Experimental Study On CNG / Diesel Dual Fuel Engine

Because of its stable chemical properties, single composition, high purity, abundant reserves, high octane number, nature gas has been highly valued by domestic and foreign research institutions.Ignited by pilot diesel natural gas will make the emissions of the engine is improved, so under the requirements of energy saving and emission reduction, for CNG/diesel dual fuel engine research is very meaningful.According to the CNG/diesel dual fuel gas supply scheme, basic algorithm of CNG/diesel substitute, to build a natural gas supply system, designed and refitted rail jet assembly and intake manifold and EGR cooling water circulation system and natural gas supply of the intake manifold multi-point injection mode, the YN38CRD2 high pressure common rail diesel engine was modified.Gas jet validation test was carried out on the platform of the natural gas control system.Test results show that The gas jet drive control waveform is relatively stable, the jet rail solenoid valve can rapidly opening and closing, opening to the closing time for the 600 μs, the peak current can reach 3A, hold current maintenance in 1 A, meet the bench test for the real-time and accurate requirements of natural gas jet.The bench test of the modified CNG/diesel dual fuel engine is carried out.The dynamic performance, economy and cylinder pressure change trend of the dual fuel engine were analyzed and compared with the original diesel engine.Test and analysis results show that the Dual Fuel Engine Refitted can basically achieve the level of the original diesel engine, especially in the high speed 1800r/min-2400r/min, the power of the dual fuel engine to be higher than the original machine 0.7-1.5%; at low speed when the economy to worse than the original machine, but in the high speed and high load conditions economy to better than the original machine; dual fuel engine the exhaust temperature will have varying degrees of increase. In the external characteristics, the exhaust temperature of dual fuel mode is about 10-40 higher than the original engine exhaust temperature C.Low speed and high load conditions, the dual fuel engine cylinder pressure than the original machine, and compared to the original machine, the position of the maximum cylinder pressure occurred by around 4 degrees CA, natural gas replacement rate can reach about 80%.