Study on micro-flame ignited (MFI) hybrid combustion characteristics of a dual-fuel optical engine at different lambdas

Xiao, Li; He, Bang-Quan; Zhao, Hua

doi:10.1016/j.fuel.2020.119796

Cited by 7 publications

(3 citation statements)

References 48 publications

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“…However, it is too hard to solve the local strain rate, due do the complex multi-ignition flames in RCCI. Therefore, a two-dimensional global stretch rate ( K S ) is used: Figure shows the stretch rate as a function of turbulent flame speed of NH 3 and CH 4 at different SOIs. For flame speed, it can be observed that the value is much higher than the SI scenarios, which is due to the promotion of multi-point auto-ignition on flame propagation under RCCI conditions.…”

Section: Resultsmentioning

confidence: 99%

Auto-Ignition and Flame Characteristics of Ammonia Reactivity-Controlled Compression Ignition Combustion in Comparison with Methane

2023

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Ammonia (NH 3 ), as a hydrogen carrier, is the key to being carbon-neutral for internal combustion engines. However, the poor combustion properties of NH 3 hindered the development of NH 3 engines. In the current study, an optical engine is adopted and the autoignition and flame characteristics of NH 3 reactivity-controlled compression ignition (RCCI) combustion (in comparison to CH 4 ) are optically studied. The experimental results show that there exists a critical injection timing for the effect of pilot fuel on NH 3 combustion. Before the critical timing, the combustion phase (auto-ignition) will delay because of the less over-rich pilot fuel. In addition, lowtemperature heat release is observed for NH 3 /n-heptane under early injection timing conditions. When comparing the two fuels, the autoignition timing is delayed while the combustion duration (CA05-90) is shorter for NH 3 combustion. The main reason is that the low chemical reactivity of NH 3 inhibits the auto-ignition of the pilot fuel (n-heptane), while the next oxidation pathways of NH 3 are extremely fast. Flame images show that, for NH 3 RCCI combustion, the highest probability of auto-ignition is in the bottom and NH 3 flame nearly propagates from the edge to the center, which is mainly due to the temperature inhomogeneity of the cylinder. Meanwhile, for CH 4 combustion, the highest probability of auto-ignition is in the center of the cylinder, and CH 4 flame nearly propagates from the center to the edge. The current study revealed the similarities/differences between NH 3 and CH 4 under RCCI conditions and can give some insights into the application of NH 3 engines.

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Section: Resultsmentioning

confidence: 99%

Auto-Ignition and Flame Characteristics of Ammonia Reactivity-Controlled Compression Ignition Combustion in Comparison with Methane

2023

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“…Various injection strategies [3][4][5][6][7][8], engine operation conditions [9][10][11] and fuel blends [12][13][14][15][16][17][18] of DME-fueled engines have been investigated. Youn et al [8] showed that the use of DME was associated with a higher pressure and earlier increase in the Energies 2022, 15,1912 2 of 11 heat release rate (HRR) compared to diesel, because the ignition delay was shorter, the vaporization characteristics were more favorable, and the cetane number was higher.…”

Section: Introductionmentioning

confidence: 99%

Combustion Performance and Low NOx Emissions of a Dimethyl Ether Compression-Ignition Engine at High Injection Pressure and High Exhaust Gas Recirculation Rate

Youn

Jeon

2022

Energies

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Dimethyl ether (DME) is a promising alternative to diesel for compression-ignition (CI) engines used in various industrial applications. However, the high nitrogen oxide (NOx) emissions of DME combustion have restricted its use. The primary cause of high NOx emissions is a high combustion temperature. In this study, a high exhaust gas recirculation (EGR) rate was used when testing a common-rail direct injection CI engine suitable (with minor modifications) for a passenger car. A modified fuel supply system created high injection pressure during evaluation of combustion performance. The physical and chemical properties of DME were the principal determinants of the ignition delay, combustion speed, and heat release rate. Although a high injection pressure accelerated formation of the fuel-air mixture and the combustion speed, combustion performance deteriorated with increased NOx emissions. An increased EGR rate affected combustion and the NOx concentration. A high EGR rate effectively reduced NOx formation and emission under low-temperature combustion conditions. Also, the good DME combustion characteristics were maintained when the EGR rate was high, unlike for an ultra-low sulfur diesel engine.

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“…A micro combustor is one of the most important components of a micro energy system. The research of micro flame [1,2] is the basis for the development of high-efficiency and high-reliability micro combustors. Research of flame on a small scale [3,4] is significant to completely understand micro combustion characteristics.…”

Section: Introductionmentioning

confidence: 99%

Flame characteristics influenced by the angle of burners for non-premixed C3H8/air

2022

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The study of micro flame characteristics is an essential basis for developing micro combustors. Therefore, the non-premixed C3H8/air micro flame characteristics were experimentally studied. Flame length, flame shape and blow-out limit were studied by varyingthe equivalence ratio (?),the inlet velocity of C3H8/air (v)and angles of the burner. The results showed ignited non-premixed C3H8/air had 3combustion states: noflame, a stable flame, and a blow-out flame. Whether ignited non-premixed C3H8/air could form astable flame mainly depended on ? and v. In addition, total flame lengths increased with the increase of ? and v firstly. However, when ? increased to a certain value, total flame lengths were independent of ? and only affected by v. Moreover, flame length and shape were affected by the angle of the burner. Instead, the blow-out limit was found to be associated solely with ?, but not the burner angle. The findings of this study provided fundamental data for the development of high-efficiency microcombustors.

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Study on micro-flame ignited (MFI) hybrid combustion characteristics of a dual-fuel optical engine at different lambdas

Cited by 7 publications

References 48 publications

Auto-Ignition and Flame Characteristics of Ammonia Reactivity-Controlled Compression Ignition Combustion in Comparison with Methane

Auto-Ignition and Flame Characteristics of Ammonia Reactivity-Controlled Compression Ignition Combustion in Comparison with Methane

Combustion Performance and Low NOx Emissions of a Dimethyl Ether Compression-Ignition Engine at High Injection Pressure and High Exhaust Gas Recirculation Rate

Flame characteristics influenced by the angle of burners for non-premixed C3H8/air

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