Changing bubble dynamics in subcooled boiling with TiO2 nanoparticles on a platinum wire
Özbey, Arzu and Karimzadehkhouei, Mehrdad and Sefiane, Khellil and Koşar, Ali (2017) Changing bubble dynamics in subcooled boiling with TiO2 nanoparticles on a platinum wire. Journal of Molecular Liquids, 242 . pp. 456-470. ISSN 0167-7322 (Print) 1873-3166 (Online)
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Official URL: http://dx.doi.org/10.1016/j.molliq.2017.07.061
Bubble dynamics in pool boiling provides a suitable platform for researchers to understand the mechanisms of subcooled boiling heat transfer. Besides, the effects of nanoparticles on this phenomenon have not been fully understood yet. In this study, the effect of TiO2 nanoparticles (with two weight fractions, 0.002% and 0.005%) mixed in de-ionized water during subcooled pool boiling on a thin platinum wire with a diameter of 250 μm was experimentally investigated for working bulk fluid temperatures between 30 and 50 °C at atmospheric pressure, and new bubble dynamics phenomena were reported. Applied heat fluxes varied from onset of nucleate boiling point to higher heat fluxes up to nucleation jet flow. The experiments were visualized with a high speed camera system, and acquired videos and images were utilized for analysing prevalent phenomena, such as bubble-bubble and nucleation site-bubble interactions, surface tension and Marangoni convection, structural disjoining pressure, pinning and nanoparticles deposition effects as well as the main mechanisms. In general, migration, coalescence, leaping and detaching were recorded for nanofluids with weight fractions of 0.002 wt% and 0.005 wt%, while oscillation, dancing and stick processes were exclusively observed only in nanofluids with a weight fraction of 0.005 wt%. The images, results, and related discussion provide new knowledge and physics for pool boiling phenomena on platinum fine wires in the presence of nanoparticles.
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