The thermal analysis kinetic method was employed to solve the activation energies of the thermal decomposition reactions of urea and cyanuric acid, with the purpose of understanding the formation of deposits in the diesel engine SCR system. The deposit reaction kinetic model was established by optimizing the reaction paths and reaction kinetic parameters based on the thermal analysis test data of the key components in the deposit. The result shows that the established deposit reaction kinetic model can accurately describe the decomposition process of the key components in the deposit. Compared to the Ebrahimian model, the simulation precision of the established deposit reaction kinetic model is significantly improved above 600 K. The activation energies of the urea and cyanuric acid decomposition reactions are 84 kJ/mol and 152 kJ/mol, respectively, after model parameters identification. The identified activation energies were closest to those of the Friedman one-interval method indicating that the Friedman one-interval method is reasonable to solve the activation energies of deposit reactions.
Keywords: deposit; reaction kinetic; selective catalytic reduction; thermal analysis technology; urea.