A skeletal chemical kinetic mechanism for ammonia/n-heptane combustion

Xu, Leilei; Chang, Yachao; Treacy, Mark; Zhou, Yuchen; Bai, Xue‐Song

doi:10.1016/j.fuel.2022.125830

Cited by 66 publications

(21 citation statements)

References 49 publications

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“…Recently, skeletal and reduced chemical mechanisms have been developed for ammonia/n-heptane blends. 18,20 The combustion characteristics, including the IDTs and laminar burning velocities calculated using a homogeneous reactor, agreed well with the experimental results. However, gaps remain in our understanding of the kinetics of ammonia.…”

Section: Introductionsupporting

confidence: 74%

“…The results showed that the IDTs can also be accurately predicted by the skeletal mechanism with variations in oxygen and ammonia concentrations. Moreover, the numerical results showed good agreement with the experimental results in terms of the lamina burning velocities, species distribution for pure fuel and DFs under different pressures and ammonia substitution ratios . The results predicted from this mechanism were compared with four mechanisms.…”

Section: Methodssupporting

confidence: 57%

“…A skeletal chemical kinetic mechanism including 69 species and 389 reactions was employed for all the simulations. This mechanism was developed based on the decoupling methodology, , which consists of three parts, a complete sub-mechanism for C0-C1 hydrocarbons, a reduced sub-mechanism for C2-C3 hydrocarbons, and a skeletal fuel-specific sub-mechanism.…”

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%

“…Xu et al investigated the extinction limits of cool and hot diffusion flames for ammonia/ n -dodecane blends in a counterflow burner. Ammonia exhibited a dilution effect, that suppressed the extinction limits of cool and hot flames.…”

Section: Introductionmentioning

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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Section: Introductionsupporting

confidence: 74%

Section: Methodssupporting

confidence: 57%