Technology Development of Novel Aftertreatment High Pressure Diesel Delivery Unit to Meet Future Emission Regulations for Medium-Heavy Duty Diesel Engines

Future emission regulations (Euro VII, LEV IV, Tier V, China VII, etc.) will impose more stringent requirements both in terms of regulated pollutants emissions and CO2 for On-Road and Off-Road Diesel applications. The higher regulatory stringency will require more complex AfterTreatment System (ATS) architectures featuring a more frequent implementation of a Diesel Dosing Unit (DDU) in the exhaust as technology enabler for the overall compliance. Currently available DDUs work at low pressure (LP) fuel supply around 5 bar and often require a mixer downstream in the exhaust line to ensure the right level of fuel atomization, evaporation and mixing. The usage of high pressure (HP) fuel supply at around 200 bar, together with component design enhancement and dedicated spray targeting generates advantages in terms of CO2 and pollutant emissions both during Diesel Particulate Filter (DPF) regeneration and normal modes. To quantify the advantages, steady state and transient tests were executed on a state of the art 6.6 L Diesel engine where the HP-DDU was assessed in comparison with LP-DDU which was part of the baseline ATS. The comparison between the two technologies was made by installing the HP-DDU in two ATS layouts: same mixing length and minimal mixing length both removing the mixers which were present in the baseline LP-DDU ATS layout. During DPF regeneration, both layouts tested showed benefit in THC (up to 20%), CO (up to 95% at low flow, 50% at medium flow) and BSFC (up to 1.5-2.0%). Additionally, transient testing highlighted better temperature control and higher residual O2 (after fuel oxidation over the DOC) leading to shorter DPF regeneration duration. In normal mode, the CO2 benefit from a reduced back pressure (up to 10% at rated power) due to the mixer removal was estimated. Considering all the measured benefits, the Dumarey developed HP-DDU technology is considered promising for compliance with upcoming CO2 and emission regulations worldwide.