Comparison of the performance of a spark ignition engine fueled by a mixture of isooctane and unleaded gasoline: an experimental and numerical analysis

Abstract This pioneering study focused on evaluating four distinct compositions, in addition to standard gasoline, within a spark ignition engine, following the rigorous specifications of the DIN70020 standard, under full load conditions. The meticulously conducted tests involved the introduction of varying volumes of isooctane (10%, 20%, 30%, and 40%) into the mixture, thus opening new perspectives on performance and combustion characteristics in a realistic engine operation context. The addition of isooctane, a key component of commercial unleaded gasoline, presents significant advantages in the context of spark ignition engines. This is primarily due to the high vaporization enthalpy of isooctane, a property that directly impacts combustion processes. Indeed, this characteristic reduces the maximum temperature reached in the engine cylinder, thereby contributing to a notable decrease in nitrogen oxides (NOx) emissions. Rigorous experiments demonstrated a significant reduction in emissions, reaching up to 5% for the I10 blend (10% isooctane +90% commercial unleaded gasoline), accompanied by a notable improvement in the maximum value of the indicated mean effective pressure and overall efficiency. These empirical findings were corroborated by numerical simulations using the DIESL-RK software, revealing an average convergence of results ranging from 0.47% to 3.92%. This combination of experimental approaches and numerical modeling thus provides a thorough understanding of the potential benefits of incorporating isooctane into unleaded gasoline, paving the way for future innovations in fuel and engine optimization.