Abstract
A water injection in engine is one of the effective technologies to reduce combustion temperature and to mitigate the knocking tendency. In this study, effects of water injection in T-GDI (turbo-charged gasoline direct injection) engine were investigated experimentally. The water was injected into the intake port near intake valves. Engine tests were conducted at 2000 rpm of engine speed with various engine loads and WOT (wide open throttle) conditions ranged from 1500 rpm to 6000 rpm. It revealed that the BSFC (brake specific fuel consumption) was decreased as the water/fuel ratio was increased within a certain level. The significant effect of water injection on fuel consumption is found at high load condition. With the increase of water/fuel ratio, the spark timing and MFB (mass fraction burned 50) were advanced due to the reduction of combustion temperature, and AFR (air/fuel ratio) was increased. THC and CO emissions with water injection around stoichiometry were slightly increased, but NOx (nitrogen oxides) emission was decreased. In rich condition, THC and CO were decreased but NOx emission was increased.
KEYWORDS : Water Injection, BSFC (brake specific fuel consumption), Turbo Gasoline direct injection (T-GDI) Engine, Ignition timing, NOx emission