Flow visualization and analysis of self-rewetting fluids in a model heat pipe

Savino, Raffaele; Cristofaro, Davide De; Cecere, Anselmo

doi:10.1016/j.ijheatmasstransfer.2017.07.090

Cited by 26 publications

(3 citation statements)

References 40 publications

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“…So, these fluids were proposed for the first time by Abe and Savino [25][26][27]. Savino et al [28] investigated experimentally and numerically the thermal performance of self-rewetting fluids in an innovative heat pipes. Analysis done by visualize the flow in a groove heat pipe where the Marangoni convection presented a major role on the heat transfer enhancement.…”

Section: Introductionmentioning

confidence: 99%

Thermal performance of self-rewetting gold nanofluids: Application to two-phase heat transfer devices

Zaaroura

Harmand

Carlier³

et al. 2021

International Journal of Heat and Mass Transfer

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Section: Introductionmentioning

confidence: 99%

Thermal performance of self-rewetting gold nanofluids: Application to two-phase heat transfer devices

Zaaroura

Harmand

Carlier³

et al. 2021

International Journal of Heat and Mass Transfer

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“…In addition to the variation induced by the preferential evaporation of the more volatile component, this leads to a reverse Marangoni effect along the liquidvapor interface towards the hotter region [10]. One of the most interesting applications of this effect is a spontaneous liquid inflow towards hot spots or dry patches of evaporation-based heat transfer devices [11].…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis of a Flat Plate Pulsating Heat Pipe with Self-ReWetting Fluids during a parabolic flight campaign

et al. 2018

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A Flat Plate Pulsating Heat Pipe (FPPHP) filled with an ordinary liquid (water) and a self-rewetting mixture (dilutes aqueous solutions of long-chain alcohols with unusual surface tension behaviour) is investigated under variable gravity conditions on board a 'Zero-g' plane during the 65 th Parabolic Flight Campaign of the European Space Agency. The FPPHP thermal performance in terms of evaporator and condenser temperatures, start-up levels and flow regimes is characterized for the two working fluids and a power input ranging from 0 to 200W (up to 17 W/cm 2 at the heater/evaporator wall interface). The experimental set-up also includes a transparent plate enabling the visualization of the oscillating flow patterns during the experiments. For a low power input (4 W/cm 2 ), the pulsating heat pipe filled with pure water is not able to work under low-g conditions, because the evaporator immediately exhibits dry-out conditions and the fluid oscillations stops, preventing heat transfer between the hot and cold side and resulting in a global increase of the temperatures. On the other hand, the FPPHP filled with the self-rewetting fluid runs also during the microgravity phase. The liquid rewets several times the evaporator zone triggering the oscillatory regime. The selfrewetting fluid helps both the start-up and the thermal performance of the FPPHP in microgravity conditions.

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“…In particular, for temperatures above T min the surface tension of such fluids is an increasing function of temperature, and as a result Marangoni effects draw fluid towards regions with higher temperature. This unusual behaviour has stimulated interest in the potential use of such fluids in various heat-transfer applications, such as pool boiling, spray boiling and heat pipes, because in these contexts it tends to reduce dry-out, and hence to enhance the overall heat transfer, by rewetting hot surfaces, and so has led to them being termed "self-rewetting" fluids (see, for example, the work of Zhang [5], Abe, Iwasaki and Tanaka [6,7], Abe [8], Savino and collaborators [9][10][11][12][13][14][15], Hu et al [16], Hu, Zhang and Wang [17], and Wu [18]).…”

Section: Introductionmentioning

confidence: 99%

Unsteady motion of a long bubble or droplet in a self-rewetting system

et al. 2018

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Motivated by the potential use of self-rewetting fluids (i.e. fluids that exhibit a non-monotonic variation of surface tension with temperature) in various heat-transfer applications, in the present work we formulate and analyse a theoretical model for the unsteady motion of a long bubble or droplet in a self-rewetting system in a non-uniformly heated tube due to a combination of Marangoni effects due to the variation of surface tension with temperature, gravitational effects due to the density difference between the two fluids, and an imposed background flow along the tube. We find that the evolution of the shape (but not of the position) of the bubble or droplet is driven entirely by Marangoni effects, and depends on the initial value of its radius in relation to a critical value. In the case in which Marangoni effects are absent the bubble or droplet always moves with constant velocity without changing shape. In the case in which only Marangoni effects are present the bubble or droplet either always moves away from or always moves towards the position of minimum surface tension; in the latter case it ultimately fills the entire cross-section of the tube at a final stationary position which is closer to the position of minimum surface tension than its original position. In the cases in which either only Marangoni effects and gravitational effects or only Marangoni effects and background-flow effects are present the competition between the two effects can lead to a nonmonotonic evolution of the position of the centre of mass of the bubble or droplet. The behaviour of a self-rewetting system described in the present work is qualitatively different from that for ordinary fluids, in which case the bubble or droplet always moves with constant velocity without changing shape.

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Flow visualization and analysis of self-rewetting fluids in a model heat pipe

Cited by 26 publications

References 40 publications

Thermal performance of self-rewetting gold nanofluids: Application to two-phase heat transfer devices

Thermal performance of self-rewetting gold nanofluids: Application to two-phase heat transfer devices

Experimental analysis of a Flat Plate Pulsating Heat Pipe with Self-ReWetting Fluids during a parabolic flight campaign

Unsteady motion of a long bubble or droplet in a self-rewetting system

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