Study on the coal dust deposition fraction and site in the upper respiratory tract under different particle sizes and labor intensities

In order to study the dust exposure amount and coal dust deposition rule of coal miners under different labor intensity in coal mine environment, an airflow-particle two-phase coupling calculation model of human upper respiratory tract was established based on Euler-Lagrange framework, and the airflow field in the upper respiratory tract and the char-acteristics of coal dust deposition were simulated and studied. By comparing the experimental data, the relative error of simulation is in the range of 1.5 %-11.2 %. The results showed that the total deposition fraction of 1 mu m dust was the smallest (0.61-1.20 %), and was relatively less affected by respiratory intensity, and the overall distribution was uni-form. When the dust particle size increased to 7.07 mu m, the total dust deposition fraction in the nasal cavity, pharynx and larynx was in the range of 11.10 %-20.91 %, and increased with the respiratory intensity. When the dust particle size was large, the dust particles of 20 mu m and 80 mu m were mostly concentrated in the front of the nasal cavity, and the deposition amount of 80 mu m dust was about 99.52 %. It was found that with the increase of dust particle size or the increase of labor intensity, the possibility of dust being transported into lungs became smaller. The fitting function of 7.07 mu m dust escape rate and labor intensity was obtained, for example, Y7.07 mu m = 91.73-0.22n (n is labor intensity), and the escape rate of dust with 7.07 mu m particle size was up to 88.90 %. Most of them escape from the upper respi-ratory tract and enter the lungs, which provides theoretical guidance for quantifying the accumulated dust exposure amount in the lungs and monitoring respiratory dust concentration.