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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Effects of diameters and surface conditions of horizontal test cylinders on subcooled pool boiling CHFs with two mechanisms depending on subcooling and pressure

Get access (open in a dialog) DOI: 10.1615/IHTC12.4530
6 pages

要約

The subcooled pool boiling CHF data measured using test horizontal cylinders with the diameters ranging from 0.2 to around 5 mm for the subcooling ranging from zero to about 160 K at pressures from about 0.1 to 2.0 MPa were investigated to clarify the effects of test cylinder diameters in water and ethanol, and the surface conditions in water on the CHF respectively. Those CHFs for subcooling were divided two groups for lower and higher subcoolings with pressure as a parameter with two different CHF mechanisms resulting from hydrodynamic instability (HI) and heterogeneous spontaneous nucleation (HSN) as a typical trend, though there exist the CHFs for transition subcoolings between low and high subcoolings, and also the CHFs resulting from only the HI or only the HSN for all subcoolings depending on some conditions. Those CHFs resulting from the HI and the HSN were well described by the previously derived correlations representing the CHFs resulting from the HI and the HSN with the three coefficients in the correlations taking account of the effects of various cylinder diameters in the liquids. The CHFs resulting from the HI measured using 1.2 mm commercial, rough and mirror (CS, RS and MS) surface cylinders at lower pressures for lower subcoolings were almost the same with one another at the same subcooling independently of the surface conditions. On the other hand, those resulting from the HSN for MS cylinders at higher pressures for the subcoolings were clearly different from corresponding CHFs for the CS and RS cylinders which were approximately the same with each other at the same subcoolings.