Experimental Study On Exhaust Gas Diffusion Law Of Trackless Rubber Tyred Vehicle In Confined Space

With the improvement of coal production efficiency,it also has higher requirements for underground coal mine transportation efficiency.As an indispensable part of underground auxiliary transportation system,explosion-proof trackless rubber-tyred vehicle reflects the advantages of flexibility,safety,economy and efficiency in coal transportation.With the extensive use of explosion-proof diesel trackless rubber-tyred vehicles underground,its tail gas emission is far from the emission standard of road vehicles.The tail gas after explosion-proof treatment is easy to accumulate in the confined space under the coal mine and form multiphase compound pollutants in the underground particulate matter,gas and other gases.Especially in some tunnels with low ventilation,it is difficult for harmful gases to diffuse,The air quality is poor,and the health of some workers has been seriously endangered.Therefore,by monitoring the concentration of exhaust gas at multiple locations in the confined space in real time,this test analyzes its diffusion law under the influence of wind speed and vehicle speed in the confined space,which is of great significance to further control the underground environment and protect the health of workers in the future.According to the main roadway size of Lijiahao coal mine of Baotou Energy,a small-scale roadway simulation system with a length of 15m is designed in the proportion of 1:10.The air flow in the confined space is simulated by the fan,the diffusion of the tail gas of trackless rubber-tyred vehicles under different air volumes and vehicle speeds is simulated by adjusting the wind speed,and the real-time changes of the concentrations of CO,SO₂,CO₂,NO₂and NO are monitored by the gas sensing device.In the test,when the simulated trackless rubber-tyred vehicle runs stably,the CO₂ content in the tail gas produced by it is the highest,about 50 times of the CO concentration,the SO₂content is low,within 20%of the CO concentration,the content of NO₂ and no is the lowest,less than 2%of the CO concentration.The research shows that the lower wind speed and speed are easy to make the tail gas accumulate in the rear space of rubber-tyred vehicles,resulting in the increase of its concentration.By increasing the tunnel wind speed and speed above 0.6m/s,the tail gas dilution effect brought by the air flow is obvious and more economical.Moreover,the improvement of the tail gas dilution effect of trackless rubber-tyred vehicles by increasing the wind speed is stronger than speeding up the speed.In addition,under the dual influence of roadway wind speed and trackless rubber-tyred vehicle speed,the tail gas concentration at the nine monitoring points decreases significantly.The tail gas at the axis reaches the highest concentration peak,and the wind flow is more uniform,and the dilution speed of the tail gas is faster.However,the tail gas at the roadway wall is affected by the flow around the boundary layer,the peak concentration is lower,and the dilution speed is also slower.