Title:
Theoretical and experimental investigation of condensation on amphiphilic nanostructured surfaces

dc.contributor.advisor Fedorov, Andrei G.
dc.contributor.author Anderson, David Milton en_US
dc.contributor.committeeMember Graham, Samuel
dc.contributor.committeeMember Kottke, Peter
dc.contributor.committeeMember Srinivasarao, Mohan
dc.contributor.department Mechanical Engineering en_US
dc.date.accessioned 2013-06-15T02:43:17Z
dc.date.available 2013-06-15T02:43:17Z
dc.date.issued 2013-03-18 en_US
dc.description.abstract Condensation of water vapor is an everyday phenomenon which plays an important role in power generation schemes, desalination applications and high-heat flux cooling of power electronic devices. Continuous dropwise condensation is a desirable mode of condensation in which small, highly-spherical droplets regularly form and shed off the surface before a thick liquid is formed, thereby minimizing the thermal resistance to heat transfer across the condensate layer. While difficult to induce and sustain, dropwise condensation has been shown to achieve heat and mass transfer coefficients over an order of magnitude higher than its filmwise counterpart. Superhydrophobic surfaces have been extensively studied to promote dropwise condensation with mixed results; often surfaces that are superhydrophobic to deposited droplets formed in the gas phase above the surface do not retain this behavior with condensed droplets nucleated and grown on the surface. Recently, nanostructured superhydrophobic surfaces have been developed that are robust to vapor condensation; however, these surfaces still are not ideal for condensation heat transfer due to the high thermal resistance of the vapor layer trapped underneath the droplets and the reduced footprint of direct contact between the highly-spherical droplets and the underlying substrate. This work has two main objectives. First, a comprehensive free energy based thermodynamic model is developed to better understand why traditional superhydrophobic surfaces often lose their properties when exposed to condensed droplets. The model is first validated using data from the existing literature and then extended to analyze the suitability of amphiphilic (e.g. part hydrophobic and part hydrophilic) nanostructured surfaces for condensation applications. Secondly, one of the promising amphiphilic surfaces identified by the thermodynamic model is fabricated and tested to observe condensation dynamic behavior. Two complementary visualization techniques, environmental scanning electron microscopy (ESEM) and optical (light) microscopy, are used to probe the condensation behavior and compare the performance to that of a traditional superhydrophobic surface. Observations from the condensation experiments are used to propose a new mechanism of coalescence that governs the temporal droplet size distribution on the amphiphilic nanostructured surface and continually generates fresh sites for the droplet nucleation and growth cycle that is most efficient at heat transfer. en_US
dc.description.degree MS en_US
dc.identifier.uri http://hdl.handle.net/1853/47584
dc.publisher Georgia Institute of Technology en_US
dc.subject Dropwise condensation en_US
dc.subject Superhydrophobic surfaces en_US
dc.subject ESEM en_US
dc.subject Amphiphilic en_US
dc.subject.lcsh Amphiphiles
dc.subject.lcsh Nanostructured materials
dc.subject.lcsh Condensation
dc.subject.lcsh Hydrophobic surfaces
dc.title Theoretical and experimental investigation of condensation on amphiphilic nanostructured surfaces en_US
dc.type Text
dc.type.genre Thesis
dspace.entity.type Publication
local.contributor.advisor Fedorov, Andrei G.
local.contributor.corporatename George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication 22ed9217-97e1-449b-a93c-6caf41cd08d7
relation.isOrgUnitOfPublication c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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