Numerical study on calculation model of airflow temperature and humidity prediction in humid airway

In deep coal mining, the high temperature and humidity environment are one of the main disasters threatening workers and equipment. To predict the temperature and humidity of airflow in the airway accurately, this study establishes a numerical calculation model of the surrounding rock temperature, airflow temperature, and humidity under the conditions of considering the moisture evaporation and heat absorption of the airway wall, the condensation and heat release of supersaturated water vapor in the airflow, and the influence of air compression or expansion. Combined with the two-dimensional (2D) heat conduction model (considering the influence of the axial surrounding rock heat conduction of the airway), the axial strip partial moisture calculation model of the airway is proposed, and then the uniform moist wall model and the axial strip partial moist wall model are established. The influence of different parameters on the temperature and humidity of airflow is discussed by analyzing the results of numerical simulation of the uniform wet surface model (UWSM) and partly wet surface model (PWSM) of the airway wall. The results show that the surrounding rock temperature, especially the temperature distribution of the airway wall, calculated by using the 2D heat conduction model under the local humid airway conditions, is more realistic. The increment of airflow temperature decreases with the increase of wet area ratio, airflow temperature at the entrance and airway radius, and increases with relative humidity at the entrance. The calculation accuracy of temperature and humidity prediction for large ventilation networks can be further improved by using the equivalent humidity of the UWSM to replace the correction coefficient of the wet area ratio of the PWSM.