Pressure drop through a packed bed

Abstract

The importance of the development of PBMR technology for the generation of electricity in South Africa is undeniable. Part of the development includes simulation models to predict operating and transient thermal-fluid behaviour of the reactor core. With regard to thermal-fluid simulations pressure drop correlations are very important, and must be validated experimentally. The High Pressure Test Unit (HPTU) was designed, built and successfully commissioned to provide a facility capable of producing the range of experimental results required. Two types of pressure drop tests are performed on the HPTU, namely integrated and separate effects tests. In this study a data processing methodology is established that is used to convert raw experimental data into meaningful results. The data processing methodology includes criteria for the prediction of steady state conditions and an uncertainty analysis to investigate the total uncertainty in the Euler number and the friction factor for packed beds. The data processing methodology was implemented and used to estimate the uncertainty in the desired variables. The methodology proved to be successful, and the estimated uncertainties were within the desired range and confidence interval. The repeatability of the results proved to be excellent, which further supports that the tests were successfully conducted. The final results were compared with relevant correlations identified from a literature survey. The results from the separate effects tests could not be predicted by any correlations obtained from the literature and the Euler numbers were found to be significantly lower. The reason for the large deviation from existing correlations seems to be the result of an inherent characteristic of the packing arrangement of the beds. The results from the integrated effects tests were predicted reasonably well by correlations from the literature. Methods of including the influence of the walls in the prediction of the pressure drop showed that the walls could play an important role in the pressure drop through annular packed beds. This study showed that the integrity and quality of the data obtained from the HPTU is high and that the results can be used with confidence in further research of pressure drop through packed beds.