Effects of Ethanol Addition on Performance, Emission and Combustion of DI Diesel Engine Running at Different Injection Pressures

Ethanol is an alternative renewable fuel produced from various agricultural products. Ethanol-diesel emulsion technique is used for the utilization of ethanol in diesel engines wherein ethanol is used without any modification. The performance, combustion and emission characteristics of a direct injection (DI) diesel engine for off-highway application were evaluated using ethanol-diesel microemulsions. The addition of ethanol to diesel fuel simultaneously decreases calorific value, kinematic viscosity and stability of fuel. Ethyl acetate was used as an additive/ingredient to keep the blends in homogeneous and stable state. Blends (D80/E13/EA07; D70/E17/EA13; D60/E23/EA17) were selected for engine experiments based on stability behavior and fuel properties. The results showed no significant power reduction in the engine operation with ethanol-diesel microemulsions. Although, brake specific fuel consumption (BSFC) increased, improvement was observed in the brake specific energy consumption (BSEC). The thermal efficiency also improved significantly at lower loads. NOx and smoke emissions were reduced by 5-10% and 15-50%, respectively. UBHC and CO deteriorated especially at lower loads but improved at higher loads. From the combustion analysis, it was observed that the use of ethanol blended diesel fuel prolonged the ignition delay along with shortening of total combustion duration. Studies conducted at different injection pressures (200, 250, 300 and 350 bar) on different loading conditions showed that the higher injection pressure reduces CO and smoke emissions with respect to diesel fuel.