A104 A PHENOMENOLOGICAL PREDICTION OF DRYOUT BASED ON THE CHURN-TO-ANNULAR FLOW TRANSITION CRITERION IN UNIFORMLY HEATED VERTICAL TUBES(Nuclear power-1/combustion)

概要

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A phenomenological model is proposed to predict dryout in uniformly heated vertical tubes. The major point of the study was refining the initial conditions at the onset of annular flow location that starts the liquid film dryout process. The void fraction at the onset of the annular flow location has been derived from the vapor superficial velocity obtained by the churn-to-annular flow criterion with the help of the void-quality relationship. The thermodynamic equilibrium quality calculated through the iteration of flow quality using the profile-fit model to find the accurate starting point of the annular-flow in a tube. The present method was validated by worldwide data covering wide parametric ranges, a diameter of 5.1〜37.5, exit quality over 10%, a flow rate of 183〜5261 kg /m^2-s and a system pressure of 0.5〜17.7 MPa. The churn-to-annular flow transition criterion of Taitel et al.'s shows better prediction results than the other transition criteria. The present model improved the CHF prediction capability as a mean of 0.97 and root mean square error of 11% for the 3883 experimental data and extended the applicable range to the relatively low quality region.
社団法人日本機械学会の論文
2000-10-01