Graphene oxide doped ethanol droplet combustion: Ignition delay and contribution of atomization to burning rate

Mosadegh, Sepehr; Ghaffarkhah, Ahmadreza; Kuur, Colin van der; Arjmand, Mohammad; Kheirkhah, Sina

doi:10.1016/j.combustflame.2021.111748

Cited by 8 publications

(10 citation statements)

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Section: Introductionmentioning

confidence: 99%

“…As doping agents, nanomaterials have been used to improve several liquid fuels combustion characteristics, such as their burning rate and emissions, see for example [1][2][3][4][5][6] . In the context of droplet combustion, it is shown that doping of liquid fuels with nanomaterials leads to the occurrence of the atomization phenomenon [5][6][7][8][9][10][11] . This changes the spatio-temporal size distribution of the droplets and their burning rate 6 , which may influence the dynamics of coupling between the droplets and the corresponding flames.…”

Section: Introductionmentioning

confidence: 99%

“…In the context of droplet combustion, it is shown that doping of liquid fuels with nanomaterials leads to the occurrence of the atomization phenomenon [5][6][7][8][9][10][11] . This changes the spatio-temporal size distribution of the droplets and their burning rate 6 , which may influence the dynamics of coupling between the droplets and the corresponding flames. Our understanding related to the characteristics of the droplet-atomization-flame coupling is limited, and this requires further investigations.…”

Section: Introductionmentioning

confidence: 99%

“…Nucleation occurs at the liquid-liquid interface of multicomponent fuels with different boiling temperatures, at the liquid-solid interface of the droplet and its suspending mechanism, and/or at the nanomaterials surface 7,12 . For the latter, it is shown that the addition of carbonaceous nanomaterials to liquid fuels allows for absorption of the combustion heat at the materials surface, formation of nucleation sites, and as a result generation of bubbles at these sites 5,6 . Coalescence of the bubbles, transfer of heat from the flame to the bubbles, and the surface regression of the main droplet lead to formation of relatively large bubbles 4,5,13 .…”

Section: Introductionmentioning

confidence: 99%

“…However, for excessively large concentrations of the nanomaterials, the shell is relatively strong, which traps the bubbles, and suppresses the atomization. Mosadegh et al 6 showed that the amount of oxygen available in the graphene oxide molecular structure can also influence the atomization phenomenon.…”

Section: Introductionmentioning

confidence: 99%

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The role of atomization in the coupling between doped droplets dynamics and their flames

Mosadegh,

Kheirkhah

2022

Preprint

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The droplet and flame chemiluminescence dynamics as well as their coupling during atomization events of graphene oxide doped diesel are investigated experimentally.The tested doping concentrations are 0, 0.001, 0.005, 0.01, and 0.02% by weight. To minimize heat transfer between the droplet and its suspension mechanism, small diameter fibers are used for the droplet suspension. Separate shadowgraphy and OH * chemiluminescence measurements are performed at 4000 Hz to study the droplet and flame dynamics, respectively. The results show that both the droplet diameter squared and the flame chemiluminescence feature intermittent oscillations. The droplet diameter squared oscillations RMS is positively related to the number and intensity of the atomization events and the graphene oxide doping concentration. The probability density function of the inverse of the time separation between two consecutive atomization events and the power spectrum density of the droplet diameter squared oscillations feature dominant large probabilities and powers at about 25 Hz prior to the occurrence of the first intense atomization event. After the occurrence of the first intense atomization event, this frequency decreases to about 5 Hz for both.Although the intense atomization triggers the large amplitude oscillations at 5 Hz, it was argued that the retracting motion of the igniter induces the oscillations at 25 Hz.Our findings suggest that the atomization events are the root cause of the smaller frequency coupling between liquid fuel droplets doped with graphene oxide and their flames. This has implications for spray combustion research.

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