Local time-average gas holdup comparisons in cold flow fluidized beds with side-air injection

► Gas holdup comparisons in fluidized beds using different bed materials using 3D X-ray CTs. ► Side air injection has little influence on global bed hydrodynamics. ► Side air injection significantly affects local gas holdup. ► Axial coannular flow dominates. ► Wall effects influence hydrodynamics as bed diameter decreases.