Ph.D. Proposal Presentation by Vladimir Novak
Wednesday, April 21,, 2004
(Dr. Said Abdel-Khalik, Chair)
"Experimental and Numerical Studies of Internal, Turbulent, Gas-Liquid Spray Mist Flow with Ultra-Thin Evaporating Liquid Film Cooling"
Gas-liquid spray mist flow with ultra-thin evaporative liquid film is an effective cooling mechanism with extremely high heat transfer coefficients. Superior heat transfer is attained due to phase change at the interface between the ultra-thin evaporative liquid film and the mist core. The purpose of this research is to experimentally and numerically investigate this cooling mechanism for steady, internal, forced, turbulent flow, in vertical cylindrical and rectangular channels, with co-current downward or upward flows. Our interest in this technique has been motivated by the need for an extremely efficient cooling mechanism in ultra-high-power krypton fluoride (KrF) gas lasers for inertial fusion applications.
Two cylindrical channels (17.3 mm and 23.6 mm inner diameter, and 882 mm and 1052 mm long, respectively) and two rectangular channels (40 mm × 20 mm, and 40 mm × 10 mm cross section, both 622 mm long) will be used; all channels are electrically heated. Water is used as the mist liquid, and air, or helium, as the carrier gas. Three mist generating nozzles, very different in their design, are used, and their effect on cooling will be investigated. Gas flowrates and inlet mixture conditions are varied. Heat transfer dependence on the wall heat flux is studied for a range of non-boiling conditions. A mechanistic three-dimensional computer program, KIVA-3, is used for the numerical study; comparison with experimental results will be made. Preliminary values for the experimentally and numerically obtained heat transfer coefficients show a factor of 7 to 8 enhancement compared to cooling using only the carrier gas.