An energy-efficient exhaust hood for industrial buildings with strong thermal buoyancy

Ventilation is essential for the health and safety of workers in industrial buildings, as it can reduce the exposure to hazardous substances. This study used an experimental chamber with strong thermal buoyancy to measure the air velocity and pollutant concentration under two types of exhaust hoods: reinforced and traditional. The data-driven turbulence model with a new wall function was validated by comparing the simulated results with the measured data. Next, different ventilation strategies were evaluated in a small room. The reinforced exhaust ventilation had the best performance, but it also created vortices due to the impinging flow, which trapped pollutants. To solve this problem, an improved reinforced exhaust hood with multiple independent inlets was designed. Through adjustment of the velocities of these inlets, the vortices caused by wall impingement flow were minimized, resulting in a 77% decrease in pollutant concentration. For a large room, the study optimized the jet collision velocity when multiple reinforced exhaust hoods operated together. The reinforced exhaust ventilation system reduced the pollutant concentration in the breathing zone to 89% of the concentration under existing ventilation. Moreover, the improved reinforced exhaust hood provided a significant energy saving. In small and large industrial buildings, the hood reduced fan energy consumption by more than 80% and air conditioning energy consumption by more than 60%.