Effects Of Water Vapor On Soot Formation Andsoot Measurements In Adiffusion Flame

Mine fire is one of the five natural disasters of mines.Mine fire result in enormous casualty and property loss,and The victims because of the mine fire accident have more than 95% died of flue gas(main ingredient is soot)poisoning.The main ingredient in fire smoke is soot,which is the product of the imperfect combustion of hydrocarbon fuel.Mine are mostly high humidity environment,some even up to 100%.The high humidity environment can affect the generation of soot.Therefore,studying the influence of water vapor on soot formation in alkane fuel can enhance the prediction accuracy of soot generated and spread in a high humidity environment.That will have important practical significance and scientific value for smoke control and personnel evacuation and rescue.Combustion diagnostic technique is the main method for research of carbon black generation features under high humidity environment.To measurement of soot concentration in the flame,reconstruction algorithm based on the simulation calibration is built.The reconstruction algorithm combines numerical simulation and small size experiment.Algorithm Divided into two processes: simulation calibration and 3 d reconstruction.firstly: The temperature and soot concentration of Laminar diffusion flame are obtained by numerical simulation,and the flame radiation intensity are obtained by radiation intensity formulas;The R,G,B value of the flame image are obtained by the CCD camera;Fitting the relation between the flame radiation intensity and R,G,B value of flame images.secondly: According to the relation between the flame radiation intensity and R,G,B value of flame imagesto get the other conditions flame radiation intensity,and the flame temperature and soot concentration can be obtained based on conversed formation.Using MATLAB write Corresponding image processing procedures.Using the algorithm measured the temperature and soot concentration in the laminar methane/air diffusion flame,and compared with the results of numerical simulation,to verify the rationality of the reconstruction algorithm.Using numerical simulation method to study the influence of water vapor onsoot formation in a laminar methane/air diffusion flame.The reduced mechanism containing 24 reactions,finite rate chemical reaction model,Moss-Brookes soot Models and Discrete Ordinate(DO)radiation model was used in the simulation to study the influence of water vapor in the air on soot formation in a laminar methane/air diffusion flame.By analyzing the simulation results,explain the influence of water vapor on soot formation in the laminar methane/air diffusion flame.The influence of water vapor on soot formation in methane/air laminar diffusion flame mainly by affect soot growth and oxidation rate.On one hand,the presence of water vapor could decrease the flame temperature which would lead to the decrease of chemical reaction rate,consequently soot concentration decrease because of soot surface nucleation and growth rates decrease.On the other hand,The increase of water vapor in the air can expedite the reverse reaction of OH + H2 < = > H + H2O(R)(15),this could increase OH generation,but the increase of the flame volume because of the decrease of oxygen concentration would lead to the reduce of whole OH concentration,and soot production increase because of soot oxidation rate decrease.soot concentration reduce in the whole because the chemical effect of watervapor is less than its temperature effect.