The Difference Of Fine Particle Deposition In The Gas And Liquid Medium

The coolant of nuclear reactor can be selected for gas or liquid (liquid lead bismuth alloy or water and so on) medium. Fine particles exist in the fluid, flow with the movement of fluid, through the pipeline and equipment. Particle deposit on the through pipe and equipment, will have a huge risk to the safety and economic of system. At the same time, the media will experience the liquid to the gas transition process when the nuclear power plant in a serious accident state. Gas and liquid deposition of different laws, may affect the development of accidents, deteriorate the consequences of the accident. The numerical simulation of FLUENT and PDtion1.0 was carried out to calculate the fine particles (0.1μm～10μm) deposition in gas and liquid. Then the sensitivity of input parameters and the deposition rate will be obtained. Under this condition, the differential mechanism will be proposed.The gas deposition rate calculation results show that, (1) gas temperature along axial distribution logarithmic decrease. (2) thermophoresis deposition rate positively related to the temperature and negative related to the diameter and average velocity. (3) turbulent deposition rate decreases at first and then increased with the increase of average temperature gradient, positively related to diameter and average velocity. (4) the total deposition rate positively correlated with the average temperature, decrease at first and then increase with the velocity of flow.The liquid deposition rate calculation results show that, (1) liquid temperature along axial distribution linearly decreases. (2) the thermophoresis deposition rate of fine particles in the liquid is positively correlated with temperature and negatively correlated with diameter, liquid lead bismuth alloy thermophoresis deposition rate decreases with the increase of velocity, and negatively correlated in water. (3) the turbulent deposition rate of fine particles in the liquid are positively correlated with temperature gradient, average velocity and diameter. (4) the total deposition rate of liquid is decreases at first and then increases with the increase of diameter, it is positively correlated with temperature, in liquid lead bismuth alloy, it is increase at first and then decrease with the increase of velocity, it is negatively correlated in water.The differences between in gas and liquid, (1) the temperature in liquid reduce with linear but logarithmic in gas. (2) the thermophoresis deposition rate in liquid change more quickly under the same conditions. (3) the max sensitivity to particle size is air turbulence deposition rate, air total deposition rate to temperature and water total deposition rate to velocity.The difference mechanism between gas and liquid, (1) the influence of temperature to gas therm ophoresis deposition rate and turbulent deposition rate is bigger than that in liquid. (2) the influence of diameter to gas thermophoresis deposition rate and turbulent deposition rate is smaller than that in liquid. (3) the influence of velocity to thermophoresis deposition rate and turbulent deposition rate in liquid is bigger than that in gas. At low speed, liquid total deposition rate is influenced bigger, but at high speed, the gas total deposition rate is bigger one. (4) Under the same conditions, the total deposition rate in gas is bigger than that in liquid.