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dc.contributor.advisorGarimella, Srinivas
dc.contributor.authorFronk, Brian Matthew
dc.date.accessioned2014-08-27T13:38:21Z
dc.date.available2014-08-27T13:38:21Z
dc.date.created2014-08
dc.date.issued2014-06-05
dc.date.submittedAugust 2014
dc.identifier.urihttp://hdl.handle.net/1853/52265
dc.description.abstractZeotropic mixtures exhibit a temperature glide between the dew and bubble points during condensation. This glide has the potential to increase system efficiency when matched to the thermal sink in power generation, chemical processing, and heating and cooling systems. To understand the coupled heat and mass transfer mechanisms during phase change of high-glide zeotropic mixtures, a comprehensive investigation of the condensation of ammonia and ammonia/water mixtures in small diameter channels was performed. Condensation heat transfer and pressure drop experiments were conducted with ammonia and ammonia/water mixtures. Experiments on ammonia were conducted for varying tube diameters (0.98 < D < 2.16 mm), mass fluxes (75 < G < 225 kg m⁻² s⁻¹) and saturation conditions (30 < Tsat < 60°C). Zeotropic ammonia/water experiments were conducted for multiple tube diameters (0.98 < D < 2.16 mm), mass fluxes (50 < G < 200 kgm⁻² s⁻¹) and bulk ammonia mass fraction (xbulk = 0.8, 0.9, and > 0.96). An experimental methodology and data analysis procedure for evaluating the local condensation heat duty (for incremental ∆q), condensation transfer coefficient (for pure ammonia), apparent heat transfer coefficient (for zeotropic ammonia/water mixtures), and frictional pressure gradient with low uncertainties was developed. A new heat transfer model for condensation of ammonia in mini/microchannels was developed. Using the insights derived from the pure ammonia work, an improved zeotropic condenser design method for high-temperature-glide mixtures in small diameter channels, based on the non-equilibrium film theory, was introduced. The key features of the improved model were the consideration of annular and non-annular flow effects on liquid film transport, including condensate and vapor sensible cooling contributions, and accounting for mini/microchannel effects through the new liquid film correlation. By understanding the behavior of these mixtures in microchannel geometries, highly efficient, compact thermal conversion devices can be developed.
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherGeorgia Institute of Technology
dc.subjectCondensation
dc.subjectMicrochannel
dc.subjectZeotropic mixture
dc.subjectHeat and mass transfer
dc.titleCoupled heat and mass transfer during condensation of high-temperature-glide zeotropic mixtures in small diameter channels
dc.typeDissertation
dc.description.degreePh.D.
dc.contributor.departmentMechanical Engineering
thesis.degree.levelDoctoral
dc.contributor.committeeMemberGhiaasiaan, S. Mostafa
dc.contributor.committeeMemberJoshi, Yogendra
dc.contributor.committeeMemberFuller, Thomas
dc.contributor.committeeMemberWalton, Krista
dc.date.updated2014-08-27T13:38:21Z


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