Effects of fuel injection strategy and ammonia energy ratio on combustion and emissions of ammonia-diesel dual-fuel engine

Jin, Shouying; Wu, Binyang; Zi, Zhenyuan; Yang, Puze; Shi, Taifeng; Zhang, Mengjie

doi:10.1016/j.fuel.2023.127668

Cited by 52 publications

(9 citation statements)

References 38 publications

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“…In Figure C, it is seen that the NO 2 emissions decrease with the delay of injection timing; compared to the lowest NO 2 emission of 165 ppm at the SOI = −40 °CA case, the NO 2 emissions of SOI = −60 °CA and SOI = −50 °CA cases increase by 12.4 and 9.7%, respectively. When it comes to the NO 2 emission, NO 2 is easily reduced to NO in the combustion process, and it also reacts with NH 2 to convert to N 2 O at an intermediate temperature (970–1300 K) . Combined with the flame development process, it can be concluded that a more homogeneous combustion would reduce the unburned NH 3 emission and increase the NO and NO 2 emissions.…”

Section: Resultsmentioning

confidence: 99%

“…Based on a KIVA4-CHENKIN code, Tay et al observed a more complete combustion of residual fuel near the cylinder liner and in the crevice region at advanced injection timings. Another simulated work by Jin et al showed that an ITE of 49.8% was achieved at a 50% ammonia ratio by injection timing optimization. Shin and Park found that an advanced injection timing could compensate for the effect of slow flame propagation of ammonia and achieved shortened combustion duration and reduced NH 3 and N 2 O emissions.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

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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“…However, gaps remain in our understanding of the kinetics of ammonia . Recently, numerical studies have been conducted on ammonia/diesel DF engines using the pilot injection of diesel. − An increase in the ammonia substitution ratio (ASR) leads to higher unburnt ammonia and N 2 O emissions. , The N 2 O greenhouse gas effect has been approximately 300 times higher than that of carbon dioxide over a period of 100 years. Thus, fundamental studies on the combustion process of ammonia/diesel blends, including studies on the dominant mechanisms for multistage ignition and flame propagation for mixtures with thermal and compositional stratifications, are extremely important but insufficient.…”

Section: Introductionmentioning

confidence: 99%

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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“…12 NH 3 is a new type of carrier for carbon-free energy and is also used for the production of important agricultural fertilizers. [13][14][15][16] The NORR strategy is attractive as it combines the two processes of NO control and ammonia synthesis. The synthesis of NH 3 from NO is much easier than from N 2 due to the lower bonding energy of NvO, 17 thereby avoiding product disputes caused by the lower ammonia yield and faradaic efficiency of the N 2 reduction reaction (NRR).…”

Section: Introductionmentioning

confidence: 99%

The in situ decoration of Ti₃C₂ quantum dots on Cu nanowires for highly efficient electrocatalytic reduction of nitric oxide to ammonia

Li¹,

Shen²,

Xiao³

et al. 2023

Inorg. Chem. Front.

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Effects of fuel injection strategy and ammonia energy ratio on combustion and emissions of ammonia-diesel dual-fuel engine

Cited by 52 publications

References 38 publications

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

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

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

The in situ decoration of Ti₃C₂ quantum dots on Cu nanowires for highly efficient electrocatalytic reduction of nitric oxide to ammonia

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Effects of fuel injection strategy and ammonia energy ratio on combustion and emissions of ammonia-diesel dual-fuel engine

Cited by 52 publications

References 38 publications

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

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

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

The in situ decoration of Ti3C2 quantum dots on Cu nanowires for highly efficient electrocatalytic reduction of nitric oxide to ammonia

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The in situ decoration of Ti₃C₂ quantum dots on Cu nanowires for highly efficient electrocatalytic reduction of nitric oxide to ammonia