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Title: Flow measurement using micro-PIV and related temperature distributions within evaporating sessile drops of self-rewetting mixtures of 1-pentanol and water
Authors: Christy, JRE
Sefiane, K
Ebeling, JC
Seewald, T
Harmand, S
4th Micro and Nano Flows Conference (MNF2014)
Keywords: Marangoni flow;Surface tension;Evaporation;Heat transfer
Issue Date: 2014
Publisher: Brunel University London
Citation: 4th Micro and Nano Flows Conference, University College London, UK, 7-10 September 2014, Editors CS König, TG Karayiannis and S. Balabani
Series/Report no.: ID 28
Abstract: Recently interest has arisen in the use of so-called self-rewetting mixtures for micro-scale heat transfer systems. Such fluids, in which the surface tension can increase with increasing temperature, are expected to offer superior evaporative cooling performance by extending the region of operation before dryout of the heated surface sets in. Whilst improved performance has been shown in some practical situations using these fluids, it is not entirely clear as to the mechanism of such improvements. We have studied the flow within evaporating sessile drops of 1-pentanol-water mixtures using micro-PIV and have observed three stages in the evaporation process. During the first stage there appears to be a single toroidal vortex with flow inwards along the base of the drop. The vortex only occupies the central region of the drop and appears to pulsate, reducing in size during evaporation. This is followed by a second transition stage to a third stage in which the flow is directed radially outward, as observed by us for pure water droplet evaporation and in the latter stages of ethanol/water drop evaporation. Temperature measurements, using IR thermography suggest that the initial stage of evaporation may be controlled by thermal Marangoni effects as opposed to the concentration driven Marangoni flows postulated for ethanol-water mixtures.
Description: This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community,
ISBN: 978-1-908549-16-7
Appears in Collections:Brunel Institute for Bioengineering (BIB)
The Brunel Collection

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