Reduction of smoke and nitrogen oxides of a partial HCCI engine using premixed gasoline and ethanol with air

This paper investigates the combustion and emissions characteristics for a partial homogeneous charge compression ignition (HCCI) engine by injecting gasoline and ethanol into the intake port of a diesel engine with diesel fuel injected in cylinder. The experiments were conducted on a diesel engine at premixed ratio (0, 10, 20, and 30) with injection timings (0–65° BTDC), under engine speeds (1200, 1500, and 1800 rpm) and loads (10 and 20 N m). The experimental results are compared with the numerical results and found to be reasonable. The results show that the injection timing of auxiliary fuels obtains less smoke concentration at 25° BTDC than at other crank angles. The diesel engine with premixed gasoline and ethanol can reduce emissions effectively; in particular, premixed ethanol affects the emissions reduction more than premixed gasoline does. The temperature contours and velocity fields in engine cylinder from the numerical calculation are also varied with engine load for various auxiliary fuels.