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

Experiments are performed, which investigated the effect of inclination angle, 0, on saturation pool boiling of HFE7100 dielectric liquid from a smooth, 10 x 10 mm copper surface, simulating a microelectronic chip. For 0 < 90degrees and surface superheats, DeltaT(sat) > 20 K, nucleate boiling heat flux decreases with increased theta, but increases with theta for DeltaT(sat) < 20 K. Similarly, at higher inclinations and DeltaT(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 0degrees to 21 W/cm(2) at 90degrees, then decreases fast with increased theta to 4.30 W/cm(2) at 180degrees. The surface superheat at CHF also decreases with theta, from 31.7 K at 0degrees to 19.9 K at 180degrees. Still photographs are recorded of pool boiling at different heat fluxes and theta = 0degrees, 30degrees, 60degrees, 90, 120degrees, 150degrees and 180degrees. The measured average departure bubble diameter from the photographs taken at the lowest nucleate boiling heat flux of similar to0.5 W/cm(2) and theta = 0degrees is 0.55 +/- 0.07 mm and the calculated departure frequency is similar to100 Hz. (C) 2003 Elsevier Science Ltd. All rights reserved.