CO ₂ and thermal gradient based demand-driven stratified ventilation—Experimental and simulation study

Industrial production processes often emit air pollutants that have adverse health effects and affect product quality. Essentially, several mechanisms, such as mixed and stratified ventilation systems, have been established in companies to remove generated thermal and mass loads from manufacturing areas. The widely used mixed ventilation generates a homogenous temperature and pollutant level in the entire production hall. However, fresh air supply is only needed in the area that is used by employees and needed for processes. As most factories do not adjust the ventilation system to current production conditions, the production hall is over-supplied with clean and conditioned air during idle times. This study describes experimental measurements and simulation analysis to compare mixed and stratified ventilation systems. The measurements include carbon dioxide and temperature profiles with various intake airflows, intake air temperature, thermal load, and machine layouts. Results show advantages in airflow, air quality, cooling capacity, and energy demand when using automatically demand-driven stratified ventilation. The experimental results validate the thermal simulation results. Controlling the layer height, ambient temperature of the room, and concentration of contaminants are vital parameters.