Bubble behavior and nucleate boiling heat transfer in saturated FC-72 spray cooling

    Authors

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

    Comments

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    Abbreviated Journal Title

    J. Heat Transf.-Trans. ASME

    Keywords

    LIQUID-NITROGEN; SURFACE; DROP; Thermodynamics; Engineering, Mechanical

    Abstract

    Bubble behavior during saturated FC-72 spray cooling was experimentally investigated. A heater previously used for pool boiling was used to allow direct comparison. The results are analyzed to reveal the interaction between bubbles and impinging droplets. The following are presented: (1) the importance of secondary nuclei entrained by impingement droplets, (2) the role of impinging droplets on bubble parameters such as growth, diameter at puncture, lifetime, life cycle and bubble number density, and (3) the relative contribution of nucleation, especially that of secondary nuclei, to the heat transfer It is concluded that increasing the droplet flux increases the number of secondary nuclei, helps to lower surface temperature for a given heat flux, increases the overall heat transfer coefficient, and increases heat transfer due to both nucleate boiling and enhanced convection. Increasing the droplet flux also shortens the bubble growth time (i.e., resulting in earlier bubble removal) and life cycle. However increasing the droplet flux (and, therefore, secondary nucleation) for each of the three heat flux values does not affect the percentage of either nucleate or convection heat transfer. This suggests that both the nucleate and convection heat transfer are enhanced, as a result of increased secondary nuclei and turbulent mixing due to the impinging droplets.

    Journal Title

    Journal of Heat Transfer-Transactions of the Asme

    Volume

    124

    Issue/Number

    1

    Publication Date

    1-1-2002

    Document Type

    Article

    Language

    English

    First Page

    63

    Last Page

    72

    WOS Identifier

    WOS:000175917100008

    ISSN

    0022-1481

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