Ignition in an Atomistic Model of Hydrogen Oxidation
Mohammad Alaghemandi1, Lucas B Newcomb1, Jason R Green1,2,3
1Department of Chemistry, University of Massachusetts Boston , Boston, Massachusetts 02125, United States.
The Journal of Physical Chemistry. A
|February 8, 2017
Summary
Hydrogen combustion requires precise control due to low ignition energy. Reactive molecular dynamics simulations reveal optimal fuel-lean mixtures and predict ignition using hydrogen peroxide peaks and energy dissipation rates.
Area of Science:
- Chemical Engineering
- Combustion Science
- Materials Science
Background:
- Hydrogen offers a clean alternative to fossil fuels, reducing carbon dioxide emissions.
- Low ignition energy requirements for hydrogen oxidation present safety and efficiency challenges.
- Understanding microscopic combustion processes is crucial for optimizing hydrogen fuel applications.
Purpose of the Study:
- To estimate ignition times of hydrogen-oxygen mixtures using reactive molecular dynamics simulations.
- To identify optimal fuel-lean conditions for hydrogen combustion.
- To uncover predictive signatures of imminent ignition at high pressures.
Main Methods:
- Extensive reactive molecular dynamics simulations were performed on hydrogen-oxygen mixtures.
- Ignition times were calculated across a range of equivalence ratios.
- Simulation data were analyzed for pre-ignition signatures at pressures above 200 MPa.
Main Results:
- The shortest ignition time was observed for a fuel-lean mixture with an equivalence ratio of 0.5.
- A peak in hydrogen peroxide concentration was identified as a precursor to ignition, signaling it within approximately 100 picoseconds.
- A strong inverse correlation between ignition time and energy dissipation rate suggests thermal feedback's role in ignition.
Conclusions:
- Fuel-lean mixtures, specifically an equivalence ratio of 0.5, are optimal for minimizing hydrogen ignition time.
- Hydrogen peroxide concentration and energy dissipation rate serve as reliable indicators of impending ignition.
- These findings contribute to the safe and efficient utilization of hydrogen as a commercial fuel.
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