Comparative Analysis of Cylinder-to-Cylinder Variation of Parameters of an Automotive CRDI Engine

In the present work, an automotive three cylinder compression ignition engine employed with a common rail direct injection system, fuelled with diesel was investigated to analyse its performance and emission characteristics, and also cylinder-to-cylinder variation of important parameters of combustion. Variation of cylinder pressure, peak cycle pressure, rate of maximum pressure rise, rate of maximum heat release and combustion duration between the cylinders was presented as a function of brake mean effective pressure, torque and speed of the engine. Variation of carbon monoxide, unburnt hydrocarbon, oxides of nitrogen and brake thermal efficiency for the tested engine was presented as a function of brake mean effective pressure. It can be seen that measured combustion parameters show a significant variation between the cylinders, and the variation of the magnitude of average cylinder pressure was marginal. The peak pressure and combustion duration in cylinder 2 are higher by approx. 11% and 9%, respectively, than those of the other two cylinders. At a 40 Nm torque and at the lowest operated speed, the peak pressure in cylinder 2 is higher by 10% than that of the other two cylinders. This trend was also observed at the highest operated speed, with the peak pressure higher by approx. 14%. The maximum combustion duration in cylinder 2 was observed to be 9% higher than in the other two cylinders at identical comparable brake mean effective pressure values. It can also be seen that emission parameters were varied considerably with brake mean effective pressure and a trade-off point was obtained between NOx-CO, NOx-UBHC and NOx-BTE.