Coalescence-Induced Irregular Particle-Droplet Removal

Abstract In this work, we experimentally investigated the coalescence-induced irregular particle-droplet removal phenomenon. We chose graphite and iron particles, common contaminant dust in HTR-PM, with large density and irregular (non-spherical) shapes at the sub-millimeter scale. It is found that the coalescence mechanism achieves excellent performance in droplet jumping enhancement and particle removal. The maximum transport height of graphite particles was 0.55mm, and the maximum transport height of iron particles was 0.40mm. It is revealed that since the particles always sunk at the bottom of the droplet, their maximum transport height was related to the droplet departure velocity. Besides, irregular particles enhanced the droplet departure velocity. The droplet departure velocity with all graphite particles and part of iron particles was higher than that without particles. The maximum dimensionless departure velocity is 0.35 (graphite) and 0.29 (iron), 40% and 16% higher than droplet jumping with no particles. Notably, it is illustrated that the mechanism of droplet jumping enhancement with particles was similar to that with macrostructures, which reduced the viscous dissipation and improved the velocity consistency of droplets by shortening the duration of the merge stage and prolonging the duration of the contact stage. This study provided an efficient method for irregular particle removal and opened up a new possible research direction for dust removal and aerosol removal in nuclear industry applications.