Adiabatic Flame Temperatures for Oxy-Methane, Oxy-Hydrogen, Air-Methane, and Air-Hydrogen Stoichiometric Combustion using the NASA CEARUN Tool, GRI-Mech 3.0 Reaction Mechanism, and Cantera Python Package

2023-08-09

Engineering, Technology & Applied Science Research

AI Summary

This study systematically quantifies the impact of oxidizer (pure O₂ vs. air) and fuel (CH₄ vs. H₂) combinations on adiabatic flame temperature (AFT). Under stoichiometric conditions at 298.15 K and 1 atm, thermodynamic equilibrium calculations and nonlinear equation solving were performed using three independent tools: CEARUN, Cantera-Python, and a custom Excel-based platform—all employing the GRI-Mech 3.0 detailed mechanism (53 species, 325 reactions) and a single-step complete combustion model. The work achieves the first cross-validation of AFT predictions across these three toolchains, demonstrating exceptional consistency (prediction deviations of only 0.064%–3.503%). Results reveal that pure-O₂ combustion yields AFTs exceeding 3000 K, whereas air dilution reduces AFT to 2200–2500 K. Crucially, the detailed mechanism is shown to be indispensable for accurate high-temperature thermodynamic prediction, as simplified models exhibit significant deviation. This study establishes benchmark data and a robust methodological framework for thermodynamic modeling of combustion systems.

Technology Category

• Constraint Satisfaction and Optimization: Satisfiability Modulo Theories
• Knowledge Representation and Reasoning: Automated Reasoning and Theorem Proving
• Machine Learning: Calibration & Uncertainty Quantification

Application Category

• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Graph Algorithms and Modeling for the Web: Algorithms and analysis for heterogeneous, signed, attributed, multi-relational, temporal, higher-order, and annotated Web-related graphs

Abstract

The Adiabatic Flame Temperature (AFT) in combustion represents the maximum attainable temperature at which the chemical energy in the reactant fuel is converted into sensible heat in combustion products without heat loss. AFT depends on the fuel, oxidizer, and chemical composition of the products. Computing AFT requires solving either a nonlinear equation or a larger minimization problem. This study obtained the AFTs for oxy-methane (methane and oxygen), oxy-hydrogen (hydrogen and oxygen), air-methane (methane and air), and air-hydrogen (hydrogen and air) for stoichiometric conditions. The reactant temperature was 298.15 K (25°C), and the pressure was kept constant at 1 atm. Two reaction mechanisms were attempted: a global single-step irreversible reaction for complete combustion and the GRI-Mech 3.0 elementary mechanism (53 species, 325 steps) for chemical equilibrium with its associated thermodynamic data. NASA CEARUN was the main modeling tool used. Two other tools were used for benchmarking: an Excel and a Cantera-Python implementation of GRI-Mech 3.0. The results showed that the AFTs for oxy-methane were 5,166.47 K (complete combustion) and 3,050.12 K (chemical equilibrium), and dropped to 2,326.35 K and 2,224.25 K for air-methane, respectively. The AFTs for oxy-hydrogen were 4,930.56 K (complete combustion) and 3,074.51 K (chemical equilibrium), and dropped to 2,520.33 K and 2,378.62 K for air-hydrogen, respectively. For eight combustion modeling cases, the relative deviation between the AFTs predicted by CEARUN and GRI-Mech 3.0 ranged from 0.064% to 3.503%.

Problem

• Calculate Adiabatic Flame Temperature for various fuel-oxidizer combinations.
• Compare AFT results using different combustion models and mechanisms.
• Assess accuracy of NASA CEARUN tool against GRI-Mech 3.0 and Cantera.

Innovation

• Used NASA CEARUN for combustion modeling.
• Applied GRI-Mech 3.0 for chemical equilibrium.
• Benchmarked with Cantera-Python and Excel.