Distribution and removal efficiency of sulfuric droplets under two general ventilation modes

Droplets resulting from evaporation are typical airborne pollutants in industrial buildings. It is essential to investigate the effectiveness of droplet removal under general ventilation modes. In this study, the distribution of sulfuric droplets under two typical general ventilation modes, namely, the natural air inlet + mechanical exhaust (NM) system and the mechanical air supply combined with natural air inlet + mechanical exhaust (NMM) system, are numerically investigated. The effects of evaporation, initial droplet size, air change rate, and outdoor climatic parameters on the removal of sulfuric droplets are discussed. The results show that for small droplets (1 mu m, 10 mu m), evaporation hardly affects the prediction accuracy of the droplet removal efficiency, while for large droplets (50 mu m, 100 mu m), ignoring the evaporation could lead to underestimations of the droplet removal efficiency. The NM and NMM systems have similar removal efficiencies for small droplets, whereas the NMM system has a higher removal efficiency for large droplets. As air change rate increases from 10 times/h to 20 times/h, the corresponding increase in the removal efficiency becomes smaller. When the air exchange rate is 20 times/h, the removal efficiency of the droplet ranges from 40% to 62% along droplet diameter changing. In addition, as the velocity decay of the supply air jet in summer is slower than that in winter, the droplet removal efficiency of the NMM system in summer is higher. These results lay the foundation for the accurate prediction of the distribution of sulfuric droplets in industrial plants and ventilation optimization.

Automated summary

This study numerically investigates the distribution of sulfuric droplets under two typical general ventilation modes and discusses the effects of evaporation, initial droplet size, air change rate, and outdoor climatic parameters on droplet removal. The results provide a foundation for accurately predicting the distribution of sulfuric droplets in industrial plants and optimizing ventilation.