Saturation boiling of HFE-7100 from a copper surface, simulating a microelectronic chip

Abstract

Experiments are performed, which investigated the effect of inclination angle, θ, on saturation pool boiling of HFE-7100 dielectric liquid from a smooth, 10×10 mm copper surface, simulating a microelectronic chip. For θ⩽90° and surface superheats, Δ T sat>20 K, nucleate boiling heat flux decreases with increased θ, but increases with θ for Δ T sat<20 K. Similarly, at higher inclinations and Δ T sat>13 K, nucleate boiling heat flux decreases with increased inclination, but at lower surface superheats the trend is inconclusive. The developed nucleate boiling correlation is within ±10% of the data and the developed correlations for critical heat flux (CHF) and the surface superheat at CHF are within ±3% and ±8% of the data, respectively. Results show that CHF decreases slowly from 24.45 W/cm 2 at 0° to 21 W/cm 2 at 90°, then decreases fast with increased θ to 4.30 W/cm 2 at 180°. The surface superheat at CHF also decreases with θ, from 31.7 K at 0° to 19.9 K at 180°. Still photographs are recorded of pool boiling at different heat fluxes and θ=0°, 30°, 60°, 90, 120°, 150° and 180°. The measured average departure bubble diameter from the photographs taken at the lowest nucleate boiling heat flux of ∼0.5 W/cm 2 and θ=0° is 0.55±0.07 mm and the calculated departure frequency is ∼100 Hz.