Saturation and subcooled CHF correlations for PF-5060 dielectric liquid on inclined rough copper surfaces | Academic Article individual record

© 2014 by Begell House, Inc. Pool-boiling experiments investigated the critical heat flux (CHF) for degassed PF-5060 dielectric liquid on inclined and uniformly heated 10x10 mm rough copper (Cu) surfaces. The experiments tested 13 surfaces with average roughness, Ra = 0.039 (smooth-polished), 0.134, 0.21, 0.28, 0.33, 0.58, 0.71, 0.80, 0.925, 1.00, 1.21, 1.44, and 1.79 μm, at inclination angles, θ = 0° (upward facing); 60°, 90° (vertical); and 120°, 150°, 160°, 170°, and 180°(downward facing). In addition, liquid subcooling in the experiments, ΔTsub, varied from 0 K (saturation) to 30 K. The CHF increased with increasing both surface roughness and liquid subcooling, but decreased with increasing inclination angle. For all inclinations, CHFsat on the roughest surface is ∼35% higher than on the smooth-polished Cu. Moreover, regardless of Ra, CHFsat values in the downward facing orientation (180°) are typically ∼31% of those in the upward facing orientation (0°). CHF in the upward facing orientation increases linearly with increasing liquid subcooling at a rate of ∼2.2%/K, independent of Ra. This rate increases with increasing the inclination angle to as much as 4%/K in the downward facing orientation. The developed CHF correlation based on the present database accounts for surface roughness and inclination angle, and the liquid's subcooling and physical properties and agrees with the experimental data to within ±10%.

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El-Genk, M. S., & Suszko, A.
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Begell House Publisher
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