| People spend 80% of their time indoors,so the indoor environment is closely related to human health.Among them,indoor fine particles are one of the main factors that affect the indoor environment.Therefore,the movement and distribution of fine particles in the room have received widespread attention.Near-wall heat sources(such as radiators,wall lamps,etc.)are ubiquitous in the indoor environment,which is one of the important factors affecting the movement and deposition of indoor fine particles.However,there are relatively few studies on indoor particle movement and its deposition on the wall surface under the influence of near-wall heat sources.Therefore,based on the DEM discrete element method,this paper establishes a three-dimensional mathematical model of gas-solid two-phase flow,considers the two-way coupling between particles and gas,simulates the movement process of fine particles under the action of near-wall heat sources,and quantitatively characterizes the fine particles in indoor space As well as the distribution characteristics on the near-wall surface,the movement and deposition rules of particles under the influence of different radiator temperature,particle size and radiator spacing are obtained.Through research,it aims to provide theoretical guidance for understanding the movement and deposition laws of indoor fine particles under the action of near-wall heat sources and seeking control strategies.First,this paper establishes a 3D physical model of gas-solid two-phase flow and a CFD-DEM mathematical model to determine the calculation parameters of the discrete phase of particles and the continuous phase of air.By comparing with the experimental data in relevant literature and the actual observation phenomena in this paper,The accuracy of the model is verified and the feasibility of the CFD-DEM coupled simulation method is established,thereby establishing a suitable method for indoor gas-solid two-phase flow simulation.Then,this paper uses the established CFD-DEM mathematical model to conduct a gas-solid two-way coupling simulation study on the movement of indoor fine particles under the action of near-wall radiators.The movement distribution of fine particles in the indoor space under the influence of different factors such as different radiator temperatures,radiator spacing and particle size,etc.is obtained.Based on the analysis ofthe indoor air flow field and temperature field,different factors are compared and analyzed.The influence law of fine particle motion distribution.The study found that under the action of the radiator,the gas in the area directly above the radiator and the area near the ceiling has a large velocity and a high temperature;affected by the air flow,the indoor fine particles are mainly distributed near the radiator near the wall and the ceiling Area;and along the indoor height,the rising speed of the particles shows a gradually increasing trend,and after being blocked by the ceiling and changing the direction of movement,the speed gradually decreases;the temperature of the radiator increases,and the speed of the upward movement of the particles increases,And gradually move closer to the radiator near the wall during the movement;as the particle size increases,the particle beam formed above the radiator becomes thinner and thinner;the distance between the radiator plates increases,making the particles in the upper space of the radiator The concentration showed a gradual decrease in the law of change.After obtaining and analyzing the movement distribution of fine particles in the indoor space,this paper conducts a CFD-DEM two-way quantitative simulation study on the deposition of indoor fine particles under the action of radiators on the near-wall and ceiling surfaces.Quantitatively characterize the deposition of fine particles on the near-wall surface by the particle deposition concentration;comparatively analyze the influence of different radiator temperature,radiator spacing and particle size on the deposition of fine particles.The study found that: as the temperature of the radiator increases,the deposition concentration of particles on the near-wall surface gradually increases;as the particle size increases,the particle deposition concentration on the ceiling surface gradually decreases;when the particle size is less than 10?m At the time,the particle deposition concentration on the near wall surface increases with the increase of the particle size,and when the particle size is greater than 10?m,the particle deposition concentration on the near wall surface instead shows the particle size The law of increasing and decreasing;with the increase of the distance between the radiator plates,the particle deposition concentration on the near-wall surface shows a gradually decreasing rule. |
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