An experimental study on the effect of nanoparticle shape on the dynamics of Leidenfrost droplet impingement

Ulahannan, Liju; Krishnakumar, K.; Nair, Anjan R; Ranjith, S. Kumar

doi:10.1007/s42757-019-0053-7

Cited by 21 publications

(2 citation statements)

References 35 publications

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“…Their observations highlighted that, as T s elevates, the droplet's steady-state spreading diameter contracts, while its rebound height increases. Meanwhile, studies by Liu et al 37 and Ulahannan et al 44 show that, for water-suspended silver and Al 2 O 3 nanofluids, the spreading remains unchanged by T s variation within this regime. These different findings suggest that the influence of spreading and impact outcomes on T s variation may be nanofluid-specific, warranting more comprehensive investigation.…”

Section: ■ Introductionmentioning

confidence: 94%

Nanofluid Drop Impact on Heated Surfaces

Ma,

Aldhaleai,

Liu

et al. 2024

Langmuir

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We experimentally elucidate the impact dynamics of ethylene glycol (EG) droplets laden with both hydrophilic and hydrophobic SiO 2 nanoparticles (NPs) onto a flat heated surface in non-boiling, boiling, and Leidenfrost regimes. We use seven nanofluid concentrations (C p ), ranging from 0.89 to 64.3 wt %, and control the surface temperature (T s ) between 100 and 400 °C, while the nanofluid droplet's impact velocity is constant at 0.22 ± 0.02 m/s. Phase diagrams of impact outcomes are established to illustrate the effect of the additive nanoparticles on the droplets' impact dynamics, revealing that nanoparticles modify droplet impact behaviors differently in each regime. In the non-boiling regime, the droplet spreading profile remains unaffected by nanoparticles up to C p < 11.9 wt % before reaching the maximum spreading diameter (β max ). For nanofluid drops with higher nanofluid concentration, the increasing viscosity with concentration is likely to be the primary factor that affects the droplets' spreading profile in the non-boiling regime T s ≲ T sat ≈ 200 °C, as the saturation temperature. In the boiling regime 200 °C < T s ≲ 350 °C, a small amount of nanoparticle addition (C p = 0.89 wt %) promotes atomization regardless of nanoparticle wettability. Finally, manifested in a complete rebound due to an intervening vapor layer, the Leidenfrost temperature (T L ) of the nanofluid droplets is affected by both nanofluid concentration and nanoparticles' wettability. The nanofluid droplets' T L increases with higher nanofluid concentration; moreover, this Leidenfrost temperature increment is more significant for EG droplets laden with hydrophobic nanoparticles. Our results quantitatively reveal the significant influence of nanoparticle concentrations and wettability on drop spreading, impact outcome, and Leidenfrost temperature on heat surfaces, potentially benefiting applications in coating, spraying, and cooling.

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Section: ■ Introductionmentioning

confidence: 94%

Nanofluid Drop Impact on Heated Surfaces

Ma,

Aldhaleai,

Liu

et al. 2024

Langmuir

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“…If water and oil liquid droplets all have high θ SCA > 150° and low θ SA < 10° on the superliquid-repelling surface, then the wettability state of the surface converts to superamphiphobicity and it is defined as a superamphiphobic surface . These appealing features endow the superliquid-repelling surfaces with superbroad applications, such as antifouling and self-cleaning in solar cells, − enhanced molecular transmittance in seawater desalination, facilitated mass transfer in humidity control, , high-efficiency oil/water separation, and drag reduction in fluid flow. − …”

Section: Introductionmentioning

confidence: 99%

Unveiling the Relationship of Surface Roughness on Superliquid-Repelling Properties with Randomly Distributed Rough Surface Structures

Zhi

Wang

Zhang³

et al. 2022

Langmuir

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Though superliquid-repelling surfaces are universally important in the fields of fundamental research and industrial production, the understanding and development of these surfaces to impacting liquid droplets remain elusive, especially the changes of wettability states. Surface roughness is required to obtain superliquid-repelling surfaces. However, the effect of surface roughness on the transition of these surfaces’ wettability states is uncertain. Herein, we unveiled the relationship of surface roughness on regulating the wettability states of superliquid-repelling surfaces with randomly distributed rough structures through experiment and calculations. The roughness was controlled via regulating the size of surface rough structures, which were formed by a facile coating method. The results indicated that the surface rough structures could impact the value of the polar component (γs p) and then impact the wettability states of superliquid-repelling surfaces. Quantitatively, when the increment of surface roughness was low, the decrement of γs p was low and the wettability state of the superliquid-repelling surface was superhydrophobicity. When the increment of surface roughness was high, the decrement of γs p was high and the wettability state of the superliquid-repelling surface converted to superamphiphobicity. The findings will shed light onto the development of superliquid-repelling surfaces in future studies.

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