Nanosecond repetitively pulsed discharges and conventional sparks of ammonia-air mixtures in a fan-stirred cruciform burner: Flammability limits and ignition transition

Shy, S.S.; Mai, Van-Phung; Chen, Y.R.; Hsieh, H.Y.

doi:10.1016/j.jaecs.2023.100164

Cited by 2 publications

(1 citation statement)

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“…Although NH 3 has many benefits, several obstacles need to be addressed before NH 3 can be applied in combustion equipment (e.g., spark ignition (SI) and compression ignition (CI) engines). These obstacles include high-autoignition temperature, , minimum ignition energy, low flame propagation speed, , narrow flammability range, and toxicity . Taking the NH 3 application in the CI engine as an example, it requires a higher compression ratio than that of conventional transport fuel to maintain stable operation.…”

Section: Introductionmentioning

confidence: 99%

Investigating Autoignition Characteristics of Ammonia/Heptamethylnonane Mixtures Over Wide Pressure Ranges: Rapid Compression Machine Measurements and Kinetic Modeling Study

Zhang,

Zhou,

et al. 2024

Energy Fuels

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Ammonia (NH 3 ) blending combustion with highreactivity fuel has garnered substantial attention in terms of decarbonization potential in internal combustion engines. 2,2,4,4,6,8,8-Heptamethylnonane, denoted as HMN, an important large-molecular weight component for diesel and jet fuel surrogates, was selected to be blended with NH 3 in this study. The ignition delay times (IDTs) of NH 3 /HMN mixtures were measured using a heated rapid compression machine (RCM) over an extensive range of conditions (temperature of 680−1025 K, pressure of 20−100 bar, equivalence ratios of 0.5−1.0, and NH 3 energy ratio (NER) of 50−90%). Experimental results show that increasing the pressure, equivalence ratio, and oxygen concentration reduces both the total and first-stage IDTs, while an increase in the NH 3 energy ratio prolongs the IDTs. For the mixture with the lowest NH 3 energy ratio of 50%, non-Arrhenius-type behavior was observed at a pressure of 20 bar, while it transfers to a monotonic decrease of IDTs with increasing temperature at a pressure of 40 bar. An NH 3 /HMN blending mechanism was developed by merging individual NH 3 and HMN submechanisms, updating NH 3 submechanism, and adding C−N cross-reaction subset. Simulation results show that under most experimental conditions, the blending mechanism exhibits reasonable prediction on the measured NH 3 /HMN IDTs. Kinetic analysis shows that the discrepancy in the first-stage ignition between experiments and simulations may be associated with the inaccurate OH consumption proportion between HMN and NH 3 , while at the intermediate-temperature region, it may be related to the core C 0 −C 4 mechanism and the NH 3 -related reactions. Further experimental or quantum calculations are needed in the future to refine the NH 3 /HMN blending mechanism on the basis of this work.

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