MODELING OF ENTRAINMENT RATES FOR ANNULAR FLOW IN VERTICAL ANNULI
2004 (English)In: Proceeding of the Sixth International Conference on Nuclear Thermal-Hydraulics, Operation and Safety, 2004Conference paper (Refereed)
One of the challenges in thermal-hydraulic analyses of BWRs is a correct prediction of dryout occurrence in a fuel assembly. Traditionally the critical powers in fuel assemblies have been found from correlations that are based on experimental data. The drawback of this approach is that correlations are valid only for these fuel assemblies on which the experiments have been conducted. Other limiting factors are the limited ranges of experimental working conditions including pressure, mass flux and axial power distributions. To overcome the above-mentioned limitations, several different models have been proposed to predict the dryout occurrence. One of the most popular approaches is to employ a phenomenological model of annular flow, in which the mass transfer between the liquid film and the gas core is based on entrainment and deposition correlations. Most of these correlations are derived from water-air flows in vertical tubes and their applicability to other geometries in general, and rod-bundles in particular, should be analyzed. This paper presents an analysis of the entrainment rate in vertical annuli. Using the standard approach to calculate the entrainment rate, one can show that the results deviate from measurements.
Place, publisher, year, edition, pages
Entrainment rate, annular flow, dryout, annuli, modeling
Research subject SRA - Energy
IdentifiersURN: urn:nbn:se:kth:diva-79195OAI: oai:DiVA.org:kth-79195DiVA: diva2:495224
QC 201202292012-02-082012-02-082012-02-29Bibliographically approved