Explosion Proof Modification Of A Diesel Engine And Simulation Study Of Engine Intake Mixed Methane

With explosion-proof diesel engine as the main power source,trackless rubber wheel truck has been widely used in coal mine because of its high efficiency,safety,wide application range,flexibility,convenience,multi-purpose and other advantages.The original 40 Y explosion-proof trackless rubber wheel truck was taken as the research object.The exhaust system of the original truck adopted the water washing box structure,which increased the resistance of the exhaust system,resulting in increased pump qigong loss,decreased engine intake,and deteriorated combustion,which reduced the power,economy and emission of the diesel engine.In addition,the original vehicle used mechanical control engine,compared with electronic control engine,can not flexibly and accurately control the injection time and fuel injection volume,making the engine performance in fuel consumption and emissions is poor.On the basis of in-depth understanding of explosion-proof technology,the cummins Isle 340 40 diesel engine was modified for explosion-proof.A new type of exhaust explosion-proof system is designed to control the exhaust temperature by using the cooling system of high temperature exhaust spray and heat exchanger to solve the problem of increasing resistance caused by the original washing tank.The electronic control system of the engine is reformed for explosion-proof,the ECU is treated with explosion-proof box,and the electronic units such as sensors and actuators are sealed by the high sealing property of epoxy resin,so as to isolate the circuit part from the outside air,so as to realize the explosion-proof transformation of the whole electronic control system.The air under the mine contains a certain concentration of methane gas.During the actual operation of the engine,methane will inevitably be inhaled,which will affect the combustion and emission of the engine.Aiming at this problem,the use of Converge software simulation under the high load point,initial temperature,injection time temperature in cylinder)is larger than 1000 K,engine air intake with 0,0.25%,0.5%,0.75% and 1% after different volume concentration of methane's impact on engine combustion and emissions.The results show that adding methane into the air intake will shorten the ignition delay period and increase the peak value of cylinder pressure,temperature and heat release rate.From the perspective of emission,mixing methane makes NOx emission increase,carbon smoke decrease and CO increase.The effects of intake pressure,injection pressure and injection time on engine intake mixed with methane are analyzed in turn,and pure air intake is selected as a comparison to deepen the understanding of the influence of methane on engine combustion process.The results show that the above parameters have the same trend for methane/air atmosphere and air atmosphere: as the inlet pressure increases,the combustion delay period begins to shorten,the peak cylinder pressure increases,the combustion heat release becomes more rapid,NOx emission increases,and carbon smoke decreases.With the increase of fuel injection pressure,the combustion speed is greatly accelerated,the combustion delay period is shortened,the cylinder pressure peak,cylinder temperature peak and heat release rate peak are increased,NOx emission is increased,carbon smoke and CO emissions are reduced.With the delay of fuel injection time,the ignition delay period in both atmospheres was prolonged,and the cylinder pressure peak,cylinder temperature peak and heat release rate peak showed a decreasing trend.NOx emissions decreased,but CO and soot increased.