Study on the ignition delay characteristics of 2-pentanone/n-dodecane blends

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Ketones, as oxygenated fuel additives, hold promise and attract attention as a pathway to reduce emissions from conventional fossil fuels. Although the fundamental combustion and kinetic characteristics of neat long-chain alkane fuels have been extensively reported, studies on the ignition characteristics of binary fuel blends composed of ketones and long-chain alkanes remain rather limited. To investigate the ignition characteristics of 2-pentanone/ n -dodecane binary blends, ignition delay times (IDTs) were investigated using a rapid compression machine (RCM) under temperatures of 750–1000 K, blending ratios of 0–100 %, equivalence ratios of 1.0–2.0, and compressed pressures of 10–40 bar. A kinetic model was developed and validated. Results demonstrate that the addition of 2-pentanone inhibits the low-temperature oxidation reactivity of n -dodecane and increases IDTs. As the blending proportion increases, the negative temperature coefficient (NTC) behavior intensifies and shifts to lower temperatures. Increasing the termination pressure substantially shortens the IDTs and weakens NTC behavior, primarily by promoting bimolecular and pressure-dependent reactions. The equivalence ratio effect is governed by the balance between promotion and inhibition. Under fuel-rich conditions, OH radical formation and accumulation are suppressed across all temperatures, prolonging IDTs. Sensitivity analysis identifies the reaction C 5 KET 2 -OO3 = C 5 KET 2 -D3 + HO 2 as a key inhibiting pathway, terminating the chain-branching sequence. In contrast, C 5 KET 2 -OOH3-R5 + O 2 is a dominant promoting route, initiating chain branching via secondary oxygenation. Reaction pathway analysis reveals that variations in reactant concentration shift the dominant reaction mechanism from H-atom abstraction at high concentrations to intramolecular H-transfer at low concentrations. This study provides kinetic insights into oxygenated/alkane-blended fuels and the design of clean fuel formulations.

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