NO x Emission Model of Heavy-Duty Diesel Vehicles Considering Exhaust Temperature Under Real-World Driving Conditions

doi:10.12141/j.issn.1000-565X.230197

Abstract

Abstract:

Selective catalytic reduction technology (SCR) is one of the commonly used technologies to reduce nitrogen oxide (NO _x ) emissions from heavy-duty diesel vehicles. The efficiency of NO _x conversion in the SCR system is closely related to the exhaust temperature. However, the existing NO _x emission models primarily focus on vehicle driving conditions, neglecting the correlation with exhaust temperature. Thus, it increases the uncertainty of NO _x emission measurement results, and challenges the establishment of emission inventory and the assessment of emission reduction policies. This study established a NO _x emission rate library and a model based on actual vehicle operating conditions and measured emission data. Subsequently, an exhaust temperature model utilizing vehicle specific power (VSP) and heat loss coefficient was developed. Based on this, based on the chemical reaction principle in the SCR system, a NO _x emission model incorporating exhaust temperature was derived. Finally, the proposed NO _x model and the MOVES model (MOtor Vehicle Emission Simulator) were employed to estimate NO _x emissions, which are then compared and analyzed against actual emissions. Results demonstrate the effectiveness of the proposed NO _x emission model in real-world conditions, with relative errors of 9.1%, 3.9%, and 3.3% observed across three heavy-duty diesel buses. These errors represent a reduction of 24.0, 13.1, and 16.3 percentage points, respectively, when compared to the MOVES model. Additionally, analysis of NO _x emission characteristics under different operating conditions reveals that the average NO _x conversion rate of heavy diesel trucks is 39.2 percentage points higher than that of diesel buses.

Key words: heavy-duty diesel vehicle, NO _x emission, Urea-SCR, exhaust temperature model, operating condition

CLC Number:

U473.9

JI Zhe, WANG Xin, YIN Hang, et al. NO _x Emission Model of Heavy-Duty Diesel Vehicles Considering Exhaust Temperature Under Real-World Driving Conditions[J]. Journal of South China University of Technology(Natural Science Edition), 2024, 52(2): 136-144.

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序号	制造商	型号	年份	车辆类型	排放标准	整备质量/kg	发动机排量/L
1	东风	DFL5253XXYAX1B	2015	柴油货车	国四	10 875	6.70
2	东风	LZ5250XXYM5CA	2015	柴油货车	国四	9 920	6.70
3	东风	DFL1253AX1A	2015	柴油货车	国四	11 280	6.70
4	福田	BJ3255DLPJB-7	2015	柴油货车	国四	11 905	6.75
5	福田	BJ3255DLPHH-FA	2015	柴油货车	国四	11 405	6.50
6	福田	BJ1255VNPHE-5	2015	柴油货车	国四	8 050	6.70
7	福田	BJ6105CHEVCG	2015	柴油公交车	国四	11 050	6.50
8	福田	BJ6931C6MHB	2015	柴油公交车	国四	8 200	6.50
9	宇通	ZK6120CHEVPG21	2015	柴油公交车	国四	11 500	6.50
10	宇通	ZK6126CHEVG2	2015	柴油公交车	国四	12 500	6.50

车辆属性	属性值
制造商	福田
型号	BJ1255VNPHE-5
年份	2016
排放标准	国四
整备质量/kg	8 050
发动机排量/L	6.70
发动机型号	CA6DF4-18E4
最大扭矩/（N·m）	680
最大输出功率/kW	135
SCR系统	BOSCH-DeNOx2.2

车辆类型	A	B	C	m	f
柴油公交车	1.094 40	0	0.003 587 02	16.556 0	17.1
柴油货车	1.417 05	0	0.003 572 28	20.684 5	17.1