water.…”

Section: Introductionmentioning

confidence: 99%

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Non-isothermal bubble rise: non-monotonic dependence of surface tension on temperature

et al. 2014

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We study the motion of a bubble driven by buoyancy and thermocapillarity in a tube with a non-uniformly-heated walls, containing a so-called "self-rewetting fluid"; the surface tension of the latter exhibits a parabolic dependence on temperature with a well-defined minimum. In the Stokes flow limit, we derive the conditions under which a spherical bubble can come to rest in a self-rewetting fluid whose temperature varies linearly in the vertical direction, and demonstrate that this is possible for both positive and negative temperature gradients. This is in contrast to the case of simple fluids whose surface tension decreases linearly with temperature for which bubble motion is arrested for negative temperature gradients only. In the case of self-rewetting fluids, we propose an analytical expression for the position of bubble arrestment as a function of other dimensionless numbers. We also perform direct numerical simulation of axisymmetric bubble motion in a fluid whose temperature increases linearly with vertical distance from the bottom of the tube; this is done for a range of Bond and Gallileo numbers, and for various parameters that govern the functional dependence of surface tension on temperature. We demonstrate that bubble motion can be reversed and then arrested in self-rewetting fluids only, and not in linear ones, for sufficiently small Bond numbers. We also demonstrate that considerable bubble elongation is possible under significant wall confinement, and for strongly self-rewetting fluids and large Bond numbers. The mechanisms underlying the phenomena observed are elucidated by considering how the surface tension dependence on temperature affects the thermocapillary stresses in the flow.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Non-isothermal bubble rise: non-monotonic dependence of surface tension on temperature

et al. 2014

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“…3. The tension indicates a positive temperature coefficient of 7.2%/K in the temperature range from 30 to 60 C. This positive temperature dependence has been seen in some liquid alloy 21 or alcohol aqueous solution 22 in a certain temperature range. Also, there is a possibility that a slight temperature gradient in the container for the bulk liquid due to heat conduction via the needle for the drop would induce weak transport of the surfactant.…”

Section: Interfacial Tension With a Temperature Dependencementioning

confidence: 62%

A Noncontact Picolitor Droplet Handling by Photothermal Control of Interfacial Flow

Muto¹,

Yamamoto

Motosuke

2016

ANAL. SCI.

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“…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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Surface tension-driven flow in wickless heat pipes with self-rewetting fluids

Cited by 91 publications

References 7 publications

Non-isothermal bubble rise: non-monotonic dependence of surface tension on temperature

Non-isothermal bubble rise: non-monotonic dependence of surface tension on temperature

A Noncontact Picolitor Droplet Handling by Photothermal Control of Interfacial Flow

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

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