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Effects of Intake Air Humidification Coupled with Swirl Ratio on Combustion and Emissions in a Marine Diesel Engine(PDF)


2020 01
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Effects of Intake Air Humidification Coupled with Swirl Ratio on Combustion and Emissions in a Marine Diesel Engine
Cai YujieZhao ChangpuWang Ke
State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China
intake air humidificationswirl ratiomarine diesel enginenumerical simulationcombustionemission
A three-dimensional numerical model of a four-stroke marine diesel engine was established by a commercial simulation software AVL-Fire.Numerical investigations were conducted to explore the potential of intake air humidification coupled with swirl ratio to improve the trade-off relationship of NOx-soot.This paper also provided a solution to meet Tier Ⅲ emission regulations with a loss of indicated specific fuel consumption of no more than 2%.The simulation results indicate that both in-cylinder peak temperature and pressure decrease by about 2% with the increase of humidification rate.The ignition delay gets longer,and CA50 is delayed,resulting in reduced combustion thermal efficiency.The NOx emissions can be significantly reduced due to the decrease in temperature and intake oxygen concentration,with the greatest decrease of about 56.7%.An appropriate swirl ratio is conducive to fuel/air mixing.However,with the increase of swirl ratio,jet penetration becomes shorter due to jet deflection,which will influence fuel/air mixing quality.The NOx and soot emissions first increase and then decrease as the swirl ratio increases,and the soot emission is the lowest when the swirl ratio is 0.5. Furthermore, optimization is carried out on the results obtained for various humidification rates and initial swirl ratios.There are nine cases that can simultaneously reduce NOx and soot emissions.When the initial swirl ratio is 0.5,the two cases with 100% and 80% humidification rate are found to have achieved the optimum emission and meet Tier Ⅲ emission regulations.



Last Update: 2020-01-17