A study on prediction methods of the critical heat flux for upward flow in a vertical narrow rectangular channel

• The empirical CHF correlations for upward flow in a vertical narrow rectangular channel were reviewed, for high pressure condition over 40 bar.
• New Correlation-A/B, which were derived by ACE algorithm, show much more improved prediction errors than other previous CHF correlations.
• The Look-Up Table (LUT) of ACEL predicts CHF as well as New Correlations.
• Comparative analysis shows that LUT with correction factors has potential application greater than New Correlations, for low pressure condition.

The previous empirical CHF correlations for upward flow in a vertical narrow rectangular channel which is uniformly heated from both wide sides were reviewed and analyzed by using the experimental data points at pressure condition over 40 bar. The new correlations, that is, Simple Correlation and New Correlation-A/B were derived and proposed by using simple regression and ACE algorithm, and it was shown that they have more improved prediction errors than the other previous correlations. The Look-Up Table (LUT) of AECL also estimates CHF as well as New Correlation—A/B even though LUT was generated from the CHF data points in circular channels. As a result of comparative assessments of LUT and the empirical correlation of low pressure condition, it is reasonably concluded that for wider pressure condition, LUT with proper correction factors is the most pragmatic and universal CHF prediction method for rectangular channel in this study.