Study On Prediction Of Smoke Temperature In Roadway Fires Under Different Blocking Conditions

There are many combustibles and narrow space in the mine.Once a fire occurs,it will lead to heat accumulation,coal dust and gas explosion easily,resulting in a large number of casualties and property losses.The plugging control is one of the common means to prevent and control the roadway fire.Therefore,it is of great significance to study the change rule and prediction model of the flue gas temperature of the roadway fire under different plugging ratios.In this paper,experimental research and theoretical analysis are used to study the temperature field distribution and prediction model of roadway fire under different plugging ratios.The main conclusions are as follows:Taking a roadway as a prototype,a 1:10 scale roadway fire experimental system was established.The fire plugging experiments were carried out under 15 working conditions of 4 MW,6 MW,8 MW fire source power and 0%,25%,50%,75%and 100%of the air inlet side unilateral plugging ratio.The experimental results show that:the plugging ratio will change the flame combustion morphology,resulting in the increase of flame inclination angle.Under the different plugging ratios,the horizontal angle of flame is 16°,19°,20°,26° and 90°respectively.Combined with the results of the scale reduction experiment,the variation of the flue gas temperature and the attenuation law of the longitudinal distribution are obtained.The results show that when the plugging ratio is more than 50%,the effect of blocking oxygen on fire suppression is obvious.With the increase of plugging ratio,the full combustion stage of fire is shortened and the fire is extinguished quickly.Based on the equilibrium equation of fire smoke temperature control and the entrainment formula of smoke mass flow rate,combined with the plugging ratio,the longitudinal attenuation relationship of fire smoke temperature in roadway is established,and the accuracy of the theoretical model is verified by the smoke temperature data obtained from the experiment(MAE<0.0751、MAPE<0.1321%、RMSE<0.077、R2>0.9069).Based on the data of fire source power,plugging ratio,measuring point position and CO,O2,CO2 gas monitored by experiment,a prediction model of fire smoke temperature in GA-RF roadway is established.The results show that the model has good nonlinear mapping ability and strong generalization ability,and the OOB error is stable in 100 trees in the modeling process.Compared with the traditional prediction model,GA-RF method(MAE<5.5847、MAPE<5.4500%、RMSE<8.2591、R2=0.9522)have strong stability and applicability for the temperature prediction of roadway fire.