The Effect of Process Conditions on Powder Flow Properties for Slow Flow Regimes

In several industrial units and applications, particulate solids are exposed to peculiar process conditions that significantly affect their flowability. Accurate characterisation and prediction of these effects are crucial for proper design and operation control of the processes. Liquid content, environmental humidity, and temperature can directly modify the type and magnitude of the interparticle forces and, thus, the cohesive behaviour at the bulk scale. This paper reports a critical review of experimental and modelling studies regarding the quantitative assessment of the effect of powder liquid content, environmental gas humidity and temperature on the mechanics of dense particle assemblies. Particular attention is paid to novel setups and experimental protocols that aim to go beyond the limits of standard and commercial instruments. A multiscale approach is followed from the particle level to the bulk level.