CO2-free hydrogen production via microwave-driven methane pyrolysis

International Journal of Hydrogen Energy, Год журнала: 2023, Номер 48(39), С. 14565 - 14576

Опубликована: Янв. 18, 2023

Язык: Английский

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Overview of methods to characterize the mass, size, and morphology of soot

Journal of Aerosol Science, Год журнала: 2023, Номер 173, С. 106211 - 106211

Опубликована: Июнь 3, 2023

Combustion and other high-temperature processes can produce solid aerosol nanoparticles with complex morphologies, including fractal-like aggregates of primary particles. Characterizing these as well particle mass, is key to understanding their behavior in natural engineered systems, it provide clues the origin We focus here on characterization soot, although most techniques apply aggregates. A complete description aerosols would include mass morphology every particle. In practice, possible obtain detailed information individual particles from microscopy extracted samples. particular this review, tandem classifier/detector systems determine 2-dimensional mobility distributions that may be interpreted through lens fractal models. Very fast situ light scattering measurements used structure factor, related dimension, aggregate size distributions. These approaches are complementary when there appropriate models connect morphological details optical transport characteristics Over last few decades have become more sophisticated, requiring properties, but also facilitating sophisticated inferences in-situ online measurement techniques.

Язык: Английский

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Compact and accurate chemical mechanism for methane pyrolysis with PAH growth

International Journal of Hydrogen Energy, Год журнала: 2024, Номер 56, С. 1340 - 1360

Опубликована: Янв. 4, 2024

Язык: Английский

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Methane pyrolysis in packed bed reactors: Kinetic modeling, numerical simulations, and experimental insights

Chemical Engineering Journal, Год журнала: 2024, Номер 485, С. 149684 - 149684

Опубликована: Фев. 19, 2024

Pyrolysis of hydrocarbon feeds such as methane (CH4) and natural gas emerges a pivotal carbon dioxide-free large-scale hydrogen (H2) production process combined with capturing the solid material. For fundamental understanding upscaling, complex kinetics dynamics this in technically relevant reactors packed moving beds still need to be explored, particularly concerning formation its impact on reactor performance. This study integrates kinetic modeling, numerical simulations, experimental findings comprehensively understand CH4 pyrolysis under industrially conditions implications for efficient H2 capture. The investigation covers temperatures from 1273 K 1873 K, addition H2:CH4 ratios 0 4, hot zone residence time 1 7 s. Two distinct pathways lead formation: soot deposition. Each pathway originates different gas-phase precursors. An elementary-step-based reaction mechanism is coupled model polycyclic aromatic newly developed deposition light hydrocarbons. Numerical simulations are performed bed model, incorporating method moments evaluated against experiments predicts effects operating product distribution formation. It also estimates change bed-voidage over operational time. reveals that at temperature 1673 conversion exceeds 94 %, while both yields surpass 96 %. sophisticated modeling simulation framework presented herein thus provides an enhanced presents valuable tool optimizing process.

Язык: Английский

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The effect of pressure up to 6 atm over soot maturity in laminar ethylene flames

Combustion and Flame, Год журнала: 2025, Номер 274, С. 113977 - 113977

Опубликована: Янв. 15, 2025

Язык: Английский

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Physical and Chemical Effects of Ammonia on Gas Emissions and Soot Formation in Laminar Coflow Ethylene Diffusion Flames

Energy & Fuels, Год журнала: 2024, Номер 38(12), С. 11292 - 11310

Опубликована: Май 30, 2024

As a noncarbon fuel, ammonia is being explored as potential alternative. This study delves into the physical and chemical impacts of in laminar coflow ethylene diffusion flames. Initially, an experiment conducted to scrutinize flame characteristics, including temperature, these Subsequently, new C2H4–NH3–PAH model developed verified through ignition delay times, speeds, species profiles. Building on this model, analyzes effects gas emissions (CO, CO2, NO, NO2, HCN, N2O), formation polycyclic aromatic hydrocarbons (PAHs), nucleation, condensation, growth, oxidation soot The findings reveal that under constant flow rates use has minimal impact temperature. Moreover, decreases CO CO2 primarily due its dilution effect. However, such N2O significantly increase effect ammonia. Furthermore, precursors noticeably decrease with addition NH3 because inhibition PAH ammonia's Nevertheless, plays counterproductive role reducing precursor formation, resulting increased A1–A4 decreased free radicals. In assessment flames, indicates substantial drop (25.7%) inception rate A60 compared A0 when using It noteworthy primary reason for reduced lies hydrogen abstraction carbon (HACA) surface growth reduces radical H CH3 concentrations.

Язык: Английский

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A comprehensive kinetic study on low-GHG hydrogen production from microwave-driven methane pyrolysis

International Journal of Hydrogen Energy, Год журнала: 2024, Номер 77, С. 997 - 1008

Опубликована: Июнь 21, 2024

The present study focuses on the cogeneration of hydrogen (H2) and solid carbon from microwave-driven methane pyrolysis in a fluidized bed pellets. Numerical simulations using coupled gas-solid chemistry approach reveal that introducing microwave thermal effects improves conversion rate, H2 selectivity, deposition rate. chemical pathways analysis divulges once leading reaction for decomposing CH4 into H2, i.e., CH4+H ↔ CH3+H2, is completed, C2H2 mechanism onto pellets dominant pathway production, indicating almost no black (i.e., nanoparticles) formation. Carbon provide abundant surface area to enhancing selectivity resulting products. More importantly, importance more complex molecules, such as polycyclic aromatic hydrocarbons, greatly diminishes when process, implying smaller kinetic mechanisms are equally effective desirable.

Язык: Английский

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Modeling Thermal Radiation in Combustion Environments: Progress and Challenges

Energies, Год журнала: 2023, Номер 16(10), С. 4250 - 4250

Опубликована: Май 22, 2023

Modeling thermal radiation in combustion environments can be extremely challenging for two main reasons. First, the radiative transfer equation (RTE), which is cornerstone of modeling such environments, a five-dimensional integro-differential equation. Second, absorption and scattering coefficients molecular gases particulates prevalent oscillate strongly with wavenumber (or wavelength), i.e., medium nongray, requiring solution RTE large number wavenumbers. This article reviews progress that has been made this area to date an emphasis on work performed over past three decades. Progress both deterministic stochastic (Monte Carlo) solutions reviewed, addition review treatment spectral properties gases, soot, fuel droplets dominate or nongray models. The application various state-of-the-art models methods flames (particularly turbulent), fires, combustors, other systems are summarized along critical discussion pros cons methods. Finally, challenges remain highlighted future outlooks shared.

Язык: Английский

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Simultaneous Inversion of Particle Size Distribution, Thermal Accommodation Coefficient, and Temperature of In-Flame Soot Aggregates Using Laser-Induced Incandescence

Materials, Год журнала: 2024, Номер 17(3), С. 634 - 634

Опубликована: Янв. 28, 2024

Measuring the size distribution and temperature of high-temperature dispersed particles, particularly in-flame soot, holds paramount importance across various industries. Laser-induced incandescence (LII) stands out as a potent non-contact diagnostic technology for although its effectiveness is hindered by uncertainties associated with pre-determined thermal properties. To tackle this challenge, our study proposes multi-parameter inversion strategy—simultaneous particle distribution, accommodation coefficient, initial soot aggregates using time-resolved LII signals. Analyzing responses different heat transfer sub-models to rise demonstrates necessity incorporating sublimation thermionic emission accurately reproducing signals particles. Consequently, we selected particular model strategy. Our research reveals that LII-based sizing sensitive biases in particles (equivalent flame temperature), underscoring need proposed Numerical results obtained at two typical temperatures, 1100 K 1700 K, illustrate selecting an appropriate laser fluence enables simultaneous temperatures high accuracy confidence technique.

Язык: Английский

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Understanding soot formation: A comprehensive analysis using reactive models in Inverse Non-Premixed Flames

Combustion and Flame, Год журнала: 2024, Номер 267, С. 113569 - 113569

Опубликована: Июль 2, 2024

Язык: Английский

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