Fine Particulate Matter In Office Buildings Distribution Characteristics

With the deterioration of haze and the increasing emission of automobile exhaust,outdoor air pollution is becoming more and more serious,which causes serious indoor air pollution.The main cause of indoor and outdoor air pollution is the presence of suspended particulate matter in the air.In recent years,the problem of indoor particulate matter pollution has become the focus of the relevant scholars' work.Because the larger particulate matter can settle naturally under the action of gravity,and will not enter the human body with breathing,while the smaller particulate matter floats in the air for a long time,and produces secondary suspension under the influence of airflow,which is difficult to be purified,and easy to enter the human body,and seriously endangers human beings.Therefore,the study of indoor fine particulate matter has more practical significance.Based on this background,the physical model of office building is established.Turbulence and discrete phase model are used to simulate the fine particulate matter concentration distribution in office room.The effects of window opening type,the position of fine particulate matter released during air conditioning and the angle of air supply on the diffusion movement and concentration distribution of fine particulate matter in the room are analyzed.The dynamic characteristics of indoor fine particulate matter concentration in foggy and non-foggy days were tested.The results show that:(1)Under natural ventilation,fine particulate matter mainly distributes in the corner far from the door and the lower part of the room,and the concentration of fineparticulate matter in the lower part of the room by the window is higher than that in the far side of the room;when the side window is suspended,the fine particulate matter mainly distributes in the lower part of the room and the corner areas on both sides of the window;when the window is suspended,the fine particulate matter distributes uniformly in the horizontal and vertical directions;when the window is suspended,the fine particulate matter distribute The particulate matter mainly distributes at the bottom of the room and on both sides of the room,and the particulate matter concentration in the left area of the room is lower than that in the right area when the window looks to the door.Under the same indoor and outdoor conditions,the indoor fine particulate matter concentration levels of different window types were as follows: lower suspension window < side suspension window< upper suspension window < push-pull window.(2)The indoor air velocity in the air supply area is larger,which is beneficial to the diffusion of fine particles.The air velocity in the air return area is relatively small,and the diffusion of fine particles is weak,which is not conducive to the purification of indoor pollutants.Under the same conditions,when the emission source is close to the air outlet,it is more conducive to the diffusion and dilution of indoor fine particulate matter,and can reduce the indoor average fine particulate matter concentration more quickly.(3)Along the vertical direction of the room,when the angle of supply air is 0~10,the influence of supply air on indoor fine particulate matter concentration is weak.When the angle of supply air is 10 ~20 the area below the breathing plane(Z=1.2m)increases with the angle of supply air,the concentration of fine particulate matter decreases,and the area above the breathing plane(Z=1.2m)increases with the angle of supply air,and the concentration of fine particulate matter increases alongthe direction of the room The concentration of fine particulate matter in the working area is less affected at 0 ~10.The concentration of fine particulate matter increases with the increase of air supply angle in the two sides of the room.The concentration of fine particulate matter in the two sides of the room is less affected by the air supply angle at 10 ~20.The concentration of fine particulate matter increases with the increase of air supply angle in the working area.(4)In fog and haze weather,due to the closure of doors and windows,indoor and outdoor air flow is not smooth,which weakens the dilution of indoor fine particles.Fine particles have been suspended indoors,seriously affecting the health of indoor personnel. After about two and a half hours of natural sedimentation and self-purification,indoor fine particles concentration dropped to the level of indoor concentration before smoking. In NON-HAZE weather,the test found that when smokers smoked closer to the downstream of the room airflow,fine particulate matter was more likely to be discharged outdoors in a shorter time,which was more conducive to purifying the indoor environment.