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Experiments and nonequilibrium analysis of pipe blowdown. [BWR; PWR]

Journal Article · · Nucl. Sci. Eng.; (United States)
OSTI ID:6493761
Phase equilibrium blowdown models are not valid for geometries having small characteristic lengths (volume-to-break-area ratios). For such geometries, the two-phase expansion is too rapid to permit adequate heat and mass transfer between liquid and vapor to maintain phase equilibrium. The two-phase expansions observed during the present pipe blowdown experiments with dichlorodifluoromethane (R-12) were found to exhibit pronounced nonequilibrium behavior. To describe the observed nonequilibrium behavior, a model was formulated that treats the expanding two-phase fluid as a pseudo-homogeneous mixture of uniformly distributed, heat transfer dominated, spherical vapor bubbles surrounded by superheated liquid. By adjusting two empirical parameters-discharge coefficient, C/sub d/, and bubble density, N-to permit the model to simulate R-12 blowdown from one particular blowdown geometry and set of initial conditions, it was possible to use the model in predicting R-12 blowdown transients for other geometries and initial conditions as well as for pipe water blowdown.
OSTI ID:
6493761
Journal Information:
Nucl. Sci. Eng.; (United States), Journal Name: Nucl. Sci. Eng.; (United States) Vol. 69:3; ISSN NSENA
Country of Publication:
United States
Language:
English