Postponement of dynamic Leidenfrost phenomenon during droplet impact of surfactant solutions

Prasad, Gudlavalleti V V S Vara; Dhar, Purbarun; Samanta, Devranjan

doi:10.1016/j.ijheatmasstransfer.2022.122675

Cited by 21 publications

(12 citation statements)

References 42 publications

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“…Next, we shift our attention to the major focus of the present work: understanding how the presence of nanobubbles affects the droplet Leidenfrost regime. The substrate temperature at which the droplet exhibits the onset of rebound with minimal spraying is noted as the dynamic Leidenfrost temperature ( T DL ). , Figure a,b illustrates the temporal evolution of NB droplets of different concentrations and their corresponding dynamic Leidenfrost temperature T DL at a fixed impact velocity of U = 0.5 m/s. In the first column of Figure a, it is evident that the increase in nanobubble concentration leads to an increase in T DL at U = 0.5 m/s.…”

Section: Resultsmentioning

confidence: 99%

“…The schematic view of the experimental setup used in this study is illustrated in Figure . The setup is similar to our previous reports on Leidenfrost dynamics. − We have utilized a programmable hot plate (Holmarc Opto-Mechatronics Ltd., India) with a digitized temperature controller to heat the substrate to temperatures ranging from 150 to 350 °C and to maintain near-isothermal conditions on the substrate during the experiments. In this study, a square stainless-steel plate (80 mm × 180 mm) mounted on the heating element was used as the substrate.…”

Section: Methodsmentioning

confidence: 99%

“…The decreasing trend in T DL with an increase in the Weber number is similar to the Leidenfrost phenomenon studies for polymer droplets 13 and surfactant droplets. 15 At higher We, due to higher inertia, drops attain higher spreading. Due to the higher area of contact between the spreading droplet and heated substrate, a higher proliferation of nucleation sites at the fluid− solid interface leads to quicker vapor formation.…”

Section: Dynamic Leidenfrost Effect (T S ≈ T DL )mentioning

confidence: 98%

“…Analogous to our previous study of Leidenfrost phenomena with surfactant droplets, 15 we have attempted to elucidate the effect of all responsible forces of the NB fluid droplets, and we introduced a scaling relationship by combining nondimensional numbers We and Oh through least-squares regression. We illustrated the scaling relationship with experimental data points (T DL ) against the calculated data (fitted value of the scaling relation) (T DL ) in Figure 9.…”

Section: Dynamic Leidenfrost Effect (T S ≈ T DL )mentioning

confidence: 99%

“…They showed that the nondimensional maximum spreading diameter during gentle and spray boiling regimes scales with the Weber number (∼We 0.4 ), which is steeper than the power-law scaling at ambient temperatures (∼We 0.25 ). An enhancement of the Leidenfrost point or temperature (LFT) can be achieved by various methods, viz., the dispersion of polymer additives, 12,13 surfactants, 14,15 or nanoparticles. 16,17 Other avenues of LFT enhancement were achieved by substrate modification using femtosecond laser-based surface processing 18,19 or by the use of an electric field.…”

Section: Introductionmentioning

confidence: 99%

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Augmenting the Leidenfrost Temperature of Droplets via Nanobubble Dispersion

et al. 2022

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Droplets may rebound/levitate when deposited over a hot substrate (beyond a critical temperature) due to the formation of a stable vapor microcushion between the droplet and the substrate. This is known as the Leidenfrost phenomenon. In this article, we experimentally allow droplets to impact the hot surface with a certain velocity, and the temperature at which droplets show the onset of rebound with minimal spraying is known as the dynamic Leidenfrost temperature (T DL ). Here we propose and validate a novel paradigm of augmenting the T DL by employing droplets with stable nanobubbles dispersed in the fluid. In this first-of-itskind report, we show that the T DL can be delayed significantly by the aid of nanobubble-dispersed droplets. We explore the influence of the impact Weber number (We), the Ohnesorge number (Oh), and the role of nanobubble concentration on the T DL . At a fixed impact velocity, the T DL was noted to increase with the increase in nanobubble concentration and decrease with an increase in impact velocity for a particular nanobubble concentration. Finally, we elucidated the overall boiling behaviors of nanobubble-dispersed fluid droplets with the substrate temperature in the range of 150− 400 °C against varied impact We through a detailed phase map. These findings may be useful for further exploration of the use of nanobubble-dispersed fluids in high heat flux and high-temperature-related problems and devices.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Dynamic Leidenfrost Effect (T S ≈ T DL )mentioning

confidence: 98%

Section: Dynamic Leidenfrost Effect (T S ≈ T DL )mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Augmenting the Leidenfrost Temperature of Droplets via Nanobubble Dispersion

et al. 2022

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Dynamics of a Polymer Solution Droplet on a High‐Temperature Surface

Masuda

Wada²,

Okumura

et al. 2023

Chem Eng & Technol

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Droplets on a surface with a sufficiently high temperature, exceeding the boiling point of the fluid, are suitable for chemical reactions because they provide a hightemperature and well-mixed field. The dynamics of a droplet containing a polymer (xanthan gum) on a high-temperature surface was investigated. The boiling pattern was successfully classified based on the Ohnesorge number. The viscosity increase caused by polymer addition suppressed deformation during the spreading process after impact. However, at the highest polymer concentration, the central axis of the droplet was inclined, resulting in droplet rotation during bouncing. Consequently, the bouncing height was decreased by a loss in kinetic energy as the energy was partially converted to rotational energy.

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