Adhesion when Particles Touch the Sides of Air Conduits. Triboelectricity

Adhesion and Thermal Processes. When particles touch the sides of a conduit, in addition to the forces already considered in 11-15, we observe other forces, associated with the melting of the particles at the contact zone and the triboeffect, which promotes firm adhesion of the particles to the surface. 

As regards thermal stability or heat resistance, all particles may be arbitrarily divided into two groups, namely, those respectively sensitive and insensitive to the rise of temperature caused by friction. 

The adhesion characteristics of these two groups of substances were considered by Rumpf [278]. For non-temperature-sensitive particles coming into contact at low velocities (Fig. VI.26b) the adhesive force predominates over the elastic detaching force. As the flow velocity increases, however, rebounding of the particles may in fact take place. 

The rebounding of spherical glass particles up to 30 M in diameter from a steel surface arranged perpendicularly to the dust-laden flow starts at about 13 m/sec. 

For temperature-sensitive particles (Fig. VI,26a) the initial adhesion is due to the same processes as in the case of elastic particles, except that the first section (up to the point Ic) is restricted to narrow limits. A rise in the flow velocity leads to a rise in the impact energy and to the melting of. .the particles in the 

---

Adhesion when Particles Touch the Sides of Air Conduits. Triboelectricity... 

---