Emission and purification of evaporated-condensed oil droplets affected by condensation nuclei during machining

Jia-Ning Fan; Yang Yang; Yi Wang; Bo Qian; Mingyang Li; Yu Zhou

doi:10.1016/j.jhazmat.2023.132170

Emission and purification of evaporated-condensed oil droplets affected by condensation nuclei during machining

J Hazard Mater. 2023 Oct 5:459:132170. doi: 10.1016/j.jhazmat.2023.132170. Epub 2023 Jul 27.

Authors

Jia-Ning Fan¹, Yang Yang², Yi Wang³, Bo Qian¹, Mingyang Li¹, Yu Zhou³

Affiliations

¹ School of Building Services Science and Engineering, Xi'an University of Architecture and Technology, 710055 Xi'an, PR China.
² State Key Laboratory of Green Building, Xi'an University of Architecture and Technology, 710055 Xi'an, PR China; School of Building Services Science and Engineering, Xi'an University of Architecture and Technology, 710055 Xi'an, PR China. Electronic address: yangyang@xauat.edu.cn.
³ State Key Laboratory of Green Building, Xi'an University of Architecture and Technology, 710055 Xi'an, PR China; School of Building Services Science and Engineering, Xi'an University of Architecture and Technology, 710055 Xi'an, PR China.

PMID: 37517238
DOI: 10.1016/j.jhazmat.2023.132170

Abstract

Fine oil droplets emitted by evaporation-condensation during machining are typical indoor air contaminants. Airborne particles can act as condensation nuclei, facilitating the condensation of oil vapor. The physical properties of these resultant droplets significantly affect their purification efficiency. Herein, this study aimed to elucidate the emission characteristics of oil droplets formed by evaporation-condensation affected by condensation nuclei and the purification efficiency of intense field dielectric (IFD) technology for the droplets under varying airflow velocities. Results show that the removal of condensation nuclei can effectively reduce the mass of evaporated-condensed oil droplets, and the increment in the mass of oil droplets reached 1.7 times the increment in the mass of condensation nuclei. It was more effective to reduce the mass of oil droplets by removing large condensation nuclei and decreasing the amount of evaporated soluble oil, as compared to removing smaller condensation nuclei or using straight oil. Condensation nuclei mainly contributed to the generation of oil droplets below 5 µm. For droplet diameters of 0.3-5.0 µm and airflow velocities of 0.5-2.0 m/s, the purification efficiency was within the 84-96% range. The purification efficiency of the IFD purifier for oil droplets could be improved either by increasing the size of the oil droplets or by reducing the airflow velocity.

Keywords: Condensation nuclei; Evaporation-condensation; Intense field dielectric; Oil droplets; Purification efficiency.