Leidenfrost temperature: Surface thermal diffusivity and effusivity effect

Wu, Rui; Lamini, O.; Zhao, C.Y.

doi:10.1016/j.ijheatmasstransfer.2020.120892

Cited by 15 publications

(3 citation statements)

References 30 publications

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“…In this case, the droplet rises above its vapor cushion, which acts as a thermal insulator. Therefore, the droplet exists on the superheated surface for more than 300 s without instantaneous evaporation, which is well-known as the Leidenfrost effect. , The Leidenfrost temperature above which the droplet begins to levitate and droplet dynamics depend on various factors, for example, the impinging velocity of the droplet to the surface roughness/structure, − material, − and droplet species. ,,− According to Bouillant et al, it was observed that some vortices that are expected to induce mixing occur within the Leidenfrost droplet. In addition, it is considered that the temperature within the droplet is uniform and approximately saturated, owing to excellent mixing.…”

Section: Introductionmentioning

confidence: 99%

Self-Propelled Polymeric Droplet in Leidenfrost State on a Superheated Ratchet Surface

Masuda,

Okumura,

Wada

et al. 2024

Ind. Eng. Chem. Res.

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The use of milli-scale droplets has gained considerable attention in an effort to substantially reduce process size for process intensification. In order to develop a novel droplet reactor, this study investigates self-propelled Leidenfrost droplets on a superheated ratchet surface. In particular, a polymeric droplet (an aqueous solution of xanthan gum) was utilized, aiming at the application of a highly viscous fluid process. The motions of the two types of droplets (distilled water and an aqueous solution of xanthan gum) were observed using a high-speed camera. Based on the recorded movie, the velocity development after dropping was obtained by using an image-processing technique. By fitting the developing velocity to the equation of motion, three important parameters were obtained: the terminal velocity, the driving force, and the friction coefficient. The terminal velocity depended on the boiling pattern, and nucleate boiling accelerated the self-propelled velocity compared to that of film boiling. At relatively low temperatures, the terminal velocity of the polymeric droplets was slightly higher than that of the water droplets. To investigate the effect of polymer addition on droplet dynamics, the driving force and friction coefficient were discussed in more detail. The driving force increased with polymer addition because the higher viscosity suppressed deformation during motion. Consequently, a more stable motion, maintaining a smooth interface of the droplet, was achieved. In addition, the friction coefficient increased with the addition of the polymer. This phenomenon can be attributed to the decrease in vapor file thickness. Therefore, the dynamics of self-propelled droplets were significantly affected by the higher viscosity of the polymeric droplets. Furthermore, one of the most beneficial findings of this study is that even a high-viscosity droplet can be transported on a superheated ratchet. Therefore, in chemical processes involving high-viscosity fluids, self-propelled Leidenfrost droplets can potentially replace microreactors.

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Section: Introductionmentioning

confidence: 99%

Self-Propelled Polymeric Droplet in Leidenfrost State on a Superheated Ratchet Surface

Masuda,

Okumura,

Wada

et al. 2024

Ind. Eng. Chem. Res.

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“…With the increase of the wall temperatures, the fuel droplets are in four different regimes, including film evaporation (T s ≤ T sat , where T s is the surface temperature and T sat is the liquid saturation temperature), nucleate boiling (T sat ≤ T s ≤ T chf , where T chf is the temperature corresponding to the maximum heat flux), transition boiling (T chf ≤ T s ≤ T Leid , where T Leid is the liquid Leidenfrost temperature) and film boiling (T s ≥ T Leid ), respectively. When the droplets hit surfaces with the temperature higher than the Leidenfrost temperature of the droplets, the droplets are levitated upon the vapor layer resulting in a nonwetting state, which deteriorates the heat transfer [35][36][37]. This phenomenon is Leidenfrost phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Dynamic behaviors of fuel droplets impacting on the wall surfaces with different wettability and temperatures

Guo

Chen

Cai

et al. 2022

Applied Thermal Engineering

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“…It has been observed that the Leidenfrost temperature T L of a static liquid drop on a flat surface is affected by several factors, including the properties of the solid surface (thermal properties, surface roughness, surface structure [12][13][14][15]), the ambient condition (pressure and temperature [16,17]), and the properties of the liquid [18], including the contact angle on the substrate [19,20]. Although theoretical models have been developed for T L in terms of film stability [21][22][23][24][25], the common approaches often assume that the substrate is isothermal or of uniform temperature, which is at odds with the finding that surfaces can be cooled by the floating Leidenfrost drop, as quantitatively shown in Ref.…”

mentioning

confidence: 99%

How roughness and thermal properties of a solid substrate determine the Leidenfrost temperature: Experiments and a model

et al. 2023

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In this Letter, we systematically investigate the Leidenfrost temperature for hot solid substrates with various thermal diffusivities and surface roughnesses. Based on the experimental results, we build a phenomenological model that considers the thermal diffusivity of a solid substrate and derive a relationship between the surface roughness and the resulting vapor film thickness. The generality of this model is supported by experimental data for different liquids and solid substrates. Our model thus allows for a theoretical prediction of the Leidenfrost temperature and develops a comprehensive understanding of the Leidenfrost effect.

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Leidenfrost temperature: Surface thermal diffusivity and effusivity effect

Cited by 15 publications

References 30 publications

Self-Propelled Polymeric Droplet in Leidenfrost State on a Superheated Ratchet Surface

Self-Propelled Polymeric Droplet in Leidenfrost State on a Superheated Ratchet Surface

Dynamic behaviors of fuel droplets impacting on the wall surfaces with different wettability and temperatures

How roughness and thermal properties of a solid substrate determine the Leidenfrost temperature: Experiments and a model

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