The large-bore, slow-speed, two-stroke natural gas engines that frequently power natural gas pipelines are the subjects of increasingly stringent emissions standards, particularly those targeting emissions of oxides of nitrogen (NOx) and greenhouse gases (GHGs) such as methane and carbon dioxide. Running these engines near their lean limits of operation reduces combustion temperature and therefore NOx emissions but at the cost of increased misfires and combustion instability, thus increasing GHG emissions. A pre-combustion chamber (PCC) can be equipped to provide a high-energy ignition source ...
The large-bore, slow-speed, two-stroke natural gas engines that frequently power natural gas pipelines are the subjects of increasingly stringent emissions standards, particularly those targeting emissions of oxides of nitrogen (NOx) and greenhouse gases (GHGs) such as methane and carbon dioxide. Running these engines near their lean limits of operation reduces combustion temperature and therefore NOx emissions but at the cost of increased misfires and combustion instability, thus increasing GHG emissions. A pre-combustion chamber (PCC) can be equipped to provide a high-energy ignition source that extends the reliable lean limit of the engine, further reducing NOx emissions without drastically increasing emitted GHGs or reducing engine performance. A computational fluid dynamics (CFD) study was conducted to explore the effects of premixing fuel and air prior to injection into the PCC. Various premixed equivalence ratios, injected mass flow rates, and injection timings were studied and compared to a non-premixed baseline, specifically focusing on differences in GHG emissions and engine performance indicators such as peak pressure and total heat released. This work provides an examination of these results as well as recommendations for future research building off the preliminary data delivered here.