Numerical optimization and comparative study of n-butanol concentration stratification combustion and n-butanol/diesel reactivity stratification combustion for advanced compression ignition (CI) engine

In RSC, the homogeneous charge compression ignition (HCCI)-like combustion shows the lowest fuel consumption and NOx emissions, and the highest ringing intensity (RI). The reactivity control compression ignition (RCCI) combustion demonstrates the overall balanced engine performance. The benefit of the diesel induced ignition combustion on RI is evident, but the high NOx emissions are still a challenge. For CSC, the optimal case with the low concentration stratification of n-butanol achieves the good EISFC, the low NOx emissions, and the high RI. Generally, the RSC strategy is superior to the CSC strategy in terms of the control of combustion phasing, fuel efficiency, and emissions.