The Influence on the Limit Flow Ratio Caused by the Change of the Area of the Exhaust Hood Face in the Design of Push–Pull Ventilation

Abstract

This study is to investigate whether the change of the exhaust hood area has an effect on the limiting flow ratio K_L in an push–pull ventilation device, especially when the face area of the supply hood is larger than the exhaust hood. This research is based on experiment. Set up a push–pull ventilation device, change the area of the exhaust hood face under the condition of maintaining other factors unchanged. Determine the minimum exhaust volume which completely drains the given air supply without overflow by the tracer method, and the K_L could be deduced. The experimental results show that under the above experimental conditions, the change of the exhaust hood area will cause a change on the limiting flow ratio K_L, and the larger the gap between the supply and exhaust hood area, the greater the K_L value will be. Change the distance between the push and pull hood face, repeat the above experiments, it is verified that the conclusions above are still valid when the distance changes.