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Determination and Characterization of Ice Propagation Mechanisms on Surfaces Undergoing Dropwise Condensation

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dc.contributor.advisor O'Neal, Dennis L. en_US
dc.creator Dooley, Jeffrey B. en_US
dc.date.accessioned 2011-08-08T22:48:21Z en_US
dc.date.accessioned 2011-08-09T01:28:19Z
dc.date.available 2011-08-08T22:48:21Z en_US
dc.date.available 2011-08-09T01:28:19Z
dc.date.created 2010-05 en_US
dc.date.issued 2011-08-08 en_US
dc.date.submitted May 2010 en_US
dc.identifier.uri http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-8038 en_US
dc.description.abstract The mechanisms responsible for ice propagation on surfaces undergoing dropwise condensation have been determined and characterized. Based on experimental data acquired non-invasively with high speed quantitative microscopy, the freezing process was determined to occur by two distinct mechanisms: inter-droplet and intradroplet ice crystal growth. The inter-droplet crystal growth mechanism was responsible for the propagation of the ice phase between droplets while the intra-droplet crystal growth mechanism was responsible for the propagation of ice within individual droplets. The larger scale manifestation of these two mechanisms cooperating in tandem was designated as the aggregate freezing process. The dynamics of the aggregate freezing process were characterized in terms of the substrate thermal di usivity, the substrate temperature, the free stream air humidity ratio, and the interfacial substrate properties of roughness and contact angle, which were combined into a single surface energy parameter. Results showed that for a given thermal di usivity, the aggregate freezing velocity increased asymptotically towards a constant value with decreasing surface temperature, increasing humidity, and decreasing surface energy. The inter-droplet freezing velocity was found to be independent of substrate temperature and only slightly dependent on humidity and surface energy. The intra-droplet freezing velocity was determined to be a strong function of substrate temperature, a weaker function of surface energy, and independent of humidity. From the data, a set of correlational models were developed to predict the three freezing velocities in terms of the independent variables. These models predicted the majority of the measured aggregate, inter- and intra-droplet freezing velocities to within 15%, 10%, and 35%, respectively. Basic thermodynamic analyses of the inter- and intra-droplet freezing mechanisms showed that the dynamics of these processes were consistent with the kinetics of crystal growth from the vapor and supercooled liquid phases, respectively. The aggregate freezing process was also analyzed in terms of its constituent mechanisms; those results suggested that the distribution of liquid condensate on the surface has the largest impact on the aggregate freezing dynamics. en_US
dc.format.mimetype application/pdf en_US
dc.language.iso en_US en_US
dc.subject Frost formation en_US
dc.subject Ice propagation en_US
dc.subject Ice nucleation en_US
dc.subject Dropwise condensation en_US
dc.subject High speed microscopy en_US
dc.subject Crystal growth kinetics en_US
dc.subject Solidification en_US
dc.subject Surface science en_US
dc.title Determination and Characterization of Ice Propagation Mechanisms on Surfaces Undergoing Dropwise Condensation en_US
dc.type Thesis en
thesis.degree.department Mechanical Engineering en_US
thesis.degree.discipline Mechanical Engineering en_US
thesis.degree.grantor Texas A&M University en_US
thesis.degree.name Doctor of Philosophy en_US
thesis.degree.level Doctoral en_US
dc.contributor.committeeMember Banerjee, Debjyoti en_US
dc.contributor.committeeMember Brooks, Sarah D. en_US
dc.contributor.committeeMember Lalk, Thomas R. en_US
dc.type.genre thesis en_US
dc.type.material text en_US

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