Dense upflow fluidized bed (DUFB) solar receivers of high aspect ratio: Different fluidization modes through inserting bubble rupture promoters

A fluidized bed of Geldart-A particles is promoted as heat transfer fluid in the tubular solar receivers towers. pressure-driven upward particle flow affects hydrodynamic structure and properties bed. Experiments involved a tube 0.05 m internal diameter but very high height/diameter ratio (>120), representative future receiver numerous chemical reactors. Solid circulation fluxes aeration velocities were varied. Configurations bare with bubble rupture promoters compared. In tube, freely bubbling transformed into axi-symmetric slugging at level ~1 m. With promoters, prevails to about 3 m, turbulent fluidization mode develops higher up (a more chaotic two-phase system elongated unstable “gas voids” “dense solid clusters”), without detected. Experimental results for both configurations assessed compared CFD predictions by Euler n-fluid code, NEPTUNE_CFD. good agreement was obtained slug/void frequencies solids volume fraction configurations. BRPs moreover enhance through fluidizing gas, thus limiting visible rate sizes while increasing gas/particle contact, hence important designing multi-tube Whereas limits from wall suspension ~200 W/m2K, presence maintains coefficient excess 600 W/m2K.