Energy deposition and plasma propulsion during the time window of microwave-assisted CH4-O2 spark ignition with Ar/N2/CO2 dilution

Zhang, Xinhua; Wang, Zhaowen; Liu, Chaohui; Xu, Jingxing; Cheng, Xiaobei

doi:10.1016/j.combustflame.2022.112424

Cited by 6 publications

(1 citation statement)

References 29 publications

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“…It was apparent that the MW power mainly governed the critical C NH3,i , affecting an almost linear increase of the critical C NH3,i with P MW , whereas the total flow rate was secondary, demonstrating relatively small negative impact on the critical C NH3,i for a given P MW (figure 4). MW discharge has been known to operate in a relatively low electric field, having difficulties in igniting by itself, and thus it requires an external source for seed elections to breakdown a gaseous media [42][43][44][45]. As ammonia was added, not only some portion of the total electron energy was transferred to NH 3 but also the excited states of Ar lost their energy due to the collisions with NH 3 , resulted in less ionization of Ar [38].…”

Section: Addition Of Ammoniamentioning

confidence: 99%

Ammonia cracking for hydrogen production using a microwave argon plasma jet

Zhang,

Cha

2023

J. Phys. D: Appl. Phys.

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Ammonia (NH3) is a promising hydrogen carrier that effectively connects producers of blue hydrogen with consumers, giving rapid conversion of ammonia to hydrogen a critical role in utilizing hydrogen at the endpoints of application in an ammonia-hydrogen economy. Because conventional thermal cracking of NH3 is an energy intensive process, requiring a relatively longer cold start duration, plasma technology is being considered as an assisting tool—or an alternative. Here we detail how an NH3 cracking process, using a microwave plasma jet (MWPJ) under atmospheric pressure, was governed by thermal decomposition reactions. We found that a delivered MW energy density (ED) captured the conversion of NH3 well, showing a full conversion for ED > 6 kJ l−1 with 0.5-% v/v NH3 in an argon flow. The hydrogen production rate displayed a linear increase with MW power and the NH3 content, being almost independent of a total flow rate. A simplified one-dimensional numerical model, adopting a thermal NH3 decomposition mechanism, predicted the experimental data well, indicating the importance of thermal decomposition in the plasma chemistry. We believe that such a prompt thermal reaction, caused by MW plasma, will facilitate a mobile and/or non-steady application. A process combined with the conventional catalytic method should also effectively solve a cold start issue.

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