Article
Physics, Applied
Yukai Lin, Fuqiang Chu, Qiang Ma, Xiaomin Wu
Summary: This study focuses on boiling regimes below the Leidenfrost point and discovers a gyroscopic rotation phenomenon of boiling droplets on various surfaces, attributed to the viscous stress from vapor/bubble flows in surface microstructures. The rougher surface structures and larger solid-liquid contact area are more likely to generate gyroscopic rotations. The theoretical model confirms the effect of substrate temperature (boiling regime) on the spinning rate of boiling droplets and further validates the proposed mechanism of gyroscopic rotation.
APPLIED PHYSICS LETTERS
(2021)
Article
Thermodynamics
Gudlavalleti V. V. S. Vara Prasad, Purbarun Dhar, Devranjan Samanta
Summary: In this article, a novel method of increasing the dynamic Leidenfrost temperature (T-DL) by adding surfactants to water droplets was proposed and experimentally studied. The effects of Weber number (We), Ohnesorge number (Oh), and surfactant concentration on T-DL were examined, and a scaling relationship was proposed. The findings have significant implications for thermal management systems operating at high temperatures.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Review
Thermodynamics
Chang Cai, Issam Mudawar
Summary: This article provides a systematic overview of the droplet impact on a high-temperature solid surface in the film boiling regime. It discusses the parameters influencing the dynamic Leidenfrost point temperature and reviews the prior theoretical models. The article emphasizes the need for further experimental investigations and the development of an accurate theoretical and experimentally-validated model.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Multidisciplinary Sciences
Gustav Graeber, Kartik Regulagadda, Pascal Hodel, Christian Kuettel, Dominic Landolf, Thomas M. Schutzius, Dimos Poulikakos
Summary: When a liquid droplet is dispensed onto a hot surface, it hovers on a cushion of self-generated vapor due to the Leidenfrost effect discovered in 1756. This study reports a self-propulsion mechanism of Leidenfrost droplets, where they start bouncing from a resting altitude to increasing heights against gravity, violating traditional equilibrium. The continuously draining vapor cushion induces ripples on the droplet bottom surface, leading to self-sustained periodic vertical bouncing known as Leidenfrost trampolining.
NATURE COMMUNICATIONS
(2021)
Article
Thermodynamics
Bin Li, Abbasali Abouei Mehrizi, Shiji Lin, Sangwoo Joo, Longquan Chen
Summary: The impact dynamics of viscoelastic droplets on a superhydrophobic surface beyond the boiling temperature was studied, with findings suggesting that surface temperature and polymer concentration have varying effects on droplet behavior. Additionally, temperature increase or polymer concentration decrease can accelerate droplet retraction speed.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Chemical
Ze Zhou, Fuwu Yan, Gengxin Zhang, Dawei Wu, Hongming Xu
Summary: This study investigates the collision behavior of a hydrous ethanol droplet on a heated glass surface using high-speed imaging. The addition of volatile ethanol shifts the collision behavior toward explosive boiling and the Leidenfrost phenomenon. The dimensionless droplet diameter and height are mainly influenced by surface tension.
Article
Thermodynamics
Chang Cai, Hong Liu, Han Chen, Chao Si
Summary: In this study, the impact of alcohol additives on water droplets on a smooth red copper surface was experimentally investigated. The results showed that alcohol additives can enhance droplet atomization and breakup, as well as increase the dynamic Leidenfrost point temperature. It was observed that the dynamic Leidenfrost point temperature of alcohol-added water droplets at lower impact velocities was higher than that of pure water at higher impact velocities, indicating that alcohol additives can compensate for the decrease in the dynamic Leidenfrost point temperature caused by smaller impact momentum. A new triggering mechanism of the dynamic Leidenfrost effect was proposed, taking into account the surface roughness effect. An approximation model based on the pressure balance criterion was developed to explain the underlying physics of the alcohol-induced elevation in the dynamic Leidenfrost point temperature. The findings of this study provide an effective method for improving heat transfer by regulating the thermophysical properties of droplets with alcohol additives.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Nanoscience & Nanotechnology
Jiayu Du, Yanzhi Li, Xiong Wang, Qi Min
Summary: The Leidenfrost effect is detrimental to heat dissipation in high-temperature industrial applications. Single-scale structures cannot effectively inhibit this effect, but we have developed a high-temperature treatment method to fabricate superhydrophilic nickel foams that elevate the Leidenfrost point and demonstrate ultrafast droplet permeation. Theoretical analysis reveals that the superior features of these foams promote capillary wicking and vapor evacuation, resulting in significantly higher heat flux compared to solid nickel surfaces.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Physics, Multidisciplinary
Cao Chun-Lei, Xu Jin-Liang, Ye Wen-Li
Summary: Leidenfrost droplets, when placed on a surface with a temperature higher than the Leidenfrost temperature, exhibit amazing mobility due to being levitated on their own vapor cushions. Through constructing asymmetrical micro/nano textured surfaces, droplets can achieve self-propulsion by correcting vapor flow underneath them. However, the control of droplet dynamics is uncertain due to complex interactions among liquid-vapor-solid phases. In this experiment, periodic explosive boiling generates thrust force that propels droplets, with factors like radiative heat flux and nucleation sites playing crucial roles in droplet levitation.
ACTA PHYSICA SINICA
(2021)
Article
Physics, Multidisciplinary
Wang Hao, Xu Jin-Liang
Summary: This study investigates the Leidenfrost evaporation of two identical FC-72 droplets on a hot oil surface, revealing that neighboring droplets undergo three stages of evaporation: non-coalescing, bouncing, and separating. The asymmetrical temperature field on the droplet surface breaks the balance of forces acting on the droplets. Furthermore, a dual-droplet evaporation model considers four forces and demonstrates that the Marangoni force and gravity component play a dominant role in the dynamics.
ACTA PHYSICA SINICA
(2023)
Article
Thermodynamics
Konghua Yang, Kaidiao Jin, Jiawei Xiong, Yuchao Luo, Yunhong Liang, Chunbao Liu
Summary: This study developed a novel 3D method to address the Leidenfrost effect by studying the synergies of droplet velocity and surface temperature. A computational fluid dynamics simulation and high-speed video testing were conducted to investigate the dynamics of vapor and heat transfer near the Leidenfrost point. The empirical correlation between the Leidenfrost point temperature and Weber number was determined.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Engineering, Aerospace
Zhiwei Ma, Zhijun Wei, Ying Feng, Chao Wang, Wei Dong, Ningfei Wang, Baolu Shi
Summary: This study simulated the collision and deposition behaviors of aluminum/alumina droplets on a solid wall in a high temperature oxy-methane flame environment to improve the engine performance of a solid rocket motor. The results showed that the post-collision behaviors were determined by collision velocity, angle and particle size, with heat transfer playing an important role in the deposition process. A dimensionless parameter and an empirical formula were proposed to quantify the deposition rate.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Energy & Fuels
Prashant Agrawal, Gary G. Wells, Rodrigo Ledesma-Aguilar, Glen McHale, Khellil Sefiane
Summary: The article discusses a thin-film boiling engine where power output can be controlled by manipulating the position of the rotor over the substrate in a heated state. This new approach offers potential for applications in virtually frictionless engines in extreme environments, particularly at microscales or for space and planetary exploration, with propulsion outputs almost 4 times higher than traditional methods.
Article
Mechanics
Lei Wang, Shi Shangguan, Miao Qu, Yifan Ni, Yuan Ma, Yanzhong Li
Summary: In a cryogenic chilldown process, film boiling is crucial and Leidenfrost temperature (TL) represents the termination of film boiling. A study evaluating predictive models on TL and discussing the impact of chilldown acceleration approaches on TL variation revealed discrepancies in test data and the potential of TL as an indicator for acceleration assessment. Different pipe materials and structures, such as low-conductivity coating and micro-fin pipes, have unique advantages in chilldown acceleration but contribute differently to thermal energy removal.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Thermodynamics
Junhui Li, Patricia Weisensee
Summary: This study experimentally investigates the fluid breakup and Leidenfrost dynamics for droplets impacting a heated millimetric post. The findings show that the post substrate leads to a shorter droplet lifetime, a higher Leidenfrost temperature, and enhanced cooling capacity compared to a flat substrate.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyang Xu, Fangjun Hong, Chaoyang Zhang
Summary: This study introduces a self-induced jet impingement device for enhancing pool boiling performance in high power electronic cooling. Through visualization and parametric investigations, the effects of this device on pool boiling performance are studied, revealing the promotion of additional liquid supply and vapor exhausting. The flow rate of the liquid jet is found to positively impact boiling performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Wenchao Ke, Yuan Liu, Fissha Biruke Teshome, Zhi Zeng
Summary: Underwater wet laser welding (UWLW) is a promising and labor-saving repair technique. A thermal multi-phase flow model was developed to study the heat transfer, fluid dynamics, and phase transitions during UWLW. The results show that UWLW creates a water keyhole, making the welding environment similar to in air laser welding.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Xingrong Lian, Lin Tian, Zengyao Li, Xinpeng Zhao
Summary: This study investigates the heat transfer mechanisms in natural fiber-derived porous structures and finds that thermal radiation has a significant impact on the thermal conductivity in low-density regions, while natural convection rarely occurs. Insulation materials derived from micron-sized natural fibers can achieve minimum thermal conductivity at specific densities. Strategies to lower the thermal conductivity include increasing porosity and incorporating nanoscale pores using nanosize fibers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Yasir A. Malik, Kilian Koebschall, Stephan Bansmer, Cameron Tropea, Jeanette Hussong, Philippe Villedieu
Summary: Ice crystal icing is a significant hazard in aviation, and accurate modeling of sticking efficiency is essential. In this study, icing wind tunnel experiments were conducted to quantify the volumetric liquid water fraction, sticking efficiency, and maximum thickness of ice layers. Two measurement techniques, calorimetry and capacitive measurements, were used to measure the liquid water content and distribution in the ice layers. The experiments showed that increasing wet bulb temperatures and substrate heat flux significantly increased sticking efficiency and maximum ice layer thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Dan-Dan Su, Xiao-Bin Li, Hong-Na Zhang, Feng-Chen Li
Summary: The boiling heat transfer of low-boiling-point working fluid is a common heat dissipation technology in electronic equipment cooling. This study analyzed the interfacial boiling behavior of R134a under different conditions and found that factors such as the initial thickness of the liquid film, solid-liquid interaction force, and initial temperature significantly affect the boiling mode and thermal resistance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyi Wu, Dongke Sun, Wei Chen, Zhenhua Chai
Summary: A unified lattice Boltzmann-phase field scheme is proposed to simulate dendrite growth of binary alloys in the presence of melt convection. The effects of various factors on the growth are investigated numerically, and the model is validated through comparisons and examinations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shaokun Ge, Ya Ni, Fubao Zhou, Wangzhaonan Shen, Jia Li, Fengqi Guo, Bobo Shi
Summary: This study investigated the temperature distribution of main cables in a suspension bridge during fire scenarios and proposed a prediction model for the maximum temperature of cables in different lane fires. The results showed that vehicle fires in the emergency lane posed a greater thermal threat to the cables.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shuang-Ying Wu, Shi-Yao Zhou, Lan Xiao, Jia Luo
Summary: This paper investigates the two-phase flow and heat transfer characteristics of low-velocity jet impacting on a cylindrical surface. The study reveals that the heat transfer regimes are non-phase transition and nucleate boiling with the increase of heat transfer rate. The effects of jet impact height and outlet velocity on local surface temperatures are pronounced at the non-phase transition stage. The growth rates of heat transfer rate and liquid loss rate increase significantly from the non-phase transition to nucleate boiling stage.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Feriel Yahiat, Pascale Bouvier, Antoine Beauvillier, Serge Russeil, Christophe Andre, Daniel Bougeard
Summary: This study explores the enhancement of mixing performance in laminar flow equipment by investigating the generation of chaotic advection using wall deformations in annular geometries. The findings demonstrate that the combined geometry can achieve perfect mixing at various Reynolds numbers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Liangyuan Cheng, Qingyang Wang, Jinliang Xu
Summary: In this study, we investigated the supercritical heat transfer of CO2 in a horizontal tube with a diameter of 10.0 mm, covering a wide range of pressures, mass fluxes, and heat fluxes. The study revealed a non-monotonic increase in wall temperatures along the flow direction and observed both positive and negative wall temperature differences between the bottom and top tube. The findings were explained by the thermal conduction in the solid wall interacting with the stratified-wavy flow in the tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)