Experimental Study And Numerical Simulation Of The Intake Port Water Injection Technology Based On A Diesel Engine

With rapid development of Chinese economics, the quantity of vehicles has increased greatly in last two. decades. This leads to further concerns of energy crisis and environmental pollution. Diesel engines are favored with high performances. However, major pollutants NOx and soot are increasingly stringent controlled internationally. Previous research indicated that the technology of intake port water injection can significantly reduce NOx emission at the same time does not cause serious deterioration of soot emission. To verify this technology, this research forces on a symmetric study of different issues such as combustion process, NOx reduction, vibration and noise generation using the water injection technology in diesel engines, which lay the foundation for the follow-up study.The advantages and disadvantages of diesel engine combustion mixed with water are compared and analyzed in this research. The experimental evaluation is based on4100QB turbocharged diesel engine. An intake port water injection system is designed to achieve different water amount conveniently and accurately by changing the injection pulse width and injection cycle. The impacts of different water injection amount on combustion process, power performance, economy, emissions, as well as vibration and noise are examined using both experimental study and numerical simulation. The results show that with the increase in water amount, the combustion constant volume degree and thermal efficiency are improved, the peak of pressure rise rate and heat release rate increases increase, the torque increases, the fuel consumption rate has a slight decline, NOx emission decreases apparently and the biggest drop amplitude is35.5%, soot emission increases somewhat, CO emission decreases slightly, HC emission remains basically unchanged, the vibration acceleration amplitude of cylinder head, cylinder body and pump increases. When there is no water injection at high load, the total sound pressure level increases caused by certain parts resonant oscillation, but with the water injection amount increases, the resonance phenomenon is eliminated.Due to the limitation of the water injection system, the amount of water injected during tests is not sufficient to give a full understanding of influences on combustion process and to achieve the maximum NOx emission reduction, the model of original diesel and the engine with intake port water injection module are established by GT-POWER software. The models are verified by comparison between simulation and experimental torque and cylinder pressure data. The performances of engine are analyzed with high amount of water injection. The results show that when the water injection amount research4.5kg/h, the torque decreased significantly, soot emission increases conspicuously but NOx emission is reduced unclear. Therefore, appropriate amount of water injection is very important, otherwise the power performance and emission of engine would be deteriorated.