Investigation of ammonia homogenization and NOx reduction quantity by remodeling urea injector shapes in heavy-duty diesel engines

•12,000CC diesel engine capacity with 1,000 rpm and 1,700 rpm engine capacity used for experiment and simulation study.•The turbulent model and RANS equation number can investigate the evaporation quality, ammonia gas value, NOx conversion efficiency, and ammonia injector from SCR system.•Improvement mixer position can increase mixing process between ammonia gas and NOx emission.•The modification of urea injector can increase ammonia gas in the commercial SCR system by Hyundai D6CC (12.000 cc).•The solidification of urea inside the original injector hampered the distribution of urea.•The hot gas temperature can increase the ammonia generation process in the system.•The NOx concentration value and NOx conversion efficiency were described in this study by gas analyzer in the experiment. Gaseous NOx emission is very hazardous for human health and heavy-duty diesel engines contribute 40% of these global highway emissions. Among technologies for reducing emissions, DPF and SCR are most common, and are used in many automotive industries. The honeycomb-shaped catalyst and ammonia gas utilized in these methods can reduce NOx emissions by more than 90%. However, improvement of NOx emission reduction emission is needed. This study investigates two model injectors to optimize spray distribution for improve the NOx conversion quality in the diesel engine, especially a heavy-duty diesel engine, because these engines produce a huge amount of NOx concentration compared to another engines. These investigations also identified the amount of ammonia gas on the catalyst surface by utilizing 19 gas sensors. Comparison between the experiment and simulation shows the ammonia and NOx quantities from the two injector models and elucidates the temperature results for vaporization and saturation quantity, ammonia homogenization distribution, and NOx conversion in the system.