Affiliation:
1. Mechanical and Aerospace Engineering Department, University of California, Los Angeles, Los Angeles, CA 90095-1597
Abstract
The partitioning of the heat flux supplied at the wall is one of the key issues that needs to be resolved if one is to model subcooled flow boiling accurately. The first step in studying wall heat flux partitioning is to account for the various heat transfer mechanisms involved and to know the location at which the onset of nucleate boiling (ONB) occurs. Active nucleation site density data is required to account for the energy carried away by the bubbles departing from the wall. Subcooled flow boiling experiments were conducted using a flat plate copper surface and a nine-rod (zircalloy-4) bundle. The location of ONB during the experiments was determined from visual observations as well as from the thermocouple output. From the data obtained it is found that the heat flux and wall superheat required for inception are dependent on flow rate, liquid subcooling, and contact angle. The existing correlations for ONB underpredict the wall superheat at ONB in most cases. A correlation for predicting the wall superheat and wall heat flux at ONB has been developed from the data obtained in this study and that reported in the literature. Experimental data are within ±30 percent of that predicted from the correlation. Active nucleation site density was determined by manually counting the individual sites in pictures obtained using a CCD camera. Correlations for nucleation site density, which are independent of flow rate and liquid subcooling, but dependent on contact angle have been developed for two ranges of wall superheat—one below 15°C and another above 15°C.
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,General Materials Science
Reference28 articles.
1. Warrier, G. R., and Dhir, V. K., 1999, “Review of Experimental and Analytical Studies on Low Pressure Subcooled Flow Boiling,” Proceedings of the 5th ASME/JSME Joint Thermal Engineering Conference, Paper AJTE99-6233, CD-ROM Edition.
2. Hsu, Y. Y.
, 1962, “On the Size Range of Active Nucleation Cavities on a Heating Surface,” ASME J. Heat Transfer, 84, pp. 207–216.
3. Bergles, A. E., and Rohsenow, W. M., 1964, “The Determination of Forced-Convection Surface-Boiling Heat Transfer,” ASME J. Heat Transfer, 1, pp. 365–372.
4. Sato, T., and Matsumara, H., 1964, “On the Conditions of Incipient Subcooled Boiling With Forced Convection,” Bull. JSME, 7(26), pp. 392–398.
5. Davis, E. J., and Anderson, G. H., 1966, “The Incipience of Nucleate Boiling in Forced Convection Flow,” AIChE J., 12(4), pp. 774–780.
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