Experimental study on N2O emission characteristics of China Ⅵ light-duty commercial diesel vehicle
In order to study the N2O emission characteristics of China Ⅵ light-duty commercial die-sel vehicle,five China Ⅵ light-duty commercial diesel vehicles were selected for cold start world light ve-hicle test cycle(WLTC)emission testing.Results show that N2O emissions of all five vehicles exhibit were higher than 15 mg/km,with one vehicle reaching a specific emission of 28.8 mg/km,which is close to the limit of 30 mg/km.The N2O concentration tends to fluctuate under acceleration and deceleration conditions throughout the cycle,with peak values around 1.5×10-5.While the N2O emissions are compa-rable in the first three phases of WLTC,differences are primarily observed in extra high-speed phase where vehicles with NH3 leakage produce more N2O.During acceleration conditions,the vehicle has high load and exhaust temperature,resulting in an increase in NOx concentration and urea injection in the original exhaust.The excess NH3 undergoes oxidation reactions in selective catalytic reduction(SCR)re-actor and ammonia slip catalyst(ASC),which promote the generation of N2O.Additionally,under decel-eration and fuel cut-off conditions,the oxygen concertation in the post-treatment pipeline increases and the after-treatment temperature decreases.The residual NH3 in ASC undergoes oxidation reaction,which still promotes the generation of N2O and maintains a high concentration level of N2O.
light-duty diesel vehicleemission characteristicworld light-vehicle test cycle(WLTC)
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