COMBINED EFFECTS OF SUBCOOLING AND SURFACE ORIENTATION ON POOL BOILING OF HFE-7100 FROM A SIMULATED ELECTRONIC CHIP

Author: El-Genk M.

Source: Experimental Heat Transfer, Volume 16, Number 4, October/November/December 2003 , pp. 281-301(21)

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Abstract:

The effects of orientation and subcooling on pool boiling of the HFE-7100 dielectric liquid near atmospheric pressure (0.085 MPa) from a 10 × 10 mm smooth copper surface are investigated experimentally. Results are obtained for inclination angles thgr

= 0° (upward-facing), 30°, 60°, 90°, 120°, 150°, and 180° (downward-facing) and liquid subcoolings Dgr

T_sub = 0, 10, 20, and 30 K. Increasing thgr

decreases the saturation nucleate boiling heat flux at high surface superheats ( Dgr

T_sat > 20 K), but increases it only slightly at lower surface superheats. The critical heat flux (CHF) decreases slowly with increasing thgr

from 0° to 90°, and then deceases faster with increasing thgr

to 180°. CHF increases linearly with increased subcooling, but the rate increases from 0.016 K^-1 at 0° to 0.048 K^-1 at 180°. At thgr

= 0° and

T_sub = 30 K, CHF is sim

36 W/cm² and 24.45 W/cm² for saturation boiling, while at thgr

= 180° CHF = 10.85 W/cm² at Dgr

T_sub = 30 K and only 4.30 W/cm² at saturation. The developed correlation for CHF of HFE-7100, as a function of thgr

and

T_sub, is within ±10% of the present data. The recorded still photographs of the boiling surface in the experiments illustrate the effects of liquid subcooling and surface orientation at different nucleate boiling heat fluxes and surface superheats on vapor bubble accumulation and/or induced mixing at the surface.

Document Type: Research article

Affiliations: 1: Institute for Space and Nuclear Power Studies and Chemical and Nuclear Engineering Department, The University of New Mexico, Albuquerque, New Mexico, USA

Publication date: 2003-10-01

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