Department of Mechanical Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.
Hyundai Motor Company, Hwasung-si, Gyeonggi-Do, 455-963, Republic of Korea.
Sci Total Environ. 2021 Aug 15;782:146750. doi: 10.1016/j.scitotenv.2021.146750. Epub 2021 Mar 26.
As the regulations on vehicle emissions have become more stringent internationally and real-driving emissions (RDE) have been established, the on-road characteristics of emissions have gained importance in vehicle research and development. The results of the fuel consumption levels and emissions from on-road tests are affected by many factors, such as driving conditions, routes and environmental conditions. Therefore, more research and analysis are needed for the effects of environmental factors and driving conditions according to RDE phase on the NOx emissions. In this study, RDE tests were conducted by season to analyze the on-road NOx emission characteristics of lean NOx trap (LNT)- and selective catalytic reduction (SCR)-equipped diesel vehicles corresponding to the Euro 6b regulation prior to the application of the RDE regulation. The purpose of this study is to analyze the effects of seasonal factors and phases of the RDE routes on the NOx emission and NOx conversion efficiency of catalyst. In spring/autumn and summer, the engine-out and tail-pipe NOx emissions were higher 1.3-5.9 times for vehicle A and 1.3-28.4 times for vehicle B in the urban phase than in other phases. In the urban phase, the engine bay temperature was probable to rise owing to frequent stops and low-speed driving, leading to a high intake air temperature, which causes excessive NOx emission, particularly in summer. The average air filter temperature in urban phase was 11-15 °C higher than the environment temperature for vehicle A. The NOx conversion efficiency of the LNT was highest at 54.1% on motorway and the efficiency was dependent on the phase of the test route. The NOx conversion efficiency of the SCR, which is dependent on the catalyst temperature, was highest at 98.7% in spring motorway and the efficiency was affected by the combined factors of season and phases.
随着国际上车辆排放标准的日趋严格以及实际行驶排放（RDE）的建立，车辆研发中对排放的道路行驶特性越来越重视。道路行驶测试中油耗水平和排放的结果受驾驶条件、路线和环境条件等诸多因素的影响。因此，根据 RDE 阶段，需要对环境因素和驾驶条件对 NOx 排放的影响进行更多的研究和分析。本研究按照 RDE 法规实施前的欧 6b 法规，分季节进行 RDE 测试，分析了装有 lean NOx trap（LNT）和选择性催化还原（SCR）的柴油车的道路行驶 NOx 排放特性。本研究的目的是分析季节性因素和 RDE 路线阶段对催化剂 NOx 排放和 NOx 转化效率的影响。在春季/秋季和夏季，车辆 A 的城市行驶阶段的发动机出口和排气管 NOx 排放比其他阶段高 1.3-5.9 倍，车辆 B 的城市行驶阶段的发动机出口和排气管 NOx 排放比其他阶段高 1.3-28.4 倍。在城市行驶阶段，由于频繁停车和低速行驶，发动机舱温度可能会升高，导致进气温度升高，从而导致过多的 NOx 排放，尤其是在夏季。城市行驶阶段的平均空气滤清器温度比车辆 A 的环境温度高 11-15°C。LNT 的 NOx 转化效率在高速公路上最高，为 54.1%，效率取决于测试路线的阶段。SCR 的 NOx 转化效率取决于催化剂温度，在春季高速公路上最高，为 98.7%，效率受季节和阶段综合因素的影响。
