Study On Combustion Characteristics Of A Multi-point Injection Methanol/diesel Dual-fuel Engine

A six-cylinder electronically controlled high pressure common rail diesel engine is modified to a multi-point injection methanol-diesel dual fuel engine by processing intake pipe and adding a set of methanol supply system,dual fuel electrically controlled system and methanol injection control system.The effect of cylinder deactivation on combustion characteristics under different co-combustion ratio(CCR)and engine load rate and the effect of diesel injection timing and methanol injection timing on combustion characteristics of duel fuel engine are researched on the dual fuel engine(The following cylinder pressure,pressure rise rate(PRR),hate release rate(HRR),maximum cylinder pressure cyclic variation coefficient(MPCVC)and the maximum pressure rise rate cyclic variation coefficient(MPRRCVC)are based on the 1st cylinder.).1)At the condition point,the engine speed is 1400r/min,engine load rate is 15%(the torque is 130N·m),the diesel injection timing is at the best timing,the effect of cylinder deactivation on combustion characteristics is researched under different CCR.It concludes that deactivation cylinders mode shows better characteristics than the activation cylinder mode at the condition of middle CCR.With the increase of CCR,the cylinder pressure,pressure rise rate(PRR)and heat release rate(HRR)of deactivation of the 4th,5th and 6th cylinders(DC456)mode increase first and then decrease.The cylinder pressure,PRR and HRR are higher than those of activation cylinder(AC)mode under little CCR and higher than those of AC mode under large CCR.The maximum cylinder pressure cyclic variation coefficient(MPCVC)and the maximum pressure rise rate cyclic variation coefficient(MPRRCVC)of DC456 mode decrease first and then increase,and are higher than those of AC mode.With the increase of CCR,the cylinder pressure,pressure rise rate(PRR)and heat release rate(HRR)of deactivation of the 1st,2nd and 3rd cylinders(DC123)decrease.The cylinder pressure of DC123 mode is higher than that of AC mode,the PPR is higher than that of AC mode under little CCR and lower than that of AC mode under large CCR.The HRR is lower than that of AC mode.The MPCVC and MPRRCVC of DC123 mode are higher than those of AC mode under little CCR and lower than those of AC mode under large CCR.2)At the condition point,the engine speed is 1000r/min,engine load rate are 15%,25% and 35%,the CCR is medium value,diesel injection timing is at the best timing.The effect of cylinder deactivation on combustion characteristics is researched under different load rate.It concludes that deactivation cylinders mode shows better characteristics than that of the activation cylinder mode with the increase of load rate.With the increase of load rate,the cylinder pressure,PRR and HRR of DC456 mode,DC123 mode and AC mode increase.The cylinder pressure,PRR,HRR,MPCVC and MPRRCVC are higher than those of AC mode.The cylinder pressure,PRR and HRR of DC123 mode are lower than those of AC mode.MPCVC and MPRRCVC of DC123 mode are lower than those of AC mode.3)At the condition point,the engine speed is 1000r/min,engine load rate is 35%,CCR is 37%.The effect of diesel injection timing and methanol injection timing of AC mode on combustion characteristics is researched.It concludes that the AC mode shows better characteristics at the best diesel injection timing,the methanol injection timing has merely effect on the combustion characteristics.With the increase of diesel injection timing,the power and cylinder pressure of AC mode increase first and then decrease,and are lower than those of pure diesel mode.With the increase of diesel injection timing,the PRR and HRR of AC mode increase first and then decrease,and are higher than those of pure diesel mode.The MPCVC and MPRRCVC of AC mode decrease first and then increase,and are higher than those of pure diesel mode.