Study On The Effectiveness Of Airflow Organization And Pollutant Control In Hospitals In Severe Cold Regions

Large general hospitals with high turnover,concentrated patients and complex disease types are places with a high density of susceptible people and various infectious agents at the same time.the sudden outbreak of neo-coronavirus in late2019 that caused a large number of healthcare workers to be cross-infected has raised public concerns about indoor air quality in hospitals.The cold outdoor air in severe cold regions directly leads to a significant reduction in the number of window opening behaviors in hospitals,and the fact that neo-coronaviruses can remain active in cold air for long periods of time,all of which puts the safety of indoor air in hospitals in severe cold regions at greater risk.This paper uses a combination of field tests and statistical methods to analyze areas with complex space and staff structure composition such as outpatient clinics and waiting rooms,and a combination of experimental and computational fluid dynamics simulations to study a typical double ward with simple space and staff structure composition.The experimental tests include the concentrations of airborne pollutants such as carbon dioxide,respirable particulate matter and bacteria;the simulations include the study of different airflow organization and its air exchange frequency in a typical two-person ward.After specific tests,it was found that there are air quality problems in the outpatient and waiting areas of large general hospitals in severe cold areas,of which carbon dioxide exceeds the standard is the most significant,the concentration range is between 500ppm-1600 ppm in one day,and the over-standard rate in the hospital personnel gathering area in the morning period is as high as 100%;the control of inhalable particulate matter in the hospital room is better,and there are very few over-standard cases of particulate matter with only 2.5μm particle size(the degree of exceeding the standard is less than 2.3%).Because the epidemic prevention and control requires the wearing of masks to block the route of bacteria,the bacteria content in the indoor air of each hospital tested is only 50% of the relevant standards,but this situation does not mean that bacteria can still be effectively controlled after the end of the epidemic.The influencing factors of the main pollution components are statistically analyzed,including the increase in density caused by the detention of personnel,the actual output of pollutants exceeding the initial design value of the ventilation and air conditioning system,the concentration of pollutants outdoors and the rain and snow weather.A typical double ward also has different degrees of air pollution,especially the side air supply and return airflow organization form has the worst emission effect,combined with CFD simulation to conclude that the central diffuser air supply airflow organization between beds has the best effect,the average concentration of pollutants in the human breathing zone plane can be reduced by 22.7% compared with the side air supply and return form;through CFD numerical simulation to conclude that the side air supply and return airflow organization in the ward can reduce the average concentration of pollutants by 11.7% when the number of air changes per hour is increased to 9.The CFD numerical simulation shows that the average concentration of pollutant gases can be reduced by 11.7% when the number of air changes per hour is increased to 9 for the airflow organization of side air supply and return,by 10.3% when the number of air changes per hour is increased to8 for the airflow organization of central diffuser supply and return,and by 13.4%when the average concentration of pollutant gases is reduced by 9 air changes per hour for the airflow organization of side air supply and return.The average concentration of pollutant gases can be reduced by the average of 14 air changes per hour by the airflow organization of the airflow organization of the side air supply and return air,which shows that there is a mutually constraining relationship between the airflow organization form and the number of air changes in the ward,and the high efficiency airflow organization form can also ensure better indoor air quality by appropriately reducing the number of air changes.