“…In the past two decades, different non-invasive techniques have been developed to gain a deeper understanding of the interaction between fluidized bed and a relatively large freely moving particle. The most common methods are particle image velocimetry (PIV) [33,34], pressure signal analysis [22,35], radioactive particle tracking (RPT) [36][37][38][39], magnetic particle tracking (MPT) [15,32,40,41] and Lagrangian sensor system [42]. Most of these studies were carried out at ambient conditions using sensors or tracers to mimic the behaviour of a moving feedstock particle within the fluidized bed or investigating the hydrodynamic behaviour of the bed itself.…”