Large-eddy simulation of tri-fuel combustion: Diesel spray assisted ignition of methanol-hydrogen blends

Development of marine engines could largely benefit from the broader usage of methanol and hydrogen which are both potential energy carriers. Here, numerical results are pre-sented on tri-fuel (TF) ignition using large-eddy simulation (LES) and finite-rate chemistry. Zero-dimensional (0D) and three-dimensional (3D) simulations for n-dodecane spray ignition of methanol/hydrogen blends are performed. 0D results reveal the beneficial role of hydrogen addition in facilitating methanol ignition. Based on LES, the following findings are reported: 1) Hydrogen promotes TF ignition, significantly for molar blending ratios beta(X) = [H-2]/([H-2]+[CH3OH]) >= 0.8. 2) For beta(X) = 0, unfavorable heat generation in ambient methanol is noted. We provide evidence that excessive hydrogen enrichment (beta(X) >= 0.94) potentially avoids this behavior, consistent with 0D results. 3) Ignition delay time is advanced by 23-26% with shorter spray vapor penetrations (10-15%) through hydrogen mass blending ratios 0.25/0.5/1.0. 4) Last, adding hydrogen increases shares of lower and higher temperature chemistry modes to total heat release. (C) 2021 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

Automated summary

Development of marine engines could benefit from the usage of methanol and hydrogen as potential energy carriers. The study found that addition of hydrogen facilitates methanol ignition and excessive hydrogen enrichment can avoid unfavorable heat generation. Adding hydrogen can advance ignition delay time and increase shares of different temperature chemistry modes to total heat release.