Although doorway air curtains have been applied for a number of years to high traffic and open doorways of commercial buildings to cushion the effects of the external weather conditions on the internal environment, there is still considerable uncertainty with respect to the influence of different design and environmental parameters on their performance. This paper presents results of computational studies into the influence of parameters such as wind velocity, jet width, jet angle, and heat input on the efficiency of air curtains applied to doorways of small air-conditioned premises. The results indicate that the air curtain, if properly designed and installed, can provide up to 90% reduction in air exchange between the indoor space and the outdoor environment. For optimum performance, the air curtain jet velocity should be such that the curtain air reaches and just maintains contact with the floor. This critical velocity increases with external wind velocity normal to the doorway and increasing temperature difference between the indoor and outdoor air. Increasing the air jet velocity above the critical value leads to a reduction in the air curtain efficiency.

Units: SI