An experimental and kinetic modeling study of ammonia/n-heptane blends

Dong, Shijun; Wang, Bowen; Jiang, Zuozhou; Li, Yuhang; Gao, Wenxue; Wang, Zhaowen; Cheng, Xiaobei; Curran, Henry J.

doi:10.1016/j.combustflame.2022.112428

Cited by 70 publications

(30 citation statements)

References 48 publications

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“…Similar to the findings reported in rapid compression machine (RCM) studies [43,44], the hydrogen chemistry starts to dominate as the blending ratio of H 2 is higher than 5%. Dong et al [45] performed further investigations on the IDT of stoichiometric ammonia/n-heptane mixtures at high temperatures (1000 -1400 K) under 10 bar in a shock tube, which complements the data reported by Yu et al [46] which were investigated in an RCM for low-temperature autoignition. It was observed that the effect of the ammonia blending ratio is smaller at high-temperature conditions than that at low temperatures.…”

Section: Ignition Delay Timementioning

confidence: 55%

Recent Progress on Combustion Characteristics of Ammonia-Based Fuel Blends and Their Potential in Internal Combustion Engines

Zhu

Shu

2023

IJAMM

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Review Recent Progress on Combustion Characteristics of Ammonia-Based Fuel Blends and Their Potential in Internal Combustion Engines Denghao Zhu , and Bo Shu * Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt, Bundesallee 100, DE-38116 Braunschweig, Germany * Correspondence: bo.shu@ptb.de Received: 21 November 2022 Accepted: 22 December 2022 Published: 18 January 2023 Abstract: Ammonia has recently attracted numerous attentions from researchers and policy makers as promising energy and hydrogen carrier for mitigating the carbon footprints in the energy sector. The mature infrastructure for the production, storage, and transportation of ammonia allows a quick role of ammonia in energy systems. By applying green hydrogen and renewable energies, green ammonia can be produced, which makes ammonia even more attractive. Prior to the commercial use of ammonia for large-scale energy systems, e.g., internal combustion engines and stationary gas turbines, a fundamental understanding of the ignition and combustion behaviors of ammonia is essential. In the past decades, a lot of studies on ammonia combustion have been published. Those studies covered broad topics including experimental and numerical investigations which were either fundamental or practical oriented. To continuously follow state-of-the-art and to provide a brief overview of the most recent research on ammonia combustion so that others can easily identify the most relevant work, this review summarizes the recent progress on combustion characteristics of ammonia and ammonia fuel blends as well as their potential use in internal combustion engines. Combining the advantages and drawbacks identified in both fundamental and practical studies, a clearer road map for ammonia application is given.

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Section: Ignition Delay Timementioning

confidence: 55%

Recent Progress on Combustion Characteristics of Ammonia-Based Fuel Blends and Their Potential in Internal Combustion Engines

Zhu

Shu

2023

IJAMM

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“…Moreover, fewer NH 2 radicals undergo chain termination reaction pathways at higher temperatures. 19 Thus, the overall HRR was much higher than those in the other cases at T Fuel = 400 K. As shown in Figure 14b, the combustion process at 800 K shows a significant difference because ammonia can promote the oxidization of n-heptane at low-to-intermediate temperatures. 13 The oxidization of ammonia proceeds via NH which promoted the oxidization of NO to NO 2 via the active reaction NO+HO 2 ⇌ NO 2 + OH, 53 which further accelerated the oxidization of n-heptane.…”

Section: Effect Of Compositional Stratificationmentioning

confidence: 84%

“…At lower and higher temperatures, the IDTs were slightly affected by the oxygen concentrations in mixtures 2 and 4. Dong et al 19 further conducted hightemperature experiments using an HPST. The results showed that the IDTs can also be accurately predicted by the skeletal mechanism with variations in oxygen and ammonia concentrations.…”

Section: Methodsmentioning

confidence: 99%

“…Because the fuel stream side has very rich n-heptane mixtures, an ammonia-lean mixture was used and the initial ϕ NH3 was set to 0.6 to provide Comparisons of the predicted ignition delay times with the RCM 14 and HPST experiments. 19 Lines represent the numerical results using the current mechanism from Xu et al 18 The half and solid points represent the RCM and HPST experiments. sufficient oxygen for DF combustion.…”

Section: Simulation Parameters and Numerical Setupmentioning

confidence: 99%

“…Figure1. Comparisons of the predicted ignition delay times with the RCM14 and HPST experiments 19. Lines represent the numerical results using the current mechanism from Xu et al18 The half and solid points represent the RCM and HPST experiments.…”

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confidence: 99%

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Numerical Study on the Ignition and Flame Propagation of Ammonia/n-Heptane Dual Fuels

Zhao,

Li,

Sun

et al. 2023

Energy Fuels

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Ammonia is carbon-free and thus is a promising renewable fuel for carbon neutrality. However, because ammonia has low reactivity and narrow flammability range, blended fuels of ammonia/n-heptane are often used to trigger high-temperature combustion in internal combustion engines. In this study, the ignition and flame propagation of ammonia/n-heptane dual-fuels were investigated in a specified mixing layer using a skeletal mechanism via a high-fidelity simulation. The results showed that auto-ignition was initiated at the locations of the most reactive mixture fraction ξmr calculated by the zero-dimensional homogeneous reactor model. Two cool and hot flame fronts were observed to propagate both toward the fuel-lean and fuel-rich regions. A stabilized hot flame front identified by the temperature isoline was observed in the fuel-rich region as a result of the low reaction rates and adiabatic flame temperatures. The temperature of the pilot fuel (T Fuel) significantly affected the flame structures in the presence of compositional stratification. When T Fuel was increased, the dual-fuel flame structure transitioned from quadruple peaks in the heat release rate (HRR) profiles at 800 K to double peaks at 900 K and to a single peak at 1000 K. The propagation of the flame front was controlled by the cool flame during the early stage and the gradient of the ignition delay times. Subsequently, it transformed into a diffusion-driven flame. Finally, the average HRR profiles had double peaks at 800–1000 K owing to the presence of cool and hot flames. Ammonia is expected to promote the oxidization of n-heptane via the active reaction NO+HO2 ⇌ NO2 + OH at 800 K, causing a high peak of HRR.

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Kinetic study of ignition process of ammonia/n‐heptane fuel blends under engine conditions

Li,

Liu,

Wang

et al. 2024

Energy Science & Engineering

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Pilot‐ignited ammonia‐fueled engines have drawn more and more attention for low carbon emissions compared to traditional diesel engines. The ignition processes of NH3/NC7H16 mixtures under compression ignition engine‐like conditions are numerically investigated. By comparing the ignition delay times (IDTs) calculated by six ammonia mechanisms with experimental data, the Glarborg mechanism is selected. Then, the Glarborg mechanism and the Zhang detailed n‐heptane mechanism are merged into a new mechanism, which is adopted in the present study. Results show that the negative temperature coefficient behavior of the IDTs is only observed as the ammonia mass fraction is 70%. Only temperature has a significant effect on IDTs at all research conditions, and the effect of ammonia mass fraction is significant when the temperature is lower than 1000 K. However, the effects of equivalence ratio and pressure are small, especially at high temperatures, high equivalence ratios, and high pressures. Interestingly, the IDTs are categorized into three regions by temperature and ammonia mass fraction. The sensitivity analysis indicates that the sensitivity coefficients of most reactions associated with ammonia decrease with a decrease in ammonia mass fraction, whereas only R4210 is sensitive to ammonia mass fraction for n‐heptane‐related reactions. Rates of production and consumption (ROP) analyses indicate that the ammonia mass fraction mainly affects the ROPs of NC7H16, NH3, and NNH at low and medium temperatures, whereas the ammonia mass fraction affects the ROP of H2NO before the temperature of 2000 K. The ROPs of NC7H16, NH3, and NNH significantly increase with increasing temperature, whereas the ROP of H2NO slightly increases with increasing temperature. The increase of temperature in the early and middle stages is mainly contributed by the oxidation of n‐heptane, while the increase of temperature in the middle and late stages is mainly contributed by the oxidation of ammonia.

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An experimental and kinetic modeling study of ammonia/n-heptane blends

Cited by 70 publications

References 48 publications

Recent Progress on Combustion Characteristics of Ammonia-Based Fuel Blends and Their Potential in Internal Combustion Engines

Recent Progress on Combustion Characteristics of Ammonia-Based Fuel Blends and Their Potential in Internal Combustion Engines

Numerical Study on the Ignition and Flame Propagation of Ammonia/n-Heptane Dual Fuels

Kinetic study of ignition process of ammonia/n‐heptane fuel blends under engine conditions

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