Study On NOx Formation Mechanism Of A CRDI Diesel Engine Fueled With Pistacia Chinensis Bunge Seed Biodiesel

To meet the pressure of petroleum shortage and more stringent vehicle emissionregulation, Improving diesel engine economic-dynamic and emission performancebecome a mainstream. In addition, as the amount of petroleum import keeps increasing,searching for one or several kinds of alternative energy sources which can reach thediesel economic-dynamic performance demands is very urgent. At present the mostextensive use of alternative fuels are biodiesel and alcohol fuels. the manufacture ofbiodiesel is based on the esterification reaction of biological grease and low carbonalcohol in the presence of catalyst. Moreover, Biodiesel is richly originate, renewableand owns similar economic-dynamic performance with diesel. Alcohol fuel is clean,renewable oxygen-bearing fuel,90%of which comes from coal-based methanol in ourcountry. And our country’s coal reserves is relatively rich, the production technologyof coal-based methanol has been very mature, so alcohol fuel has a good applicationprospect in China.The subject of the oxygen-bearing fuel in this paper is pistache seed biodiesel andmethanol diesel. At first, composition and scale of pistache seed biodiesel wasmeasured using a mass spectrometer; Then, physical and chemical indexes as density,calorific value, surface tension and its kinematic viscosity (25°C) of pistache seedbiodiesel and methanol diesel (B0B10, B20, B30, B50, B100and M5, M10M20)were measured; influence of the changes of engine condition, alternative fuel mixingproportion, injection timing and EGR rate on NOx emissions was investigated withemphasis.In a CRDI engine without any structure changes, the NOx emission characteristicexperiment on the basis of being fuelled with different proportion pistache seedbiodiesel and methanol diesel was done. The results showed that, in the whole pme-NOx curve, biodiesel NOx emission is higher than diesel; As the proportion of biodiesel increases, NOx emissions increased significantly. However, NOx emissiondecreased significantly when M20was mixed in.On2000r/min75%load condition point, change injection timing, the CRDIengine’s NOx emission characteristic fuelled with different proportion under differentinjection timing was investigated. The results showed that, with the the injectiontiming was delayed, biodiesel NOx emissions decreases; At the same injection timing,with mixing proportion of biodiesel increases, its NOx emissions rise.On2000r/min,75%load condition points, the CRDI engine’s NOx emissioncharacteristic fuelled with different proportion under different EGR rate wasinvestigated. The results showed that, with the increase of EGR rate, biodiesel NOxemissions reduced significantly.