Kinetics-based wetting properties of microdroplets impacting respirable coal dust particles

Abstract

The removal of respirable coal dust particles has been the focus of domestic and foreign research, and the spray dust suppression technology has been adopted for the prevention and control process; it is based on the mechanism whereby liquid droplets impact dust particles. To further study the wetting properties of microdroplets impacting respirable coal dust particles based on kinetics, this study focused on the droplet morphology, and mathematical and physical models of a microdroplet impacting a respirable coal dust particle were established to explore the variation laws of the droplet spreading and wetting under central and non-central impacts, for which the CLSVOF numerical simulation approach was adopted. The results showed the occurrence of gas retention at the phase interface, which affected the droplet wetting characteristics on the coal dust surface, after the contact between the liquid and dust particles. The influence of the impact velocity, particle size ratio, contact angle, and offset distance on the droplet spreading behavior was investigated by comparative analysis of 12 working conditions with different parameters. The droplets can completely wrap the coal dust particles under only one working condition parameter (V = 5m/s,Φ = 2,θ = 90°,L = 0 μm). The microdroplets are extremely difficult to wet respirable coal dust particles and the spreading behavior of the final droplet could be divided into three states: static adsorption, complete encapsulation and permanent escape. Our results can help better understand the wetting relationship between microdroplets and respirable coal dust particles, serving as a basis for dust prevention and control.