Study On Emission Characteristics Of LNG/Diesel Dual Fuel Engine

The rapid development of science and technology brings convenience to human life,but also greatly accelerates the consumption of energy.The massive use of fossil energy has caused tremendous pollution to the global environment.In recent years,haze weather has appeared in most parts of China,greatly affecting people's lives.In this context,it is necessary to seek clean and convenient alternative energy sources.The LNG/Diesel Dual Fuel Engine is an alternative energy solution that meets the above requirements,and it greatly reduces diesel particulate emissions.In this paper,the emission characteristics of the LNG/diesel dual-fuel engine are studied in a bench test,and its particulate matter emission characteristics are studied emphatically.The LNG/diesel dual-fuel engine for testing was modified from a Yuchai YC6G270-30 engine.The effect of natural gas replacement rate on particulate emissions and conventional engine emissions replacement was studied at a speed of 1400r/min and a load rate of 10%,30%,60%and 100%respectively.At the speed of 1400r/min and load factor of 50%,the effect of pilot diesel injection timing on particulate emissions and conventional engine emissions was studied.The particulate matter emissions from the engine were investigated at 50%load rate and speeds of 1000r/min,1200r/min,1400r/min,1600r/min,and 1800r/min,respectively.The test results show that the use of natural gas instead of diesel fuel greatly reduces the level of engine particulate emissions.Under the selected experimental conditions,when the natural gas replacement rate reached 90%,the PN value decreased by at least 87.74%,and the particulate matter volume decreased by at least 80.9%.As the natural gas substitution rate increases,both the average particle size and the peak particle size of the particles will decrease.Under the selected test conditions,as the pilot diesel injection timing increases,the average particle size and peak particle size of the particulate matter decreases,and the total volume of particulate matter and PN also decreases.The volume of particulate matter is not determined by the number of small particle size particles.The PN value under pure fuel mode at 10%load is much higher than the 30%,60%,and 100%load,but the volume of particles is lower than the three.The emission levels of CO and HC in the dual-fuel mode are higher than those in the diesel mode.Both of then at 10%load ratios are higher than the other load rate conditions and are significantly higher with the replacement rates'increasment.In the medium and small loads,NO_x emissions rise first and then decrease as the replacement rate increases,and continue to increase at high loads.The k value of soot emissions of the dual-fuel mode was significantly reduced by a minimum of 15 times under 100%load conditions.As the timing of pilot diesel injections increases,CO,HC,and soot emissions decline,and NO_x emissions rise rapidly.