Study On Propagation Characteristics Of Respiratory Aerosol Droplet Contaminants In Car Cabin

With the rise of the sharing economy,the taxi industry is prevalent,and businesses such as car sharing and carpools are springing up.Carpooling with strangers can save money and enjoy high-quality service,becomimg a way for many people to travel.Therefore,the environment in car cabin is no longer a private environment and gradually becomes a public environment.The car has the characteristics of small space,strong airtightness,fast accumulation of pollutants,high density of personnel,and diverse ventilation modes.It is also one of the places where aerosol particles are transmitted.The existing research content focuses on mechanical ventilation rooms,wards,clean rooms and other large public transport such as aircraft cabins,high-speed rail cars,buses,etc.,but ignores the spread of aerosol particles in the four-seat car.The study on the propagation characteristics of aerosol pollutants in passenger compartments is of great significance.This paper firstly reviews the research status of the characteristics of the source of the aerosol particle,and gives the parameters and influencing factors of the exhaled gases and particles with different behaviors.The geometrical dimensions and air supply boundary conditions of the vehicle were measured by experiments,and the propagation characteristics of aerosols in the vehicle under several typical conditions were tested.Particle trajectory,sedimentation characteristics,average aerosol concentration in the cabin,establishing a breathing zone in front of the personnel and monitoring changes in aerosol concentration in the respiratory zone.Taking the influenza virus as an example,the probability of infection within 4 hours was analyzed.Using CO2 as a tracer gas,the ability to remove aerosol pollutants from the cabin using natural ventilation was analyzed.The results show that 240s is enough time to stabilize the aerosol concentration in the cabin,and the ventilation system has a significant effect on the aerosol concentration in the car during stabilization.The number of air changes is directly related to the aerosol concentration in the car.When only the side air ports are opened,the aerosol concentration in the car does not exceed 9.5e-14kg/m3.When the tuyere is fully open,the average aerosol concentration does not exceed 6.6e-14kg/m3.The aerosol concentrations in the human respiratory zone at different locations are also significantly different,depending on the patient's location and ventilation system.When the patient is in the front row,the aerosol concentration of the person sitting behind the patient is the largest.When the tuyere is fully open,the value is 6.2e-14kg/m3.When a patient has the flu,the risk of the person is up to 7.9%after 4 hours.When the vent is fully open,the patient has less influence on the other three in the back row,the overall aerosol concentration is the lowest,and the probability of infection of the flu is no more than 4%.Natural ventilation can effectively eliminate pollutants in the compartment,and window opening is the most influential factor.Ventilation system form and personnel arrangement have a significant impact on the propagation of aerosol pollutants inside the cabin.Choosing a reasonable ventilation system and personnel location can greatly reduce the spread of disease caused by aerosol aerosol particles.Therefore,the study of the propagation characteristics of the human exhaled aerosol particles in the compartment is important for maintaining a healthy car environment.