Dynamics of wet particle–wall collisions: Influence of wetting condition

Abstract

Particulate processes are characterised by intense contacts between particles and particles with the apparatus walls, where often liquid is present on the surfaces in form of droplets or liquid layers, e.g. in granulation and agglomeration processes. However, the influence of the liquid on collision dynamics is still not fully understood. Therefore, the influence of the liquid on wet particle–wall collisions is investigated via the coefficient of restitution (CoR). The CoR characterises the total energy dissipation during a collision and is defined as ratio of rebound velocity to impact velocity. In most literature regarding collision dynamics of wet particles, a target plate is covered by a liquid layer before the collision. However, this approach is often questioned of its similarity to real wet particle collisions. Therefore, during this work the particle was wetted before colliding with a dry or wet plate.Normal CoR was higher for a wet plate than for a wet particle. The case of a wet–wet collision is comparable to a superposition of collisions where a wet particle or a wet plate was used. Furthermore, during oblique collisions the tangential CoR was found to be smaller for a wet wall compared to a wet particle impacting on a dry wall.