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In recent years, improved combustion controllability in terms of in-cylinder reactivity stratification by using two different fuels led to introduction of dual-fuel reactivity controlled compression ignition (RCCI) strategy. This strategy has the potential to operate with a single low reactivity fuel and direct injection (DI) of the same fuel blended with a small amount of cetane improver. In the present study, a numerical investigation was conducted to simulate a single-fuel RCCI engine fueled with isobutanol -isobutanol+20% di-tert-butyl peroxide (DTBP) with an optimal injection strategy. Firstly, the effects of start of injection (SOI) timing, injection pressure, spray cone angle, and DI fuel ratio are explored. Secondly, the effect of DI fuel ratio reduction is discussed in each best case in order to decrease the high DI requirement. The results showed that -88°ATDC SOI, 1400 bar injection pressure, and 45°spray cone angle case can improve the performance and emissions compared to the baseline case (SOI=-58°ATDC, spray angle=72.5°, injection pressure=600 bar). Moreover, it was found that by advancing the SOI timing to -88°ATDC, a 20% reduction in DI ratio, 3.3% increase in gross indicated efficiency (GIE) together with reductions in CO, and NO x emissions by 3.56 and 0.254 g/kW-hr, could be achieved, respectively.

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