Browsing by Author "Eslami, Bahareh"
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Item Non-Isothermal Buoyancy Driven Exchange Flow of Miscible Fluids in Inclined Pipes(2016-12) Eslami, Bahareh; Ghasemi, Hadi; Metcalfe, Ralph W.; Alba, KamranThis thesis studies non-isothermal buoyancy-driven exchange flow of two miscible Newtonian fluids in an inclined pipe experimentally. The cold heavy fluid is released into the hot light one in an adiabatic small-aspect-ratio pipe in the Boussinesq limit. The maximal rate of interpenetration of the fluids in non-isothermal case is similar to the isothermal limit, maximal rate occurs at an intermediate angle. There has also been observed a novel asymmetric behavior in the flow never observed before in the isothermal limit in which the cold finger appears to advance faster than the hot one. Backed by meticulously-designed supplementary experiments, this asymmetric behavior is hypothetically associated with the wall contact and the formation of a warm less-viscous film of the fluid lubricating the cold more-viscous finger along the pipe. The asymmetric behavior of the flow is finally quantified over the full range of non-isothermal experiments carried.Item ROLE OF NANOCONFINEMENT ON THIN FILM EVAPORATION(2020-12) Eslami, Bahareh; Ghasemi, Hadi; Metcalfe, Ralph W.; Liu, Dong; Ardebili, Haleh; Karim, AlamgirThin film boiling and evaporation have been recognized as most efficient thermal management solutions for reliable operations of high power density electronics. Liquid-vapor phase change process plays an important role in many natural phenomena and industrial applications ranging from thermal management of electronics, power generation, water harvesting, and water desalination. Enhancing liquid-vapor phase change efficiency push the boundaries specially in electronic industry. To achieve this purpose, many efforts have been devoted for better understanding of the underlying mechanism and improving performance solutions. Recent progress in micro/nano fabrication techniques have opened an avenue for scientists and engineers to elevate thermal conversion and management by manipulating effective parameters. Herein, we aim to survey the most enlightening recent advances in developing various nanoengineered architectures for thin film evaporation enhancement including micropillars and nanowires, micro/nano porous membranes, hierarchical structures, and micro/nano channels. We study their functionalities and compare their efficiencies. In the next step, we focused on the role of planar nanoporous membranes in thermal management due to their high heat removal potential. We utilized anodic aluminum oxide (AAO) membranes and a high heat flux of 560 W/cm2 is achieved with wall superheat of ~ 60 ℃. Thin film boiling as the next stage of pool boiling dramatically increases the bubble departure frequency as a result of reduced conduction resistance in liquid microlayer. As boiling regime enters the thin film region, the bubble diameter significantly shrinkages promoting the departure process. Moreover, separate liquid-vapor pathways play a critical role by providing liquid to nucleation sites in a more efficient way. This work suggests utilizing thin film boiling as an advanced strategy for promoting heat removal performance in high power electronics.