Analysis of exergy losses in laminar premixed flames of methane/hydrogen blends

Liu, Yusen; Zhang, Jiabo; Ju, Dehao; Huang, Zhen; Han, Dong

doi:10.1016/j.ijhydene.2019.07.123

Cited by 19 publications

(4 citation statements)

References 36 publications

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“…The effect of CO2 on flame instability exceeded that of N2. In terms of thermodynamic analysis, Liu et al [21] studied the combustion of methane/hydrogen mixed fuel in engines. The H2 addition ratio increased from 0% to 70%, resulting in a decrease in thermal conductivity loss.…”

Section: Introductionmentioning

confidence: 99%

Effects of Hydrogen Addition on the Thermal Performance and Emissions of Biomass Syngas Combustion in a Horizontal Boiler

Suxing,

Yu,

et al. 2024

Energies

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Due to its low calorific value, abnormal phenomena such as incomplete combustion and flameout may occur during the combustion process of biomass syngas. The applicability of adding hydrogen can assist in the combustion of biomass syngas in boilers to overcome the above defects, and the effects need to be investigated. In this study, a multi-mechanism model is employed to numerically simulate the flow and combustion of a horizontal boiler burning biomass syngas. The reliability verification of the model is conducted by comparing it with the experimental results of combustion in a domestic boiler with biomass syngas. From the views of multi-fields and synergy, the effects of hydrogen addition on the thermal performance and emissions of biomass syngas are further expounded. Two scenarios are taken into consideration: hydrogen addition at a constant fuel volume flow rate and constant heat input. The result indicates that hydrogen addition significantly affects the multi-field synergy, which is advantageous for improving the heat transfer performance and combustion efficiency of biomass syngas. However, when the hydrogen addition ratio exceeds 20% at a constant fuel volume flow rate and 25% at constant heat input, its impact may be reduced. When the hydrogen content increases, the outlet temperature of the combustion chamber decreases, and pollutant emissions are effectively controlled. The turbulent kinetic energy at the reversal section decreases, and the uniformity of the flow field improves. These results provide certain guidance for the efficient utilization of biomass syngas and the operation of boilers burning biomass syngas.

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Section: Introductionmentioning

confidence: 99%

Effects of Hydrogen Addition on the Thermal Performance and Emissions of Biomass Syngas Combustion in a Horizontal Boiler

Suxing,

Yu,

et al. 2024

Energies

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“…Many investigations have recently been focused on the study of the fundamental characteristics of a methane-hydrogen-air flame (hythane-air flame), which provide the essential knowledge for the implementation of hydrogen-enriched methane as a fuel. There has been numerical analyses of models with detailed reaction mechanisms [1][2][3][4][5][6][7][8][9][10][11][12] and experimental investigations, mainly within the well-known setups of a combustion bomb [13][14][15][16][17][18][19][20][21], a counter flow [22][23][24][25][26], burner-stabilised flames [20,[27][28][29][30][31][32][33][34], and other configurations [35,36]. In [3], it is concluded that hydrogen chemistry supports the combustion of methane, extending the operating limits of lean burners.…”

Section: Introductionmentioning

confidence: 99%

Activation Energy of Hydrogen–Methane Mixtures

Moroshkina,

Ponomareva,

Mislavskii

et al. 2024

Fire

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In this work, the overall activation energy of the combustion of lean hydrogen–methane–air mixtures (equivalence ratio φ = 0.7−1.0 and hydrogen fraction in methane α=0, 2, 4) is experimentally determined using thin-filament pyrometry of flames stabilised on a flat porous burner under normal conditions (p=1 bar, T = 20 °C). The experimental data are compared with numerical calculations within the detailed reaction mechanism GRI3.0 and both approaches confirm the linear correlation between mass flow rate and inverse flame temperature predicted in the theory. An analysis of the numerical and experimental data shows that, in the limit of lean hydrogen–methane–air mixtures, the activation energy approaches a constant value, which is not sensitive to the addition of hydrogen to methane. The mass flow rate for a freely propagating flame and, thus, the laminar burning velocity, are measured for mixtures with different hydrogen contents. This mass flow rate, scaled over the characteristic temperature dependence of the laminar burning velocity for a one-step reaction mechanism, is found and it can also be used in order to estimate the parameters of the overall reaction mechanisms. Such reaction mechanisms will find implementation in the numerical simulation of practical combustion devices with complex flows and geometries.

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“…The exergy loss and exergy loss ratio in syngas flames (H 2 /CO) were calculated and investigated, and the results revealed that increasing pressure, inlet temperature, and hydrogen concentration in fuel can reduce the exergy loss ratio of the flames [ 26 , 27 ]. Han et al [ 28 , 29 , 30 ] developed a series of works about the thermodynamics analysis of combustion processes. The hydrogen flame, hydrogen/methane flame, and ammonia/hydrogen flame were investigated, as well as the effect of component concentration in the flame was analyzed.…”

Section: Introductionmentioning

confidence: 99%

“…However, the combustion method of ammonia has not been completely studied. Only Han et al [ 30 ] developed a thermodynamic analysis of the ammonia/hydrogen premixed flame. Few works have been conducted to investigate the influence of ammonia addition on the thermodynamics efficiency of the combustion process in hydrocarbon flames.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Exergy Loss of Ammonia Addition in Hydrocarbon Diffusion Flames

Sun

Zhang

Sun

et al. 2022

Entropy

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In this paper, a theoretical numerical analysis of the thermodynamics second law in ammonia/ethylene counter-flow diffusion flames is carried out. The combustion process, which includes heat and mass transfer, as well as a chemical reaction, is simulated based on a detailed chemical reaction model. Entropy generation and exergy loss due to various reasons in ammonia/ethylene and argon/ethylene flames are calculated. The effects of ammonia addition on the thermodynamics efficiency of combustion are investigated. Based on thermodynamics analysis, a parameter, the lowest emission of pollutant (LEP), is proposed to establish a relationship between the available work and pollutant emissions produced during the combustion process. Chemical reaction paths are also analyzed by combining the chemical entropy generation, and some important chemical reactions and substances are identified. The numerical results reveal that ammonia addition has a significant enhancement on heat transfer and chemical reaction in the flames, and the total exergy loss rate increases slightly at first and then decreases with an increase in ammonia concentration. Considering the factors of thermodynamic efficiency, the emissions of CO2 and NOx reach a maximum when ammonia concentration is near 10% and 30%, respectively. In terms of the chemical reaction path analysis, ammonia pyrolysis and nitrogen production increase significantly, while ethylene pyrolysis and carbon monoxide production decrease when ammonia is added to hydrocarbon diffusion flames.

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Analysis of exergy losses in laminar premixed flames of methane/hydrogen blends

Cited by 19 publications

References 36 publications

Effects of Hydrogen Addition on the Thermal Performance and Emissions of Biomass Syngas Combustion in a Horizontal Boiler

Effects of Hydrogen Addition on the Thermal Performance and Emissions of Biomass Syngas Combustion in a Horizontal Boiler

Activation Energy of Hydrogen–Methane Mixtures

Numerical Investigation of Exergy Loss of Ammonia Addition in Hydrocarbon Diffusion Flames

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