Saturation pool boiling of HFE-7100 dielectric liquid in a simulated reduced gravity

Abstract

The effects of simulated reduced gravity on nucleate boiling and Critical Heat Flux (CHF) of the hydrofluoroether. HFE-7100 dielectric liquid from a 1.0-cm2 smooth copper surface are investigated experimentally. Reduced gravity is simulated by varying the inclination angle of the surface, θ, from 0° (upward-facing, 1-g) to 180° (downward facing, zero-g) in 10°–30° increments. Results show that nucleate boiling heat fluxes at surface superheats, ΔTsat>13 K are highest at 0° and decrease with increased θ to 180°. At lower superheats, however, the nucleate boiling heat flux data are inconclusive, with the lowest and highest values occurring at 120° and 180°, respectively. The developed correlations for saturation nucleate boiling, as a function of θ, is within ± 10% of the data. Correlations for the normalized CHF to that at 0° (or CHFR), and of the surface superheat at CHF (⩽31.7 K) are also developed as functions of θ. The CHFR decreases slowly as θ increases from 0° to 120°, then faster for θ>120°, consistent with earlier work for dielectric and non-dielectric liquids. The surface superheat at CHF also decreases as θ increases reaching its lowest value at 180°. Photographs of saturation nucleate boiling at θ=0°, 30°, 120° and 180°, support the nucleate boiling heat flux measurements. This work demonstrated that dissipation heat fluxes of 24.45 and 4.30 W/cm2 could be removed from a high performance computer chip by saturation nucleate boiling of HFE-7100 at 0° (or 1g) and 180° (or zero-g), at surface superheats of 31.7 and 19.9 K, respectively.