Mechanism of micro-explosion of water-in-oil emulsified fuel droplet and its effect on soot generation

Shiquan Shen, Kai Sun, Zhizhao Che, Tianyou Wang, Ming Jia and Junqian Cai

Energy, 2020, vol. 191, issue C

Abstract: In this study, the mechanism of micro-explosion of single droplets of water-in-oil (W/O) emulsified fuels and its effect on the soot generation are investigated experimentally using suspended droplets. Two distinct breakup modes are observed as the droplets are heated, namely catastrophic micro-explosion after water coalescence at a lower surfactant concentration and puffing at a higher surfactant concentration without water coalescence. To understand the underlying physics of such transition, the water/oil interfacial tension is investigated. It is found that the increase of water/oil interfacial tension after the deactivation of surfactant can significantly accelerate the coalescence of dispersed water, and effectively increase the temperature of bubble nucleation. The deactivation of surfactant is a prerequisite for the occurrence of catastrophic micro-explosion. The reason is found to be that the catastrophic micro-explosion can be induced by the explosive vaporization of water only if the dispersed water coalesces rapidly into large droplets to explode violently at a high superheat degree. The surfactant concentration in emulsified fuels influences the deactivation temperature of surfactant. Therefore, the catastrophic micro-explosion can be controlled to occur by adjusting the surfactant concentration in emulsified fuels. In addition, it is also found that the micro-explosion of W/O emulsified fuel during the combustion can effectively decrease the soot generation due to uniform fuel/air mixture formed after the micro-explosion.

Keywords: Micro-explosion; Droplet breakup; Emulsified fuel; Combustion (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (11)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:191:y:2020:i:c:s0360544219321838

DOI: 10.1016/j.energy.2019.116488

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