Unsteady heat-moisture transfer of wet airway in deep mining

WANG Yi-jiang(王义江)^{1, 2}, ZHOU Guo-qing(周国庆)¹, WU Lei(毋磊)²

(1. State Key Laboratory for Geomechanics and Deep Underground Engineering
(China University of Mining and Technology), Xuzhou 221116, China;
2. School of Mechanics and Civil Engineering, China University of Mining and Technology,
Xuzhou 221116, China)

Abstract:To study the mechanism of unsteady heat-moisture transfer of wet surrounding rock in deep mining, a series of experiments with different initial and boundary conditions were carried out. Test results show that rock temperature decreases quickly at the initial stage, and reduces slowly to be a constant value finally for transient heat-moisture transfer. The quasi-steady surface temperature of wet airway is lower than that of dry airway due to the moisture transfer. The diffusion radius is less than the cooling radius owing to the large diffusion resistance. The outlet airflow enthalpy of wet airway is much larger than that of dry airway. Latent heat caused by the moisture transfer plays a significant role in a deep thermal environment. For periodic heat-moisture transfer, temperature, humidity and enthalpy of outlet airflow and rock temperature also change periodically. The wave amplitude of rock temperature decreases gradually with increasing distance away from the airway surface, and the wave phase of rock temperature is also behind that of airflow. Moreover, direction of the heat-moisture transfer between airway and airflow is bidirectional, which is different from results of transient transfer.

Key words:unsteady heat-moisture transfer; wet airway; deep mining; moisture content; airflow enthalpy