Numerical investigation on particle removal and energy consumption of supplied and recirculated ventilation for industrial workshop

In the weld back-cleaning process, many high-concentration pollutants are produced, which can lead to health problems after prolonged exposure. In this study, a novel recirculating stratified ventilation system is proposed that combines supply and recirculating ventilation. It reduces indoor particulate concentration and exhausts air volume based on the air gouging process in a casting workshop. The influences of the supplied and recirculated air velocities on the particle removal efficiency and energy consumption were investigated and compared with those of a traditional exhaust system. The computational fluid dynamics-discrete phase model coupling method was adopted. First, the feasibility of the model was verified using previously published experimental data. The concentration of the unsteady particles was then simulated with different supplied and recirculated air velocities in the ventilation system. The particles were dispersed owing to the influence of the heat-source temperature. With an increasing supplied air velocity and constant recirculated air velocity, the average particle concentration was decreased. The results show that the particle removal efficiency can be improved by approximately 100%, and 90% of the energy can be saved to achieve the same removal efficiency as a traditional ceiling exhaust system.