Numerical investigation of the effects of fan-coil airflow direction on distribution and deposition of indoor pollutant particles

Abstract

Given the high concentration of particulate pollutants in the indoor environment compared to outdoor environment and their harmful effects on human health, it is important to examine the effect of indoor ventilation systems on distribution and deposition of particulate pollutants. Floor-mounted fan-coils have various airflow directions, but the effects of different directions on particle distribution and deposition have not been investigated in previous studies. Thus, the present study aims to investigate the indoor air quality in a room with vertical, 60 inclined, 30 inclined, and horizontal discharge fan-coils. Accordingly, the concentration of particles with a uniform initial distribution was evaluated in the room while considering the occupants’ thermal comfort conditions for four different modes of airflow using computational fluid dynamics and solver packages developed in OpenFOAM® solver by the authors. The particles with 2.5, 10, and 25 μm diameters were considered to examine the effect of particles size on their distribution and deposition. The results indicated that the percentages of 2.5 μm filtered particles for vertical, 60 inclined, 30 inclined, and horizontal fan-coil discharge modes after 600 s were about 93, 84, 76 and 93%, respectively. Also, for all discharge modes, the percentage of 2.5 μm deposited particles on the floor was less than 1%. The results also indicated that after about 975, 1800, 1390 and 940 s, the concentration of 2.5 μm particles reached 1% of their initial concentration, for vertical, 60 inclined, 30 inclined and horizontal fan-coil discharge modes respectively. As the particle size increased, the percentage of filtered particles decreased, while the percentage of particles deposited on the floor increased. Specifically, the percentages of deposited 25 μm particles under the vertical, 60 inclined, 30 inclined and horizontal discharge modes were about 36, 45, 66, and 49%, respectively.