Adaptation of a Freon-12 CHF Correlation to Apply for Water in Uniformly Heated Vertical Tubes. Part 2: Based on CHF Data for Water at Pressures in the Range 6-20 MPa

摘要

An examination of more than 5000 sets of experimental data for critical heat flux (CHF) in uniformly heated vertical tubes internally cooled by high pressure water has shown that the CHF correlation proposed in Part 1 of this work is accurate for water at pressures up to approximately 17 MPa, provided that minor modifications are made to the Prandtl number index, and the saturation boiling length function. For pressures greater than 17 MPa, CHF values calculated from the correlation are increasingly lower than the experimental data, particularly at low saturation boiling length ratios (<100). This deficiency results from the significance of the surface tension number in the correlation and the accuracy to which the values of surface tension and latent heat are known as they approach zero at the critical pressure. As in the previous work, data have been excluded in which either the mass flux is less than 300 kg s exp -1 m exp -2 or thermal equilibrium exit qualities are less than 0.1. (Atomindex citation 13:711171)