Experimental Study Of Airflow And Pollutant Dispersion In Cross-ventilated Multi-room Buildings Under Different Ventilation Path

Indoor air quality?IAQ?problem and associated health risks,determined by the indoor air pollutant,are of great concern in modern society.Due to the outbreak of SARS in 2003 and the global infection of COVID-19 in 2019,maintaining healthy and safe indoor air quality has been widely recognized.Natural ventilation has been demonstrated to be a ventilation strategy that can maintain a healthy and comfortable indoor air quality as well as plays a key role in influencing the indoor pollutant dispersion.Therefore,it is very important to understand the influence of different ventilation paths,the location of pollution source and the ventilation rate on the indoor flow field and pollutant dispersion characteristics under natural ventilation.In this paper,the effects of different ventilation paths on air distribution and pollutant dispersion in multi-room buildings are studied by means of experimental measurement.With SF₆ as tracer gas,the classical Wells-Riley model was used to evaluate the risk of indoor airborne transmission of infectious diseases.In this paper,a natural ventilated scaled?1:2?multi-room test chamber is taken as the research object.The prototype of the test chamber is a common central-corridor slap-shaped building.A wind wall system was developed to simulate the cross-ventilated environment.The window and door in each room was used as cross ventilation openings for the study,enabling three ventilation path test scenarios for the experiments.The variation of the pollutant source location was also considered.Tracer gas technique was employed to reveal the pollutant dispersion features in the multi-room chamber under different scenarios.Both the air velocity and tracer gas concentrations at selected key positions in the chamber were measured and compared.Based on the data obtained,the pollutant dispersion characteristics are analyzed;taking indoor airborne infectious diseases as an example,the risk assessment of pollutant dispersion was evaluated in this paper.This results shows that under the same conditions of incoming flow rate,first,the pollutant concentration in the index room is lower than that in the receptor room;second,under corner release mode the concentration values in index room are almost twice larger than that in index unit under central release mode,the concentrations in receptor room can be up to 40%higher than that in corresponding receptor room under center release mode;finally,under the scenarios setting in this paper,the probability of infection in the receptor rooms are all higher than that in the index room,and the corner release mode will increase the risk of infection,and the infection risk of which is about 2 times higher than that in the central release mode.Increased ventilation rate can effectively reduce air-borne certain common respiratory infections and influenza.The meaning of this study is to give some useful insights into the airflow pollutant dispersion process in cross-ventilated multi-room buildings and provide a valuable database for the validation of CFD simulations.Meanwhile,the results could provide a reference for the exposure risk assessment airborne infectious diseases.