Exploration of the Relationships between the Spraying Condition and Wetting Behavior on Coal Surface of Dust Suppression Droplet: Improving the Utilization Rate

Abstract

Dust suppression through water-based media is an important technical means, which is of great significance to industrial process safety and environmental protection. In order to improve the utilization rate of droplets, the dynamic spreading process of droplets impacting the coal surface was studied by the coupled level-set and volume-of-fluid methods (CLSVOF) method. The spread area was calculated by the binary method to characterize the wetting effect. Dimensionless spread area per unit volume (DSAPUV) was proposed to represent the utilization of droplets. The results show that the droplet spreading fracture process can be divided into three stages: initial deformation period, spreading fracture period, and stable period. When the particle size was not being changed, the area of dimensionless spread does not increase consistently with velocities, but there exists an optimal critical velocity of impingement, which is 17 m/s for the maximum dimensionless spread area reached by droplets with a diameter of 30 μm and 19 m/s for the maximum dimensionless spread area reached by droplets with a diameter of 50 μm. Droplet size is directly proportional to the dimensionless spread area. The maximum dimensionless spread areas of the droplets were all reached during spreading, and the time required increased gradually with increasing particle sizes. It was found that the effect of droplet size on the utilization of droplets was obvious when their size ranged from 10 μm to 50 μm, and their velocity ranged from 15 m/s to 20 m/s.