Heat transfer enhancement of micro oscillating heat pipes with self-rewetting fluid

Hu, Yi; Liu, Tengqing; Li, Xuanyou; Wang, Shuangfeng

doi:10.1016/j.ijheatmasstransfer.2013.11.031

Cited by 86 publications

(30 citation statements)

References 17 publications

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“…More recently, work on self-rewetting fluids was extended to microgravity conditions for space applications on the International Space Station. Savino et al (2013), and Hu et al Hu et al (2014) demonstrated that the use of these fluids within micro oscillating heat pipes led to an increase in the efficiency of these devices. In a slightly different context, it was very recently shown that the presence of a minimum in surface tension can also have a significant impact on the dynamics of the flow giving rise to very interesting phenomena such as the thermally induced "superspreading" (Karapetsas et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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%

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

et al. 2014

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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%

“…In this case, the convection heat mechanism is driven by the reverse Marangoni effect. Thus, Marangoni effects may play an important role in energy heat transport phenomena [13][14][15][36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

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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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“…heat transfer, of relevant devices such as heat pipes. 36,38 The motion of liquid droplets on solids is relevant to a wide range of areas. 3,5 Body forces or external gradients can generate motion in liquid droplets.…”

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confidence: 99%

On the motion of a sessile drop on an incline: Effect of non-monotonic thermocapillary stresses

Mamalis

Koutsos

Sefiane

2016

Applied Physics Letters

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We studied the short-time contact-line dynamics of a self-rewetting sessile droplet sliding ''freely'' on a silicone oil layer, on an inclined, uniformly heated substrate under nonisothermal conditions (liquid-solid). The effect of thermocapillarity and the contribution of surface tension gradients (Marangoni effect) to the droplet motion was investigated. The temperature of the substrate in conjunction with the non-monotonic surface tension/temperature dependence of the deformed self-rewetting droplet were found to significantly affect the early-stage inertial-capillary spreading regime. Infrared (IR) thermography images were also acquired to investigate the generation of thermal patterns at the liquid surface due to the strong surface-tension gradients. Our results demonstrate that the presence of strong surface tension driven flows at the liquid interface combined with droplet deformation (contact-angle hysteresis) give rise to complex droplet dynamics. The interplay between thermocapillary stresses and body forces result in enhanced spreading rates, temporal non-monotonic dependence of the contact-line speed as well as the droplet motion overcoming gravity in some instances.

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Heat transfer enhancement of micro oscillating heat pipes with self-rewetting fluid

Cited by 86 publications

References 17 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

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

On the motion of a sessile drop on an incline: Effect of non-monotonic thermocapillary stresses

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