Experimental Study On Exhaust Emission Reducing Of Diesel Engine Using EGR And High Pressure Injection Technique

Increasingly stringent emission regulations continuously put forward new challenge for diesel engine technology.SCR will be adopted in the early stage by the engine enterprise as the first way of medium and heavy-duty diesel engine to meet the China IV emissions.With the deeper and deeper understanding of the technical solution,the emission control technology by using EGR + DPF is gradually taken seriously.But,the effective after treatment equipment,such as SCR,DPF have the disadvantages such as expensive,complicated structure,short service life,maintenance difficulties and other issues.So the built-in purification is needed to reduce the original emissions of diesel engine to reduce dependence on the after treatment.In this situation,this paper focus on the without after treatment emission problem.By combining the EGR and High pressure jet technology,the structure of WP7 engine was selected and optimized.At the same time,the working condition of the engine was calibrated and optimized to explore the technical route feasibility to achieve China IV emissions without after treatment.Aiming at WP7.300E408 diesel engine,the structure was optimized.The parts,such as the fuel injector,combustion chamber,cylinder head,EGR cooler,turbocharger were selected.The five points,A100,B100,C100,B50,C50 in the ESC discharge cycle were selected to conduct the selection of DOE,and the final test parts were determined by the emissions performance of each part.According to the emissions requirements,the DOE was designed after determining the scope of the calibration parameters.The Engine test bench was automatic calibrated,which can greatly reduce components selection experiment testing work,thus to accelerate the process of test.Emission calibration on ESC,ELR,ETC was conducted.Because the program was China IV emissions without after treatment,to meet the requirements of emission,Rail pressure was calibrated higher than usual.The main injection timing in the emission area is very small,mostly behind 5 deg.At the same time,post injection only open at the emission area.The engine full load curve,performance curve and emission test were conducted to validate the result of the engine performance and emissions.The test results showed that without after treatment line can meet the requirements of China IV emissions and has a certain margin.The study found that only the fuel consumption was higher than the SCR version design requirements in all engine performance parameters,the rest of the parameters meet the design requirements.But considering urea consumption and fuel consumption,the fuel consumption rate difference will further decrease.According to the results of performance and emissions test,the emission of WP7.300 E408 diesel engine can meet the requirements of IV emissions limits without after treatment,which achieved the purpose of this research.