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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Frost Formation and Growth on Hydrophilic, Hydrophobic, and Biphilic Surfaces

Get access (open in a dialog) DOI: 10.1615/IHTC15.tpp.008643
pages 8951-8961

Abstract

The purpose of this research is to test if biphilic surfaces mitigate frost and ice formation. Frost forms when humid air comes into contact with a surface that is below the dew point and freezing temperature of water. Many engineering systems are hindered by frost, such as aeronautics, refrigeration, and wind turbines. Most past research has looked at increasingly superhydrophobic materials to delay frost formation. These materials are very dependent on operating conditions and surface roughness, which fluctuate easily. Our hypothesis is that a biphilic surface will slow the frost formation process as well as create a less dense frost layer. The water vapor will preferentially condense on the hydrophilic areas, thus controlling where the nucleation will first occur. This can control the size, shape, and location of the frost nucleation. To fabricate these surfaces, a hydrophobic material was coated on a silicon wafer, and a pattern of hydrophobic material was removed using photolithography to reveal the hydrophilic silicon-oxide. The circles were patterned at different pitches and diameters. The heat sink was comprised of two parts: a solid bottom half, and a finned, upper half. Half of the heat sink sat inside of a polyethylene base for insulation. Tests were conducted in quiescent air at room temperature and varying humidity, 2°C and 20−55%. The power input to the Peltier cooler was 2 or 8 W. All tests showed a trend that biphilic surfaces delay frost formation more effectively than plain hydrophilic or hydrophobic surfaces, with smaller patterns outperforming larger patterns.