使用便携式排放测试系统（portable emission measurement system，PEMS）对3辆重型柴油车进行道路排放测试，以发动机负荷率及CO2排放率作为发动机低负荷或高负荷工况划分依据，结合比排放、瞬态排放等对低负荷工况CO，CO2，NOx和PN23及冷起动过程排放特性进行分析，并探究低负荷工况下PN10比排放变化规律。研究结果表明：使用CO2排放率作为划分依据的低负荷工况更具代表性，低负荷工况下CO，CO2，NOx和PN23比排放值较高，CO，NOx，PN23易超出标准限值，冷起动过程存在大量高CO和NOx比排放的低负荷工况点，且将PN计数粒径范围下限由23 nm降低至10 nm后低负荷工况下PN10比排放将会翻倍。

 

By using a portable emission measurement system(PEMS), the road-based emission tests were conducted on three heavy-duty diesel vehicles. The engine load rate and CO2 emission rate were used as the reference for dividing the engine into low load or high load conditions. Combined with specific emissions, transient emissions and etc, the emission characteristics of CO, CO2, NOx, PN23 under low load conditions and during cold start process were analyzed, and the variation law of PN10 specific emissions under low load conditions was explored. The research results indicate that the low load condition based on CO2 emission rate is more representative. Under low load conditions, the specific emissions of CO, CO2, NOx, and PN23 are higher, and CO, NOx, and PN23 are prone to exceed the standard limits. There are a large number of low load working points with high CO and NOx specific emissions during the cold start process. Furthermore, reducing the lower limit of PN counting particle size from 23 nm to 10 nm will result in a doubling of PN10 specific emissions under low load conditions.