Experimental investigation on microexplosion of single isolated burning droplets containing titanium tetraisopropoxide for nanoparticle production

Combustion characteristics and liquid-phase visualisation of single isolated diesel droplet with surface contaminated by soot particles

“…5 for contaminated droplet were less than 4%. Typical findings on stable and uniformly suspended particle suggests earlier and longer period of disruptive combustion with higher concentration of precursors and nanoparticles [6][7][9][10]. Those findings, however, are distinctly different from the random soot contamination on a droplet surface because they are not in the same particle laden condition as the present work.…”

“…Higher boiling point of low volatile particle increases the temperature within the surface layer, resulting temperature gradient across the droplet [9] and characterised similar to liquid-phase diffusion theory. In disruptive phase, particles accumulated on the droplet surface formed an impermeable shell and superheat the fuel heterogeneously that lead to microexplosions [10]. Combustion of nanofluid experienced similar disruptive phase and shell formations with various slurry fuel studies [11][12], but with lesser magnitude of disruptions and deviations of linear droplet surface regressions.…”

Impact of co‐flow on the spray flame behaviour applied to nanoparticle synthesis

“…However, the relevance of droplet micro‐explosions for an entire flame spray is still part of ongoing research. It is likely that the micro‐explosions occur also for the precursor‐solvent mixture used in this study (zirconium n ‐propoxide/ n ‐propanol/ethanol) as it was obtained for similar metal‐alkoxide precursors, e.g., titanium isopropoxide . Previous studies reported that fine ZrO 2 nanoparticles with a monomodal size‐distribution and a major single tetragonal crystal phase are obtained for this precursor‐solvent combination, indicating that the droplet‐to‐particle conversion is not the dominating growth mechanism.…”

“…The type of particle formation mechanism (gas‐to‐particle versus droplet‐to‐particle) strongly depends on the precursor chemistry at elevated temperatures and can be chemically modified by sophisticated selection of the solvent . A deeper understanding of the particle formation mode can be obtained from single droplet combustion experiments, which have demonstrated micro‐explosions for most of the common FSP precursors . Micro‐explosions are triggered by homogeneous and/or heterogeneous gas nucleation inside the liquid droplet, while the latter has been reported to be the dominating mechanism .…”

“…A deeper understanding of the particle formation mode can be obtained from single droplet combustion experiments, which have demonstrated micro‐explosions for most of the common FSP precursors . Micro‐explosions are triggered by homogeneous and/or heterogeneous gas nucleation inside the liquid droplet, while the latter has been reported to be the dominating mechanism . Secondary droplet breakup, e.g., through a droplet micro‐explosion, would obviously be beneficial for the precursor release and affects the location (here the height above the nozzle) for the onset of particle nucleation in the FSP process.…”