Experimental study of the indoor aerosol-dynamics for a low-momentum ventilation system with an air purifier unit

Abstract

We present an experimental study on the aerosol-dynamics within a test setup representing a class or conference room situation. To ensure realistic flow patterns, the blockage and heat release of the persons are simulated using 18 thermal manikins. The aerosol source is realized by a generator, attached to a thermal manikin, providing a realistic exhalation of artificial saliva. Two different ventilation scenarios are studied regarding aerosol concentration distribution and removal-efficiency. Additionally, the influence of a mask attached to the source and the effect of a moving person on the resulting aerosol concentrations are investigated. Time and spatially resolved concentrations are measured using 61 particulate matter sensors, installed on three height levels. The ventilation scenarios comprise window opening and a lowmomentum ventilation concept, where the air is extracted underneath the ceiling and reenters purified (HEPA14) on floor level. Each of the examined counter measures (open-window, low-momentum ventilation and mask) resulted in a significant lower particle concentration compared to the reference scenario. The low-momentum ventilation with an air purifier unit provided the best aerosol removal-efficiency with a decrease in concentration of up to 96%, followed by the window opening with 60%. The buoyancy flow induced by the heat loads and the resulting flow field caused by the lowmomentum ventilation concept lead to well-directed particle transport towards the ceiling. Consequently, a large amount of aerosol was extracted and filtered by the ventilation system resulting in lower particle concentrations. However, local concentrations were strongly depended on the position of the aerosol source.