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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Freezing of supercooled water droplets impinging upon solid surfaces

Get access (open in a dialog) DOI: 10.1615/IHTC12.2180
6 pages

Abstract

Freezing behavior of supercooled water droplets impinging upon solid surfaces was experimentally studied. Each droplet of 2−3 mm in diameter was supercooled on a water-repellent guideway in a dry nitrogen-gas ambience adjusted to −10°C or −15°C, then blasted horizontally by a jet of pressurized nitrogen gas to impinge upon the vertical surface of a thick block made of aluminum or poly(methyl methacrylate). The behavior of the impact against the block surface and of the deformation and freezing of the droplet were observed using a high-speed videocamera. Different freezing modes were recognized to occur depending on the supercooling, the material of the block, and the finishing/treatment of the block surface. Immediate freezing inception (within 10 ms after the impact) of droplets occurred only on aluminum blocks at the lower temperature, −15°C, more preferably on a roughened surface than on a polished one. The block surface coated with a water- repellent polymer layer made the droplets bounce back before the inception of freezing even at −15°C; this finding indicates the potential of such coatings for preventing icing due to droplet freezing.