Research on NOx Emission Control of Heavy-Duty Diesel Engine Based on Exhaust Electric Heating Technology
In order to solve the problem of NOx emission deterioration of heavy-duty diesel engines under cold start condition,an exhaust electric heating system was designed independently on a heavy-duty diesel engine cold start experimental platform,and the effects of different heating power on the tailpipe NOx and the NOx amount that can be treated by electricity per kilowatt-hour was studied.The results show that with the increase in heating power from 2 kW to 8 kW,the specific NOx emissions decrease gradually,and the NOx amount that can be treated by electric-ity per kilowatt-hour increases gradually.When the heating power is fixed at 8 kW,the specific NOx emissions reaches the lowest value of 140.3 mg/(kW·h),which is 51.55%lower than that of the original engine.When the heating power is fixed at 2 kW,the NOx amount that can be treated by electricity per kilowatt-hour reaches the highest value of 1900.8 mg.Based on these results,a control strategy of the exhaust electric heater was developed by means of simulation.After the NOx conversion efficiency and fuel consumption are introduced into the control strategy as criteria,the NOx amount that can be treated by electricity per kilowatt-hour are increased by 19.27%.At this time,the tailpipe NOx emissions can be reduced from 274.76 mg/(kW·h)to 231.42 mg/(kW·h)with only electricity consumption of 0.21 kW·h.
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