Abstract: To minimize the health hazards by fugitive emissions of gases and particulate matter in high temperature industrial processes, local exhaust ventilation is often used. Overhead canopy hoods are typically used to receive contaminants from operations in which direct extracting the emissions from their sources is not possible. Due to the distance from the source and the hood, air entrainment in the plume induces a large airflow requirement at the hood. To estimate the necessary flow rate to capture the emissions, the Industrial Ventilation Manual (ACGIH) presents empirical equations that guide the design of a canopy hood. Previous works have shown the benefits of using CFD as a tool for evaluating an exhisting canopy hood design and proposing modifications to increase its efficiency. The present work aims to investigate the efficiency of a canopy hood designed using the best practice equations from the Industrial Ventilation Manual and an alternative design, consisting of modifications in the design of the first case. The results show that although the best practice equations offer a baseline to start the project of a canopy hood, it has low efficiency in capturing the emissions from hot processes that emit gases an particulate matter at high flow rates. The alternative design significantly improve the exhaust efficiency of the canopy hood.

Keywords: CFD, fugitive emissions, air pollution control, local exhaust ventilation.