Influence Of Different Airflow Organization Modes In The Atrium On The Distribution Of Particulate Matter Concentration

In today’s life,people’s daily production,life,rest and entertainment are basically spent indoors.The air quality of the indoor environment closely affects people’s health.Particulate matter is the main reason for affecting indoor air quality,and it will also cause serious harm to human health.so the research on particulate matter is very important.The distribution characteristics of indoor air distribution in buildings significantly affect the distribution characteristics of indoor particulate matter.This paper takes a commercial atrium in Xi’an as the research object,and uses CFD software to simulate the distribution characteristics of the flow field in the atrium under the methods of top-to-bottom,stratified air-conditioning and displacement ventilation(the air supply vents are arranged in two different ways in the atrium).Then,the three different airflow organization modes and the concentration distribution characteristics of particulate matter(PM2.5,PM10)in the atrium under summer working conditions are obtained.The internal flow field and particulate matter field of the atrium are judged for each airflow organization mode.The conclusions of this study are as follows:(1)From the perspective of flow field distribution:under the cooling condition in summer,comparing the four different air supply methods,under the top-to-bottom return method,the "chimney effect" of the atrium is more obvious,and the uniformity of the wind field distribution in the working area is relatively high.Poor,the temperature distribution uniformity is better.The proportion of wind speed and temperature compliance is above 50%.Under the stratified air conditioning mode,the uniformity of wind speed and temperature distribution is good,but the wind speed in the working area is low,and the area with wind speed≤0.3m/s only accounts for 48%,which is easy to produce a feeling of blowing.In the displacement ventilation(internal arrangement of the tuyere),the uniformity of wind speed and temperature distribution is also good,the wind speed and temperature of the working area are within the comfortable range,the proportion of the temperature reaching the standard is more than 70%,and the proportion of the wind speed reaching the standard is as high as 95%.Under the methods of stratified air conditioning and displacement ventilation(internal arrangement of air vents),the "chimney effect" in the atrium is not obvious,and the vertical temperature stratification phenomenon is obvious.Under the displacement ventilation(arrangement around the tuyere),the "chimney effect" in the atrium is more obvious,the uniformity of the wind field distribution in the work area is good,and the uniformity of the temperature distribution is poor,and the wind speed and temperature in the work area are within the comfortable range.The proportion of the temperature reaching the standard is more than 80%,and the proportion of the wind speed reaching the standard is as high as 99%.(2)For the particle concentration distribution:the distribution characteristics of the flow field have a significant impact on the particle concentration distribution.①From the perspective of the entire atrium space,in the top-down delivery mode,the particles will converge in the central area of the atrium,and in the vertical direction,the particles will spread to the entire atrium space with the rising airflow;in the tiered air supply mode,the particles will In the atrium,there is a distribution characteristic of the word "1".The concentration of the word "1" is high in the area of the word "1",the concentration on both sides of the word "1" is low,and the concentration around the atrium is high.In the air mode,when the air supply outlets are evenly arranged inside the atrium,the particles are basically concentrated in the working area of the atrium,and the upper part of the atrium is almost in the clean area;when the air supply outlets are evenly arranged around the atrium,the concentration of particles is distributed in the top delivery area.The air supply method of the lower return is the same,converging to the central area of the atrium,and spreading to the entire atrium space along with the updraft in the vertical direction.②From the perspective of the inner working area of the atrium,under the air supply mode of layered air conditioning,the concentration of particulate matter in the human work area is relatively low,followed by the top and bottom return air supply mode.The air quality in the working area is greatly reduced.③Combining the flow field distribution characteristics of three different airflow organization modes,the place with high particle concentration distribution just coincides with the area where the local circulation of the airflow and the intersection of the airflow occur.At the same time,the thermal buoyancy effect generated by the rising thermal airflow will also increase the concentration of particulate matter in the building.④Under the four methods,the compliance rate of PM10 concentration in the atrium is basically above 90%,which is at a relatively high level.Therefore,in terms of indoor particulate matter control,it is necessary to strengthen the monitoring of PM2.5 concentration,focusing on the study of PM2.5 in air-conditioned rooms.At the same time,it can increase the fresh air volume,increase the return air or exhaust air ratio,and adopt a reasonable airflow organization method to reduce the indoor PM2.5 concentration.