Abstract
The surfaces used for investigating nucleate pool boiling for four working fluids had mini- and micro-fins of variable configurations, cross-sections and pitches, restrained by perforated foil or mesh cloth with various pore/opening diameters. Unique enhanced structures on these surfaces formed a system of interconnected horizontal and vertical tunnels. Four structured surfaces were proposed, each being a system of subsurface tunnels connected to 10 and 5 mm fins or 1 and 0.5 mm mini-fins. Measurement results for boiling water, ethanol, Fluorinert FC-72 and R-123 from more than 60 samples constituted the database used to verify the proposed theoretical models. These models were based on the results from the visualization studies, including internal visualization allowing observation of bubble nucleation, growth and displacement inside the tunnels, and on the analysis of existing boiling models for mini- and micro-structures.
Highlights
Traditional cooling methods based on natural or forced convection used in thermal management of electronic devices and systems are not capable of achieving the required performance in terms of effective heat removal
Harnessing boiling processes occurring on enhanced surfaces with an adequately formed system of subsurface tunnels is a very effective cooling option
The highest heat transfer coefficients, about 47.5 kW/m2K, were noted for the 10 mm fins with tunnels spaced at the highest pitch (2.5 mm) and pores with the largest diameter (0.5 mm)
Summary
Traditional cooling methods based on natural or forced convection used in thermal management of electronic devices and systems are not capable of achieving the required performance in terms of effective heat removal. Harnessing boiling processes occurring on enhanced surfaces with an adequately formed system of subsurface tunnels is a very effective cooling option. The change of phase that accompanies a boiling process provides high heat fluxes at small temperature differences between the heating surface and the saturated fluid, increasing the heat transfer coefficient and reducing the size of heat exchanger. The author of this paper and his collaborators at the Kielce University of Technology have been carrying out in-depth research devoted to determining pool boiling heat transfer coefficients for various working fluids from surface structures with mini- and micro-fins and/or subsurface tunnels and constructing theoretical models [1,2,3,4,5,6,7]. This article summarizes the results of the analysis of pool boiling from four types of mini- and microstructured surfaces
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