Investigation in the Characteristics of the Personal Ventilation Using Computational Fluid Dynamics

Abstract

Detailed information of transient exhaled air dispersion and recirculation in the breathing zone can be obtained using computational fluid dynamics (CFD) to generate detailed numerical models and obtain the necessary information. In this study, interaction of free convection flow around human body with respiration flow of breathing and vertical personalized flow from personalized ventilation (PV) system was simulated using a commercial CFD package. Impact of breathing process on personal exposure effectiveness εp was evaluated for different operating and environmental conditions. Re-inhaled exposure index εRI for exhaled CO2 was used to assess the amount of exhaled air re-inhaled due to the interaction between personalized and exhaled airflows. Another objective of this study was to consider the risk of airborne infection transmission, caused by undesirable transport and dispersion of exhaled pathogens to surrounding air when infected individual uses PV. Results show that calculation of personal exposure effectiveness would be sufficiently accurate to give proper information about the protection of occupant with a PV system also without the breathing simulation included. The operating mode of a PV proved as the main factor for dispersion of exhaled air and its transport to the background room air, resulting in an increased risk of airborne infection transmission.