以一款满足国六b排放标准的重型柴油车为研究对象，研究了加装电加热装置的双级SCR系统在不同环境温度下的整车排放特性。研究表明，冷起动阶段的NO_x排放是控制关键。通过发动机本体的热管理（燃烧模式切换）与后处理系统的热管理（电加热使能）协同作用，整车在不同环境温度下的CHTC-HT循环排放结果显示：相比－10 ℃，在10 ℃和40 ℃时，NH₃排放分别降低76.74%和83.97%。N₂O排放分别降低48.71%和66.94%，而NO_x排放则均上升了约19%，PN₁₀排放分别增加到3.91倍和10.79倍，PN₂₃排放分别增加到5.52倍和15.05倍。CHTC-HT测试循环的前400 s是NO_x和PN₁₀排放产生的高峰期，NO_x产生的原因主要是温度的影响，PN₁₀产生的原因主要是尿素喷射产生的颗粒物和冷凝水对颗粒物的作用。前后级尿素喷射比例调整对NH₃和N₂O排放有较大的影响，在催化剂处于高温区间时，后级尿素喷射量的增加使得NH₃与N₂O排放增加。

Taking a heavy-duty diesel vehicle compliant with China Ⅵ b emission standards as the research subject, the vehicle emission characteristics under different ambient temperatures were researched by introducing a dual-stage SCR system equipped with an electric heating device. Through the synergistic effect of engine thermal management (combustion mode switching) and aftertreatment thermal management (electric heating enablement), the vehicle emission test results in CHTC-HT cycle showed different emissions levels under different ambient temperatures. Compared to cycle-averaged emission results collected at －10 ℃, NH₃ emissions at 10 ℃ and 40 ℃ decreased by 76.74% and 83.97% respectively, and N₂O emissions decreased by 48.71% and 66.94% respectively. Meanwhile, the cycle-averaged NO_x emissions increased by approximately 19% at both temperatures, while PN₁₀ emissions increased to 3.91 times and 10.79 times respectively, and PN₂₃ emissions increased to 5.52 times and 15.05 times respectively.The first 400 seconds of the CHTC-HT test cycle represented the peak period for NO_x and PN₁₀ emissions. The primary cause of PN₁₀ emissions stemmed from particulate matter generated by urea injection and the interaction of condensate with particulate matter. The front to rear urea injection ratio significantly impacted NH₃ and N₂O emissions. At high temperatures, increasing rear urea injection led to the higher NH₃ and N₂O emissions.