Engine performance and emission effects of diesel burns enriched by hydrogen on different engine loads

•Effect of engine load on performance of an H2 enriched diesel engine was tested.•Hydrogen assisted diesel combustion was experimentally investigated on a CI engine.•A great improvement on CO, CO2 and smoke emissions was observed with hydrogen addition.•Dramatic increase on NOx emissions with H2 addition at full loads was obtained.•An important reduction on NOx was achieved with H2 addition at partial loads.

Although diesel engines will be used in future too, they are the indispensable part of our daily lives. However, steadily decreasing emission regulations limit values and cost increases due to corresponding need of hi-tech aftertreatment systems, and diesel fuels' increasing price in recent years force researchers to use alternative fuel types to use on diesel engines. In this work, hydrogen which is in gas phase is sprayed with gas injector from intake port and ignition is provided by diesel fuel coming from diesel injector. Sent hydrogen's energy content is stabilized at 30% in overall fuels and all tests committed are performed in 1100 rpm stable engine speed. Also, in different engine loads (40%, 60%, 75% and 100%) intake air enrichment with hydrogen effect on diesel engine's engine performance, emissions and effect on combustion have been examined. Obtained results show that in part load conditions enriched with hydrogen, NOx emissions and soot emissions can be taken under control. However on, full load condition (100% engine load), with hydrogen addition, dramatical rise of NOx emissions is observed. Working conditions with hydrogen + diesel fuel, it is obtained that engine load affects NOx emissions significantly. On full load conditions, enriched with hydrogen, even though there is some rise in THC emissions, there are progresses in CO2 and CO emissions. Besides, peak in-cylinder gas pressure and peak heat release rate have risen in hyrogen enriched condition.