Discrete element modelling of packed rock beds for thermal storage applications

[摘要] ENGLISH ABSTRACT: The increased necessity to obtain power from other sources than conventionalfossil fuels has led to the growing interest in solar power. The problem withthe proposed technology is that it can only provide power during the dayand therefore requires some sort of storage system, if power is to be suppliedthroughout the day and night. A number of storage systems exist, but the oneof particular interest for this research, is packed rock beds. Rock beds have theadvantage that if designed right, they have the potential to be one of the mostcost effective means of storing thermal energy for solar power plants. DiscreteElement Models (DEM) of rock beds were therefore developed through bothexperimental and numerical procedures, by conducting a series of sensitivity,calibration and verification studies.The developed models were then used to study various aspects associated withrock beds, which were either too impractical, impossible or too expensive toconduct through actual experimental work. This research focused specificallyon the potential of constructing self-supporting tunnels within the rock bedsin order to improve the air flow uniformity through the bed, while minimizingthe pressure drop. It was observed that if the appropriate steps were followed,stable self-supporting tunnels could be formed. Valuable information such asthe rock orientations resulting from different packing directions could also be derived from the models and finally, a method to convert the DEM models intothe appropriate format such that it could be imported into a CFD preprocessorfor future CFD studies, was developed.

[发布机构] Stellenbosch University