Modeling particle loss in ventilation ducts

Abstract

Empirical equations were developed and applied to predict losses of 0.01-100 µm airborne particles making a single pass through 120 different ventilation duct runs typical of those found in mid-sized office buildings. For all duct runs, losses were negligible for submicron particles and nearly complete for particles larger than 50 µm. The 50 th percentile cutpoint diameters were 15 µm in supply runs and 25 µm in return runs. Losses in supply duct runs were higher than in return duct runs, mostly because internal insulation was present in portions of supply duct runs, but absent from return duct runs. Single-pass equations for particle loss in duct runs were combined with models for predicting ventilation system filtration efficiency and particle deposition to indoor surfaces to evaluate the fates of particles of indoor and outdoor origin in an archetypal mechanically ventilated building. Results suggest that duct losses are a minor influence for determining indoor concentrations for most particle sizes. Losses in ducts were of a comparable magnitude to indoor surface losses for most particle sizes. For outdoor air drawn into an unfiltered ventilation system, most particles smaller than 1 µm are exhausted from

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A DNS Study of Aerosol Deposition in a Turbulent Square Duct Flow

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Investigating a selection of mixing times for transient pollutants in mechanically ventilated, isothermal rooms using automated computational fluid dynamics analysis

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