Investigation on the Contaminant Distribution with Dedicated Outdoor Air System in Restaurant

Abstract

The continual transmission of epidemics makes health workers aware of the importance of airborne transmission in special cases. The well-known equation Wells-Riley highlights the importance of ventilation to dilution of infectious aerosol as well. And the airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been confirmed. The main problem of the coronavirus disease 2019 (COVID-19) epidemic of three families in a restaurant in Guangzhou lies in unreasonable ventilation. An air-conditioning system of Ceiling radiant cooling plate (CRCP) combined with a dedicated outdoor air system (DOAS) has been proposed in this paper. The simulation of the diffusion of tiny exhaled droplets is carried out through SF6 tracer gas. A numerical simulation of the original indoor air distribution of the restaurant and that of the new air-conditioning system has been conducted. Pollutant concentrations of different indoor locations and exposure indexes under four working conditions of ventilation rates 3, 6, 9, and 12 ACH are calculated. The results suggest that the air supply mode of air conditioners put forward in this paper can decrease the risk of indoor infection to a large extent. When the ventilation rate is 1L/s, the probability of infection is very high. With the increase in ventilation times, the risk of infection gradually decreases. Offering suitable ventilation in crowded spaces can greatly prevent and control the air transmission of coronavirus.