Experimental Research on Aerosol Scrubbing Mechanism under Submerged Jet Condition

In severe reactor accidents, the phenomenon of aerosols being captured and retained in the liquid as they follow the gas through the liquid phase often occurs during the discharge process of the suppression pool. It is one of the important thermal-hydraulic phenomena that affect the migration and release of radioactive source terms. Understanding the scrubbing characteristics of aerosols under this condition is of great significance for the radioactive assessment after severe accidents. The paper conducted experimental research on the scrubbing efficiency of aerosol under submerged jet conditions, exploring the influence of parameters such as aerosol diameter, liquid pool temperature, submergence, and injection pressure on the scrubbing efficiency of aerosol. When gas is injected into the liquid phase through a rupture or nozzle in the form of a jet, the entrained droplets generated by high-speed airflow shear will retain a large amount of aerosols in the liquid phase through the inertia effect. The experimental results indicate that an increase in injection pressure enhances the inertial effect, thereby improving the scrubbing efficiency. The increase in submergence also increases the residence time and probability of aerosols in contact with gas-liquid interfaces, ultimately leading to an improvement in scrubbing efficiency. Under steam jet conditions, the generation of thermophoresis and diffusiophoresis effects can improve the scrubbing efficiency of small-diameter aerosols. Under different submergence depths, there is a decreasing and then increasing relationship between scrubbing efficiency and aerosol diameter, with a turning point of around 0.3 μm. The change in liquid and gas temperature can alter the steam condensation rate and temperature gradient, thereby altering the scrubbing efficiency by affecting the thermophoresis and diffusiophoresis effects. After the temperature of the liquid pool decreases, the increase in temperature gradient and steam condensation rate will further improve the scrubbing efficiency. There is an approximate logarithmic relationship between the scrubbing efficiency and the gas-liquid phase temperature difference under the same injection pressure and submergence conditions. However, there are certain constraints on the proportion of thermal effects such as thermophoresis and diffusiophoresis, as well as the effects of inertia and submergence. By summarizing existing relevant experiments and fitting empirical formulas for predicting scrubbing efficiency under submerged jet conditions based on the dominant scrubbing mechanism, the predicted relative deviation range is －15%-25%, which can provide data and theoretical support for relevant experiments and models.