DefinePK

Abstract

The exhaust residual gases and effective release energy are known as essential factors, which influence engine performance and emission characteristics. Herewith we estimated the effect of residual gas on peak pressure rise, effective release energy, and engine emissions. It is complicated to determine the residual gas ratio, the effective release energy under the various testing conditions from the experiments. Through combined experimental and simulation methods we eliminated certain above drawbacks. From results of the research, we thoroughly investigated the effects of engine speed, air-fuel ratio, valve overlap, combustion duration, intake port diameter-bore ratio, and bore-stroke ratio on the internal exhaust residual gases recirculation. We also found that the increase in the exhaust residual gas ratio from 1% to 5% was due to the peak firing temperature decrease from 2900 K to 1250 K, the peak pressure rise decrease from 8 to 5.5 bar/deg, the effective release energy decrease from 0.85 to 0.53 kJ, the NOx emission reduction from 11.3 to 2.12 g/kwh and the engine brake torque decrease from 20.3 to 9 Nm.