Numerical investigation of heterogeneous nucleation of water vapour on PM 10 for particulate abatement

Dust dispersion during the pulse-jet cleaning process with the diffuser effect of the cartridge filter

A special conical diffuser was presented and fixed on the top of the filter cartridge to improve the flow field. The existence of the diffuser can disperse the jet flow from the nozzle, and the high-speed airflow can act on more areas of the filter cartridge, including the top area of the filter cartridge. To improve the cleaning efficiency, the present study is aimed at optimizing the structure of the filter cartridge. The DPM model was used to simulate the dust dispersion process and the falling dust sedimentation from the filter under the action of the pulsed airflow. To validate the established model, the pressure values at the monitoring points were analyzed and compared with the related experimental results. It is found that the pressure values are consistent with the experimental results. Moreover, the installation distance and the size of the diffuser were studied and their influence on the dust distribution on the surface of the filter cartridge. It is found that the dust removal effect is relatively better when the installation distance is 90 mm and the size radius is 25 mm. The maximum dust concentration can be reduced by 15 mg/m³. The present research results can provide theoretical guidance for the cleaning process of the filter cartridge and finally improve the dust-removal efficiency of the dust collector.

Bacteria as Cloud Condensation Nuclei (CCN) in the Atmosphere

Bacteria activation and cloud condensation nuclei (CCN) formation have been studied in the atmosphere using the classical theory of heterogeneous nucleation. Simulations were performed for the binary system of sulfuric acid/water using laboratory-determined contact angles. Realistic model simulations were performed at different atmospheric heights for a set of 140 different bacteria. Model simulations showed that bacteria activation is a potentially favorable process in the atmosphere which may be enhanced at lower temperatures. CCN formation from bacteria nuclei is dependent on ambient atmospheric conditions (temperature, relative humidity), bacteria size, and sulfuric acid concentration. Furthermore, a critical parameter for the determination of bacteria activation is the value of the intermolecular potential between the bacteria’s surface and the critical cluster formed at their surface. In the classical nucleation theory, this is parameterized with the contact angle between substrate and critical cluster. Therefore, the dataset of laboratory values for the contact angle of water on different bacteria substrates needs to be enriched for realistic simulations of bacteria activation in the atmosphere.