Cycle-Resolved NO Measurements in a Two-Stroke Large-Bore Natural Gas Engine

Abstract

Cycle-resolved NO data were acquired from a Cooper-Bessemer GMV 4TF two-stroke engine to better understand and quantify large bore natural gas engine NOx emission. The cycle resolved NO data were extracted separately from the engine’s cylinder two and four exhaust ports and taken simultaneously with cycle resolved pressure traces, conventional steady-state emission measurements and a variety of additional performance and diagnostic data. The test variables were intake manifold boost pressure, ignition method and ignition timing. Relationships between individual cycle pressure traces and the NO produced by that cycle were investigated. Furthermore, mass-averaged NO values were calculated and integrated in order to compare with average exhaust emissions from a steady-state analyzer and combustion pressure characteristics. The steady measurements revealed that NO and NO2 emissions respond differently to the test variables. The mass averaged cycle-resolved NO values compare well with the steady exhaust emission measurements and exhibit strong correlations with peak pressure and crank angle location of peak pressure.