Computational Study of Contaminant Control by Multi-slotted Hoods in an Industrial Exhaust System

The subject of this paper is the numerical simulation of the capture of contaminants with a local exhaust system. The objective is to evaluate the influence of multi-slotted hoods on the capture efficiency and its impact on indoor air quality. The ventilation in the proximity of slots and the contaminant dispersion throughout the room were predicted using the commercial tool Fluent. Characteristics of the polluted air were examined for different geometrical opening configurations for a two-dimensional model. Two parameters were examined: the number of slots and the slot width. Two-dimensional simulations revealed that, at a constant volumetric exhaust flow rate, a gradual reduction in contaminant concentration is experienced throughout the room as the number of slots increases. It was found that there is an optimal number of slots that reduces this concentration to 12% compared with a non-slotted hood system. The slot width analysis also revealed the existence of an optimum value for which the contaminant reduction is maximal. Following this basic assessment, computations were performed on a more realistic, three-dimensional model. These preliminary calculations indicate that flow computations need to be three-dimensional to address real-life situations more accurately.