Experimental air curtain solution for refuge alternatives in underground mines

•A series of model experiments evaluated sealing efficiency of air curtain device.•Effects of ACD configuration and interruption by transiting personnels was studied.•An optimized, double-sided, baffle-equipped ACD with compressed air is proposed. To provide an optimal aerodynamic sealing solution for an alternative refuge in underground mine, a commercial air knife was selected as the air curtain device (ACD) for its lower compressed air use and uniform airflow. A series of simulated chamber model experiments were then performed to evaluate the sealing efficiency of different ACD configurations and the influence of interruption by transiting personnel on ACD performance. By considering the overall sealing efficiency, stability and air consumption, a double-sided ACD equipped with a baffle on the side exposed to harmful gases inside the entrance of the protected door is proposed as the most suitable configuration. This requires compressed air to be supplied at a pressure of 0.10–0.20MPa to generate an air barrier, which means that a standard compressed air cylinder (40L, 15MPa) can provide suitable sealing conditions for a period of about 3.5min.