Agglomeration Processes and Mechanisms of CO₂ Snow Inside a Tube

Abstract

This article experimentally investigates the agglomeration mechanism of CO₂ primary particles inside a tube. The results show that a complicated particle motion in the upper portion of the tube is responsible for the formation of large snow particles. The high speed and complicated motion of the snow particles inside the tube provide both the opportunities and time for the collision of particles, which implies that only particle deposition and re-entrainment cannot completely describe the phenomenon of particle agglomeration. The results also show the mechanisms of particle agglomeration inside a tube, which include primary particle agglomerate in jet vortexes, agglomerated particles flowing upward into the recirculation region, particle clusters growing in the recirculation flow, and finally particles being released with the jet flow. A minimum tube length (30 mm in this case) is needed to ensure the complete formation of the agglomeration mechanisms with recirculation flow, and thus the formation of considerable amounts of agglomerated particles. The results of this study thus improve current understanding of the agglomeration process and mechanisms of CO₂ snow formation inside a tube.

Copyright 2014 American Association for Aerosol Research