Experimental Study On The Effects Of Diesel Blended With DNBE/1-octanol On Combustion And Emission Performance Of Heavy-duty Diesel Engines

Di-n-butyl ether（DNBE）and 1-octanol,two C₈ isomers,are of great value to realize the constant trade-off between diesel engine efficiency and emissions.In this work,different average effective pressures at the common speed of 1454 r/min of diesel engine are selected to represent low,medium and high load.The effects of different volume fraction（0,10%,and 20%）of DNBE/1-octanol blended fuels,different injection strategies（including main injection time and injection pressures）and speed on the combustion characteristics,fuel economy and emission characteristics of six cylinder heavy-duty diesel engine under low,medium and high loads were studied and analyzed.The weighted economy and emissions under the condition of world harmonized stationary cycle（WHSC）are discussed.The results show that under the condition of no interference with the engine injection strategy,brake specific fuel consumption（BSFC）increased and brake thermal efficiency（BTE）decreased when diesel blended with DNBE/1-octanol.Blending 1-octanol is more beneficial to control nitrogen oxides（NO_x）emission at the same load,but its reduction effect on soot,hydrocarbon（HC）,and carbon monoxide（CO）emissions are not as obvious as DNBE.The advance of main injection time leads to the increase of cylinder pressure peak of all the fuels,the advance of combustion phase and heat release time,and the decrease of BSFC.The increase of injection pressures promoting the cylinder pressure peak and heat release rate are responsible for the advance of heat release time,while the change of BSFC is greatly affected by loads.The pollutant emission analysis shows that the advance of main injection time and the increase of injection pressure cause the increase of NO_x emission of diesel and blended fuel and the decrease of CO emission,which has little effect on HC.The loads are the main reason to cause the change of soot emission with the main injection time.The soot emission gradually decreases with the increase of injection pressure.Diesel blending with DNBE or 1-octanol can reduce soot emission,but the BSFC of blended fuel is higher than that of diesel.Compared with low load,HC,CO and soot emissions of diesel and blended fuel are lower at higher load（BMEP=1.54 MPa）,while NO_x is on the contrary.When the main injection time is 14°CA BTDC,the emission reduction effect of 1-octanol blends is better than that of DNBE,but DNBE blends have a lower soot emission.With the increase of speed,the cylinder pressure and heat release rate curves and BTE of all fuels decrease,and the BSFC increase.The emission analysis shows that the increase of speed is conducive to reduce NO_x and CO emissions,has little impact on HC,but will have an adverse impact on soot emissions.In addition,DNBE or 1-octanol blended fuels have a more positive effect on reducing the pollutant emission than diesel at the speed of 1500 r/min.