Influence of Diesel Engine Intake Throttle and Late Post Injection Process on the Rise of Temperature in the Diesel Oxidation Catalyst

In order to effectively implement DPF(Diesel Particulate Filters)regeneration control,thermal management of exhaust products before and inside Diesel Oxidation Catalyst(DOC)is necessary.In the present study,the Influence of the intake throttle valve and late post injection process on temperature rise inside DOC is analyzed through engine bench tests.The steady experiment results show that adjustment of the intake throttle valve can effectively increase exhaust temperature before DOC;in particular,with intake throttle valve opening at 20%,temperature before DOC can be increased by about 170℃ with respect to the full opening.An increase in the late post injection quantity can produce a significant rise of the temperature inside DOC,however its impact on the exhaust temperature before DOC is relatively limited.As the late post injection quantity increases,Hydrocarbon(HC)emissions also grow;in the present work it is shown that with a proper injection quantity,a considerable temperature increase inside the DOC can be obtained with relatively low HC emission.More specifically,with the intake throttle valve at 30%and DOC reaching ignition temperature as the late post injection quantity is increased,the exhaust temperature after DOC can be made larger than 550℃,adequate for DPF active regeneration.

Experimental Analysis of the Influence of Exhaust Thermal Management on Engine NO_(x) Emission

Exhaust thermal management is essential to allow engines to meet the Euro VI emissions standards and reducing nitrogen oxide emissions is one of the most important targets being pursued nowadays.Along these lines,in the present study,engine’s thermal performances have been evaluated on the basis of a WHTC test,namely a transient engine dynamometer schedule defined by the global technical regulation(GTR)developed by the UN ECE GRPE group(the GTR is covering a world-wide harmonized heavy-duty certification(WHDC)procedure for engine exhaust emissions).The influence of thermal management on fuel consumption,intake,and tailpipe NO_(x) have been quantitatively analyzed for the overrun state.The results have shown that there can be a strong influence on the after-treatment temperatures and tailpipe NO_(x).In particular,the average temperature upstream of the diesel oxidation catalyst(DOC)has been found to increase from 245°C to 254°C,the average temperature of the selective catalytic reduction(SCR)to increase from 248°C to 253°C,the SCR’s minimum temperature to increase from 196°C to 204°C,and the peak value of the NO_(x) emissions in the low-temperature region to decrease from 73 to 51 mg/s.However,the influence of the overrun state’s thermal management strategy on the fuel consumption,the air intake,the ammonia storage,the NO_(2)/NO_(x) ratio,and the urea consumption has been observed to be relatively limited.