Experimental Investigation of an AdBlue^® Injection System and Implementation on a Dual-Fuel (Diesel/LPG) Engine

Euro 6 Diesel vehicles use Diesel Particulate Filters (DPF) and Urea-Selective Catalytic Reduction (SCR) to reduce particulate matter and NOx emissions. Accurate exhaust gas NOx and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${{\mathrm{O}}_2}$</tex> measurements are critical to assess aftertreatment system effectiveness. Tests on a 2019 Dacia Stepway, equipped with DPF and SCR, revealed unreliable ECU data for NOx and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${{\mathrm{O}}_2}$</tex> sensor readings obtained from an automotive scan tool. To address this, CAN messages from NOx sensors were captured and calibrated using a laboratory-type UniNOx (Continental) sensor. From the data gathered it was possible to implement an AdBlue aftertreatment system on a laboratory diesel engine, controlled via a developed injection scheme, to optimize NOx reduction through precise AdBlue injection. Details of the developed system are detailed in this paper. Chassis dynamometer testing utilizing the test vehicle showed consistent 24ppm tailpipe NOx levels, regardless of engine load, whilst the laboratory setup achieved stable value of 30ppm whilst minimizing ammonia slip. During active DPF regeneration on the test vehicle, higher exhaust temperatures challenged the SCR system, briefly increasing NOx emissions. Oxygen concentration differences between engine-out and tailpipe gases allowed soot oxidation quantification, matching DPF soot reduction reports from the scan tool.