Study On The Influence Of Different Indoor Environmental Factors On The Motion Characteristics Of Inhalable Particulate Matter

Studies have shown that humans live in indoor environments about 70-90% of the time.With the improvement of life quality and the increasing emphasis on human health,indoor environment quality has attracted more and more attention from people.The inhalable particulate matter in the indoor environment is easy to carry virus and bacteria from the human respiratory tract into the body,which has an impact on human health.Indoor environmental factors are complex and diverse,and factors such as wall materials,air humidity,ventilation and indoor activities will cause indoor particulate matter movement changes.Therefore,it is of great significance to study the influence of different indoor environmental factors on the motion characteristics of inhalable particulate matter.Through the combination of experimental research and numerical simulation,we explore the movements and causes of inhalable particulate matter under different indoor environmental factors(humidity,ventilation,human activity),and understand the changing rule in the mass concentration and number concentration of particulate matter.The main research work of this paper is as follows:1.The indoor relative humidity was adjusted to the requirement of the experiment(RH = 50%,60%,70%,80%)by the humidity control instrument.In the case of four kinds of humidity,the mass concentration,number concentration and suspension rate of particulate matter on the breathing surface of indoor people sitting were analyzed.The mass concentration and number concentration in air are closely related to relative humidity.2.The variation of indoor particulate matter concentration was studied by changing the ventilation velocity of indoor central air conditioner.Under different ventilation wind speeds,the variation of the particle concentration of different particle sizes is different.When the diameter of particulate matter is greater than 2.0 μm and the concentration of particulate matter in the air is less than the initial concentration.It can be seen that air conditioning ventilation can play a purification effect on indoor particulate matter with larger particle size.3.CFD technology was used to simulate the variation of mass concentration in different ventilation wind speeds in the room,compare and analyze with the experiment,and analyze the indoor airflow velocity field.When the central air conditioner is turned on,the mass concentration of the particulate matter in the plane rises rapidly and then decreases,and a part of the particle escapes from the return air outlet,and a part of the particle settles.From the velocity field,it can be found that the vortex existing in the room is one of the factors causing the complex movement of the particles.4.During the gait cycle of foot walking,the airflow around the shoes and the movement of the particles were studied.A high-speed airflow is generated in the gap between the shoe and the ground,and the particulate matter deposited on the ground is carried into the air.Both the top of the shoe and the heel of the shoe produce vortices of different sizes.These vortices play an important role in the resuspension of the particles.The innovations can be summarized as follows: Based on the results of previous research,the relative humidity range is expanded,from low humidity(50%)to high humidity(80%).The effects of four relative humidity on the movement of particles caused by human walking are studied.The effects of central air conditioning on particle mass concentration and number concentration were studied by a combination of numerical simulation and experiment.The walking process of the footsteps in a gait cycle is more accurately simulated,and the airflow and particle motion around the shoes are analyzed.This paper analyzes the influence of different indoor environmental factors on the motion characteristics of inhalable particulate matter,which is of great significance for improving indoor environment.