Research On Movement And Deposition Of Particles In Different Fluid Media

The phenomenon of particle diffusion and deposition is commonly exist in field of nature and industrial production.The density,thermal conductivity,specific pressure and dynamic viscosity of different fluid media have important influence on deposition of particles.The rule of particle movement and deposition in air,liquid sodium and supercritical water medium are studied respectively.It is helpful to analyze the law of haze movement,particle movement in gas exhaust channel of power plant,the rule of particle movement and deposition in coolant channel of fast reactor core and supercritical water reactor.The experiment system of particle movement in different fluids media are designed to provide reference for building the experimental platform.Using ANSYS CFD software,the particle movement and deposition in the air,liquid sodium and supercritical water medium is studied by the method of numerical simulation.The geometric model of rectangular channel and ring channel are established by using ICEM software,and the computational models are introduced into the FLUENT software.The movement and deposition rules of particles in air,liquid sodium and supercritical water are calculated in rectangular channel.The movement and deposition rules of particles in supercritical water medium are calculated in the circular channel.It is concluded that the particle movement and deposition in different fluids have commonness and difference.Commonness of particle motion deposition in different fluids:The particle concentration at the inlet is smaller than the particle concentration at the outlet,and the particle concentration distribution at the outlet section is high at the center,but low at the boundary.The particle concentration near the wall is higher than that in the mainstream.The difference of particle motion deposition in different fluids:The fluctuation of particle motion is the largest in the air medium,and the fluctuation of particle motion in liquid sodium and supercritical water is small.The particle concentration in the air medium is the largest,and the particle concentration in liquid sodium and supercritical water is small.Calculating the efficiency of thermophoresis deposition in different fluids by self-made PA-MO-DE program.The mechanism of particle movement and deposition in different fluids are analyzed.The effects of particle size,temperature difference and velocity on the efficiency of particle deposition are calculated.The mechanism of particle agglomeration,decomposition,thermophoresis deposition and turbulence deposition is analyzed.It is found that the agglomeration increase the particle size,which is beneficial to the deposition of particles in liquid sodium and supercritical water,but is not conducive to the deposition of particles in the air.The decomposition decrease the particle size,which is beneficial to the deposition of particles in liquid sodium and supercritical water,but is not conducive to particle deposition in the air medium.The particles in different fluids media are moving to the direction of low temperature under the temperature gradient by thermophoresis force.The parlicies are deposited in the direction of low velocity under the velocity gradient by turbulence force.The experiment system of particle motion in air,liquid sodium and supercritical water medium are designed.The main equipment of different experimental systems are compared.It is concluded that the experimental systems of different fluids medium contains visual experimental section,cooling device and particle motion detection device.The visualized experimental section in air medium is rectangular pipe,the experimental section is cooled by water,the particle motion detection device is PDA.The visualization experiment section in liquid sodium medium is high temperature resistant rectangular pipe.The particles circulate in the experimental section.The experimental section is cooled by air,and the particle motion detection device is electromagnetic induction particle concentration detector.The visualized experimental section in supercritical water medium is a high temperature and high pressure resistant annular pipe.The particles circulate in the experimental section.the experimental section is cooled by air,and the particle motion detection device is a tracer particle detector.