Numerical Study of Thermophoretic and Inertial Deposition of Aerosol Particles on a Heat Exchanger Tube Under Flue Gas Conditions

Recovering low‐grade waste heat from coal‐fired flue gas is crucial for improving power plant efficiency and reducing emissions. However, substantial aerosol deposition on heat exchanger tubes undermines long‐term system performance. Although thermophoresis dominates submicron particle transport under thermal gradients, many existing studies overlook the coupled effects of turbulence and particle‐surface interactions in the medium‐to‐low temperature range typical of heat recovery applications. To address these gaps, we developed and validated a comprehensive computational fluid dynamics (CFD) model that integrates large eddy simulation (LES) for resolving turbulent flow around tubes, a discrete phase model (DPM) for tracking particle motion under thermophoretic and Brownian forces, and a user‐defined sticking/rebound criterion for particle‐wall interactions. Model validation against experimental and numerical benchmarks confirmed its accuracy in capturing vortex shedding, thermophoretic deposition, and particle impact behavior. Key results demonstrate that total deposition efficiency reaches a lower particle deposition efficiency at Stokes numbers ( St ) between 0.01 and 0.1, delineating the transition from thermophoresis‐ to inertia‐dominated regimes. For St < 0.01, thermophoresis dominates particle deposition, with deposition efficiency decreasing at higher flow velocities and with larger particles. For St > 0.1, inertial impaction dominates, particularly on tube windward surfaces. Furthermore, while larger gas‐to‐wall temperature gradients enhance deposition—especially for small particles—this effect weakens as particle inertia increases. This work establishes a reliable predictive framework for aerosol deposition under practical flue gas conditions, providing valuable guidance for designing fouling‐resistant heat recovery systems.