Phenomenological model of urea water solution dosage strategy for urea-selective catalytic reduction systems

Selective Catalytic Reduction (SCR) is the latest technology adopted to diesel engines of automobiles to transform NO_x. The required reducing agent (NH₃) is generated after engine exhaust by injecting Urea in the form of Urea Water Solution (UWS). There are some numerical methods with limited experimental details to estimate the behavior of UWS droplets in a heated environment, and some of them have been implemented into CFD codes. In the CFD codes, many numerical relationships are not validated for the evaporation of UWS droplets. In the SCR system of modern automobiles, the dosage strategy is based on DOE techniques. But, the theoretical method is required for UWS dosage during optimization of the SCR system. So, an integrated zero-dimensional model is required for dosage strategy during simulation studies so that exact dosage could be possible based on NO_x, flow rate, and temperature of exhaust gas to suit actual SCR situations. In the present work, a phenomenological model is developed based on theoretical correlations, experimental data generated by authors, and data from the literature.