Study on Chemical Kinetic Mechanism of Methanol/Ammonia/n‐Heptane for Engine Combustion

Methanol and ammonia are considered promising low‐carbon fuel blends for engine applications; however, achieving stable ignition under compression–ignition conditions remains challenging. As a result, a small quantity of n‐heptane can be introduced as a highly reactive pilot fuel to initiate the combustion process. In this study a detailed mechanism is firstly constructed by combining the n‐heptane mechanism with the methanol/ammonia mechanism. In order to reduce the computational cost for the simulation of the engines, the mechanism is then reduced. This results in a reduced mechanism containing 171 species and 1307 reactions being developed. The consistency between detailed mechanisms and reduced mechanisms were evaluated through validation against experimental data. It is shown that the developed mechanisms can predict ignition delay time and laminar flame speed with good accuracy. Three‐dimensional simulation study is performed on a methanol/ammonia/n‐heptane compression ignition engine using the developed mechanisms. Results show that an increase in the ammonia blending ratio leads to a reduction in engine power, while significantly decreasing CO 2 emissions. A shorter pulse width generally leads to slightly elevated peak pressure and temperature, and contributes to lower CO emissions. The two mechanisms exhibit good consistency in predicting cylinder pressure, peak average temperature, peak temperature, NO, N 2 O, CO 2 , et cetera. Overall, the developed reduced mechanism can be used for engine simulations with good computational efficiency.