Experimental And Numerical Simulation Study On Combustion Fuelled With N-pentanol/diesel Blended Fuels Coupled Piolt-injection Strategy

In the face of increasingly serious environmental pollution and shortage of fossil energy,the development and application of alternative fuels is considered to be one of the effective ways to solve the problem.The oxygen element of alcohol can significantly reduce the soot emission of diesel engines.N-pentanol is a kind of long carbon chain alcohol,which is more soluble in diesel than short carbon chain alcohol,making it a very competitive alternative fuel for diesel.In order to provide a theoretical basis for the application and popularization of alternative fuels in diesel engines,it is necessary to study the experiment and simulation calculation of n-pentanol/diesel blendeds.First,based on a four-cylinder diesel engine,a study on the strategy of blending n-pentanol with diesel and pilot-injection was carried out.The results show that blending n-pentanol can significantly reduce the emissions of soot,but would lead to a small increase in HC,CO and NO_X emissions.Compared with single injection,pilot-injection strategy can reduce NO_X emission.With the increase of pilot-injection rates,NO_X emission decreases,but the emissions of soot,CO and HC would increase.When the pilot-injection amount remains unchanged,increase the pilot-main intervals,NO_X emission would be decreased,while the emissions of soot,CO and HC would increase.In order to further understand the influence of n-pentanol/diesel hybrid fuel coupling pilot-injection strategy on engine combustion process and emissions,the simplified mechanism of heptane-butylbenz-pentanol-PAH was coupled into the CONVERGE software to carry out numerical simulation of D100,P25 and P50.The results show that:compared with the single injection,the pilot-injection strategy can reduce the temperature,change the equivalence ratio slightly,reduce the OH,increase the soot,reduce the NO concentration and the NO_X emission,and increase the emissions of CO and HC.With the increase of pilot-injection rates and pilot-main intervals,the temperature and the equivalence ratio increase,the OH decrease,the soot distribution area and concentration reduce,the NO concentration and NO_X emissions are small,the CO and HC concentrations increase.After adding n-pentanol,the temperature decreased and equivalence ratio of the mixed fuel increased,the soot distribution and concentration decreased,but the concentration of NO,CO and HC increased.With increased EGR rate,the peak value of cylinder pressure and the maximum heat release rate of the three fuels in single injection decreased;Under the pilot-injection strategy,the peak value of the pilot-injection heat release decreases,the pressure and the maximum heat release rate of the main injection cylinder decrease;under all injection strategies,with the decrease of the temperature in the cylinder,the equivalence ratio tends to be uniform,the NO_X emission decreases,but the emissions of soot,CO and HC increase at the same time.With the increase of EGR rate and the addition of n-pentanol,the increase range of soot and NO_X will decrease,and the increase range of CO and HC emissions will increase;by continuing to add the pilot-injection strategy,soot increase amplitude and NO_X decrease amplitude increase,CO and HC emission increase amplitude continue to increase.