Water droplets on bio-mimicked hierarchical roughness exhibit superhydrophobic properties, such as large contact angles, minor dynamic hysteresis, and high mobility. Vapor condensation on such superhydrophobic surface enables rapid condensate removal and surface cleaning, thereby significantly enhancing the heat transfer coefficient. In this paper, research attention is given to dropwise condensation on/in specially designed one-tier and hierarchical roughness structures. Utilizing a normal optical tomographic system composed of a Sensi-Cam and a Nikon microscope, close-up visualization is conducted to characterize small condensate droplets, in size of a few micrometers, between structural units of roughness. Experimental snapshots show that, within the one-tier roughness, condensate droplets tend to stick to surrounding structures. Low mobility of these droplets extends their residence time, and therefore increases their average diameter. In comparison, surface energy of the hierarchical structure is significantly reduced. As a result, small condensate droplets behave nonsticky to their surroundings, which enable rapid drain of the droplets and accomplish self-cleaning of the structure. Because of high mobility, the droplet average diameter in the two-tier structure is smaller than those in the one-tire roughness. Condensation sites reach the maximum in the middle of the structure where dew point of moisture is reached. Less condensation droplets on both the top and bottom of the roughness are blamed to the unsaturated moisture and the reduced humidity, respectively.
Skip Nav Destination
Article navigation
Research-Article
Dropwise Condensation on/in High Roughness Structures
Steve Q. Cai,
Steve Q. Cai
Teledyne Scientific Company,
1049 Camino Dos Rios,
Thousand Oaks, CA 91360
e-mail: qingjun.cai@teledyne.com
1049 Camino Dos Rios,
Thousand Oaks, CA 91360
e-mail: qingjun.cai@teledyne.com
Search for other works by this author on:
Avijit Bhunia
Avijit Bhunia
Teledyne Scientific Company,
1049 Camino Dos Rios,
Thousand Oaks, CA 91360
1049 Camino Dos Rios,
Thousand Oaks, CA 91360
Search for other works by this author on:
Steve Q. Cai
Teledyne Scientific Company,
1049 Camino Dos Rios,
Thousand Oaks, CA 91360
e-mail: qingjun.cai@teledyne.com
1049 Camino Dos Rios,
Thousand Oaks, CA 91360
e-mail: qingjun.cai@teledyne.com
Avijit Bhunia
Teledyne Scientific Company,
1049 Camino Dos Rios,
Thousand Oaks, CA 91360
1049 Camino Dos Rios,
Thousand Oaks, CA 91360
Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received December 22, 2015; final manuscript received November 17, 2016; published online January 18, 2017. Assoc. Editor: Jim A. Liburdy.
J. Heat Transfer. Apr 2017, 139(4): 041501 (6 pages)
Published Online: January 18, 2017
Article history
Received:
December 22, 2015
Revised:
November 17, 2016
Citation
Cai, S. Q., and Bhunia, A. (January 18, 2017). "Dropwise Condensation on/in High Roughness Structures." ASME. J. Heat Transfer. April 2017; 139(4): 041501. https://doi.org/10.1115/1.4035354
Download citation file:
Get Email Alerts
Cited By
Entropic Analysis of the Maximum Output Power of Thermoradiative Cells
J. Heat Mass Transfer
Molecular Dynamics Simulations in Nanoscale Heat Transfer: A Mini Review
J. Heat Mass Transfer
Related Articles
Evaporation of Condensate Droplets on Structured Surfaces with Gradient Roughness
J. Heat Transfer (August,2015)
Characteristics of Droplet Growth Behavior on Hydrophobic Micro-textured Surfaces
J. Heat Transfer (August,2015)
A rebounding droplet impacting on a static droplet
J. Heat Transfer (August,2015)
Nucleate Boiling Comparison between Teflon-Coated Plain Copper and Cu-HTCMC in Water
J. Heat Transfer (August,2018)
Related Proceedings Papers
Related Chapters
Introduction
Two-Phase Heat Transfer
Liquid Cooled Systems
Thermal Management of Telecommunications Equipment
Thermal Design Guide of Liquid Cooled Systems
Thermal Design of Liquid Cooled Microelectronic Equipment