E105 ナノフルイド液滴衝突による高温面の冷却特性(OS1&9 マイクロエネルギー変換・熱・流動(マイクロ))

概要

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Experiments were carried out to explore boiling heat transfer during successive impacts of single nanofluid drops onto a hot solid surface. Nucleate boiling heat transfer and critical heat flux were improved when nanometer-sized titanium-dioxide particles were dispersed in water drops. In contrast, colloidal dispersion of the nanoparticles degraded the heat transfer in the film boiling regime at high wall temperatures. A thin nanoparticle layer was formed on the wall during the nanofluid drop impacts to improve the surface wettability. Observation of the impact process revealed that the droplet spreading area at low wall temperatures was wider for the nanofluid drops. An increase in the contact area was expected to be a primary cause of the nucleate boiling heat transfer improvement. At high wall temperatures, a central liquid jet was formed following the impact only in the case of pure water drops, which would be the evidence of a significant heat transfer. It was suggested that violent phase change induced immediately after the impact of nanofluid drop deteriorated the liquid-solid contact in the later stage.
一般社団法人日本機械学会の論文
2011-06-22