Experimental and numerical investigation of dual-fuel CI ammonia engine emissions and after-treatment with V₂O₅/SiO₂–TiO₂ SCR

Ammonia (NH₃) is one of the most promising fuels regaining interest in recent years, as an alternative to fossil fuels. It is often suggested as a more favorable solution than supplying pure hydrogen due to its higher volumetric energy density. In this study a dual fuel CI engine running on ammonia and diesel mixture was tested, as a means to utilize ammonias potential in diesel engines. The injection strategy was port injection for ammonia, where it was mixed with air, and direct injection of diesel oil. A set of different NH₃-diesel mixtures were tested. Due to partial substitution of diesel fuel by NH₃ the elementary composition of fuel has changed. It increased nitrogen's and reduced carbon's mass in the combustion chamber. Consequently, the exhaust species have also changed. The Fourier Transform Infrared Spectroscopy was used to analyze the composition of flue gas. On top of investigating changes in CO₂, CO, HC, NO_X, residual ammonia molar fraction was observed. Possibility of using residual ammonia to activate selective catalytic reduction (SCR) system and its effectiveness in different operating points of engine were investigated. As part of the research, a numerical model of operation of the used SCR system was also developed. Results from the experiments have served to validate numerical model. Created model was then used to analyze wider spectrum of operating conditions of the engine and SCR.