Dispersion and deposition of nano aerosol particles in a concentric annulus are investigated numerically. Lattice Boltzmann method and lagrangian particle tracing procedure was used to simulate natural convection flow and to obtain particle trajectories, respectively. Drag, Saffman lift, gravity, buoyancy, Brownian motion and thermophoretic are forces that were included in particle equation of motion. Particle deposition decreases as aerosol particles diameter increases due to Brownian and Thermophoretic effect. Particle removal increases at greater Rayleigh number at constant particle diameter.