Super adiabatic combustion of carbon-free and carbon-containing fuels

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-03-19 DOI:10.1016/j.combustflame.2025.114106

Jennifer L. Schurr , Atmadeep Bhattacharya , Alexander A. Konnov , Ossi Kaario

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引用次数: 0

Abstract

The present work provides a new perspective on super adiabatic combustion (SAC) of fuel/air mixtures involving methane, ethane, propane, butane, heptane, iso-octane, 1-hexene, toluene, ammonia, and hydrogen. The simulations cover the temperature range of 1200–2000 K, initial pressures of 1–50 atm, and equivalence ratios of 0.5–2.0. The detailed chemical kinetic mechanism C3MechV3.5 has been used for 0D simulations in a constant volume batch reactor with Cantera 2.5.0. It has been found that SAC can be observed in lean, stoichiometric, and rich mixtures. While all hydrocarbon fuels show a strong correlation with each other, hydrogen and ammonia produce a significantly different pattern of SAC compared to carbon-containing fuels. Two reasons for super adiabaticity have been identified: (1) the super-equilibrium of H₂O, NO, and/or CO₂ due to the time delay between their production and consumption, and (2) the energy intensive dissociation reactions of, e.g., N₂, H₂O, and CO₂. Furthermore, it has been found that a super-equilibrium of H₂O always indicates super adiabaticity. For paraffinic hydrocarbons, since SAC is primarily governed by C₀-C₁ and NO_x reactions, the low and intermediate temperature auto-ignition chemistry involving alkyl-peroxyl radical and the poly-aromatic hydrocarbon (PAH) reactions do not influence SAC.

Novelty and Significance Statement

As of now, super adiabatic combustion (SAC) has been shown mainly for rich premixed hydrocarbon/oxidizer mixtures. In the present work, SAC is reported for a wide range of equivalence ratios covering lean, stoichiometric, and rich mixtures of different classes of hydrocarbons in air. This work also presents a comprehensive analysis of SAC characteristics. Furthermore, the SAC of hydrocarbon fuels is compared with that of carbon-free fuels ammonia and hydrogen. For the first time in the literature, the following key facts about SAC are now reported: (a) there are different trends in SAC of hydrocarbon/air mixtures at different initial pressures and temperatures, (b) ammonia and hydrogen have significantly different trends, and (c) for linear and branched paraffins, SAC can be correlated with the number of carbon atoms in the fuel molecule. In this work, it has been pointed out that there is experimental data in the literature where the super-equilibrium of the water molecule has been observed during auto-ignition, but not linked to SAC. Therefore, the results presented in this work establishes SAC as an important topic in modern combustion chemistry research.

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来源期刊

Combustion and Flame 工程技术-工程：化工

CiteScore

9.50

自引率

20.50%

发文量

631

审稿时长

3.8 months

期刊介绍： The mission of the journal is to publish high quality work from experimental, theoretical, and computational investigations on the fundamentals of combustion phenomena and closely allied matters. While submissions in all pertinent areas are welcomed, past and recent focus of the journal has been on: Development and validation of reaction kinetics, reduction of reaction mechanisms and modeling of combustion systems, including: Conventional, alternative and surrogate fuels; Pollutants; Particulate and aerosol formation and abatement; Heterogeneous processes. Experimental, theoretical, and computational studies of laminar and turbulent combustion phenomena, including: Premixed and non-premixed flames; Ignition and extinction phenomena; Flame propagation; Flame structure; Instabilities and swirl; Flame spread; Multi-phase reactants. Advances in diagnostic and computational methods in combustion, including: Measurement and simulation of scalar and vector properties; Novel techniques; State-of-the art applications. Fundamental investigations of combustion technologies and systems, including: Internal combustion engines; Gas turbines; Small- and large-scale stationary combustion and power generation; Catalytic combustion; Combustion synthesis; Combustion under extreme conditions; New concepts.