Emission Performance Optimization And Analysis Of Small Diesel Engine With Electronically Controlled High Pressure Common Rail Injection

Current non-road diesel engine emission standard of China is relatively strict,especially for those below 19 kW,comparing to large and medium power diesel engines.Only a few kinds of non-road single cylinder diesel engines are approved by China?emission standard which was issued by environmental protection department,due to structural constraint,etc.Therefore,it is of great academic significance and engineering value to develop a new generation single cylinder diesel engine,and make some research on its combustion mechanism and low emission performance.Research work is based on the 192F diesel engine.The electronically controlled high pressure common rail injection technology is used to optimize the performance and emission.After analyzing the parameter differences such as the injection pressure of the electronically controlled high pressure common rail injection system and the mechanical,the combustion system was redesigned.The injection pressure of the common rail system is bigger than the mechanical.In order to reduce the amount of fuel in the combustion chamber and improve combustion,the airway was improved and the intake swirl ratio was reduced.At the same time,the flow coefficient of the intake and exhaust passages were increased.The combustion system of the 192F common rail diesel engine is formed at this time.After calculating and setting the injection system calibration parameters,such as the injection volume,rail pressure and injection timing,etc,studied the effect of injection parameters MAP changes on the emission of prototype at various operating conditions.And through the measurement of high pressure tubing pressure and cylinder pressure,the combustion process was analyzed.It is concluded that under big load conditions,increasing the rail pressure can improve the premixed combustion quality and reduce post-combustion.Also with delaying the injection to reduce NO_X emission,not to cause too much smoke and particulate matter emission.At small and medium load working conditions,increasing the rail pressure can improve the atomization and combustion quality for reducing HC and CO emission.However the rail pressure is limited by the fuel spray characteristics with combustion chamber match and NO_X emission.There is an optimum rail pressure value of each working condition.Taking the calibrated working condition as an example,the optimal injection parameters of the rail pressure,injection advance angle and pre-injection amount are 110 MPa,2?A BTDC and 1.0 mg/str..In the same speed but small load working conditions,the injection advance angle can be in advance,for improving the cylinder combustion temperature and reducing the duration of combustion,which effectively reduce HC and CO.At different speed working conditions,with the reduction of the speed,the rail pressure reducing and the injection advance angle increasing to optimize combustion and reduce emission.The use of pre+main injection scheme can reduce the combustion delay time,reduce the highest average combustion temperature in the cylinder to optimize the overall emission.The 192F common rail diesel engine is optimized according to surface conditions by designing the combustion system and calibrating injection parameters.Performance and emission measurements are made according to the steady-state test cycle(eight operating conditions).The primary emission results for CO,HC+NO_X,and PM are 3.66,5.72,and 0.35g/(kW·h).Having more than 40%degradation margin compared to emission standard limit value of China?.By now it has met the emission standard through the deterioration test,and the prototype has passed emission standard in the environmental protection department.