Numerical multiphysics modelling of Wick-Boiling in a crud with porosity variations to determine local Nickel Ferrite depositions within crud due to deep bed filtration

CRUD;MODEL;MULTIPHYSICS;NON-UNIFORM POROSITY;CORE;POROSITY;NICKEL FERRITE;WICK BOILING;DEEP BED FILTRATION

Madhavan, Varunkumar

关键词: CRUD;    MODEL;    MULTIPHYSICS;    NON-UNIFORM POROSITY;    CORE;    POROSITY;    NICKEL FERRITE;    WICK BOILING;    DEEP BED FILTRATION;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/90598/MADHAVAN-DISSERTATION-2016.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Impacts of porosity variations through porous deposits with chimneys where wick boiling contributes to bulk of heat transfer, on thermal performance, solute concentration levels and particle number density distribution are examined through a two-dimensional model. The multi-physics model is described by a coupled system of a thermal model, a momentum transfer model, a solute concentration transport model and a particle transport and absorption model. Various appropriate numerical methods were developed to solve each of these models. Porosity variations were found to have significant impacts on peaking local solute and particle number concentrations within the deposits. This accentuates neutron flux absorption and hence reduces the flux in local vicinity and furthers axially offset anomalous effects of power generated within the core. The peaking values may also be aggravating corrosion locally over the cladding elements. The particle deposition model developed here gives insight towards how the particles are generally packed around the chimney and how the local porosity evolves and varies. It was found that local porosity within the deposits tends to be low near the chimney walls and is generally increasing while moving away from the walls. Local Nickel Ferrite absorption within the crud is estimated using this model and results obtained from Particle Assembly/Constrained Expansion (PACE) models. The rate of absorption of these particles is hugely affected by the non-uniformity of the porous deposits. The estimated values approach observed values when the porous deposits are treated with locally varying porosities rather than when they're with a generally uniform porosity.