Article
Thermodynamics
Eric D. Lee, Daniel Maynes, Julie Crockett, Brian D. Iverson
Summary: This paper presents an experimental study on drop impingement and thermal atomization on hydrophobic and superhydrophobic surfaces. The results show that superhydrophobic surfaces can completely suppress atomization and the maximum atomization temperature as well as the time of maximum atomization are both related to the parameters of the superhydrophobic surfaces.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
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)
Review
Thermodynamics
V. S. Devahdhanush, Issam Mudawar
Summary: Jet impingement boiling is a thermal management technique with critical heat flux (CHF) as an important safety parameter. This article provides a systematic review of studies in the field of jet impingement CHF, including experimental jet CHF studies, parametric effects, and techniques for increasing CHF.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Mechanics
Deekshith P. Naidu, Susmita Dash
Summary: The impact dynamics of compound droplets with an encapsulated air bubble on a solid substrate is investigated. The volume of the counterjet formed is dependent on the volume of air and liquid in the droplet, and independent of the liquid viscosity and impact velocity. The spreading characteristics of the compound droplet do not significantly vary compared to a pure droplet with the same liquid volume. A model is proposed to predict the maximum spread during the impact of a hollow droplet based on energy interaction.
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
Chemistry, Physical
Zhiping Yuan, Sihang Gao, ZhiFeng Hu, Liyu Dai, Huimin Hou, Fuqiang Chu, Xiaomin Wu
Summary: The study proposed enhanced jumping methods for droplets on superhydrophobic surfaces, which achieved a nearly theoretical limit of energy transfer efficiency through more orderly flow inside the droplets enabled by a designed structure. The ultimate jumping improved the application of water droplet jumping and enabled other low surface energy fluids to jump.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2021)
Article
Thermodynamics
Haoyu Ding, Jin Zhao, Zhenyu Zhang, Kai Xu, Luxin Fu, Xu He
Summary: The factors influencing the formation of impinged spray are analyzed using computational fluid dynamics (CFD) modeling. Free spray and impinging sprays with three impinging distances are simulated using the Eulerian-Lagrangian multiphase method. The results are validated with experimental data. The impact of air flow, generated by gas entrainment of spray, also influences the spray.
Article
Thermodynamics
M. J. Gibbons, A. Garivalis, S. O'Shaughnessy, P. Di Marco, A. J. Robinson
Summary: This study investigates the effects of electric fields on evaporating water droplets on a heated substrate, revealing that the electric fields influence the shape, mechanics, and heat transfer of the droplets. The results suggest that the electric fields exert different forces on droplets with different wetting states, leading to variations in droplet shape and behavior.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Mechanics
Gaurav Upadhyay, Vedant Kumar, Rajneesh Bhardwaj
Summary: Studying the impact dynamics of a water droplet on a superhydrophobic flexible substrate reveals energy conversion and rebound phenomena during impact. By altering the characteristic timescales of the droplet and cantilever beams, the overall system dynamics are influenced.
Article
Mechanics
Kai Sun, Lingyun Shu, Feifei Jia, Zhe Li, Tianyou Wang
Summary: Vibration on superhydrophobic surfaces is an effective method for removing droplets. This study experimentally investigated the dynamics of droplets on vibrating superhydrophobic surfaces and established a theoretical model to explain the physics behind droplet detachment caused by vibration. It was found that different droplet oscillation patterns exist and the critical condition for droplet detachment depends on the droplet energy compared to the surface adhesion energy. The study also revealed the impact of vibration frequency and amplitude on droplet detachment time.
Article
Thermodynamics
Navid Saneie, Varun Kulkarni, Bruce Treska, Kamel Fezzaa, Neelesh Patankar, Sushant Anand
Summary: Investigated microbubble dynamics inside water droplets boiling on superhydrophilic textured substrates using high-speed X-ray phase contrast imaging (XRPCI), revealing that bubble density variations are similar regardless of texture spacing at a given surface temperature. Analyzed heat flux removed by single bubble and all bubbles at a given time for the first time, showing highest dissipation through latent-heat component occurs at the beginning and decreases thereafter. Findings and analysis are expected to guide further research on engineering more efficient boiling heat transfer surfaces.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Mechanics
K. Tang, T. A. A. Adcock, W. Mostert
Summary: In this study, we conducted novel numerical simulations to investigate the process of bag breakup in liquid droplets. We examined the early-time drop deformation and the late-time formation of a bag film in comparison with theory and experiment. By adopting the manifold death (MD) algorithm, we achieved grid convergence of fragment statistics and analyzed the mechanisms of bag film disintegration. Furthermore, we investigated the effects of liquid Ohnesorge number on the bag breakup process and found a non-monotonic relationship between the average diameter of bag film fragments and Oh.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Chemistry, Multidisciplinary
S. Nootchanat, S. Boonmeewiriya, A. Parnsubsakul, N. Insin, S. Ekgasit, K. Wongravee
Summary: A simple, efficient, and economical method was presented to prepare superhydrophobic gold film embedded on PDMS sheets without surface pretreatment. Systematic investigations revealed that the generated gold film contains uniform spherical gold particles with complex hierarchical structures, which play a crucial role in the superhydrophobic property. The durability of the fabricated gold film was demonstrated by various tests, showing no disorientation in the main structures and their superhydrophobic properties.
MATERIALS TODAY CHEMISTRY
(2021)
Article
Engineering, Chemical
Shiva Moradi Mehr, Mohammad A. Charsooghi, Luca Businaro, Mehdi Habibi, Ali-Reza Moradi
Summary: This article presents the liquid version of the famous two-balloon experiment using superhydrophobic substrates. The experiment investigates different droplet sizes, substrates of different hydrophobicities, and various channel pathways to measure morphometric parameters of the droplets. The results show that pumping occurs from the smaller droplet to the larger one on superhydrophobic substrates, while the curvature radius indicates the direction of pumping when one or both of the droplets are positioned on a normal substrate.
Article
Mechanics
K. Hasegawa, Y. Manzaki
Summary: The paper investigates the spreading and atomization dynamics of an aqueous 2-propanol solution on sunflower oil, demonstrating firework-like behavior caused by the Marangoni effect. It also discusses the Marangoni flow driven by temperature gradient, liquid droplet count and size distribution, as well as fingering instability and comparison with capillary model of the interface between the IPA solution and sunflower oil.
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)