A Dryout mechanism model for rectangular narrow channels at high pressure conditions

Abstract A Dryout mechanism model for rectangular narrow channels at high pressure conditions is developed by assuming that the Kelvin–Helmholtz instability triggered the occurrence of Dryout. This model combines the advantages of theoretical analysis and empirical correlation. The unknown coefficients in the theoretical derivation are supported by the experimental data. Meanwhile, the decisive restriction of the experimental conditions on the applicability of the empirical correlation is avoided. The expression of vapor phase velocity at the time of Dryout is derived, and the empirical correlation of liquid film thickness is introduced. Since the CHF value obtained from the liquid film thickness should be the same as the value obtained from the Kelvin–Helmholtz critical stability under the same condition, the convergent CHF value is obtained by iteratively calculating. Comparing with the experimental data under the pressure of 6.89–13.79 MPa, the average error of the model is −15.4% with the 95% confidence interval [-20.5%, −10.4%]. And the pressure has a decisive influence on the prediction accuracy of this model. Compared with the existing Dryout code, the calculation speed of this model is faster, and the calculation accuracy is improved. This model, with great portability, could be applied to different objects and working conditions by changing the expression of the vapor phase velocity when the Dryout phenomenon is triggered and the calculation formula of the liquid film.