Study on the characteristics of aerosol diffusiophoresis deposition on the outer surface of a vertical circular tube

The deposition behavior of aerosols due to diffusiophoresis directly influences the migration and deposition of radioactive materials following an accident. This is critical in analyzing source term migration and the precise evaluation of radiological consequences for personnel. Several aerosol deposition experiments were conducted under steam condensation conditions on the external surface of the cooling tube to investigate the diffusiophoresis deposition characteristics of particles in the containment vessel when the PCS system is activated. The experiments demonstrated that the diffusiophoresis deposition rate on the external surface of the cooling tube decreases with increasing steam density but increases with the rise in steam volume fraction. Theoretical analysis combined with data extraction techniques determined the aerosol concentration decay rate on the external surface of the cooling tube under the sole influence of diffusiophoresis. An improved diffusiophoresis deposition model incorporating suction effects was proposed based on relevant heat transfer studies involving non-condensable gases. The comparison of model results showed that the deviation between the improved model and experimental values is within ±10%, outperforming the predictions of the original model. According to the improved model and experimental results, it was found that a 38mm tube diameter is more susceptible to the accumulation of incondensable gases, and the suction effect has a more significant promoting influence on diffusiophoresis deposition compared to a 19mm tube diameter.