Development of a reduced n-heptane/toluene/tetrahydrofuran mechanism for dual-fuel engine combustion prediction

Tetrahydrofuran (THF) is being proposed as a promising alternative fuel for internal combustion engines. However, the reaction chemistry of THF for multi-dimensional engine simulations has not been well established. In this study, a reliable n-heptane/toluene/THF mechanism was developed to simulate combustion of diesel and THF dual-fuel engine. Firstly, a reduced THF reaction mechanism was obtained by employing various mechanism reduction methods. Secondly, a combined mechanism was constructed based on decoupling methodology, which contained the reduced oxidation sub-mechanisms of n-heptane, toluene and THF, a reduced C2-C3 mechanism and a detailed H2/CO/C1 mechanism. Thirdly, the reaction rate constants of selected reactions involved in the combined mechanism were optimized and the newly developed reduced tri-component mechanism consisting of 65 species among 214 reactions. Subsequently, validations of the developed mechanism were performed using the previously published experimental results of ignition delay times in shock tubes, species mole fractions in laminar premixed flames and jet-stirred reactors, and laminar flame speeds. Meanwhile, dual-fuel engine experiments were conducted and new experimental data of in-cylinder pressure and heat release rate were also used to verify the developed mechanism. The validation indicates that the n-heptane/toluene/THF mechanism of this work can be applied for predicting the combustion process of diesel and THF dual-fuel engine.