Scaling relation for high-temperature biodiesel surrogate ignition delay times

• A scaling relationship for high-temperature biodiesel ignition times is presented.
• Negative pressure, carbon chain length, and oxygen mole fraction scaling are seen.
• The equivalence ratio scaling depends on the oxygen mole fraction.
• The activation energy depends on the oxygen mole fraction and pressure.

High-temperature Arrhenius ignition delay time correlations are useful for revealing the underlying parameter dependencies of combustion models, for simplifying and optimizing combustion mechanisms for use in engine simulations, for scaling experimental data to new conditions for comparison purposes, and for guiding in experimental design. We have developed a scaling relationship for Fatty Acid Methyl Ester (FAME) ignition time data taken at high temperatures in 4%O2/Ar mixtures behind reflected shocks using an aerosol shock tube:τign[ms]=2.24×10-6[ms](P[atm])-0.41(ϕ)0.30(Cn)-0.61exp37.1[kcal/mol]R̂u[kcal/mol K]T[K]Additionally, we have combined our ignition delay time data for methyl decanoate, methyl palmitate, methyl oleate, and methyl linoleate with other experimental results in the literature in order to derive fuel-specific oxygen-mole-fraction scaling parameters for these surrogates. In this article, we discuss the significance of the parameter values, compare our correlation to others found in the literature for different classes of fuels, and contrast the above expression’s performance with correlations obtained using leading FAME kinetic models in 4%O2/Ar mixtures.