Effects of ammonia substitution on hydrogen/air flame propagation and emissions

Lee, J.H.; Lee, S.I.; Kwon, Oh Chae

doi:10.1016/j.ijhydene.2010.07.104

Cited by 164 publications

(31 citation statements)

References 22 publications

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“…In order to improve the lower combustion intensities of ammonia, hydrogen-added ammonia flames have been studied [3][4][5][6][7]. Lee et al [3,4] experimentally investigated the laminar burning velocity of hydrogen-added ammonia/air premixed flames.…”

Section: Introductionmentioning

confidence: 99%

“…Lee et al [3,4] experimentally investigated the laminar burning velocity of hydrogen-added ammonia/air premixed flames. They showed the laminar burning velocity and Markstein numbers at the atmospheric pressure and clarified that the laminar burning velocity increases and the Markstein number decreases with an increase in hydrogen concentration.…”

Section: Introductionmentioning

confidence: 99%

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Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Hayakawa

Goto

Mimoto

et al. 2015

Fuel

519

210

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h i g h l i g h t sLaminar burning velocities of ammonia/air flames at high pressures are evaluated. Maximum value of laminar burning velocity of ammonia/air flame is about 7 cm/s. Laminar burning velocity decreases with the increase in the pressure. Markstein length increases with the increase in equivalence ratio. Markstein lengths at high pressure are lower than those at 0.1 MPa. a b s t r a c tAmmonia is expected to be useful not only as a hydrogen-energy carrier but also as a carbon-free fuel. In order to design an ammonia fueled combustor, fundamental flame characteristics of ammonia must be understood. However, knowledge of the characteristics of ammonia/air flames, especially at the high pressures, has been insufficient. In this study, the unstretched laminar burning velocity and the Markstein length of ammonia/air premixed flames at various pressures up to 0.5 MPa were experimentally clarified for the first time. Spherically propagating premixed flames, which propagate in a constant volume combustion chamber, were observed using high-speed schlieren photography. Results indicate that the maximum value of unstretched laminar burning velocities is less than 7 cm/s within the examined conditions and is lower than those of hydrocarbon flames. The unstretched laminar burning velocity decreases with the increase in the initial mixture pressure, tendency being the same as that of hydrocarbon flames. The burned gas Markstein length increases with the increase in the equivalence ratio, the tendency being the same as that of hydrogen/air flames and methane/air flames. The burned gas Markstein lengths at 0.1 MPa are higher than those at 0.3 MPa and 0.5 MPa. However, the values of burned gas Markstein length at 0.3 MPa and 0.5 MPa are almost the same. In addition, numerical simulations using CHEMKIN-PRO with five detailed reaction mechanisms which are presently applicable for the ammonia/air combustion were also conducted. However, qualitative predictions of unstretched laminar burning velocity using those reaction mechanisms are inaccurate. Thus, further improvements of reaction mechanisms are essential for application of ammonia/air premixed flames.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Hayakawa

Goto

Mimoto

et al. 2015

Fuel

519

210

View full text Add to dashboard Cite

show abstract

“…Kumar et al [13] evaluated the laminar burning velocity as related to heat loss from ammonia/hydrogen/air flames and pointed out the importance of OH, H and O radicals for the laminar burning velocity. Lee et al [14,15] experimentally clarified the laminar burning velocity and Markstein number of ammonia/hydrogen/air flames under atmospheric pressure. Li et al [16] investigated the characteristics of NOx formation from ammonia/hydrogen/air flames and clarified that the NOx concentration decreases with an increase in the concentration of ammonia in the fuel at stoichiometric conditions.…”

Section: Introductionmentioning

confidence: 99%

Laminar burning velocity and Markstein length of ammonia/hydrogen/air premixed flames at elevated pressures

Ichikawa

Hayakawa

Kitagawa

et al. 2015

International Journal of Hydrogen Energy

322

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HydrogenEffects of pressure Laminar burning velocity Markstein length a b s t r a c t Ammonia shows promise not only as a hydrogen-energy carrier but also as a carbon-free fuel. However, combustion intensity of ammonia must be improved to enable its application to practical combustors. In order to achieve this, hydrogen-added ammonia/air flames were experimentally and numerically investigated at elevated pressures up to 0.5 MPa. The hydrogen ratio, which is defined as the hydrogen concentration in the fuel mixture, was varied from 0 to 1.0. The unstretched laminar burning velocity and Markstein length of spherically propagating laminar flames were experimentally evaluated. The results showed that, unstretched laminar burning velocity increases non-linearly with an increase in the hydrogen ratio. The Markstein length varies non-monotonically with an increase in the hydrogen ratio. The unstretched laminar burning velocity, and the Markstein length decrease with an increase in the initial mixture pressure. Although the decrease in the Markstein length is larger when the initial mixture pressure increases from 0.1 to 0.3 MPa, the values of Markstein lengths at 0.5 MPa are almost the same as those at 0.3 MPa.

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“…Furthermore, the combustion of H 2 -NH 3 mixtures is much more attractive with further beneficial characteristics of enhancing H 2 combustion safety and making H 2 flames visually detectable. Combustion of NH 3 and H 2 mixtures makes H 2 utilization easily controllable and diminishes the associated safety problems [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Study on using hydrogen and ammonia as fuels: Combustion characteristics and NO_xformation

Jun

Huang

Kobayashi

et al. 2014

Int. J. Energy Res.

323

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SUMMARYThis paper evaluates the potential of hydrogen (H2) and ammonia (NH3) as carbon‐free fuels. The combustion characteristics and NOx formation in the combustion of H2 and NH3 at different air‐fuel equivalence ratios and initial H2 concentrations in the fuel gas were experimentally studied. NH3 burning velocity improved because of increased amounts of H2 atom in flame with the addition of H2. NH3 burning velocity could be moderately improved and could be applied to the commercial gas engine together with H2 as fuels. H2 has an accelerant role in H2–NH3–air combustion, whereas NH3 has a major effect on the maximum burning velocity of H2–NH3–air. In addition, fuel‐NOx has a dominant role and thermal‐NOx has a negligible role in H2–NH3–air combustion. Thermal‐NOx decreases in H2–NH3–air combustion compared with pure H2–air combustion. NOx concentration reaches its maximum at stoichiometric combustion. Furthermore, H2 is detected at an air‐fuel equivalence ratio of 1.00 for the decomposition of NH3 in flame. Hence, the stoichiometric combustion of H2 and NH3 should be carefully considered in the practical utilization of H2 and NH3 as fuels. H2 as fuel for improving burning performance with moderate burning velocity and NOx emission enables the utilization of H2 and NH3 as promising fuels. Copyright © 2014 John Wiley & Sons, Ltd.

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Effects of ammonia substitution on hydrogen/air flame propagation and emissions

Cited by 164 publications

References 22 publications

Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Laminar burning velocity and Markstein length of ammonia/hydrogen/air premixed flames at elevated pressures

Study on using hydrogen and ammonia as fuels: Combustion characteristics and NO_xformation

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Effects of ammonia substitution on hydrogen/air flame propagation and emissions

Cited by 164 publications

References 22 publications

Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Laminar burning velocity and Markstein length of ammonia/hydrogen/air premixed flames at elevated pressures

Study on using hydrogen and ammonia as fuels: Combustion characteristics and NOxformation

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Study on using hydrogen and ammonia as fuels: Combustion characteristics and NO_xformation