Precombustion Chamber Design for Low NOx Emissions from Large Bore NG Engines
Precombustion chambers (PCCs) are an ignition technology for large bore, natural gas engines enabling increased combustion stability while extending the lean limit of operation. In this work the role that the PCC plays in the formation of oxides of nitrogen (NOx) is investigated. Additionally, new PCC designs are explored as a means for reducing engine-out NOx emissions. Previous research indicates that the PCC is responsible a significant portion of engine-out NOx, especially near the lean limit of engine operation. Experimental results from a large bore lean burn 2-stroke cycle engine are presented. The data shows that the PCC is responsible for a significant part of engine-out NOx emissions. However, the results indicate that the PCC NOx does not form in the PCC. Rather, the results show NOx forms within the gas jet after it penetrates into the main chamber combustion gases. Five PCC concepts are developed in the scope of reducing NOx. A test plan is created to compare the baseline PCC configuration to the performance of the new PCC concepts. Three of the concepts demonstrate improved combustion stability while reducing engine-out NOx. A PCC flow model is created to better understand PCC operational characteristics. The research was funded by the Pipeline Research Council International (PRCI).