Study On Combustion And Emission Characcteristics Of High Pressure Commom Rail Diesel Engine Burning Biodiesel-Diesel Blended Fuel

In recent years, China’s energy and environmental problems become more and more serious, vehicles as a main part of fossil energy consumption, its emissions are one of important sources of environmental pollution. This report is discussing the new technologies, such as electronically controlled, common rail, direct injection, turbocharged and intercooled in diesel engine, and the diesel-biodiesel fuel used in the diesel engine research, here is the main points about subjects:Study characteristics of the diesel engine, including combustion characteristics, power performance, fuel consumption, emission characteristics, when using different types of diesel-biodiesel blends; study pilot quantity and intervals of the two-injection impact on diesel engine combustion and emission characteristics both in single injection and pre-main injection; study diesel engine combustion and emission characteristics with different advanced injection angles and fuel injection pressure; study parameters on diesel engine, using the orthogonal experiment with fuel injection pressure, injection timing, pilot injection quantity and the interval of pre-main injection.Through a large number of bench test of diesel engine, the main research results are as follows:With the increase of biodiesel proportion, the starting point of combustion is in advance, the biggest advance Angle of CA10 is 0.5 ° CA; Combustion duration becomes shorter, as much as 0.9 ° CA; The maximum combustion pressure in cylinder rises, its biggest ascending range is up to 5.91%; The maximum combustion temperature in cylinder rises, its biggest ascending range is up to 4.14%; The brake specific fuel consumption increases, its biggest ascending range is up to 5.35%, it has little difference while the brake specific fuel consumption is converted to equivalent brake specific fuel consumption; the NOx emissions have little change, whereas the smoke can reduce greatly, the biggest decreasing amplitude is up to 60.57%.When in a fixed injection amount of 30 mg, as the adding ratio of biodiesel is from 10% to 50%, diesel engine output torque decreases by up to 7.32%; The brake specific fuel consumption increases by up to 7.8%; the smoke can reduce greatly by up to 64%; the brake thermal efficiency, equivalent brake specific fuel consumption and NOx emissions change slightly, which is less than 3%.When in a fixed injection amount of 30 mg, as the Injection pressure gradually increased from 70 MPa to 160 MPa, diesel engine output torque increases by up to 11.2%, and the brake thermal efficiency increases by up to 13.4%, correspondingly the brake specific fuel consumption and equivalent brake specific fuel consumption decrease, the smoke can reduce greatly by up to 58.69%, whereas the NOx increases greatly by up to 116.34%;When the Injection timing gradually increased from 2 ° CA to 13 ° CA (ATDC), diesel engine output torque increases by up to 6.89%, and the brake thermal efficiency increases by up to 6.8%, correspondingly the brake specific fuel consumption and equivalent brake specific fuel consumption decrease, the smoke can reduce greatly by up to 40.46%, whereas the NOx increases greatly by up to 157%;While performing pilot injection, with the increase of pilot injection quantity, the maximum pressure rise rate change greatly. Pressure rise rate of pilot injection quantity that bellows 3.2 mg is less than that of single injection, and pressure rise rate of pilot injection quantity that more than 5.2 mg is higher than that of single injection; the NOx can declines slightly by up to 19.67%, whereas the smoke increases greatly by up to 58.97%; The pilot injection quantity has little influence on diesel engine output torque, brake thermal efficiency, rake specific fuel consumption and emissions.Performing an orthogonal test by using the injection interval, the injection pressure, the pilot fuel injection quantity and the fuel injection advance Angle as factors, and the result of the test was analyzed by using the rang analyze and weight matrix analysis, and found that:the injection pressure has most significantly influence on aggregative indicator of diesel engine output torque, brake thermal efficiency, NOx emissions and smoke emissions, followed by injection timing and injection interval, pilot injection quantity has least influence on it.