Theoretical analysis of the characteristics of critical heat flux in vertical narrow rectangular channels under motion conditions

摘要

A mathematical three-fluid model of annular upward flow including additional forces of ocean conditions has been developed to predict the critical heat flux (CHF) in uniformly heated vertical narrow rectangular channels. The mathematical model is based on fundamental conservation principles: the mass and momentum conservation equation of the liquid film, liquid droplets and the vapor core and the mass and momentum transfers between the three-fluid together with a set of closure relationships. An analysis code with Visual Fortran 6.5 has been developed. The effects of motion and inlet mass flux fluctuation on the CHF are analyzed, respectively. Comparisons between prediction results and experimental data show good precision and accuracy. With the applications of the present code, the influences of the amplitude and period of inlet mass flux fluctuation on the CHF in rectangular channels are analyzed, respectively. The influences of the amplitude and period of heaving and rolling motion on the CHF are also investigated. The obtained analysis results are significant to the improvement of design and safety operation of the reactor system.