Study On The Influence Of General Ventilation Combined With Local Air Supply On Pollutant Control And Thermal Environment In Isolation Ward

In recent years,mass outbreak of respiratory infectious diseases have brought serious threats to people’s life safety.During the outbreak of the virus,a large number of infected patients were admitted to hospitals,which laid the potential for large-scale nosocomial infection.Isolation ward,as a measure to effectively control the source of infection and cut off transmission routes,has attracted much attention in this context.At present,domestic and foreign scholars have conducted researches on pollutant control and thermal environment assurance in isolation wards when using general ventilation,but the research on the effect of personalized ventilation on reducing the risk of cross infection is still in the exploratory stage.Based on this,this paper proposes a local air supply mode to control pollutant diffusion from the source,and uses Fluent 2021 R1numerical simulation software to explore the influence of local air supply mode combined with overall ventilation mode on pollutant control and thermal environment of the isolation ward.Its main research contents and conclusions are as follows:（1）In order to optimize the local air supply,this paper firstly explored the influence of three parameters of local air supply on the ventilation efficiency and the pollutant concentration nonuniform coefficient in the isolation ward when the ventilation mode of top supply by diffuser and bottom exhaust combined with the optimal local air supply is used in the isolation ward through the orthogonal simulation method.The orthogonal simulation analysis shows that the optimal parameter combination is when the local air supply velocity V is 1.2m/s,the air supply Angleθis15°and the air supply port width D is 10cm.Then,the effect of pollutant control and thermal environment of the ward were analyzed when the ventilation mode of top supply by diffuser and bottom exhaust combined with the optimal local air supply is used in the isolation ward.The research shows that:The temperature and wind speed of most indoor areas can meet the requirements of human comfort under this ventilation mode.（2）The ventilation rate is an important factor affecting air distribution in isolation ward.In this paper,the influence of different ventilation rate(6h^-1,10h^-1,14h^-1 and 18h^-1)on the pollutant control and thermal environment of the isolation ward was investigated by numerical simulation when the ventilation mode of top supply by diffuser and bottom exhaust combined with the optimal local air supply is used in the isolation ward.The results showed that:When the ventilation rate increased to 10h^-1,increasing the ventilation rate had little effect on the infection probability at different locations and ward ventilation efficiency;When the ventilation rate is 10～14h^-1,the indoor wind speed and temperature distribution are relatively suitable.Overall,the recommended ventilation rate is 10～14h^-1.（3）Local air supply is greatly affected by general ventilation.By means of numerical simulation,this paper explores the influence of the combination of local air supply and three different general ventilation modes,which are the same side up-supply and down-exhaust ventilation,the opposite side middle-supply and down-exhaust ventilation,the opposite side up-supply and down-exhaust ventilation on the pollution control and thermal environment of the isolation ward.The research shows that:Local air supply can improve the ventilation capacity of ward without affecting the stability of indoor air flow;The pollutants control effect of the opposite side middle-supply and down-exhaust ventilation combined with local air supply is the best,but its indoor airflow comfort is poor.The air distribution of the same side up-supply and down-exhaust ventilation combined with local air supply is the most stable,but its pollutants control effect is the worst,and its infection probability is the highest.The research results provide a method,scheme reference and theoretical basis for further research on the control of pollutant diffusion and ensuring indoor air quality in isolation wards.