Study On Indoor Dispersion Of The Outdoor Particulate Pollutants Based On Euler-lagrange Method

In recent years,the serious deterioration of outdoor air quality and the flood of smog make concentration of pollutants increase indoor,which is harmful to the health of indoor people.The outdoor particles mainly enter into the room through doors,windows and ventilation systems.After reaching the room,the diffusion and distribution of the indoor particles seriously affect IAQ.The main factor affecting the diffusion of particles is the air flow.The research of this kind of diffusion is a hot field in the current IAQ.It is of great scientific significance and value to develop for us to improve the related research methods and reveal the physical mechanism of its diffusion.In this paper,the effect of airflow on the diffusion of granular pollutants is theoretically analyzed and numerically simulated.In this paper,the influence of PM2.5 on IAQ and office environment in a typical graduate studio of a university in the winter and summer is systematically studied by learning from predecessors' theoretical,simulation and experimental research results of the diffusion problems and utilizing modern numerical computation technology.The specific work is as follows.Firstly,PM2.5 was analyzed in the force.The result showed gravity,drag force and Brown force were the main forces.At the same time,the way of particles pouring into the room was explained.It was found that the particulate matters in the heating room which closed doors and windows in winter were mainly brought into the room by the permeation wind,and about air conditioning room in the summer closing doors and windows they were mainly brought by air conditioning.The concentration of outdoor particle pollution source is referred to the air quality forecast month by month.Secondly,the physical model of room under different conditions was established inwinter and summer.The Euler Lagrange method was used to simulate the temperature field,velocity field and the concentration field of the particles in the room under different conditions.In winter,it was divided into two kinds of conditions: floor heating and radiator heating,and in summer it was divided into three kinds of mixed ventilation from both sides(send up and back down),displacement ventilation and floor air supply.At last corresponding results were obtained by simulation.Finally,according to the analysis of the simulated results,it was found that the concentration of particles in different air flow forms was completely different.In winter,the air flow in the room was mainly influenced by the temperature gradient in the room besides the influence of the infiltration wind.Under the two heating modes,the particle concentration field in the room was affected by the air velocity field and the particles mainly exist under the window.The distribution of particles in the floor heating room was more conducive to the health of the persons,and the temperature field was also more uniform.However,the heating of the radiator will bring more particles to the room,and the heat source of the radiator heating room had a much greater impact on the particles than the floor heating.Besides,we can see that the cold air infiltration and window heat transfer have great influence in the temperature field distribution.The particles in the air-conditioned room were mainly affected by the air flow in summer.It was found that the distribution of particles in the mixed ventilation room was more beneficial to the health of the people,but the temperature distribution was not uniform.As the particles of mixed ventilation entered the room,they would be disturbed by the velocity of air,so they moved directly to the outlet side,and only a small amount of particles were distributed elsewhere in the room.The distribution of particles in the displacement ventilation was chaotic,and the particles moved from the ground to the outlet of the upper room with the air flow,after that they were full of the whole room.And in a room,the floor air sent particles directly to the upper room,and then moved downward because of gravity and circulation,causing a large number of particles to gather near the vent.In winter,because of closed doors and windows,small gaps,limited grain,and low concentration,in the selection of floor heating,as long as the room had a good sealing property of doors and windows,it could be more easy to control for indoor particulatepollutants,but the room still needed an air ventilation when the outdoor air quality might be good.Although the concentration of outdoor particles was relatively low in summer,the indoor concentration was still high because of the relatively large air supply.And,the particles in the room could only be controlled by air conditioning in summer.In addition to paying attention to the filter of air conditioning,using high efficient filter network,it would effectively solve the problem of high concentration of indoor particles,and further improve the indoor air quality to select and adopt more effective air organization forms.The theoretical exploration,simulation calculation and motion analysis of the particle diffusion in the room in the paper will definitely have a certain reference value and guiding significance for the layout design of building rooms and air distribution design of air conditioning in the future.