Options
Wettability-confined liquid-film convective cooling: Parameter study
Date Issued
01-11-2018
Author(s)
Koukoravas, Theodore P.
Indian Institute of Technology, Madras
Ganguly, Ranjan
Megaridis, Constantine M.
Abstract
We study experimentally the cooling of a mm-thick, heat-spreading metal plate of O(10 cm2) area, which is heated locally by an embedded heat source with area O(1 cm2). A liquid jet impinges orthogonally on the plate several hydraulic diameters away from the localized heat source, and gets diverted on a surface track passing over the heated region, thus cooling the plate. Capillary-driven, directional transport of the cooling liquid (water) is achieved by rendering the metallic substrate hydrophobic and laying a wettable, diverging track on it, connecting the jet impact point at its narrow end with the heated region, which is either at the wider end of the track or around the half-way point. Cooling performance is evaluated in terms of sensible heat transfer at various flow rates for different track wedge angles and relative position of the heat source, a situation that emulates cooling of an integrated circuit (chip). The effect of thermocapillary stresses, which oppose the flow under certain conditions, is analyzed; effective strategies to overcome such effects are also devised and implemented. Finally, a thermocapillarity-resilient, multi-track design that exhibits superior performance (as compared to single-track designs) is rationalized and demonstrated. We observe that maintaining the track width below the capillary length of the working fluid is vital for improved cooling performance. Cooling can be improved by using multiple, narrow tracks fed by individual impinging jets or a track design that splits the jet into multiple streams laid over the heated domain. Heat removal rates of the order of 100 W/cm2 are attained without phase change at coolant flow rates as low as ∼1 mL/s and chip superheats of 65 °C. The approach opens up new opportunities for heat removing devices that rely on advective cooling facilitated by wettability-patterned metal substrates.
Volume
126