Investigation of the main factors of the process of ignition of a homogeneous mixture from compression in an ICE

An overview of the advantages of an engine with the ignition of a lean homogeneous mixture from compression (HCCI), among which, above all, economic and environmental indicators are presented. There were considered the disadvantages of this engine, hampering the release of batch production, and the main is the difficulty in providing in the combustion chamber the conditions for self-ignition of the working homogeneous mixture near TDC in the entire range of engine operating conditions. The ways of solving the problems of controlling the ignition of the working mixture in the combustion chamber, reducing the noise level and fighting the occurrence of shock loads with increasing load, starting the cold engine and improving the engine with the HCCI process are presented. The main ones can be a combination of distributed and direct injection using variable valve timing and exhaust gas recirculation, the joint use of controlled turbocharging and exhaust gas recirculation, a change in the heating of the working mixture at the inlet to the engine, external and internal exhaust gas recirculation (EGR) phases of gas distribution, regulation of the chemical composition of fuel and changes in the intensity of heat transfer and the dynamics of temperature growth in the cylinder, primarily due to changes in the piston crown temperature. The results of computational studies of the influence of various parameters on the process of ignition of a homogeneous mixture on compression are presented. It is established that the greatest effect on the process of homogenization of the air-fuel mixture is caused by an increase in the surface temperature of the bottom of the piston. Reducing the diameter of the fuel droplets from 0.1 mm to 0.03 mm results causes an increase in the relative mass of evaporated fuel by a factor of 2. Increasing the temperature of the fuel at the inlet also effectively increases the relative mass of the evaporated fuel.

HCCI process, mixture formation, homogenization, lean mixture, exhaust gas recirculation, valve timing change, fuel evaporation