Bubble behavior and heat transfer mechanism in FC-72 pool boiling

    Authors

    D. E. Rini; R. H. Chen;L. C. Chow

    Abbreviated Journal Title

    Exp. Heat Transf.

    Keywords

    SURFACE; MODEL; FLUX; Thermodynamics; Engineering, Mechanical

    Abstract

    A transparent heater made of a thin synthetic diamond substrate along with a high-speed camera was used to investigate bubble behavior during pool bailing. The heater design, combined with the selected FC-72 liquid, overcame the difficulty of previous thin-film heater experiments where transparency and adequate heat flux could not be simultaneously achieved. It also resulted in an essentially uniform temperature field over the heater surface. The growth and merging of bubbles were visualized and quantitatively documented. The relative contribution from phase change to the overall heat flux was determined at several heat flux levels, At a heat flux level half of the critical heat flux (CHF), surface bubble nucleation was found to contribute to more than 70% of the heat transfer from the heater surface. At a similar heat flux level, the ratio of dry to wetted area was determined to exceed 1/3, significantly higher than that predicted by a recent hydrodynamic model for CHF (approximately 1/16). This result suggests that modifications are needed for the hydrodynamic model when applied to highly wetting fluid on nearly isothermal surfaces. The merging of bubbles to form vapor blankets over the heater surface was observed, as has been assumed in recent hydrodynamic models.

    Journal Title

    Experimental Heat Transfer

    Volume

    14

    Issue/Number

    1

    Publication Date

    1-1-2001

    Document Type

    Article

    Language

    English

    First Page

    27

    Last Page

    44

    WOS Identifier

    WOS:000166397100002

    ISSN

    0891-6152

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