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Title: Simultaneous droplet impingement dynamics and heat transfer on nano-structured surfaces

Abstract

This study examines the hydrodynamics and temperature characteristics of distilled deionized water droplets impinging on smooth and nano-structured surfaces using high speed (HS) and infrared (IR) imaging at We = 23.6 and Re = 1593, both based on initial drop impingement parameters. Results for a smooth and nano-structured surface for a range of surface temperatures are compared. Droplet impact velocity, transient spreading diameter and dynamic contact angle are measured. The near surface average droplet fluid temperatures are evaluated for conditions of evaporative cooling and boiling. Also included are surface temperature results using a gold layered IR opaque surface on silicon. Four stages of the impingement process are identified: impact, boiling, near constant surface diameter evaporation, and final dry-out. For the boiling conditions there is initial nucleation followed by severe boiling, then near constant diameter evaporation resulting in shrinking of the droplet height. When a critical contact angle is reached during evaporation the droplet rapidly retracts to a smaller diameter reducing the contact area with the surface. This continues as a sequence of retractions until final dry out. The basic trends are the same for all surfaces, but the nano-structured surface has a lower dissipated energy during impact and enhances themore » heat transfer for evaporative cooling with a 20% shorter time to achieve final dry out. (author)« less

Authors:
; ; ; ;  [1]
  1. Mechanical Engineering, Oregon State University, 204 Rogers Hall, Corvallis, OR 97331-6001 (United States)
Publication Date:
OSTI Identifier:
21305671
Resource Type:
Journal Article
Journal Name:
Experimental Thermal and Fluid Science
Additional Journal Information:
Journal Volume: 34; Journal Issue: 4; Conference: ECI International Conference on Heat Transfer and Fluid Flow in Microscale, 21-26 Sep 2008; Other Information: Elsevier Ltd. All rights reserved; Journal ID: ISSN 0894-1777
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; DROPLETS; HEAT TRANSFER; SURFACES; BOILING; EVAPORATION; NANOSTRUCTURES; EVAPORATIVE COOLING; IMPINGEMENT; HYDRODYNAMICS; HEIGHT; WATER; FLUIDS; NUCLEATION; TRANSIENTS; TEMPERATURE DEPENDENCE; VELOCITY; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K

Citation Formats

Shen, Jian, Graber, Christof, Liburdy, James, Pence, Deborah, and Narayanan, Vinod. Simultaneous droplet impingement dynamics and heat transfer on nano-structured surfaces. United States: N. p., 2010. Web. doi:10.1016/J.EXPTHERMFLUSCI.2009.02.003.
Shen, Jian, Graber, Christof, Liburdy, James, Pence, Deborah, & Narayanan, Vinod. Simultaneous droplet impingement dynamics and heat transfer on nano-structured surfaces. United States. doi:10.1016/J.EXPTHERMFLUSCI.2009.02.003.
Shen, Jian, Graber, Christof, Liburdy, James, Pence, Deborah, and Narayanan, Vinod. Sat . "Simultaneous droplet impingement dynamics and heat transfer on nano-structured surfaces". United States. doi:10.1016/J.EXPTHERMFLUSCI.2009.02.003.
@article{osti_21305671,
title = {Simultaneous droplet impingement dynamics and heat transfer on nano-structured surfaces},
author = {Shen, Jian and Graber, Christof and Liburdy, James and Pence, Deborah and Narayanan, Vinod},
abstractNote = {This study examines the hydrodynamics and temperature characteristics of distilled deionized water droplets impinging on smooth and nano-structured surfaces using high speed (HS) and infrared (IR) imaging at We = 23.6 and Re = 1593, both based on initial drop impingement parameters. Results for a smooth and nano-structured surface for a range of surface temperatures are compared. Droplet impact velocity, transient spreading diameter and dynamic contact angle are measured. The near surface average droplet fluid temperatures are evaluated for conditions of evaporative cooling and boiling. Also included are surface temperature results using a gold layered IR opaque surface on silicon. Four stages of the impingement process are identified: impact, boiling, near constant surface diameter evaporation, and final dry-out. For the boiling conditions there is initial nucleation followed by severe boiling, then near constant diameter evaporation resulting in shrinking of the droplet height. When a critical contact angle is reached during evaporation the droplet rapidly retracts to a smaller diameter reducing the contact area with the surface. This continues as a sequence of retractions until final dry out. The basic trends are the same for all surfaces, but the nano-structured surface has a lower dissipated energy during impact and enhances the heat transfer for evaporative cooling with a 20% shorter time to achieve final dry out. (author)},
doi = {10.1016/J.EXPTHERMFLUSCI.2009.02.003},
journal = {Experimental Thermal and Fluid Science},
issn = {0894-1777},
number = 4,
volume = 34,
place = {United States},
year = {2010},
month = {5}
}