Behavior of airflow and methane at heading faces with auxiliary ventilation system

The airflows and methane gas concentrations at a heading face with forcing, exhausting and combined systems of ventilation were examined in a reduced scale model gallery. Methane was emitted at the face. Methane concentration was measured and its accumulation was visualized by Titanium tetrachloride (TiCl4). The location of the duct end gives significant effects on the airflow. The optimal airflow rate through a forcing and exhausting duct and duct end locations to reduce hazard of methane accumulation were investigated for the combined system of ventilation. Methane accumulation was investigated in another reduced scale model. Water was used instead of air and very fine bubbles generated by electrolysis were employed as tracer in this model. The behavior of bubbles in water is quite similar to that of methane in the air. The airflow and methane accumulation were also examined when a large machine such as a road heading machine is placed near the heading face.