A novel nonintrusive technique is presented to investigate hydrodynamic and thermal behavior of gas–solid spout-fluidized beds with liquid injection, by simultaneously capturing visual and infrared images. Experiments were performed in a pseudo-2D bed with draft plates filled with glass or ¿-alumina particles to investigate the effect of liquid injection and particle properties on the flow characteristics. For the glass particles under dry and wet conditions, time-averaged particle velocities show similar quasi-steady-state behavior. However, under wet conditions, lower particle velocities were observed in both spout and annulus as compared with the dry system. Whereas, ¿-alumina particles do not show considerable variation in the particle ...