Liu Yingshuai, Tan Jianwei, Liu Chenxing, He Yunli
Shandong Huayu University of Technology, Dezhou, China.
National Lab of Auto Performance and Emission Test, School of Mechanical and Vehicular Engineering, Beijing Institute of Technology, Beijing, China.
PLoS One. 2025 Apr 29;20(4):e0320323. doi: 10.1371/journal.pone.0320323. eCollection 2025.
In the actual use process, especially under the low exhaust temperature in urban conditions, the actual NOx emission of diesel engines using the Urea SCR technology is higher than expected, which seriously affects the application of Urea SCR technology in urban diesel vehicles. To solve the defects of low-temperature freezing, urea crystallization in the exhaust pipeline at low exhaust temperature, and insufficient activity of the Urea SCR system at low exhaust temperature in the actual application process of the Urea SCR technology, this paper uses the Portable Emission Measurement System (PEMS) vehicle test system to run the real-world. A SAIC Hongyan Dump truck that meets the China VI emission standard is tested and studied, and the real-world emission characteristics of the Solid SCR system and the Urea SCR system are compared and studied. Among other things, solid-state SCR systems use solid ammonium as a precursor to ammonia, a change that reduces clogging problems due to icing and hydrolysis evaporation crystals at low temperatures compared to conventional aqueous urea solutions. This results in more reliable system operation in cold environments. Solid-state SCR technology offers a more efficient and reliable solution for diesel exhaust treatment through its unique ammonia supply method, system optimization and environmental adaptability, helping to reduce environmental pollution from diesel vehicles. The test results show that: Under real-world operation conditions, the NOx conversion efficiency of the Urea SCR system and the Solid SCR system with the same injection strategy is increased by 0.5% and the NOx emission is reduced by 8.9% when the window average temperature is 228.8°C and 231.3°C. For the PN emission, no matter whether the Urea SCR system or the Solid SCR system is selected, the results have little influence. Based on the Solid SCR system, CO, HC, NO, NOX, and other pollutant emission factors gradually decrease and tend to be relatively stable with the increase in vehicle speed. The Solid SCR technology is a promising NOx emission control technology for diesel engines.
在实际使用过程中，尤其是在城市工况下排气温度较低时，采用尿素选择性催化还原（Urea SCR）技术的柴油发动机实际氮氧化物（NOx）排放量高于预期，这严重影响了Urea SCR技术在城市柴油车辆中的应用。为了解决Urea SCR技术实际应用过程中存在的低温冻结、排气温度低时排气管道内尿素结晶以及Urea SCR系统在低温下活性不足等缺陷，本文利用便携式排放测量系统（PEMS）车辆测试系统进行实际道路运行。对一辆符合国六排放标准的上汽红岩自卸车进行测试研究，比较研究了固体SCR系统和Urea SCR系统的实际道路排放特性。其中，固态SCR系统使用固体铵作为氨的前驱体，与传统的尿素水溶液相比，这种变化减少了低温下因结冰和水解蒸发结晶导致的堵塞问题。这使得系统在寒冷环境下运行更可靠。固态SCR技术通过其独特的氨供应方式、系统优化和环境适应性，为柴油废气处理提供了一种更高效、可靠的解决方案，有助于减少柴油车辆对环境污染。测试结果表明：在实际道路运行工况下，当窗口平均温度分别为228.8°C和231.3°C时，采用相同喷射策略的Urea SCR系统和固态SCR系统的NOx转化效率提高了0.5%，NOx排放量降低了8.9%。对于颗粒物数量（PN）排放，无论选择Urea SCR系统还是固态SCR系统，结果影响都很小。基于固态SCR系统，一氧化碳（CO）、碳氢化合物（HC）、一氧化氮（NO）、氮氧化物（NOX）等污染物排放因子随着车速的增加逐渐降低并趋于相对稳定。固态SCR技术是一种很有前景的柴油发动机NOx排放控制技术。
