Methanol and hydrogen oxidation kinetics in water at supercritical states

Journal Article · Mon Jul 01 04:00:00 EDT 1996 · Combustion and Flame

DOI:https://doi.org/10.1016/0010-2180(95)00247-2· OSTI ID:264397

Alkam, M K; Pai, V M; Butler, P B ^[1]; Pitz, W J ^[2]

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1. Univ. of Iowa, Iowa City, IA (United States). Dept. of Mechanical Engineering
2. Lawrence Livermore National Lab., CA (United States)

The oxidation kinetics of methanol and hydrogen in a supercritical water medium were investigated. Numerical analyses were performed using an isobaric, plug-flow reactor model coupled with the Chemkin Real-Gas software package to handle real-gas thermodynamic effects and elementary kinetics. In the present work, select unimolecular reactions that involve thermal decomposition have been corrected for the high-pressure conditions found in supercritical reactors. Predictions of fuel destruction rates obtained using an elementary reaction mechanism for hydrogen oxidation under isobaric, isothermal supercritical conditions (P > 22.1 MPa, and T > 374 C) were verified by comparison with previous experimental results obtained in a laboratory-scale supercritical water reactor. The H{sub 2}-O{sub 2} model is a subset of a proposed elementary reaction mechanism for methanol oxidation which was also verified by comparing the present model predictions of the kinetic rate calculations with previous measurements. The mechanism was validated over a temperature range of 726 to 873 K, a fuel concentration range of 0.001 to 0.004 mole/L, and at a pressure of 246 bar. To facilitate future computational fluid dynamic (CFD) modeling efforts in SCWO, a two-step reduced reaction mechanism was constructed to simulate the oxidation process of methanol in supercritical water and H{sub 2}O. The reduced model reflects the sequential oxidation of methanol into carbon monoxide, and eventually into final products consisting primarily of carbon dioxide and H{sub 2}O. The calculations of the two-step reduced mechanism matched the elementary reaction model well with respect to major species concentration profiles.

• OSTI ID: 264397
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 106; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
10 SYNTHETIC FUELS
COMBUSTION KINETICS
HYDROGEN FUELS
MATHEMATICAL MODELS
METHANOL
OXIDATION
PYROLYSIS
SUPERCRITICAL STATE
THERMODYNAMICS
WATER VAPOR