Title:
Binary fluid heat and mass exchange at the microscale in internal and external ammonia-water absorption

dc.contributor.advisor Garimella, Srinivas
dc.contributor.author Nagavarapu, Ananda Krishna en_US
dc.contributor.committeeMember Fuller, Thomas
dc.contributor.committeeMember Graham, Samuel
dc.contributor.committeeMember Jeter, Sheldon
dc.contributor.committeeMember Koros, William
dc.contributor.department Mechanical Engineering en_US
dc.date.accessioned 2013-01-17T21:00:28Z
dc.date.available 2013-01-17T21:00:28Z
dc.date.issued 2012-08-14 en_US
dc.description.abstract Absorption space-conditioning systems are environmentally benign alternatives to vapor compression systems and have the capability of being driven by waste heat. However, a lack of practically feasible and economically viable compact heat and mass exchangers is a major limitation in the success of this technology. The viability of the absorption cycle depends upon the performance of the absorber, which experiences large heat and mass transfer resistances due to adverse temperature and concentration gradients during the phase change of the binary mixture working fluid, resulting in large overall component sizes. Understanding of the coupled heat and mass transfer during binary fluid mixture absorption at the microscales is critical for the miniaturization of these components, which will enable broad implementation of this technology. The proposed study aims to achieve this by investigating ammonia-water absorption for two distinct flow configurations: external falling films and internal convective flows. For the falling-film absorption case, ammonia-water solution flows around an array of small diameter coolant tubes while absorbing vapor. This absorber is installed in a test facility comprising all components of a single-effect absorption chiller to provide realistic operating conditions at the absorber. Local temperature, pressure, and flow measurements will be taken over a wide range of operating conditions and analyzed to develop a heat and mass transfer model for falling-film ammonia-water absorption. A microscale convective flow absorber will also be investigated. This absorber consists of an array of parallel, aligned alternating shims with integral microscale features, enclosed between cover plates. These microscale features facilitate flow of various fluid streams and the associated heat and mass transfer. The use of microchannels induces high heat and mass transfer rates without any active or passive surface enhancement. The microscale absorber for small-scale applications will be evaluated over a wide range of operating conditions on a single-effect absorption heat pump breadboard test facility. The study will conclude with a comparison of the two flow configurations for absorption, with recommendations for their application in future miniaturization efforts en_US
dc.description.degree PhD en_US
dc.identifier.uri http://hdl.handle.net/1853/45777
dc.publisher Georgia Institute of Technology en_US
dc.subject Absorption en_US
dc.subject Heat transfer en_US
dc.subject Water en_US
dc.subject Ammonia en_US
dc.subject Miniaturization en_US
dc.subject Mass transfer en_US
dc.subject.lcsh Heat Transmission
dc.subject.lcsh Air conditioning
dc.subject.lcsh Heat pumps
dc.title Binary fluid heat and mass exchange at the microscale in internal and external ammonia-water absorption en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Garimella, Srinivas
local.contributor.corporatename George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename College of Engineering
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relation.isOrgUnitOfPublication c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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