Study On The Influence Of Different Injection Modes On Combustion And Emission Of N-butanol Engine

In this paper,n-butanol was used as engine fuel,and the effects of different injection modes on combustion,conventional emissions and particulate emissions of n-butanol engine were studied by using different in-cylinder direct injection proportions.This research was mainly divided into three parts.The first part was the preparatory work.Firstly,to meet the test requirements,test bench,refitting fuel injection system and debugging electronic control system were finished.Then the exploratory test was carried out and worked out the final test plan.The second part carried out the experimental research according to the specific test scheme.Under six direct injection ratios,The combustion state and conventional gas emission performance of the engine were compared through experiments.The ignition advance angle,excess air coefficient and load were selected as the main parameters.Through the analysis of combustion and emission rules,the appropriate injection strategy under different operating conditions was explored.The third part mainly studied the particulate matter in the engine exhaust.Based on the second part,the representative variables were selected from the first set of test variables,to analyze the particulate matter emission of the engine under three direct injection ratios.At the same time,the effects of engine speed and in-cylinder direct injection time on particulate matter emission were also explored.Explored the influence of various parameters on particulate matter emissions under different injection ratios of engines,and to explore the composite injection technology route to reduce particulate matter emissions.The main conclusions drawn from the experimental study are as follows:（1）When the direct injection ratio increased,the cylinder pressure,heat release rate,in-cylinder temperature,average indicating pressure and thermal efficiency first rose and then decreased,the crankshaft corner position of peak cylinder pressure and maximum heat release rate gradually moved back,the effective fuel consumption rate increased,the CO value and HC value first decreased and then rose,and the NOx value first increased and then decreased.The power performance and economy of ND₂₀I were better.（2）The peak values of maximum cylinder pressure,heat release rate and in-cylinder temperature occurred at high direct injection ratio under heavy load.When the direct injection ratio was large,the indicated engine pressure and fuel economy were better.When the direct injection ratio was small,HC emissions would also increase.Under heavy load conditions,ND₆₀I and ND₈₀I would achieve better power performance and fuel economy,but it would increased the emission of NOx.（3）The optimum ignition time of each direct injection ratio was different.The optimum ignition advance angle of small proportion direct injection ratio was 20°CA BTDC,while that of large proportion direct injection ratio was about 15°CA BTDC.With the increase of ignition advance angle,the number concentration of nuclear states decreased and the accumulation state increased at ND₆₀I and NDI.At ND₂₀I,the number concentration of nuclear state and accumulated state increased.（4）With the increase of excess air coefficient,the number concentration of nuclear states decreased first and then increased at NDI,while the number concentration of aggregated states decreased gradually.However,at ND₆₀I and ND₂₀I,the number concentration of nuclear states decreased all the time,while the number concentration of aggregates decreased slowly.With the increase of load,the number concentration of nuclear state decreased,the number concentration of accumulated state increased,and the total number concentration of particulate matter decreased at NDI and ND₆₀I.At ND₂₀I,the number concentration of nuclear and accumulative particles increased with the increase of load.（5）With the increase of rotational speed,the particles gradually transformed from nuclear state to accumulative state,the number concentration of nuclear particles gradually decreased,and the accumulative particles gradually increased.With the delay of direct injection time,the number concentration of nuclear and accumulative particles decreased first and then increased.