Development of optimized conical diffuser inlet continuous-flow reactor for investigation of aerosol formation and growth mechanism

Abstract

Aerosol particles are key factors affecting air quality, climate change, and human health. Continuous-flow reactors (CFRs) are widely used to understand the formation and growth mechanisms of aerosol particles to ensure a sustainable, healthy air environment and mitigate climate change. In this study, the design of a conical diffuser inlet (CDI) equipped with CFR and static mixer through computational fluid dynamics has been optimized for repeatable and reliable investigations. In addition, a grid entropy-based mixing analysis (GEMA) method was developed to quantify the mixing status of aerosol particles in the designed CDI-CFR with a static mixer. Particle behavior parameters in the reactor including residence time and particle penetration ratios (Rτ and P(τo), respectively) were derived to quantitatively evaluate the design optimization quality. The averaged grid entropy was also quantified using the GEMA method for the design optimization. The recirculation in the reactor was observed over threshold flow rates (1.0 and 0.5 L/min at CDI angles (θ) of 15 and 30°, respectively) without a static mixer, while the static mixer installed at the end of the inlet tubing (End-point) suppressed the recirculation threshold to much higher flow rates (2.6 and 1.2 L/min at the θ = 15 and 30°, respectively). The 15° inlet cone with the End-point static mixer showed the best reactor performance based on the three particle behavior parameters assessed under simulated conditions. The reliability of the simulation results was also validated by comparing them with experimental flow visualization.