Study On Emission Characteristics Of Explosion-proof Diesel Engine Fueled With F-T Diesel And Its Oxygenated Blends

At present,explosion-proof trackless rubber vehicles are widely applied to underground operations in domestic coal mines.As the power source of the trackless rubber vehicle,the explosion-proof diesel engine is converted from conventional diesel engine,equipped with explosion-proof device such as exhaust gas treatment tank and flame arrester which are installed at the end of exhaust system to reduce exhaust temperature and ensure the safety of coal mine.However,the modification of the exhaust system increases the back pressure and leads to the increase of exhaust pollutants.Especially in the underground environment with poor ventilation,it will cause the accumulation of suspended pollutants,which are harmful to the health of practitioners.Therefore,improving the high pollution of explosion-proof diesel engine has important theoretical significance and engineering value.In this paper,the original exhaust system of ISDe180-30 diesel engine is modified with exhaust gas treatment tank and corrugated flame arrester.The influence of explosion-proof modification on the economy and emission characteristics of the engine was studied through engine bench test.Meanwhile,we measured and compared the percentage of pollutants,which are collected before and after the exhaust gas treatment tank,and researched the adsorption and reduction effect on particulate matter,HC and other pollutants of exhaust gas treatment tank.In addition,we used diesel(D100),F-T diesel(FT100),F-T diesel/biodiesel blended fuel(BD20)and F-T diesel/PODE blended fuel(P20)on the explosion-proof diesel engine,and analyzed the effects of F-T diesel and its oxygenated fuel on the economy and emission characteristics of explosion-proof diesel engine.In addition,the exhaust particulate of explosion-proof diesel engine was collected through the water-gas separator with sintered glass-fiber filter.Through scanning electron microscope test,we observed the morphology of exhaust particulate,and reaserch the effects of engine operating conditions,fuel types and exhaust gas treatment tank on exhaust particulate.And the quantitative parameters such as box dimension and primary carbon particle size were calculated by Matlab image processing technology.The main work and conclusions of this paper are as follows:(1)Compared with original engine,the economy and emission characteristics of explosion-proof engine get worse,the brake specific fuel consumption of explosion-proof diesel engine increased by 2.51%,the brake thermal efficiency decreased by 2.35%,and the emissions of NO_x,CO,HC and particulate increased by 17.21%,30.63%,24.55%and28.16%,respectively.(2)By comparing the concentration of exhaust pollutants in the entry and exit of exhaust gas treatment tank,it is found that exhaust gas treatment tank has a certain emission reduction and absorption effect on the emission of pollutants.Especially under heavy loads,the reduction rate of particulate matter reaches 61.27%,the reduction rate of HC is 17.23%,while the reduction rate of NO_x and CO is 1.34%and 0.36%respectively.In addition,to prove that exhaust gas treatment tank has a certain absorption and emission reduction effect on HC pollutants,we conducted a fluorescence test of the water coolant in the tank and found that large number of aromatic hydrocarbon components in water.(3)The explosion-proof engine fueled with F-T diesel has better fuel economy and emission characteristics than 0#diesel.And the use of oxygen-containing mixed fuels BD20and P20 can effectively reduce the emissions of CO,HC and particulate matter in explosion-proof engine.Compared with FT100,the CO emission of BD20 and P20 are respectively reduced by 9.56%and 12.83%;HC emission are respectively reduced by 6.79%and 11.94%;particulate matter emission are respectively reduced by 5.58%and 31.31%.However,oxygened blended fuel will lead to poor NO_x emission and fuel economy characteristics.Compared with FT100,the NO_x emission of BD20 and P20 respectively increased by 21.32%and 24.90%,and the brake specific fuel consumption respectively increased by 4.71%and 12.56%,the brake thermal efficiency respectively decreased by2.59%and 1.76%.(4)In this paper,we use particle collection device to gather exhaust particles at the front and rear of the tank,and observe the microscopic morphology of particles under scanning electron microscope(SEM).Calculated by the Fraclab software,the box dimension of exhaust particles is mainly distributed between 1.68 and 1.86.The explosion-proof engine fueled with FT100 performed the less box dimension than that of D100,indicating that the particles aggregate closer.And explosion-proof engine fueled with BD20 performed higher the box dimension than FT100.In addition,the box dimension of the particles collected at the exit of tank is larger than that at the entry.The primary carbon particle diameter of exhaust particle was statisticed and calculated by Image J software,and it is mainly concentrated in 10nm～50nm.The primary carbon particle diameter of exhaust particle when fueled with different fuels is:D100>FT100>BD20.Meanwhile,with the increase of engine load and speed,the primary carbon particle diameter becomes larger.However,the exhaust gas treatment tank has no effect on primary carbon particle diameter.