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

• Solketal showed reduced soot formation and a slightly longer ignition delay. • The hydroxyl group likely contributes to solketal’s greater oxidative activity. • Solketal enhances fuel oxidation under low injection energy conditions. • Biodiesel–solketal blends confirm solketal’s oxidation-promoting effects. • Diesel R33 showed the best behavior at 3 wt% solketal, revealing a non-linear effect. 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