Spray ignition of n-alkanes in diesel and jet fuels: Effects of temperature, pressure, and N₂ and NO addition

This study investigates the effects of NO-addition and N₂-dilution on the autoignition process of n-C₁₀–n-C₁₄ alkanes, which are important components of diesel and kerosene-based jet fuels. The study is motivated by the need for a comprehensive understanding of the effects of nitrogen oxides (NO_x) and N₂ on the fuel ignition process. This understanding is essential to enable the effective employment of advanced combustion engine technologies, such as exhaust gas recirculation (EGR) and Rich-Quench-Lean (RQL) gas turbine combustors. Ignition delay time (IDT) measurements were performed under various combustion conditions relevant to practical engine operation and low-temperature oxidation chemistry in a constant-volume combustion spray chamber device. The experimental results show that N₂-dilution consistently results in longer IDTs for the fuels tested. On the other hand, NO-addition has a temperature-dependent effect, shortening the IDTs for T > 692 K and vice versa. The magnitude of reactivity promotion or inhibition depends on NO concentration, temperature, pressure, and equivalence ratio. Based on the tested NO-addition levels, the inhibition of reactivity is approximately ten times greater than the promotion of reactivity caused by NO. The study fills a gap in the literature by providing comprehensive fundamental combustion data for n-C₁₀–n-C₁₄ fuels. This data, along with the corresponding analysis, can be used by engine researchers in developing more efficient and cleaner combustion engine technologies.