Simulated Study On Combustion Process Of DME And Non-standard Diesel Blended Fuel In Diesel Engine

DME for Diesel Engine can reduce the NOx emissions and achieve smoke-free combustion, but due to the extremely low viscosity of liquid DME, problems such as stuck, wear of plunger of fuel supply system and leakage of DME were common. By mixing different proportions of DME in the low-quality non-standard diesel, the problems above were solved, and also the utilization of oil was improved, significant economic benefit was obtained.Firstly, determination the physical and chemical characteristics of blended fuel D30 (Dimethyl ether/non-standard heavy diesel), experiment has been carried out on the diesel engine adopting blended. fuel D30 after the transformation of diesel fuel supply systems. With the test data and structural parameters of diesel engine, diesel model 4100QBZL was established in the FIRE software and the correctness of the model was verified by comparative analysis of the simulation results and test results. Diesel engine spray process and emission distribution of the D30 and diesel were comparatively analyzed and studies shows that D30 with smaller penetration, higher spray velocity, and faster fuel droplet evaporation speed, combustible gas mixture formed rapidly. Meanwhile D30 played the role of reducing the highest temperature, soot emissions and NOx emissions.On this basis, the high proportion of dimethyl ether/non-standard diesel D70, D80 and D90 were simulated using diesel engine model, the cylinder mean pressure, mean temperature and mass fraction of emissions of three kinds of the blended fuel and diesel were compared, and the cylinder concentration field and concentration field of emissions were also studied. The results showed that:the peak of outbreak pressure in cylinder and in-cylinder temperature of the three blended fuel were lower than that of diesel, the mass fraction of NOx formed was significantly reduced and final value of soot is almost zero. It can be seen that the fuel concentration region, the formation of nuclear fire and flame propagation process and NOx, soot formation region were different from that of diesel from the analysis of concentration field in cylinder.Finally, the effect of injection advance angle and injection duration on the combustion process of the high proportion dimethyl ether/non-standard diesel was investigated. The results showed that:with the increase of fuel injection advance angle, the maximum combustion pressure, temperature and mass fraction of NOx was increased, but the final value of soot decreased. The effect of the injection duration on the combustion process was exact opposite.