BT-8 Application of Advanced Mixture Boiling Methods to Vertical Thermosiphon Reboiler Design

J. W. Palen, C. C. Yang, R. S. Kistler, and S. B. Yilmaz

New methods for calculating the boiling heat transfer coefficient for wide boiling-range mixtures were implemented into the HTRI RTF-2 Computer Program, tested against mixture data from the HTRI intube boiling data bank, and adjusted for better prediction. The four types of new methods which were installed in the Program are as follows:

  • New single component nucleate boiling correlations
  • New nucleate boiling mixture corrections
  • Vapor-phase resistance effects
  • New empirical adjustments for very wide boiling mixtures

The first three types of additions had been presented in previous HTRI reports, but had not been implemented and adjusted for flow boiling conditions. In addition, further improvements were found to be necessary for the very wide boiling-range mixtures, as presented for the first time in this report.

The new methods were tested against data from three different tube bundles. Five different mixtures were used with boiling ranges from 10 °F to greater than 500 °F.

The main advantage of the new methods is thought to be the probability for better extrapolation outside the data set, due to their more fundamental basis. However, significant improvement in prediction of the present data set was also achieved. The standard deviation of heat flux predictions for the entire data set was reduced from 44.6 percent for the previous methods to 25.5 percent for the new methods.