Unraveling Pressure Effects in Laminar Flame Propagation of Ammonia: A Comparative Study with Hydrogen, Methane, and Ammonia/Hydrogen

Zhang, Jianguo; Mei, Bowen; Li, Wei; Fang, Jun; Zhang, Yan; Cao, Chuangchuang; Li, Yuyang

doi:10.1021/acs.energyfuels.2c01766

Cited by 22 publications

(9 citation statements)

References 36 publications

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“…91 However, the application of hydrogen energy faces many problems and challenges in terms of storage, transportation, and use. 92 Ammonia, another kind of hydrogen, is a clean hydrogen carrier fuel and a promising hydrogen storage medium. The only products after combustion are water and nitrogen, which have the advantage of being carbonfree.…”

Section: Pressure Dependencementioning

confidence: 99%

“…In the face of severe carbon emissions, carbon-free fuels have recently attracted interest, and hydrogen energy is one of the most promising energy sources of the future . However, the application of hydrogen energy faces many problems and challenges in terms of storage, transportation, and use . Ammonia, another kind of hydrogen, is a clean hydrogen carrier fuel and a promising hydrogen storage medium.…”

Section: Advances In the Experimental Study Of The Flammability Limit...mentioning

confidence: 99%

See 1 more Smart Citation

Flammability Limits of Combustible Gases at Elevated Temperatures and Pressures: Recent Advances and Future Perspectives

Yan

Wang

et al. 2022

Energy Fuels

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The flammability limits are essential parameters that reflect the risk of a gas explosion and are affected by the temperature, pressure, and inert gas. Many industrial processes are run at high temperatures and high pressures. Incidents involving combustible gas explosions are frequent; however, issues with gas explosion safety at high temperatures and pressures are never addressed. There have been no substantial advances in theoretical prediction for a long time and a dearth of perfect theories and systematic data collection. Many factors, such as thermal decomposition and slow oxidation, need to be considered at high temperatures and high pressures, which causes difficulties in measurements and inadvertently increases the potential explosion risk. This paper reviews the historical experimental research on the flammability limit of combustible gases at elevated temperatures and pressures and the prediction model of flammable limits by examining the influence mechanism of high temperatures and high pressures. An overview of the theory of flammability limits, criterion of flammability limits, experimental studies, and current status of flammability limit prediction models for combustible gases at high temperatures and pressures are highlighted to help establish and improve the accuracy of flammability limit prediction models at high temperatures and pressures.

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Section: Pressure Dependencementioning

confidence: 99%

Section: Advances In the Experimental Study Of The Flammability Limit...mentioning

confidence: 99%

Flammability Limits of Combustible Gases at Elevated Temperatures and Pressures: Recent Advances and Future Perspectives

Yan

Wang

et al. 2022

Energy Fuels

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“…Based on a constant-volume combustion chamber (CVCC), Mei et al 15 explored the characteristics of laminar flame propagation of the NH 3 /O 2 /N 2 mixture and found that the mole fraction of key radicals (such as OH, NH 2 , and H) was increased with the elevation of adiabatic flame temperature. Kanoshima et al 16 and Zhang et al 17 evaluated the temperature and pressure effects on ammonia/air flame and observed that compared with those of methane/air flame, ammonia/air flame exhibited a higher temperature exponent and a pressure exponent of near zero. The above studies have yielded valuable insights into NH 3 combustion in IC engines under high-temperature and -pressure conditions.…”

Section: Introductionmentioning

confidence: 99%

Effects of Injection Timings and Energy Ratios on the Combustion and Emission Characteristics of n-Heptane/Ammonia RCCI Mode

Zhang,

Chen,

et al. 2024

Energy Fuels

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Blending with a high-reactivity fuel is recognized as an effective way to overcome poor combustion and heavy emissions of ammonia (NH 3 ). In this study, we investigated the combustion performance and nitrogen-based emissions of an nheptane/ammonia blend in an optical engine operating under reactivity-controlled compression ignition (RCCI) mode, addressing the n-heptane energy ratio and injection timing. Considering the long ignition delay time of pure ammonia, the n-heptane energy ratio was selected as 20−40%, and the injection timings were selected as −70 to −35 °CA aTDC. The results demonstrate the substantial impact of both variables on engine performance. Notably, a critical injection timing (SOI = −50 °CA aTDC) was identified, exhibiting optimal combustion stabilities, while an increased n-heptane energy ratio facilitated the expansion of the stable operating conditions and increased the indicated mean effective pressure by up to 6.4%. Combustion visualization showed a transition in combustion mode from flame propagation to sequential autoignition with the advancement of injection timing, resulting in a more homogeneous combustion. Meanwhile, optimal flame development was observed at the critical injection timing. As the heptane fraction decreased, autoignition timing was obviously retarded and flame development depended on the local temperature field, suggesting the potential for the modulation of combustion mode through controlling the injection timing and energy ratio. Regarding nitrogen-based emissions, an advanced injection timing correlated with more homogeneous combustion, leading to a decrease of NH 3 by up to 47.7% and an increase of NO and NO 2 by approximately up to 65.9 and 22.4%, respectively. As the n-heptane energy ratio decreased, unburned NH 3 emissions increased by up to 40.4%, while NO 2 emissions decreased by up to 11.2%. NO emissions exhibited an initial increase followed by a subsequent decrease, and the maximum value reached 2698 ppm at the n-heptane energy ratio of 30%. N 2 O emissions displayed negative correlations with the autoignition timing and flame propagation speed, consistent with the observed variations in combustion stabilities.

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“…Due to the presence of the N element in NH 3 molecules, the problem of high NO x emission caused by ammonia fuel needs to be solved. In order to improve the characteristics of ammonia, more reactive fuels can be used for doping with ammonia, such as methane (Valera-Medina et al, 2015) and hydrogen (Zhang et al, 2022). Since methane is the main component of natural gas fuel widely used in gas turbines, using ammonia/methane blends is one way to promote ammonia as an alternative fuel to natural gas (An et al, 2021;Sun J. et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Premixed combustion and emission characteristics of methane diluted with ammonia under F-class gas turbine relevant operating condition

Zhang

Zhao

et al. 2023

Front. Energy Res.

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Ammonia has been used on a small scale in other industrial equipment, such as gas turbines, as a carbon-free fuel. However, ammonia fuel suffers disadvantages such as high ignition temperature, low flame velocity and high NOx emissions. Doping with ammonia using a more reactive fuel, such as methane, can solve the above problems. Therefore, under the relevant operating conditions of the gas turbine (T = 723 K, p = 16.5 atm), the effect of ammonia content on the combustion and emission characteristics of laminar premixed methane flames was numerically investigated. This research uses the PREMIX code from ANSYS CHEMKIN-PRO 2020 and Okafor chemical kinetic mechanisms and provides a reference for our subsequent analysis of gas turbine operating conditions. Firstly, the emission data of major pollutants under different ammonia content (XNH3 = 0–1.0) and equivalent ratio (Φ = .6–1.4) were calculated. Then, the laminar premixed flame structure is analyzed under the lean fuel conditions associated with gas turbines (Φ = .6, .8). Finally, the effect of ammonia addition on the chemical reaction path of NO and CO emission was studied. The results show that ammonia/methane mixture fuel is more suitable for combustion at .6 < Φ < .8 under high temperature and pressure. High ammonia content (XNH3 > .6) and low equivalent ratio can reduce NO and CO emissions. The molar fractions of H, O, and OH radicals and flame temperature decreased with the increase in ammonia content. In addition, high temperature and high pressure conditions and ammonia content greatly influence the reaction path of NO and CO production. The increase in pressure resulted in a change in the primary reaction that produced NO. In conclusion, this study guides reducing the emission of NO and CO from lean side of gas turbine plants.

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Unraveling Pressure Effects in Laminar Flame Propagation of Ammonia: A Comparative Study with Hydrogen, Methane, and Ammonia/Hydrogen

Cited by 22 publications

References 36 publications

Flammability Limits of Combustible Gases at Elevated Temperatures and Pressures: Recent Advances and Future Perspectives

Flammability Limits of Combustible Gases at Elevated Temperatures and Pressures: Recent Advances and Future Perspectives

Effects of Injection Timings and Energy Ratios on the Combustion and Emission Characteristics of n-Heptane/Ammonia RCCI Mode

Premixed combustion and emission characteristics of methane diluted with ammonia under F-class gas turbine relevant operating condition

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