Upcoming emission limits such as Euro VII will make it necessary to further reduce the NO_x emission level of internal combustion engines while stricter CO₂ limits demand lower fuel consumption. Early closing of the intake valves (Miller timing) leads to reduced combustion temperatures due to lower effective compression ratio, and therefore lower formation and emission of nitrogen oxides. Miller timing is frequently used in gasoline engines, while in Diesel engines it competes with exhaust gas recirculation (EGR). When both measures are applied simultaneously, this may lead to increased emission of soot using standard Diesel fuel, as combustion temperature and oxygen content of the charge become too low. This work shows the investigation of different intake valve timings on an externally supercharged single-cylinder heavy-duty Diesel engine, stationary operated with hydrogenated vegetable oil (HVO), oxymethylene ether (OME), and standard Diesel fuel (DF). The synthetic fuels have a higher cetane number than DF, which supports ignition at lower temperatures. Moreover, OME has a soot-free combustion, which allows an extension of the operating limits without increased emissions. The results show that especially with Miller timing a high-performance turbocharging system is crucial, since higher boost pressure is required to compensate for the filling losses due to the earlier intake closing. The application of a high EGR rate is limited in this case, leading to a trade-off between Miller timing and EGR. All fuels show a reduction in nitrogen oxides of up to 40% with an improved efficiency of more than 3% at a typical road-load point. Measures to reduce ignition delay were found to be necessary, especially for DF. For OME, increased soot formation does not occur when combining Miller timing with low rail pressure, reduced boost pressure or EGR, which promotes simultaneous application of the measures resulting in minimized emissions of nitrogen oxides.

即将出台的排放限制（如欧 VII）将使得有必要进一步降低内燃机的 NO _x排放水平，同时更严格的 CO ₂限制要求降低油耗。由于较低的有效压缩比，提前关闭进气门（米勒正时）会导致燃烧温度降低，从而减少氮氧化物的形成和排放。米勒正时常用于汽油发动机，而在柴油发动机中，它与废气再循环 (EGR) 竞争。当这两种措施同时应用时，这可能会导致使用标准柴油燃料的烟灰排放增加，因为燃烧温度和充量的氧含量变得太低。这项工作展示了对使用氢化植物油 (HVO)、甲醛醚 (OME) 和标准柴油 (DF) 固定运行的外部增压单缸重型柴油发动机的不同进气门正时的研究。合成燃料的十六烷值高于 DF，后者支持在较低温度下点火。此外，OME 具有无烟灰燃烧，这允许在不增加排放的情况下扩展操作限制。结果表明，尤其是在米勒正时，高性能涡轮增压系统至关重要，因为需要更高的增压压力来补偿由于提前关闭进气口造成的充气损失。在这种情况下，高 EGR 率的应用受到限制，导致米勒定时和 EGR 之间的权衡。在典型的道路负载点，所有燃料的氮氧化物减少高达 40%，效率提高 3% 以上。发现有必要采取措施减少点火延迟，尤其是对于 DF。对于欧米茄，