Electrically Heated Mixer for Low Temperature AdBlue Dosing, Mitigating Deposit, and Meeting Future Low NOx and GHG Regulations

There is worldwide attempt to reduce both NOx and CO₂ emissions of Diesel vehicles. A common way to reduce CO₂ is via increasing engine fuel economy. This yields higher NOx emission from engine, in turn requiring higher rates of urea (AdBlue^™) injection for more efficient NOx reduction in the SCR catalyst. But more urea injection also increases the risk of forming urea deposits. In this work, we discuss using an Electrically Heated Mixer (EHM^™) to mitigate deposit risks while injecting varying amounts of urea, including high injection rates. Testing was conducted on a 5.2 lit. engine, demonstrating a pathway to meet MY2027 GHG phase-2 regulation with changes primarily in the controls and calibration strategies. CO₂ reduction strategy included engine down-speeding and increased EO-NOx. This required higher urea dosing during cold start conditions and lower exhaust temperatures during hot start, in turn increasing the challenges involved in achieving the MY2027 ultra-low NOx regulation 0.02 g/hp-hr (0.027 g/kW-hr). The EHM^™ evaluated in this study enabled dosing high urea dosing quantities to achieve NOx conversion efficiency without concerns for deposit. Urea injection rate varied by 6.5-fold, from 93 to 600 g/h (26 to 167 mg/s). It is shown that EHM effectively hinders urea deposit risks, yielding near-zero deposits.