Fig. 1. Schematic diagram of experimental apparatus

Fig. 2. Snapshot of TSI 3321 aerodynamic particle size spectrometer

Fig. 3. Physical model of particle deposition in horizontal circular tube section

Fig. 4. Diagram of effective roughness model

Fig. 5. Comparison of dimensionless deposition rate predicted by three models and historical data (from left to right, the revised formula in this paper, Ahmadi model^[17] and Wood model^[11] are shown)

Fig. 6. Comparison of penetration test results for stainless steel pipe (D=50 mm, L=5 m)

Fig. 7. Comparison of penetration test results for carbon steel pipe (D=50 mm, L=5 m)

Fig. 8. Dimensionless relaxation time of aerosols with different particle sizes under different pipe diameters

Fig. 9. Comparison of experimental results of penetration rate of 10 μm aerosol in stainless-steel pipes at the length of 5 m and diameters of 50 mm, 110 mm respectively

Fig. 10. Comparison of experimental results of penetration rate of 2 μm, 5 μm aerosol in stainless-steel pipes at the length of 5 m and diameters of 50 mm, 110 mm respectively