Nimodia, S., Senthilkumar, K., Halbe, V., Ghodke, P. et al., "Simultaneous Reduction of NOx and Soot Using Early Post Injection," SAE Technical Paper 2013-26-0055, 2013, doi:10.4271/2013-26-0055.
The effect of early post injection in diesel engine was studied with respect to engine out emissions and torque output. Initial tests indicated that there is significant reduction of soot for same NOx or with reduced NOx due to early Post Injection (POI) in traditional high speed diesel engine depending on various operating conditions. Further studies indicated that varying the post injection quantity and timing improved engine out NOx and soot emissions significantly and that the degree of this influence depends on speed and load of the engine. Additional investigations like study of heat release curve and air by fuel ratio were done to understand this effect completely.