Numerical investigation of the impacts of ammonia injection on the performance of EF7 engine with CNG fuel

Natural gas is known as one of the clean fuels the employment of which in vehicles results in the decrease of emissions and greenhouse gases. In addition, ammonia is known as one of the hydrogen carrier fuels the co-burning of which with natural gas leads to increment of combustion efficiency. In this paper, a numerical investigation is performed on the impacts of ammonia injection on the emission production and performance of a CNG-fueled EF7 engine. At first, the gaseous fueled EF7 engine has been modeled in AVL BOOST software and the main parameters of the engine at 6000 RPM and full load condition have been extracted and compared with experimental data for validation purpose. Then, the ammonia has been injected by 5% and 10% injection ratio by 4 injectors mounted on the air manifold into the engine, and the results of its injection into the engine are studied. By injection of ammonia, the engine power and brake mean effective pressure has been changed minimally. However, the in-cylinder temperature increased resulted in a decrement in CO and HC emissions up to 27% and 7.5%. On the other hand, the increase of in-cylinder temperature also led to an increase in NOx production which increased up to 43.4% for 5% ammonia injection and 118.7% for 10% ammonia injection.