Research On Water Injection Into Intake Ports Of Diesel Engine In Order To Lower NOx Emission

The pollution due to emissions of automobile is the main cause of atmospheric pollution. The crucial discharges of diesel engine are NOx emissions and (PM) particle material emissions. So lowering NOx and PM emissions is the ultimate handicap along developing of diesel engines. Utilizing technology of water injection into intake ports can both lower largely NOx emissions and economize oil.High temperature is the chief matter resulting in produce of NOx. Only if we would find a kind of way to lower combustion temperature,'the NOx emissions will be reduced evidently. Because of its great latent heat, water can absorb heat and boil away, so as to lower combustion temperature. Meanwhile in the condition of high temperature, water vapors can participate in combustion. Water gas reaction will happen, which will reduce carbon particle in flame, and reform combustion performance, so improve combustion efficiency.The article developed a kind of technology of water injection into intake ports for 4135G diesel engine, meanwhile designed a suit of water injection system. It can be applied simply to diesel engine, because it is unnecessary to change engine's configuration. It only needs a set of water injection system of installation before intake pipe of diesel engine. The running mode of engine can be switched between water injecting mode and no-water mode by the system. And quantity of water will be adjusted by the system when engine works in the water injecting mode. A favorable conclusion is educed through experiment.The article introduced in detail the scheme of water injection system, test-bed and the direction optimizing the system. Water injection system includes pulverization system and controlling system of water quantity. Pulverization system includes air resource, water resource and gas-mist nozzle; controlling system of water quantity includes booster, controlling circuits. Water quantity is decided by hydraulic pressure and gas pressure. Tests include sensitive test, test of emissions, oil consuming test, and combustion pressure curve test. It is showedthat NOx emissions can be reduced evidently. The direction of optimizing system includes optimal water quantity and design of closed loop controlling system.