Numerical Study on the Effect of Diesel Engine Emissions by Controlling Water Injection through the Exhaust Manifold

NOx and soot emissions have become an important concern for diesel engine due to the stringent emission standards and also due to the trade-off characteristics between them. Water injection is one of the efficient methods to reduce NOx and soot emissions withbetter trade-off. A computational study is conducted to investigate the NOx and soot emissions when water is injected through exhaust manifold in a single-cylinder DI diesel engine. The simulations are conducted for two casesi.) Water injection in the exhaust manifold when the exhaust valve is open ii.) Water injection in the exhaust manifold when the exhaust valve is reopened during suction stroke. These simulations are carried out for threewater injection quantities 6mg,16mg and 24mg. The water injection could reduce NOx emissions with better NOx and soot trade-off, due to the thermal, dilution and chemical effects. The water injection throughexhaust manifold strategy utilizes the exhaust gas heat to vaporize the water molecules and also createsan internal EGR effect. Results indicated that the NOx is reduced by about 73-75% when 16mg of water is injected. At this water quantity, it is also observed that the NOx and soot trade-off is less. In addition,as the water quantity increases the difference in NOx and soot emission values of the two cases are getting narrowed.