Spatio – temporal temperature variations during droplet impingement evaporation : effects of nanofluid and nano-structured surface Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/z890rx209

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Droplet and spray impingement cooling are typically used in high heat flux thermal management. In this thesis, droplet impingement and evaporation heat transfer characteristics are determined from measured spatially- and temporally- varying fluid and surface temperatures. Unique to this study is the documentation of the effects of using a nanofluid and a nano-structured surface for dropwise cooling by comparison of heat transfer characteristics with that of water droplet impingement on a polished surface. Temperatures were determined using radiation intensities recorded using an Infrared (IR) camera. The impingement surface is either comprised of IR transparent silicon, which permits near-surface fluid temperature measurements, or an IR opaque gold coated surface, which permits surface temperature measurements. A range of surface heat fluxes, resulting in both single-phase and boiling conditions are studied. Three different impingement surfaces have been tested, including polished silicon, nano-structured porous silicon, and gold coated polished silicon. The nanofluid is a water-based carbon nanotube suspension. Five major droplet impingement and evaporation stages have been identified: initial impact, boiling (if the surface temperature was sufficiently high), approximately constant diameter evaporation, stepwise fast receding contact line evaporation, and simultaneously decaying diameter and contact angle final dryout period. The surface temperature spatial distribution shows the lowest temperature values within the contact area bulk region and increasing temperature values toward the contact line region and beyond. The basic temperature trends and evaporation behavior are similar for the polished and nano-structured surface while the nanofluid exhibits some distinction. Evaporation times are reduced up to 20% and 37% using the nanostructured surface and nanofluid, respectively. Considering the evaporation time reduction as a measure of droplet cooling performance, the nano-enhanced surface and nanofluid may improve heat transfer in droplet impingement and spray cooling applications.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Keyword
Subject
Rights Statement
Publisher
Language
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Laura Wilson(laura.wilson@oregonstate.edu) on 2009-04-09T19:50:38Z (GMT) No. of bitstreams: 1 Graber_thesis.pdf: 3783797 bytes, checksum: 17257669648309ba0c9b2805aee20f9b (MD5)
  • description.provenance : Submitted by Christof Graber (graberc@onid.orst.edu) on 2009-03-27T00:06:07Z No. of bitstreams: 1 Graber_thesis.pdf: 3783797 bytes, checksum: 17257669648309ba0c9b2805aee20f9b (MD5)
  • description.provenance : Approved for entry into archive by Julie Kurtz(julie.kurtz@oregonstate.edu) on 2009-04-01T16:29:21Z (GMT) No. of bitstreams: 1 Graber_thesis.pdf: 3783797 bytes, checksum: 17257669648309ba0c9b2805aee20f9b (MD5)
  • description.provenance : Made available in DSpace on 2009-04-09T19:50:39Z (GMT). No. of bitstreams: 1 Graber_thesis.pdf: 3783797 bytes, checksum: 17257669648309ba0c9b2805aee20f9b (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items