Fast NO Measurements In a Two-Stroke Large Bore Natural Gas Engine
In order to better understand NOx formation in large bore natural gas engines, cycle resolved NO data is acquired. The data is taken using a Cambustion Ltd. Fast NO analyzer, model fNOx400. The work is performed on a Cooper-Bessemer GMV-4TF two-stroke large bore natural gas engine. Cycle resolved NO data is extracted from cylinders two and four on the GMV-4TF. Somme data is also taken from cylinder one, which has different articulation than two and four. Cycle resolved pressure traces are acquired using a Redline combustion analysis system and synchronized with the cycle resolved NO measurements. In order to produce varying values of average NO emissions, data is taken using both a five-point boost map and a five-point ignition map. Since NOx emissions are influenced by combustion variability, relationship[s between individual cycle pressure traces and the NOx produced by that cycle are investigated. Furthermore, mass averaged NO values are calculated and integrated in order to compare with average exhaust emissions from a Rosemount five gas analyzer. When relating the cycle resolved pressure traces to the respective cycle resolved NO traces, it is found that the cycles with higher peak pressures, and hence more complete heat release, produce more NO. Conversely, the cycles with lower peak pressures and hence incomplete combustion, produce less NO. When the mass averaged NO values are computed, they compare well with the exhaust emission values taken with the Rosemount analyzer.