Experimental investigation of urea injection parameters influence on NO_x emissions from blended biodiesel-fueled diesel engines

The present work submits an investigation about the effect of urea injection parameters on NO_x emissions from a four-stroke four-cylinder diesel engine fueled with B20 blended biodiesel. An L₉(3⁴) Taguchi orthogonal array was used to design the test plan. The results reveal that increasing urea concentration leads to lower NO_x emissions. Urea flow rate increment has the same influence on NO_x emission. The same result is obtained by an increase in spray angle. Also, according to the analysis of variance (ANOVA), urea concentration and then urea flow rate are the most effective design parameters on NO_x emissions, while spray angle and mixing length have less influence on this pollutant emission. Finally, since the result of confirmation test is in good agreement with the predicted value based on the Taguchi technique, the predictive capability of this method in the present study could be deduced.