Effects of injection timing on combustion exothermic pattern and partial emissions of ammonia/diesel dual-fuel engine
With a marine single-cylinder diesel engine as the research object,the effects of injection timing on combustion and emission characteristics of the ammonia/diesel dual-fuel engine were studied by using the combustion mode of ammonia pre-mix and diesel direct injection.The results show that,compared with pure diesel mode,after ammonia injection,the peak cylin-der pressure Pmax of the dual-fuel engine drops,the ignition time is delayed,the combustion duration is extended,maximum pressure rise rate Rmax decreases,the emissions of CO2 and NOx decrease,and the emissions of unburned ammonia and N2O in-crease significantly.In dual-fuel mode,with the advance of diesel injection time,the in-cylinder combustion situation is im-proved,Pmax and Rmax rise,the emissions of unburned ammonia and N2O decrease,NOx emission increases,the soot emission de-crease first and then increase,and CO2 emission has no significant change.As the load increases,Pmax and Rmax rise,but the in-crease in ammonia injection reduces the air charge in the cylinder,so the ignition time is delayed and the combustion duration is extended.Meanwhile,the emissions of CO2,soot and NOx increase,and the emissions of unburned ammonia and N2O de-crease.The optimal injection timing is-5°CA at 25%and 75%load rates when the combustion stability is given priority.If the primary goal is to reduce greenhouse gas emission,the optimal injection timing is-15°CA at 25%load rate and-10°CA at 75%load rate.With NOx emission reduction as the primary objective,the injection timing is-5°CA for both 25%and 75%load rates.
万方数据
维普
