Analysis of the effect of water on methanol combustion under engine-related conditions based on a newly developed reduced mechanism

Abstract

Methanol is widely regarded as an ideal alternative fuel due to its direct synthesis from carbon dioxide, ease of transportation, and excellent combustion characteristics. Due to the costly dehydration step in the methanol production process, the direct use of aqueous methanol is a good option. In this study, a reduced NT-M model with 62 species and 222 reactions for methanol/diesel blends using a decoupling methodology was developed. The validated NT-M model improves the prediction accuracy of laminar flame speeds for methanol at fuel-rich conditions compared to other mechanisms. In addition, the effect of water addition on methanol combustion was analyzed. The result shows that increasing the water content of methanol leads to an increase in IDT and a decrease in LFS. The extent of the chemical effect of water on methanol combustion is influenced by the equivalence ratio. The chemical effect of water at low equivalence ratios is almost negligible. The reaction CH3OH + HO2CH2OH + H2O2 has the most significant effect on IDT. Interestingly, the addition of water inhibits the forward progress of this reaction, leading to an increase in IDT. Moreover, the chemical effect of water leads to an increase in LFS.