Thermophoresis is an important mechanism of micro-particle transport due to temperature gradients in the surrounding medium.It has numerous applications

especially in the field of aerosol technology.This study has numerically investigated the thermophoretic deposition efficiency of particles in a laminar gas flow in a concentric annulus using the critical trajectory method.The governing equations are the momentum and energy equations for the gas and the particle equations of motion.The effects of the annulus size

particle diameter

the ratio of inner to outer radius of tube and wall temperature on the deposition efficiency were studied for both developing and fully-developed flows.Simulation results suggest that thermophoretic deposition increases by increasing thermal gradient

deposition distance

and the ratio of inner to outer radius

but decreases with increasing particle size.It has been found that by taking into account the effect of developing flow at the entrance region

higher deposition efficiency was obtained

than fully developed flow.