Integration And Optimization Of The NO_x Catalyst For Diesel Engine

With the rapid development of economy in the world, more and more attentions from the government and society are paid on vehicle emissions. The implementation of stricter emission standard promotes the development of the purification technology of engines. Since diesel engine runs in lean burn condition, it's far from enough to make its NOx emission meet the stricter emission standard using only in-cylinder methods. So it's very important to study after-treatment technology to purify the NOx emission of diesel exhaust in lean burn condition.In this paper the light-off and space velocity performances of diesel lean NOx catalyst composed of Ag/Al2O3 with ethanol as the reductant have been evaluated in the engine test bench. The purifying performances to NOx and HC, CO of this catalyst used alone and combination with two oxidation catalysts respectively have also been studied through Euro III standard test (ESC). A conclusion is drawn that diesel lean NOx catalyst must be used together with the oxidation catalyst to purify HC,CO and NOx simultaneously. A set of strategies to optimize the adding of the ethanol reductant has also been brought forward in this paper. In the condition of optimization, the diesel engine which originally only met Euro II can meet the requirement of Euro III, using the combination of the NOx catalyst and the oxidation catalyst.In the environment of 1D numerical simulation software Boost, the model of the whole engine working process has been established and the influence of the exhaust after-treatment system to the performance of power and economy of the engine has been analyzed.