Soot formation and ignition properties of diesel fuels with solketal in an injection chamber

The global energy transition drives an enhanced emphasis on innovative fuel design approaches. Novel renewable fuel components are being sought that are drop-in compatible and exhibit synergistic interactions within fuel components. Isopropylidene glycerin (solketal) is a promising candidate, offering favorable chemical and physical properties due to its high molecular oxygen content. This study investigates the soot formation tendency and ignition behavior of solketal in a high pressure and high temperature injection chamber. Its combustion characteristics under varying injection parameters and chemical influences were evaluated in comparison with 1,3-dioxolane and a reference fossil diesel fuel. Additionally, the influence of solketal in a binary biodiesel-solketal system and in Diesel R33 was examined. Solketal exhibited a soot-reducing effect alongside an increased ignition delay. Comparison with 1,3-dioxolane suggests that the enhanced oxidative reactivity is attributable to the hydroxyl functionality. This interpretation is supported by low-temperature combustion indicators and observations in the biodiesel-solketal system. The Diesel R33 results showed that a concentration of 3 wt% solketal provides the most favorable performance characteristics. This demonstrates how targeted blending strategies can unlock beneficial combustion effects. Such insights open promising pathways for developing advanced, future-ready fuel formulations.