Diffusion and Separation of Two-Phase Contaminants VOCs and Oil Droplet in Machining Processes and a Synergistic Control Design

Modern machining workshops commonly face two major challenges: VOCs and oil droplet pollution, and excessively high energy consumption for environmental control. Efficiently improving the workshop environment and reducing energy consumption for environmental control is crucial for achieving sustainable operation of industrial buildings. Using large eddy simulation, this study first reveals the influence of the Richardson number (Ri) on the flow development of intermittently airflow and the dispersion of two-phase pollutant. In low-Ri conditions, intense entrainment occurs at the flow edge with the surrounding air, promoting pollutant dispersion; when Ri ≤ 0.98, the horizontal dispersion range of both VOCs and oil droplets can reach 1.9 times the equivalent diameter of the pollution source (dp). In contrast, the interaction between high-Ri airflow (Ri ≥ 29.4) and the surrounding air manifests as mild shear, resulting in relatively limited diffusion ranges for VOCs and oil droplets, at 1.3 dp and 1.2 dp, respectively. Then, the study also found that when 0.16 ≤ Ri ≤ 117.6, significant gas-droplet separation of VOCs and oil droplets typically does not occur within a height range of 5 meters above the source, creating conditions for the synergistic control of two-phase pollutants. Finally, the study proposes a near-field environmental control method using VOCs-Oils Synergistic Purifiers (VOSP). Compared with increasing the air changes rate, using VOSP not only ensures that the air quality in the worker breathing zone meets NIOSH standards, but also saves 48% of energy consumption annually. The research findings contributes to improving industrial building environments and saving energy.