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As the product of transesterification between various oils and alcohols, biodiesel exhibits characteristics of renewability and a wide range of raw materials. The ignition delay times (IDTs) of methyl oleate (MEOLE) and methyl linoleate (MLINO), the primary constituents of biodiesels, were measured in a heated rapid compression machine (RCM) to investigate the impact of C C double bond on the reactivity and autoignition characteristics. The experiment was conducted under two pressures of 8 bar and 10 bar at an equivalence ratio of 0.3–0.8 and a temperature range of 800–1000 K. The qualitative investigation unveiled the influence of compressed pressure, equivalence ratio, and oxygen mole fraction on the IDT of MEOLE and MLINO under varying compressed temperatures. Besides, a comparison of the IDTs for two fuels with different unsaturation degrees under identical conditions revealed that MEOLE exhibited greater reactivity at low temperatures compared to MLINO, while the increase in unsaturation degree can moderate and enhance reactivity at high temperatures. Moreover, three kinetic models in the literature were validated against the newly measured IDTs. The results indicate that the detailed lumped kinetic model exhibits better predictive capacity compared to other models, but it still underestimates the reactivity of MEOLE and MLINO within the investigated temperature range. Subsequently, the detailed kinetic model was optimized based on sensitivity analysis, resulting in excellent agreement between the predicted values of the optimized model and experimental data. Furthermore, accurate predictions were made regarding the relative reactivity changes of MEOLE and MLINO with temperature. Finally, different types of experimental data in the literature were employed to validate the optimized model, yielding satisfactory results. [ABSTRACT FROM AUTHOR]

• The auto-ignition characteristics are studied for gasoline/HCB blends. • The blending ratio affects the TIDTs by the FIDTs. • A detailed mechanism is applied to successfully predict the trend of the auto-ignition of blends. • The dominating reactions are identified to account for the variation of ignition delay time. Gasoline/Hydrogenated catalytic biodiesel blending fuel is a prospective alternative fuel for gasoline compression ignition (GCI) engine which has the potential to solve the ignition difficulties of GCI especially at low load conditions. However, the autoignition behavior of gasoline/hydrogenated catalytic biodiesel blends is unknown. In this study, the ignition delay times of gasoline/hydrogenated catalytic biodiesel (HCB) blends were measured in a heated rapid compression machine over a wide range of conditions (the temperature range of 655–870 K, pressures of 10 and 15 bar, equivalence ratios of 0.5–1.5). Experimental results show that the measured ignition delay time of the gasoline/HCB blends exhibits negative-temperature coefficient behaviors under the investigated conditions. The total ignition delay times diminish with rising pressure, equivalence ratio and HCB ratio in the blends. The simulation results of ignition delay times for gasoline/HCB blends using a detailed mechanism are compared with experimental data. The detailed model can predict the trends of ignition delay time well during low-to-intermediate temperature region. Finally, kinetic analyses were performed under different compressed pressure, temperature, equivalence ratios and blending ratios. The dominating reactions and decisive factors of ignition are explored to gain a deeper understanding of the ignition characteristic of gasoline/HCB blends. It is found that the autoignition of fuel is completely caused by HCB related reactions at low temperature, which explains why the blending of HCB can expand the working condition downward from the perspective of chemical kinetic. [ABSTRACT FROM AUTHOR]