Thermodynamic aspects of combustion in gasoline engines fitted with a multiple fuel injection

Abstract

The multiple fuel injection is being applied not only in diesel engines but in direct injection gasoline engines as well. The injection duration in gasoline engines is similar (pressure values at present approx. 20 MPa) to the injection duration of diesel fuel. The methodology and results of the tests related to the fuel dose division and injection strategy on the thermodynamic indexes during the combustion process have been presented in the paper. The tests were performed for several ways of fuel dose division at injection pressures of 5, 10 and 20 MPa (modifying also the time of the injection). The paper presents: state of research on the effects of multiple injection in gasoline engines, research equipment and methodology when applying the Rapid Compression Machine, estimation of the thermodynamic indexes, injection strategies, influence of injection pressure on the thermodynamic indexes, single fuel dose, two-phase fuel injection, three-phase fuel injection, changes in the combustion pressure, changes of the average thermodynamic temperature of the charge in the cylinder, heat release rate, heat release and relative value of the heat used for strategies, the influence of the fuel injection pressure on the course of the combustion in a Rapid Compression Machine including the course of the heat release