Steady-state and transient heat transfer phenomena of water: An experimental and theoretical investigation at near-critical pressures

Heat transfer to water in the near-critical region is studied for steady-state and transient phenomena. Over 12,000 data points from the literature have been collected to investigate the applicability of four different dimensionless numbers based on bulk properties. None of the dimensionless numbers gave satisfactory results. However, a new approach based on the pseudo steam mass fraction and the q/G ratio may be worthy of further investigation. In addition, a transient depressurization experiment from supercritical to subcritical pressures leading to a boiling crisis is was also performed. The boiling crisis occurs at far lower pressures than predicted using only the Leidenfrost temperature. A simple model, applied to predict the wall temperature distribution during the depressurization, was compared to the experimental data. It is limited to predicting the transient behavior of the wall temperature along the tube. However, the model was able to predict the final temperature distribution reasonably well.