Investigation of particle transport in offices equipped with ceiling-mounted personalized ventilators

The performance of ceiling-mounted personalized ventilators (PV) in reducing particle migration between office stations was assessed. The PV nozzles were integrated with peripheral diffusers that were able to form a canopy of conditioned air around the occupant. A numerical CFD model was developed to simulate the flow, temperature and particle concentration fields. Validation against experimental measurements and published experimental data was performed. The canopy was effective in reducing the migration of particles from the macroclimate to the microclimate region and low intake fractions of 1.90 × 10−4 and 5.9 × 10−4 were achieved for particle sizes of 1 μm and 0.01 μm, respectively. The PV jet was capable of maintaining an intake fraction of 3.6 × 10−4 for fine particle sizes (1 μm) and 2.95 × 10−4 for ultrafine particles (0.01 μm) when the particle-emitting source is in the proximity of the occupant. However, in spite of the good inhaled air quality achieved by the PV nozzle, the particle deposition rate on solid surfaces that are easily reached by the occupant is high when the source is placed in the microclimate.

► A ceiling-mounted coaxial PV nozzle was modeled.
► Particle transport and distribution was investigated using two sources locations.
► The predicted flow characteristics were validated experimentally.
► The nozzle was able to deliver improved air quality to the occupants breathing zone.
► The canopy provided a protective zone by reducing particles migration.