Investigation of the CHF correlation for a narrow rectangular channel under a downward flow condition

摘要

In present study, CHF experiments were conducted to evaluate and improve existing CHF correlations for narrow rectangular channels under a downward flow condition. A test section heated on both sides simulates a subchannel of plate-type fuels in a research reactor. The experiment covers a wide range of flow conditions: 0–2739 kg/m2s for mass flux, 37–99 °C for inlet temperatures and 120–224 kPa for outlet pressures. The experimental data obtained in the present study are compared with prediction results of existing CHF correlations. From the evaluation, the correlation proposed by Kaminaga et al., (hereafter referred to as Kaminaga correlation) shows the best prediction performance for the experimental data among them. However, it was also found that the Kaminaga correlation still contains a large degree of uncertainty relative to the experimental data. In this study, we attempted to improve the Kaminaga correlation to minimize its prediction uncertainty. For this purpose, we investigated the gap size, mass flux and subcooling effects on the CHF in a narrow rectangular channel based on both the present and Mirshak CHF data. Finally, the Kaminaga correlation was modified to consider the effects of the gap size, mass flux, and subcooling on the CHF.