Large-scale diesel engine emission control parameters

Emission tests were carried out on a large-scale medium-speed supercharged diesel engine (∼1 MW per cylinder) with control parameters compression ratio, start of ignition (SOI) and fuel type (light and heavy fuel oil, LFO and HFO). Emissions of NOx, CO, hydrocarbons (HC), smoke (FSN) and particulate matter (PM) were measured and are discussed in relation to the control parameters. Regarding turbocharger influence on emissions the control parameters by-pass and waste-gate are also briefly addressed.The results show that NOx, CO and FSN decrease while HC emissions increase with later SOI (more delay) for all loads (25–100%). The influence of compression ratio (CR) on NOx is the inverse of this; decreasing CR gives increased NOx. Nozzle design is important for emissions control and less holes and bigger diameter for a certain injection angle seems preferable. Fuel type is important too, and in general LFO produces less gaseous or particulate emissions. Diesel engine turbocharger by-pass and waste-gate valves do affect the emissions. PM emissions were found to decrease with the load (∼Bmep) for propulsion mode, showing an increase with load for generator mode for HFO; for LFO decreasing PM emissions were found with increasing load for both generator and propulsion mode.