Numerical and Experimental Analyses of Room and High Temperature Dense, Granular Flows Coupled to Flow Property Measurements for Solar Thermal Energy Storage
Yarrington, Justin D.
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Solar thermal energy storage using sintered bauxite particles as a storage media is a useful tool for extending the operation and increasing operating temperatures of concentrated solar power systems (CSP). The flow behavior of sintered bauxite particles was characterized in this work to better inform the design of next generation CSP technologies. Room temperature granular flows of sintered bauxite particles were examined along an inclined plane. Flow properties needed to drive numerical granular models were measured to improve model predictions for Carbobead CP particles. Particle shape and size distributions were determined by coupling optical microscopy to an in-house image processing algorithm. The impulse excitation technique was used to measure elastic and shear moduli, and compute Poisson’s ratio. The coefficient of restitution was measured by dropping particles on a surface and determining the kinetic energy before and after impact using high resolution particle tracking velocimetry. An inclined flow experiment was performed to characterize granular flows of Carbobead CP particles using particle image velocimetry. Numerical models of the experiment using the discrete element method were built with the measured flow properties and compared with experimental results. High temperature flow properties were measured to predict the high temperature flow behavior for Carbobead CP particles up to 800 °C. A numerical flow model at room temperature was extended to high temperature using the measured flow properties to determine the influence of temperature on the flow behavior.