Experimental and Numerical Study of Dual-Chamber Thermosyphon

dc.contributor.advisor Joshi, Yogendra
dc.contributor.author Pal, Aniruddha en_US
dc.contributor.committeeMember Bhavnani, Sushil,
dc.contributor.committeeMember Forney, Larry J.,
dc.contributor.committeeMember Ghiaasiaan, Seyed Mostafa,
dc.contributor.committeeMember Shelton, Samuel
dc.contributor.department Mechanical Engineering en_US
dc.date.accessioned 2007-08-16T17:55:16Z
dc.date.available 2007-08-16T17:55:16Z
dc.date.issued 2007-05-18 en_US
dc.description.abstract An experimental and numerical investigation was conducted to study boiling and condensation - the two most important phenomena occurring in a dual-chamber thermosyphon. Boiling experiments were carried out using water at sub-atmospheric pressures of 9.7, 15 and 21 kPa with a three-dimensional porous boiling enhancement structure integrated in the evaporator. Sub-atmospheric pressure boiling achieved heat fluxes in excess of 100 W/cm2 with negligible incipience superheat, for wall temperatures below 85 oC. Reduced pressures resulted in reduction of heat transfer coefficient with decrease in saturation pressure. The boiling enhancement structure showed considerable heat transfer enhancement compared to boiling from plain surface. Increased height of the structure decreased the heat transfer coefficient and suggested the existence of an optimum structure height for a particular saturation pressure. A parametric study showed that a reduction in liquid level of water increased the CHF for boiling with plain surfaces. For boiling with enhanced structures, the liquid level for optimum heat transfer increased with increasing height of the enhanced structure. A numerical model was developed to study condensation of water in horizontal rectangular microchannels of hydraulic diameters 150-375 µm. The model incorporated surface tension, axial pressure gradient, liquid film curvature, liquid film thermal resistance, gravity and interfacial shear stress, and implemented successive solution of mass, momentum and energy balance equations for both liquid and vapor phases. Rectangular microchannels achieved significantly higher heat transfer coefficient compared to a circular channel of similar hydraulic diameter. Increasing the inlet mass flow rate resulted in a higher heat transfer coefficient. Increasing the inlet temperature difference between wall and vapor led to a thicker film and a gradually decreasing heat transfer coefficient. Increasing the channel dimensions led to higher heat transfer coefficient, with a reduction in the vapor pressure drop along the axial direction of the channel. The unique contributions of the study are: extending the knowledge base and contributing unique results on the thermal performance of thermosyphons, and development of a analytical model of condensation in rectangular microchannels, which identified the system parameters that affects the flow and thermal performance during condensation. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/16251
dc.publisher Georgia Institute of Technology en_US
dc.subject Modeling en_US
dc.subject Sub-atmospheric pressure en_US
dc.subject Condensation en_US
dc.subject Microchannels en_US
dc.subject Enhanced structures en_US
dc.subject Boiling en_US
dc.subject Thermosyphon en_US
dc.subject.lcsh Heat Transmission en_US
dc.subject.lcsh Thermosyphons en_US
dc.subject.lcsh Condensation en_US
dc.subject.lcsh Ebullition en_US
dc.title Experimental and Numerical Study of Dual-Chamber Thermosyphon en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Joshi, Yogendra
local.contributor.corporatename George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication 63ef328b-076b-44b7-92a9-0f7dd03fa1fa
relation.isOrgUnitOfPublication c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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