Analysis of the porosity variations in a pebble-bed reactor core

Abstract

The variation in porosity of a packed column is an important parameter in its design. The flow patterns, mass transfer, heat transfer, and other transfer phenomena are dependent on the porosity variations in the column. Physical experiments are normally employed to study the porosity characteristics of packed columns. Only a few numerical investigations into the porosity of packed columns have been performed. The objective of this study is to develop numerical procedures to analyse the porosity of numerically generated packed columns (axial distribution, radial distribution, and representative elementary volume). Numerical procedures have the advantage of better accuracy and are easier and faster (than experimental studies) to conduct. The development of the models is discussed in detail, and the algorithms and implementation of the codes are explained. Validation tests that were conducted show that the implementation of the models is correct. Four data sets were analysed with these procedures. These preliminary results show the general trends discussed in the literature. The results suggest that the numerical models were correctly derived and implemented. The results also indicate that the numerically generated packed beds are (relatively) good representations of physical packed beds.