Assessment of Ring Injectors for Reducing NOx and PM Emissions of Diesel Engines FINAL REPORT

Transportation assume no liability for the contents or use thereof. The contents do not necessarily reflect the official views or policies of the State of California or the Department of Transportation. This report does not constitute a standard, specification, or regulation. Abstract The effects of ring injectors on the performance of a selective catalytic reduction (SCR) system have been investigated. The investigation was divided into two parts. First the mixing effectiveness of circular and rectangular ring injectors on a heated turbulent jet were investigated. The experiments were carried out using a turbulent jet facility at the Center for Energy and Environmental Research and Services (CEERS) laboratory. For this part of the investigation, air was used as both injection and exhaust gases. Results indicate that the ring injector enhances mixing process between the axial flow and the injecting flow with the rectangular injector having a higher mixing effectiveness. In part two of the investigation, an SCR system with a rectangular two-hole ring injector was developed and the system was tested using the exhaust of a 3-cylinder aspired diesel engine under a moderate shaft loading condition, using ammonia gas as the reducing agent. Results show nearly 80% reductions in NOx emissions. Further study is underway to assess the effect of opposed exhaust flow ammonia injection and tab mixer to identify the best configuration for development of high efficiency automated prototype SCR unit.