Effects of Diesel Main Injection Timing on Combustion and Emission of Hydrogen/Diesel Dual-Fuel Engine under Highland Hypoxia Environment
To study the effect of diesel main injection timing on the combustion and emission of a hydrogen/diesel dual-fuel engine in a plateau oxygen-deficient environment,a hydrogen/diesel dual-fuel engine test rig was con-structed,and the engine combustion and emission characterization tests were carried out in a plateau oxygen-deficient environment at an altitude of 2000 m at the maximum torque speed of 1600 r/min and under 30%,50%,and 70%loads.The results show that:the main pre-injection interval is fixed,with the postponement of the diesel main injec-tion timing,the peak cylinder pressure decreases,the phase corresponding to the peak transient exothermic rate is shif-ted back,the carbon smoke,and CO emission rises,and the NOX emission decreases;under the three loads.The maxi-mum reductions in dual-fuel NOX emissions were 53.9%,57.9%,and 40%,respectively.When the hydrogen substi-tution rate is 27.4%,21.2%,and 15.4%at the three loads,respectively,NOX emission rises,CO,and CO2 emission decreases compared with the diesel-only mode,and at 30%load,when the diesel main injection timing is-8°CA ATDC,CO emission and CO2 emission decrease by 46.5%and 17.3%,respectively,in the dual-fuel mode,and at 30%and 50%loads,carbon soot emission decreases with an average reduction of 21.55%and 11.69%,respectively,and carbon soot emission increases with an average increase of 32.62%at 70%load.
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