Research On The Effect Of Combustion With Water On The Performance Of Sequential Turbocharged Diesel Engines

With the increasingly serious environmental problems,the deteriorating situation of petroleum resources and the increasingly strict emission regulations of various countries,the working performance and emission requirements of diesel engines are constantly improving.In order to effectively improve the working performance of the diesel engine,optimize the combustion process,reduce the emission of nitrogen oxides and suppress the large amount of soot particles,this article uses the TBD234V6 diesel engine as a prototype,and transforms the conventional supercharging system into a sequential supercharging system to study the mixing the effect of water combustion technology on the combustion and emission characteristics of successively boosted diesel engines.?1?Based on the TBD234V6 diesel engine,the original supercharging system was transformed into a sequential supercharging system.Through the test,the switching operating point of the successive supercharging diesel engine was determined to be 40%P_e0.On this basis,the design of water-blended fuel system and the preparation of emulsified oil were carried out.The test results showed that:the three emulsifiers Span80,Tween80 and Op-10 were used in combination of 8:1:1 or 7:2:1.A large amount of emulsified oil mixed with water can be prepared for TBD234V6 diesel engine for experimental research.?2?Through experiments,the effects of water mixing rates of 3%,6%,9%,12%and 15%on the combustion characteristics and emission performance of successively boosted diesel engines were studied.The test results show that:when the water blending rate is 0,successively pressurized diesel engines are powered by pure diesel oil.When 10%P_e0?P_e?40%P_e0,compared with the original engine,the maximum combustion pressure is increased,the power is enhanced,and the fuel consumption rate Decrease,before the turbo exhaust temperature,NOx and Soot emissions decrease;when 45%P_e0?P_e?100%P_e0,compared with the original engine,the maximum combustion pressure drops slightly,the difference in fuel consumption rate is small,the exhaust temperature before the turbo,NOx emissions and Soot decreased.With the gradual increase of the water mixing rate,the maximum combustion pressure of successively boosted diesel engines decreased,and the fuel consumption rate,NOx and Soot emissions were significantly improved.Based on the calculation of the multi-objective gray decision theory model,through subjective and objective weighting methods,10%P_e0,25%P_e0,50%P_e0,80%P_e0 and 100%P_e0 are selected as the representative working point of low,medium and high load,After calculation,it is concluded that the optimal water mixing rate of successively boosted diesel engines is 15%.?3?AVL-fire simulation software was used to further study the comparison of the water mixing rate of 20%,25%and 30%with the optimal water mixing rate of 15%.Finally,through comprehensive analysis,the most advanced turbocharged diesel engines in this paper were determined.The best water mixing rate is 15%.In addition,the simulation results also show that the same load,with the increase of water mixing rate,the maximum combustion pressure,cylinder temperature and power are showing a downward trend.When the water mixing rate is30%,the maximum combustion pressure and cylinder temperature are the same as Compared with the water mixing rate of 15%,the decline is the largest.The respectively decline rates are about 7.8%and 10.9%.When 10%P_e0?P_e?40%P_e0,the equivalent fuel consumption rate gradually decreases,while at 45%P_e0<P_e?100%P_e0,the increase of the water mixing rate leads to an increase in the equivalent fuel consumption rate;the mass fraction of NO and Soot,the concentration field of NO and the concentration field of Soot have been significantly improved.