Parametric study of pool boiling from porous graphite foams in dielectric liquids

Experiments are conducted that investigated pool boiling of FC-72 liquid at saturation and 10, 20, and 30 K subcooling on porous graphite and smooth copper surfaces measuring 10 × 10 mm. The nucleate boiling heat flux, Critical Heat Flux (CHF), and surface superheats at boiling incipience are compared. Theses heat fluxes are also compared with those of other investigators for smooth copper and silicon, etched SiO2, surfaces and micro-porous coating. No temperature excursion at boiling incipience on the porous graphite that occurred at a surface superheats of < 1.0 K. Conversely, the temperature excursions of 24.0 K and 12.4–17.8 K are measured at incipient boiling in saturation and subcooled boiling on copper. Nucleate boiling heat fluxes on porous graphite are significantly higher and corresponding surface superheats are much smaller than on copper. CHF on porous graphite (27.3, 39.6, 49.0, and 57.1 W/cm2 in saturation and 10 K, 20 K, and 30 K subcooled boiling, respectively) are 61.5%–207% higher than those on copper (16.9, 19.5, 23.6, and 28.0 W/cm2, respectively). The surface superheats at CHF on the porous graphite of 11.5 K in saturation and 17–20 K in subcooled boiling are significantly lower that those on copper (25 K and 26–28 K, respectively). In addition, the rate of increase of CHF on porous graphite with increased subcooling is ~ 125% higher than that on copper.

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Experimental parametric study of hierarchical micro/nano electrodeposited (six-step) pattern with respect to volcano-shape morphology in pool boiling performance augmentation

Experimental Heat Transfer ◽

10.1080/08916152.2021.1991511 ◽

2021 ◽

pp. 1-24

Author(s):

Hamed Shakeri ◽

Hesam Moghadasi ◽

Hamid Saffari

Keyword(s):

Parametric Study ◽

Pool Boiling

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Effect of Tube Inclination on Pool Boiling Heat Transfer

Journal of Heat Transfer ◽

10.1115/1.521456 ◽

1999 ◽

Vol 122 (1) ◽

pp. 188-192 ◽

Cited By ~ 23

Author(s):

M.-G. Kang

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Inclination Angle ◽

Parametric Study ◽

Boiling Heat Transfer ◽

Pool Boiling ◽

Tube Surface ◽

Enhanced Heat Transfer ◽

Tubular Heat Exchanger ◽

Pool Boiling Heat Transfer

An experimental parametric study of a tubular heat exchanger has been carried out under pool boiling conditions to determine effects of the tube inclination angle on pool boiling heat transfer. Through the study, it can be concluded that (1) tube inclination gives much change on pool boiling heat transfer and the effect of the inclination angle is more strongly observed in the smooth tube and (2) if a tube is properly inclined, enhanced heat transfer is expected due to the decrease in bubble slug formation on the tube surface and easy liquid access to the surface. [S0022-1481(00)01201-9]

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Effect of Inclination on Pool Boiling of FC-72 Dielectric Liquid on Porous Graphite

Heat Transfer: Volume 4 ◽

10.1115/ht2005-72289 ◽

2005 ◽

Cited By ~ 4

Author(s):

Jack L. Parker ◽

Mohamed S. El-Genk

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Inclination Angle ◽

Boiling Heat Transfer ◽

Pool Boiling ◽

Nucleate Boiling ◽

Porous Graphite ◽

Nucleate Boiling Heat Transfer ◽

Boiling Heat Transfer Coefficient

Saturation pool boiling experiments of FC-72 liquid on a flat, porous graphite and smooth copper surfaces measuring 10 × 10 mm investigated the effect of surface orientation on nucleate boiling and Critical Heat Flux (CHF). The inclination angle of the surface increased from 0° (upward-facing) to 60°, 90°, 120°, 150°, and 180° (downward facing). Results demonstrated significant increases in the nucleate boiling heat transfer coefficient and CHF on porous graphite, compared to those on copper. At low surface superheats, increasing the inclination angle increases the nucleate boiling heat transfer coefficient, which decreases with increased inclination angle at high surface superheats. These results and the measured decreases of CHF with increased inclination angle are consistent with those reported earlier by other investigators for dielectric and non-dielectric liquids. On smooth surfaces and micro-porous coatings, the reported fractional decreases in CHF with increased inclination angle are almost identical, but markedly larger than those measured in this work on porous graphite. On these surfaces the reported CHF in the downward-facing position (180° inclination) is ∼10–20% of that in the upward-facing position (0° inclination), compared to ∼53.3% on porous graphite. The CHF values of FC-72 liquid on porous graphite, which also decreased with increased inclination angle, are correlated using the general form suggested by Kutatelatze (1961) to within ± 5% of the experimental data.

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