选择性催化还原技术（SCR）是降低重型柴油车氮氧化物（NO _x ）排放的常用技术之一，且SCR系统内的NO _x 转化率与尾气温度密切相关。然而，现有的NO _x 排放测算模型主要考虑车辆行驶工况，缺少与排气温度的关联分析，从而增加了NO _x 排放测算结果的不确定性，对排放清单的建立和减排政策的评估提出了挑战。本研究基于车辆实际运行工况和实测排放数据，建立NO _x 排放速率库和NO _x 排放率模型。随后，建立基于机动车比功率（VSP）和热损失系数的尾气温度模型。在此基础上，根据SCR系统中的化学反应原理，建立基于尾气温度的NO _x 排放模型。最后，利用建立的NO _x 模型和MOVES模型（移动源排放测算模型）分别估算NO _x 排放量，并与实际排放情况进行比较分析。结果表明，本研究所提出的考虑实际路况下尾气温度的NO _x 排放模型可以有效提高NO _x 排放测算的准确性，在3辆重型柴油公交车上的NO _x 测算相对误差分别为9.1%、3.9%和3.3%。相较于MOVES模型，相对误差分别降低了24.0、13.1和16.3个百分点。对不同运行工况下的NO _x 排放特性分析表明，重型柴油货车的平均NO _x 转化率比柴油公交车高39.2个百分点。

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.