Article
Thermodynamics
Jiayu Du, Yanzhi Li, Xiong Wang, Xinxin Wu, Qi Min
Summary: Textured surfaces have the potential to inhibit Leidenfrost phenomenon and improve thermal management of high heat flux devices. Different surface structures, such as micro/nanostructures and macro-pillar arrays, have been fabricated and their effects on Leidenfrost point and water droplet dynamics are studied. Micro/nanostructures reduce the vapor pressure and increase the Leidenfrost point, while macrostructures achieve a higher Leidenfrost point through capillary wicking and high permeability. Theoretical models are established to predict Leidenfrost point considering the influence of surface structures.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Chemistry, Multidisciplinary
Chung-Te Huang, Ching-Wen Lo, Ming-Chang Lu
Summary: This study developed a superhydrophobic surface with a double-reentrant groove (DRG) array, which can suppress the Leidenfrost effect and reduce the contact time of droplets impacting a solid surface at high temperatures.
Article
Thermodynamics
Song Yang, Yu Hou, Dongdong Zhou, Xin Zhong
Summary: This study investigates the impact of ethanol concentration on the spreading dynamics of an ethanol-water droplet on a supercooled surface. The findings show that the maximum spreading factor exhibits a non-monotonic behavior with ethanol concentration. This behavior is due to the direct influence of ethanol concentration on liquid viscosity and surface tension, as well as the effect of surface cooling on droplet temperature and liquid properties. The maximum internal spreading factor, which also shows a non-monotonic trend, dominates the maximum spreading. The study also suggests that the difficulty in accurately predicting the temperature-dependent spreading boundary layer thickness of the droplet may contribute to the deviations between predicted and experimental results.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Chemistry, Physical
Xiaonuo Huang, Leping Zhou, Xiaoze Du
Summary: In this study, the molecular dynamics method is used to simulate the dynamic Leidenfrost phenomenon of droplets impacting high-temperature surfaces with different wettability. The results show that a hydrophilic surface favors a lower dynamic Leidenfrost temperature compared to a hydrophobic surface, determined by the atomic potential energy. It is also found that there is a critical contact angle that can trigger the Leidenfrost phenomenon at different surface temperatures.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
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
Song Yang, Yu Hou, Dongdong Zhou, Xiufang Liu, Xin Zhong
Summary: We investigated the impact of liquid properties and surface supercooling on the spreading dynamics of a droplet consisting of binary ethylene-glycol and ethanol. The maximum spreading factor is determined by both surface supercooling and solution concentration. The relationship between maximum spreading factor and surface supercooling depends on the concentration of ethylene-glycol. We proposed a new model for the maximum spreading factor, considering the effect of surface cooling in viscous dissipation, which improves the prediction accuracy for droplet spreading on surfaces with different supercooling degrees.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(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, Mechanical
Jia Luo, Shuang-Ying Wu, Lan Xiao, Zhi-Li Chen
Summary: This study investigated the mechanism and parameters affecting the contact time of droplet impacting on solid surfaces using numerical simulation method and water spring theory. The results showed that increasing Weber number or decreasing cylinder diameter effectively reduced contact time, with surface wettability having the greatest impact on contact time.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Review
Chemistry, Multidisciplinary
Zhifeng Hu, Fuqiang Chu, He Shan, Xiaomin Wu, Zhichao Dong, Ruzhu Wang
Summary: This review comprehensively summarizes the progress on phenomena, mechanisms, regulations, and applications of droplet impact on superhydrophobic surfaces. The focal points are droplet contact and rebound, and various applications are classified according to their requirements. The review also points out the remaining challenges and outlines future research directions.
ADVANCED MATERIALS
(2023)
Review
Chemistry, Physical
Xingjian Yu, Yu Zhang, Run Hu, Xiaobing Luo
Summary: The dynamics of water droplet bouncing is highly dependent on liquid properties, surface characteristics, and ambient pressure. Achieving no droplet/surface contact, which is crucial for droplet bouncing, can be realized through various methods such as lowering the Weber number of droplet, designing hydrophobic surfaces, actively maintaining the air/vapor film, vibrating the liquid bath, and applying electric/magnetic/pressure fields.
Article
Thermodynamics
Edmund Lim, Boon T. Ng, Yew M. Hung, Ming K. Tan
Summary: This study investigates the suppression of the Leidenfrost effect for a droplet rolling on an inclined surface coated with graphene. The graphene coating enables vapor to escape through the nanostructure, obstructing the formation of a continuous vapor layer. The experiment observes three interesting regimes of contact boiling, intermittent contact boiling, and transient contact boiling when the droplet rolls onto the graphene-coated surface. Overall, there is a maximum temperature reduction of 64 degrees C on the heated surface with the graphene coating.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Daehee Kwon, Dongkuk Kang, Eunseop Yeom
Summary: This study reinvestigates the impact and boiling characteristics of metallic surfaces, focusing on the recovery phase of the vapor layer. It finds that the transient impact force and excellent heat transport properties of metallic materials are key factors in the recovery of the vapor layer.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Zhengxuan Xu, Jian Li, Zhaohui Yao, Ji Li
Summary: The study analyzed the evaporation behavior of liquid droplets on superheated surfaces using numerical simulation, examining the effects of wettability and Ja number under different conditions. The evaporation pressure at the bottom of droplets exhibited periodic oscillation, with detailed analysis on the influence of surface properties and Ja number.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Chemistry, Physical
Sanchari Bhattacharjee, Sandip Khan
Summary: Molecular dynamics simulations were conducted to study the wettability of hydrophilic and hydrophobic imidazolium-based ionic liquid nano-droplets on a graphite surface under a perpendicular electric field. The results showed that the electric field significantly influenced the orientation of water dipoles, charge distribution, contact angle, and hydrogen bonds, leading to shape deformation and ion depletion from the liquid-vapor interface of the droplet, which depended on the hydrophilicity or hydrophobicity of the ILs.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Mechanics
Yaolin Tai, Yang Zhao, Xinyu Guo, Linan Li, Shibin Wang, Zhenyan Xia
Summary: The bouncing dynamics of microdroplets with varying viscosities on a superhydrophobic surface were investigated through numerical simulations. It was found that the contact time of the droplets remains constant over a wide Weber number range in the low-viscosity regime, but increases with impact velocity in the high-viscosity regime. New scaling parameters were proposed to describe the viscosity effect and characterize the contact time in different viscosity regimes. The study also revealed that viscous dissipation is significant even for relatively low-viscosity fluids, providing valuable insights for understanding and controlling microdroplet dynamics.
Article
Thermodynamics
Xiaojun Dong, Xue Liu, Bin Ma, Pei Ding, Shaohang Yan, Yanwu Wang, Yu Hou, Tianwei Lai
Summary: This study investigates the frosting characteristics and heat transfer in confined flow channels, and finds that the cooling surface temperature and humidity ratio are the main factors affecting the frost growth rate. The frost growth rate decreases overall, and the frost thickness in the counter flow case is 28.99% larger than that in the parallel flow case.
HEAT AND MASS TRANSFER
(2023)
Article
Chemistry, Physical
Tianwei Lai, Shaohang Yan, Yanwu Wang, Xue Liu, Mingchen Qiang, Wenjing Ding, Yutao Liu, Yu Hou
Summary: In this paper, a novel grooved bearing using liquid hydrogen as lubricant is proposed for reliable operation in high-speed liquid hydrogen centrifugal pump. The static performances of the bearing are evaluated numerically, and the structural parameters are optimized to improve load capacity and suppress cavitation effectively.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Thermodynamics
Yu Yang, Chunchen Sheng, Gaoqiao Luo, Shuangtao Chen, Yu Hou, Liang Chen
Summary: This study evaluates three mean-line methods for the design of high-speed turbo-coolers and establishes a coupling model to predict the off-design performance and system size. The results show that the SS-CR approach has a slightly higher expander efficiency at the design point, but the PR approach performs better at low speeds. In terms of system volume, the SS-CR approach is superior to the other two methods. When the cooling capacity is controlled at 2000 W, the SS-CR approach also has a slightly higher expander efficiency compared to the other two methods.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2023)
Article
Engineering, Mechanical
Qi Zhao, Mingchen Qiang, Shaohang Yan, Xue Liu, Yu Hou, Tianwei Lai
Summary: Gas foil bearing is widely used in high-speed turbomachinery for its high speed, adaptability, and eco-friendly characteristics. In this study, a quasi-2-dimensional mechanical model considering Coulomb friction is proposed to analyze the Coulomb damping dissipation characteristics of the bearing. Different structural parameters have an impact on the frictional performance of the bump foil bearing.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2023)
Article
Thermodynamics
Liang Chen, Jing Fan, Pingtao Zhang, Runfeng Xiao, Yansong Si, Shuangtao Chen, Yu Hou
Summary: This paper investigates a finned tube heat exchanger with dual-side phase change heat transfer to enhance the thermal management of intermittent high-power output electronics. The use of two-phase heat transfer fluid on the tube side significantly increases the heat-charging power and storage effectiveness of LHTES. The study also reveals that the storage effectiveness decreases with the increase of condensation pressure while the mass flow rate of the tube-side fluid has no obvious effect.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Yu Zhang, Pingtao Zhang, Liang Chen, Shuangtao Chen, Yu Hou
Summary: This paper introduces a stacked-plate jet impingement microchannel (SP-JIMC) heat sink with highly-dense micro-fins and numerically investigates its thermal and hydraulic performance using single-phase water as coolant. Comparative analysis with other types of heat sinks demonstrates that the SP-JIMC offers better cooling performance and temperature uniformity. The study also explores the influence of structural parameters on heat transfer characteristics and proposes improvements such as dual-side micro-fins and convex/concave impinged surfaces to further enhance the thermal performance.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Xiaoling Yang, Liang Chen, Zhefeng Wang, Shuangtao Chen, Yu Hou
Summary: Spontaneous condensation process of moist air in a high-speed turbo-expander was investigated experimentally and numerically. A liquid fraction of 0.8% was achieved at the turbo-expander outlet corresponding to a relative humidity of 76.9% at 303.2 K. The nucleation process and droplet distribution in the turbo-expander were studied, and the wetness loss due to condensation mainly occurred in the impeller.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Xiaoling Yang, Liang Chen, Zhefeng Wang, Shuangtao Chen, Yu Hou
Summary: This paper investigates the characteristics of an open-loop air cycle for room temperature applications and studies the effects of the first stage compression ratio and the expander inlet temperature on the refrigerator performance. A system model is established based on numerical simulation and verified by experiments.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2023)
Article
Thermodynamics
Runfeng Xiao, Yicheng Zhang, Liang Chen, Junxin Wang, Shuangtao Chen, Yu Hou
Summary: This paper conducts simulations of supercritical heat transfer of R134a in horizontal tubes to study the effects of circumferential heat conduction on heat transfer deterioration and explain the abnormal phenomena of higher temperature distribution in non-gravity supercritical flow. The results indicate that heat transfer deterioration is caused by impaired specific heat and heat conduction in the boundary layer, and the subsequent heat transfer recovery is due to enhanced thermal conduction and turbulent convection. A dimensionless parameter called the Biot number is defined to characterize the thermal resistance ratio of circumferential conduction to convective heat transfer. The redistribution of wall temperature caused by circumferential conduction affects supercritical convection in horizontal tubes, and non-gravity supercritical flow may have higher wall temperature when the Biot number is small. The deterioration of the top surface can be significantly alleviated by using a tube with larger wall thickness or thermal conductivity.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Song Yang, Yu Hou, Dongdong Zhou, Xin Zhong
Summary: This study investigates the impact of ethanol concentration on the spreading dynamics of an ethanol-water droplet on a supercooled surface. The findings show that the maximum spreading factor exhibits a non-monotonic behavior with ethanol concentration. This behavior is due to the direct influence of ethanol concentration on liquid viscosity and surface tension, as well as the effect of surface cooling on droplet temperature and liquid properties. The maximum internal spreading factor, which also shows a non-monotonic trend, dominates the maximum spreading. The study also suggests that the difficulty in accurately predicting the temperature-dependent spreading boundary layer thickness of the droplet may contribute to the deviations between predicted and experimental results.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Multidisciplinary Sciences
Jin Tao, Geng Li, Qiwei Sun, Youjia Chen, Dawei Xiao, Huicheng Feng
Summary: This paper proposes an approach to automatically identify historic villages from remote sensing images and accurately calculate their geographical coordinates based on deep learning algorithm. The approach is tested in Conghua, a region with fast development that retains many historic villages. Comparison experiments of image classification and object detection models are conducted to determine the most suitable identification algorithm. The results show that the object detection algorithm achieves a higher recognition accuracy of 95.61% compared to the image classification algorithm. By using the Historical-Modern tag as a filter, villages with a certain proportion of historic features can be discriminated. The research identifies 1531 historic villages in Conghua and marks their spatial locations. This study extends the application of deep learning algorithms in remote sensing image targets, promoting the integration of heritage conservation and artificial intelligence research.
SN APPLIED SCIENCES
(2023)
Article
Thermodynamics
Kaimiao Zhou, Liang Chen, Shanfeng Li, Kang Zhao, Ze Zhang, Shuangtao Chen, Yu Hou
Summary: Liquid hydrogen is crucial for large-scale hydrogen energy development, and the Claude cycle is commonly used for hydrogen liquefaction. The hydrogen turbo-expander plays an important role in determining the efficiency and reliability of the system. This study uses mean-line design and loss models to develop a hydrogen turbo-expander, and CFD simulations are used to analyze the flow field and loss mechanisms. The results show that the hydrogen turbo-expander has higher passage efficiency compared to the helium expander due to its lower viscosity and smaller losses.
APPLIED THERMAL ENGINEERING
(2023)
Review
Thermodynamics
Xiaoling Yang, Rong Xue, Ning Wang, Zhilong Huang, Haiyang Zhang, Xiufang Liu, Liang Chen, Yu Hou
Summary: Spray cooling with liquid nitrogen has advantages for achieving cryogenic temperature, and the process can be divided into three stages: cavitating flow, spray breakup, and cooling process. This paper summarizes published literatures on these stages. A brief review shows that the correlation between thermodynamic parameters and spray cooling characteristics is not fully understood. Future research should focus on gaining a deeper insight into heat transfer mechanisms and enhancing the application of cryogenic spray.
Article
Thermodynamics
Yang Meng, Yicheng Zhang, Junxin Wang, Shuangtao Chen, Yu Hou, Liang Chen
Summary: This paper proposes a reverse-bootstrap turboexpander-compressor (TEC) scheme for the direct recovery of expansion work into the cooling capacity of small air-separation plants. A mathematical model is established for the codesign and off-design analysis of TEC, which is validated by experimental data. The use of a reverse-bootstrap compressor in the original turboexpander can increase the isentropic coefficient by 12%. The codesign of the turboexpander and the coaxial compressor can further increase the isentropic coefficient by 7.1% under design condition, resulting in an 8.1% improvement in cooling power and a 1.7% reduction in required heating power. The results demonstrate that the proposed reverse-bootstrap TEC with the codesign method is an effective way for energy recovery in small refrigeration systems.
Review
Computer Science, Cybernetics
Bowen Ji, Xuanqi Wang, Zekai Liang, Haoyang Zhang, Qianchen Xia, Liang Xie, Huijiong Yan, Fanqi Sun, Huicheng Feng, Kai Tao, Qiang Shen, Erwei Yin
Summary: This review compares the advantages and disadvantages of different sensor-based approaches for designing data gloves and demonstrates the superiority of flexible strain sensor-based data gloves in metaverse applications. It also presents some latest commercial data gloves and their function modules based on flexible strain sensors. Additionally, it summarizes the potential applications of gesture recognition in various fields of the metaverse and concludes the existing problems and development prospects of current data gloves based on flexible strain sensors. We are optimistic that novel flexible strain sensor-based data gloves will have a transformative impact on achieving accurate, low-latency, and immersive gesture interaction in the metaverse.
INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION
(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)
