Numerical investigation of interpersonal respiratory aerosol transmission risks and mitigation strategies in an impinging jet ventilation room

Abstract

Impinging jet ventilation (IJV) systems offer significant advantages in maintaining indoor air quality. However, the influence of thermal stratification on the spread of the respiratory aerosol in IJV rooms has not yet been fully studied. The present study used validated numerical simulation methods to investigate the transport of respiratory aerosols and their impact on occupant exposure under typical thermal stratification conditions. Furthermore, the efficacy of various return vent layout strategies in controlling aerosol exposure was systematically evaluated. The results showed that the respiratory aerosol is ‘lock-up’ under thermal stratification scenarios at the height near the thermal stratification interface or infected person. This locking behaviour is contingent upon the relative positioning of the infected person in relation to the thermally stratified interface. The aerosol exposure in IJV rooms can be effectively reduced by reasonably adjusting the thermal length scale (L_m) to generate suitable thermal stratification. When L_m is kept between 1.15 and 1.27, exposed individuals’ intake fraction (iF) is the lowest overall. Moreover, in IJV systems employing the exhaust/return-split configuration, it is recommended to situate the return vent near the thermal stratification height. In this case, the iF can be reduced by approximately 25–60%.