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International Heat Transfer Conference 16

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

RETARDED FROST SPREADING ON SUPERHYDROPHOBIC SURFACES WITH PATTERNED MICROPILLARS

Yugang Zhao
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore

Chun Yang
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Republic of Singapore

DOI: 10.1615/IHTC16.cod.022451
pages 2341-2348


SCHLÜSSELWÖRTER: Condensation, Heat transfer enhancement, micropillars, superhydrophobic

Abstrakt

Frost on a solid surface spreads essentially via building up ice bridges between condensed droplets. Modulation of condensate droplet distributions by inducing morphological patterns is thus an effective approach to control frost spreading. Many researchers have shown the use of superhydrophobic surfaces with nanoscale or hierarchical roughness for retarding frost spreading by promoting condensate droplet jumping. Here, we report effective retardation of frost spreading using micropillar patterned superhydrophobic surfaces. We investigated the effects of pillar size and pillar pitch on condensation frosting. Systematic experiments were carried out to examine the dependence of the frost spreading velocity and the ice coverage ratio on pillar size and pillar pitch. We found that given a pillar size there is a critical value for pillar pitch where the minimum frost spreading velocity and ice coverage ratio occur. Our results also showed that compared to the smooth hydrophilic/hydrophobic surfaces, with proper pillar size and pillar pitch the frost spreading velocity can be reduced by one order of magnitude and the ice coverage ratio can be reduced to 1/3. Additionally, we developed an analytical model to describe the frost spreading on a structured surface with micropillars and the model predictions were compared with our experimental results. Our findings facilitate understanding of the frost spreading dynamics which can lead to the novel designs of frost-free surfaces.

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