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ISSN Online: 2377-424X

ISBN Print: 0-89116-909-1

International Heat Transfer Conference 9
August, 19-24, 1990 , Jerusalem, Israel

CRITICAL HEAT FLUX DURING NATURAL CONVECTIVE BOILING IN VERTICAL UNIFORMLY HEATED TUBES SUBMERGED IN SATURATED LIQUID

Get access (open in a dialog) DOI: 10.1615/IHTC9.190
pages 111-116

Abstract

An experimental study has been made of critical heat flux (CHF) of natural convective boiling in vertical uniformly heated tubes. The experiment was performed at a pressure of P = 0.1 to 3.1 MPa for the tube diameter of D = 1.12 to 18.4 mm, the tube length of L = 23 to 960 mm and three kinds of liquids. The effects of the pressure which corresponds to the density ratio ρGL ranging from 6.24 × 10−4 to 0.236 and of the ratio of L/D = 5 to 857 on the CHF, are mainly discussed. The experiment shows that the characteristics of the CHF can be first divided into two regimes at a point that a nondimensional parameter of D* = D/√(σ/g(ρLG)) is equal to about 13. In addition, the CHF in D* < 13 can be divided into two regimes: the CHF of L/D < 240 takes place under the condition of slug or annular flow and then the CHF data can be predicted with an accuracy of ± 20 % by [2], and the CHF of L/D = 857 may be caused by a flooding. On the contrary, the CHF in D* > 13 occurs under the same condition as the CHF in pool boiling. Then the CHF data are also correlated by [4], in which the tube diameter has no effect on the CHF.