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First Thermal and Fluids Engineering Summer Conference

ISSN: 2379-1748
ISBN: 978-1-56700-430-4

HETEROGENEOUS SURFACES WITH ENGINEERED WETTABILITY FOR CONTROLLING WETTING DYNAMICS DURING CONDENSATION

DOI: 10.1615/TFESC1.mph.012978
pages 1883-1886

Emre Olceroglu
Department of Mechanical Engineering and Mechanics Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA

Matthew McCarthy
Department of Mechanical Engineering and Mechanics Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA


KEY WORDS: Condensation, Superhydrophobic Surfaces, Engineered Wettability

Abstract

Heterogeneous surfaces with engineered wettability patterns have been fabricated and tested showing spatial control and ordering of droplets across multiple length scales during condensation heat transfer. Surfaces with mixed wettability have been fabricated, where rectangular arrays of superhydrophilic nanostructured islands are organized in linear patterns on a primarily superhydrophobic nanostructured substrate. Nucleation and droplet growth are promoted on the microscale engineered sites, resulting in the coalescence and continued growth of the condensate into millimeter scale droplets without jumping. These droplets are spatially ordered into linear arrays and promote shedding-mode removal at larger diameters. The surfaces have been characterized using environmental scanning electon microscopy (ESEM) as well as high-speed imaging during optical microscopy. The heterogeneous designs have been shown to delay the onset of flooding as compared to superhydrophobic surfaces, where at increased supersaturations droplets become highly pinned and the surfaces transition to filmwise condensation.