Prediction of CHF in vertical heated tubes based on CFD methodology

•Improved RPI wall boiling model was used to study DNB phenomena.•DNB phenomena and CHF value were obtained by CFD method.•Maximum deviation between predicted and experimental CHF was less than 15.0%.•Mean absolute relative error of predicted CHF was 7.1%.

Two-fluid model coupled with improved RPI wall boiling model (CHF model) was employed to investigate the departure from nuclear boiling (DNB) phenomena in vertical pipes under extremely high heat flux by using FLUENT 14.5 code. The distributions of temperature before and after DNB and the critical heat fluxes (CHF) at corresponding DNB points were obtained. The maximum deviation of predicted CHFs with experimental data was less than 15.0%. The results proved that two-fluid model coupled with CHF model was qualified to predict CHF accurately. This work can be referred when one predicts CHF in complicated geometry by CFD methodology.