Providing occupants with cool fresh air through personalized ventilation (PV) is said to provide both thermal comfort and good breathable air quality(BAQ) to an occupant in an office space. However, studies show that PV might help in spreading contaminants in the space in case the PV user wasinfected which may compromise the health of uninfected occupants in the same room. More recent applications use intermittent PV to enhance comfort,however using a dynamic airflow enhances turbulence in the occupant microclimate. Therefore the spread of contaminants in the space might be moresignificant than in the case of a PV system operating under steady conditions. This study investigates the effect of a localized dynamic personalizedventilator (PV) coupled with a mixing ventilation system (MV) on the dispersion of contaminants in a typical office space in case the PV user wasinfected. A transient 3D computational fluid dynamics model (CFD) was used to assess the velocity, temperature and particle concentration fields in themacroclimate. The model was then validated through experiments by using a thermal manikin in an experimental chamber at a temperature of 26°C(80 L/s) and a PV temperature of 22°C (3.5 L/s). The experimental chamber was equipped with an aerosol source generating contaminants located atthe mouth level of the manikin representing a contaminated occupant. There was a good agreement between experimental and predicted values. The modelwas then simulated for three typical frequencies (0.3 Hz, 0.5 Hz, and 1 Hz) and average flowrates (3.5 L/s, 5 L/s, 7.5 L/s) to find the operatingfrequency and average flowrate which would minimize the dispersion and deposition of contaminants in the macroclimate. Preliminary results show thatincreasing the fluctuation frequency and average flowrate would enhance the spread of exhaled contaminants in the macroclimate. Hence, an infectedoccupant is better off operating the PV at low frequencies and low flow rates (0.3 Hz and 3.5 L/s) which would still provide comfort but would preventthe contamination of other possible occupants in the room.

Keywords: personalized ventilation, localized dynamic airflow, computational fluid dynamics, particles, confinement