Efficiency of a heated air curtain under cross-jet temperature gradients

The infiltration of unconditioned outdoor air to controlled indoor environments can have negative impacts on the energy performance and indoor environmental quality of buildings. Air curtains can be used to reduce infiltration through entrance doors where transit is frequent. The stability and performance of air curtains strongly depends on the combination of jet and environmental forces that act on them, including forces due to cross-jet density gradients and injection of buoyancy in the jet. This study addresses the performance of a heated air-curtain system by means of validated computational fluid dynamics (CFD) simulations. Two performance indicators are considered: (1) separation efficiency (related to mass transport), and (2) thermal efficiency (related to heat transport). The results indicate that based on the performance indicators, the use of a heated air curtain is not favorable over the use of an isothermal air curtain.