Abstract/Summary

People pay close attention to prevent and control the airborne transmission of respiratory diseases, and effective ventilation can reduce the cross-infection risk. Nevertheless, in winter, poor indoor ventilation is common, and the survival rate of the virus is also high. The issue of cross infection in enclosed spaces should be worthy of more attention especially during winter. This study was to comprehensively compare the dispersion of exhaled particles with different diameters under different air distributions for heating. Computational fluid dynamics (CFD) method validated by experiments was utilized to model the exhaled particle dispersion in a two-person typical office under five air distributions (i.e., Mixing Ventilation (MV), Stratum Ventilation (SV), Deflection Ventilation (DeV), Impinging Jet Ventilation (IJV), and Wall Attachment Jet ventilation (WAJ)) having potentials for heating. Results showed that different air distributions had significant impacts on the characteristics of exhaled particle dispersion in heating mode. The difference of average normalized particle concentration at the breathing zone can be up to 8 times. Additionally, the particle dispersion in winter can be distinct from that in summer due to effect of positive thermal buoyancy, especially for fine particles (d ≤ 10 μm). With the specified conditions of this study, according to the proportions of removed exhaled particles, DeV performed best with a removal efficiency of more than 60% for fine particles, followed by SV, WAJ, and IJV. The removal efficiency for fine particles of DeV, SV, WAJ, and IJV were 61.86%, 52.43%, 38.95%, and 36.40% respectively. MV with a typical layout of high-side supply and ceiling exhaust exhibited the worst performance, with a removal efficiency of only 27.61%.