Study on mechanisms of methane/hydrogen blended combustion using reactive molecular dynamics simulation

Abstract

Methane is an ideal alternative to other fossil fuels but requires great bond strength to bond dissociation, which leads to poor ignition performance. Hydrogen, as a promising and environmental-friendly fuel, has a very high calorific value, the addition of which is considered as an effective approach to enhance the methane combustion. In this study, the ReaxFF reactive force field molecular dynamics (ReaxFF-MD) simulation is used to study the process of methane/hydrogen blended combustion with various amounts of hydrogen addition. The results show that the addition of hydrogen can promote the methane combustion by accelerating the consumption of methane. In addition, the instant when methane starts to participate in the reaction is advanced. However, with the increase of hydrogen content, the promoting effect of methane combustion weakens as the temperature increases. It is found that the enhanced OH production resulted from the hydrogen addition not only promotes the initiation but also affects the intermediate and final products of methane combustion. Furthermore, compared with pure methane combustion, the addition of hydrogen significantly lowers the activation energy by up to 50% but the enhancement is becoming weaker with the increasing amount of hydrogen addition. This research provides atomistic insights into the methane/hydrogen blended combustion that could potentially benefit its practical application.