Numerical Analysis of Ventilation Effectiveness in Occupied Zones and Its Air Quality Control for Various Industrial Ventilation Systems by Using Push-Flow

Abstract

When the generation of pollutants is assumed locally in industrial workspaces, such as factories or industrial plants, there is a legal obligation in Japan to set up local exhaust systems of a hood and a push-pull type. The local exhaust systems are effective in controlling the diffusion of pollutants generated in the workspace, and much research has already been done on the performance of these systems. However, there have been virtually no studies on the performance of push flow type ventilation systems for industrial workspaces, which have a local supply inlet and are able to directly dilute and control the direction of the convective flow of the contaminants. In this paper, CFD (Computational Fluid Dynamics) simulations are carried out in order to confirm the performance of a push flow type local ventilation system for industrial workspaces, which are characterized by a large enclosure with specific pollutants generation in local areas. The Normalized Concentration in the Occupied Zone (C_n) which is the ratio of the average contaminant concentration in the occupied zone (C_a) to the concentration for completely mixed indoor air (C_p) is used to evaluate the effectiveness of local ventilation for industrial workspaces.