Measurement of flow properties coupled to experimental and numerical analyses of dense, granular flows for solar thermal energy storage

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From: Solar Energy(Vol. 207)
Publisher: Elsevier Science Publishers
Document Type: Report
Length: 373 words

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Keywords Granular flow transport; Solar particle heating receivers and reactors; Thermal energy storage; Granular flow properties; Discrete element method Highlights * Refractory granular media enable high temperature solar thermal energy storage. * Granular flow is characterized by particle flow properties. * Controlled measurements of granular flow properties needed for accurate numerical flow analysis. * Discrete element method predicts bulk granular flow behavior at ambient conditions. Abstract Granular flows of sintered bauxite proppants were examined along an inclined plane for solar thermal energy storage applications. Granular flow properties needed to drive numeric granular models were measured for improved numerical model predictions for Carbobead CP 50/140, 40/100, and 30/60 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 static sliding friction was measured using the slip-stick method, and the static rolling friction was determined from measured shear on particles positioned between two hot-pressed plates. The coefficient of restitution was measured by dropping particles on a surface and determining the kinetic energy before and after impact with the surface using high resolution particle tracking velocimetry. Particle size did not significantly impact the coefficients of restitution and static rolling friction, however, particle shape distribution resulted in a large variation in measurements. An inclined flow experiment was performed to characterize granular flows of Carbobead CP 30/60 particles using particle image velocimetry. Numerical models of the experiment using discrete element method were generated with the measured mechanical properties as inputs for comparison with experimental results. A constant directional torque rolling friction model best predicted bulk granular flow behavior. Good agreement between the model and experiment was achieved at ambient, steady state conditions, with average velocity differences Author Affiliation: (a) George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA (b) Department of Mechanical and Aerospace Engineering, University of Dayton, Dayton, OH 45469, USA * Corresponding author. Article History: Received 19 February 2020; Revised 4 June 2020; Accepted 15 June 2020 Byline: Malavika V. Bagepalli (a), Justin D. Yarrington (a), Andrew J. Schrader (a,b), Zhuomin M. Zhang (a), Devesh Ranjan (a), Peter G. Loutzenhiser [peter.loutzenhiser@me.gatech.edu] (a,*)

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Gale Document Number: GALE|A640502048