CONTRIBUTION PAR HOMOGÉNÉISATION DE LA COMBUSTION DANS UNE CHAMBRE DE COMBUSTION D’UN MOTEUR DIESEL

Abstract

In order to investigate the concept that constitutes a viable approach to achieve high efficiencies and low emissions of nitrogen oxides (NOX) and particulate (PM), this study was introduced by applying the operating conditions of the diesel engine to the homogeneous charge compression ignition (HCCI) engine. In this work, we present an analysis of the impacts of the equivalence ratio (ɸ), the intake charge temperature (TIVC), the intake charge pressure (PIVC), the compression ratio (CR) and the exhaust gas recirculation (EGR) rate on the combustion parameters. The results of these impacts were analyzed and discussed in detail. The ANSYS CHEMKIN-Pro software and the combined chemical kinetics mechanism were used to perform simulations for a closed homogeneous reactor under conditions relevant to HCCI engines. The calculation process is based on one single zone in the combustion chamber. The results show that HCCI combustion is more practical for very lean mixtures and the decreasing of mixing ratio lead to decreases engine emissions. Moreover, when the temperature TIVC decreases from 277°C to 177°C, the indicated mean effective pressure (IMEP) increases from 6.34 bars to 8.62 bars. On the other hand, Diesel-RK software was used to study the effect of three different fuels, Heavy Diesel, Diesel No.2 and Hexadecane on engine performance and emissions. The results obtained were compared with those found with the baseline diesel fuel (Hexadecane). Simulation results relate to efficiency and power parameters such as piston engine power, torque and specific fuel consumption, as well as ecological parameters such as specific CO2 and NOX emissions. The results allow us to expect a decrease in NOX emissions from Heavy diesel fuel used.