Numerical and Experimental Investigation of PM1 Particle Charging in Ventilation Ducts with Coupled Electrostatic and Flow Fields

In this study, a novel numerical model was established that considered the bidirectional coupling effect between the flow field and the electric field. The experiment of gas velocity interference with charger current is designed. For the first time, the migration of air ions in an electrostatic field was verified by experiment and qualitatively analyzed. Using a novel numerical model validated through the experiment, the charging process of aerosol particles under the coupling effect of the flow field and electrostatic field was further quantitatively analyzed. The results show that an increase in gas velocity leads to a linear increase in downstream charge density and electric field strength. An increase in the gas velocity leads to the downstream migration of air ions, resulting in the loss of particle charge. This phenomenon is inversely correlated to particle size. The charge loss was greatest between 0.5 and 2 m/s. The charge enhancement ratio of 0.01 μm particles after 1 s resident time was nearly 80%, which was almost twice that of 0.1 and 1 μm particles. The charge enhancement ratio of 0.01 μm particles was 2 ∼ 3 times larger than that of 0.1 and 1 μm particles at the same migration distance. Increasing the migration distance of submicrometer aerosols in the electrostatic field can effectively enhance the particle charge. These provide new theoretical support for the application of air purification and microbial inactivation.