Article
Engineering, Manufacturing
Yu Liu, ZuMing Liu
Summary: Keyhole behavior and weld pool thermal state have a significant impact on the stability of the plasma arc welding process. This research proposes a new method to evaluate the weld pool thermal state by analyzing the front side reflected plasma angle. Experimental results show that the reflected plasma angle is related to the weld pool thermal state.
JOURNAL OF MANUFACTURING PROCESSES
(2022)
Article
Engineering, Industrial
Weilu Zhou, Chuanbao Jia, Fangzheng Zhou, Chuansong Wu
Summary: This paper investigates the keyhole and weld pool behavior in the initial stage of keyhole plasma arc welding (K-PAW) of medium-thick plates. A special visual sensing structure is used to obtain images of the keyhole and weld pool, allowing direct observation of their growth and flow under different welding conditions. The study quantitatively analyzes the trends of keyhole dimensions and classifies the characteristics of weld pool flow. Additionally, the molten metal flow cycle and cloud cluster are observed using a new visual sensing method. The findings provide a more intuitive way to study K-PAW and offer important guidance for the first normal penetration in medium-thickness plate K-PAW processes.
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
(2023)
Article
Chemistry, Physical
Junnan Qiao, Chuansong Wu, Yongfeng Li
Summary: The study investigates the impact of acoustic radiation force on the plasma arc welding process, showing that it enhances plasma arc pressure and gas shear stress, leading to an improved keyholing capability. Numerical simulations and experimental validation confirm the findings, highlighting the importance of acoustic radiation force in ultrasonic-assisted plasma arc welding.
Article
Thermodynamics
Youmin Rong, Lu Wang, Ruolin Wu, Jiajun Xu
Summary: Laser butt welding experiments were conducted to observe the keyhole and weld pool with high speed imaging. The characteristics of the keyhole and weld pool geometries were extracted by image processing, showing that increased welding speed led to decreased keyhole diameter and weld pool widths. A double cylindrical heat source model considering keyhole angle and diameter was derived to predict weld size with good simulation accuracy. The thermal analysis based on this model had higher accuracy when validating with time-averaged results.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Engineering, Manufacturing
Yongfeng Li, Shuoshuo Tian, ChuanSong Wu, Manabu Tanaka
Summary: Comparative experiments were conducted to investigate the effects of ultrasonic vibration on the flow of molten metal, weld pool size, and keyhole size in plasma arc welding. It was found that ultrasonic vibration changed the shape of the keyhole, reduced the size of the molten pool and keyhole entrance, and enhanced the penetration capability of the keyhole.
JOURNAL OF MANUFACTURING PROCESSES
(2021)
Article
Optics
Hao Cheng, Li Kang, Jincheng Pang, Boce Xue, Dong Du, Baohua Chang
Summary: High heat input parameters significantly impact the quality of laser-welded joints at different welding positions, leading to poor mechanical properties. Conversely, low heat input parameters result in less influence of welding position on the quality of laser-welded joints.
OPTICS AND LASER TECHNOLOGY
(2021)
Article
Automation & Control Systems
Zhenmin Wang, Haoyu Chen, Qiming Zhong, Sanbao Lin, Jianwen Wu, Mengjia Xu, Qin Zhang
Summary: The study introduces a data-driven deep learning approach based on ViT for welding penetration recognition, achieving high accuracy through the construction of a large dataset and training of various ViT models. By applying the attention rollout method for visualization of regions of interest, the reliability and effectiveness of the approach are confirmed.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2022)
Article
Automation & Control Systems
Jorge Andres Giron-Cruz, Jesus Emilio Pinto-Lopera, Sadek C. A. Alfaro
Summary: Gas metal arc welding (GMAW) is an important industrial process, and there have been efforts to convert it into a stable process with minimal human interference. However, achieving automated control similar to a human expert is still challenging. This research introduces two intelligent systems for real-time control of weld bead geometry in the GMAW process.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2022)
Article
Engineering, Manufacturing
Yan-Xin Cui, Yong-Hua Shi, Qiang Ning, Yun-Ke Chen, Bao-Ri Zhang
Summary: By developing a vision system and using image processing algorithms, the dynamic behavior of the keyhole-weld pool profiles can be captured and analyzed in real-time welding process. It was found that the keyhole length was dynamically adjusted internally while maintaining a quasi-steady state during welding. The proposed method provides a solid foundation for studying welding processes and improving keyhole tungsten inert gas welding.
ADVANCES IN MANUFACTURING
(2021)
Article
Engineering, Manufacturing
Zishun Wang, Yonghua Shi, Xiaobin Hong, Baori Zhang, Xiyin Chen, Aiwen Zhan
Summary: The change of gap width is crucial in K-TIG welding, and maintaining consistent gap width is challenging. An HDR system was designed for weld pool monitoring, and the behavior of weld pool under different gap changes was analyzed, recommending avoidance of welding from a large gap to a narrow one.
JOURNAL OF MANUFACTURING PROCESSES
(2022)
Article
Chemistry, Multidisciplinary
Haohao Jing, Xin Ye, Xiaoqi Hou, Xiaoyan Qian, Peilei Zhang, Zhishui Yu, Di Wu, Kuijun Fu
Summary: This study investigates the weld penetration variation in laser-MIG hybrid welding under a sensitive laser power range. Experimental welding and CFD simulation were conducted to analyze the factors affecting weld formation. The results show that a laser power of 7.5 kW yields better weld-forming effects within the sensitive laser power range.
APPLIED SCIENCES-BASEL
(2022)
Article
Chemistry, Physical
Wei Cheng, Xinqiang Ma, Junlin Zhang, Zhaoyang Yan, Fan Jiang, Shujun Chen
Summary: Mathematical statistics were used to study the stability of weld pool and the elimination of weld defects in aluminum alloy plasma arc keyhole welding. Results showed that adjusting mass transfer position once achieved optimal results for weld joints, enabling the weld pool to resist disturbances and meet mechanical requirements.
Article
Materials Science, Multidisciplinary
Sindo Kou
Summary: The study demonstrated that a specific index can serve as a crack-susceptibility indicator for straight columnar dendritic grains growing side by side, whether using an elliptical weld pool or a teardrop-shaped pool in welding processes.
SCIENCE AND TECHNOLOGY OF WELDING AND JOINING
(2021)
Article
Engineering, Manufacturing
Xumin Guo, Zuming Liu, Xingchuan Zhao, Wenbin Zhang
Summary: Controlling heat output and force in the arc source is crucial for improving keyhole stability in welding. This study developed a double-layer hybrid arc torch by adding two outer tungsten electrodes symmetrically. The results showed that the hybrid arc with two free arcs had symmetrical arc pressure. The additional heat input from the free arcs could be transferred into the keyhole bottom, requiring less constraint arc current to form a stable fully penetrated keyhole.
JOURNAL OF MANUFACTURING PROCESSES
(2023)
Article
Materials Science, Multidisciplinary
Jingbo Liu, Fan Jiang, Shujun Chen, Bin Xu, Guokai Zhang
Summary: The keyhole welding process in Variable Polarity Plasma Arc Welding significantly improves weld quality, but introduces pool instability. Investigating molten metal flow within keyholes reveals convergence and separation points, which induce weld pool instability. Increases in keyhole area and reduction in pinch angle reflect pool instability. These findings provide a theoretical basis for weld control and advance vision-based intelligent manufacturing welding techniques.
SCIENCE AND TECHNOLOGY OF WELDING AND JOINING
(2023)
Article
Materials Science, Multidisciplinary
Guanlan Zhang, ChuanSong Wu, Jinqiang Gao
Summary: This study conducted numerical simulations and experimental validation on the ultrasonic vibration-assisted friction stir welding (UVaFSW) process by considering the synchronous interaction mechanism between ultrasonic vibration, tool, and thermo-mechanical behavior. The results showed that the use of a line source of ultrasonic energy improved the computation accuracy and reduced the interfacial friction coefficient.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Review
Automation & Control Systems
Sachin Kumar, Vidit Gaur, ChuanSong Wu
Summary: This article introduces the application and adaptability of machine learning in modern welding systems, and discusses the importance of machine learning in improving welding quality and reducing costs.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2022)
Article
Metallurgy & Metallurgical Engineering
Maoju Tan, ChuanSong Wu, Hao Su
Summary: Friction stir welding (FSW) and ultrasonic vibration-assisted FSW (UVaFSW) experiments were conducted on AA2024 aluminum alloy and AZ31B magnesium alloy plates to investigate the effects of ultrasonic vibration on the microstructures and mechanical properties of dissimilar joints. The results showed that ultrasonic vibration enhanced the mechanical interlocking degree and reduced the thickness of intermetallic compounds in the weld nugget zone (WNZ), leading to an improved joint tensile strength. The acoustic softening effect of ultrasonic vibration played a more important role than its thermal effect. This research lays a foundation for process optimization and joint quality control in the welding of dissimilar AA2024 and AZ31B alloys, which have great application prospects in aerospace industries.
WELDING IN THE WORLD
(2023)
Article
Chemistry, Physical
Maoju Tan, ChuanSong Wu, Lei Shi
Summary: The hybrid structures of AA2024 aluminum alloy and AZ31B magnesium alloy have great potential in the aerospace industry due to their lightweight and high specific strength. However, achieving high-quality welding between these dissimilar alloys is a key challenge. In this study, friction stir welding (FSW) tests were conducted on AA2024 aluminum alloy and AZ31B magnesium alloy plates. The intermetallic compounds (IMCs) formed at the bonding interface were analyzed using various techniques. It was found that the IMCs in the dissimilar AA2024/AZ31B FSW weld had a double-layer structure and larger thickness.
Article
Materials Science, Multidisciplinary
Qi Wang, Guochao Gu, Chuanbao Jia, Kan Li, Chuansong Wu
Summary: Keyhole plasma arc welding (PAW) is used to join super duplex stainless steel (SDSS) and achieves full-penetration joints of medium-thickness plates in a single pass. However, the key-holing processes in PAW result in different thermal cycles and microstructures, with substantial differences in the content of austenite and the presence of oxide inclusions. The microstructure in the heat-affected zone (HAZ) is complex, with ferrite and diverse forms of austenite, including grain boundary austenite, intragrain austenite, and Widmansta euro tten austenites. Corrosion resistance is significantly affected by the presence of secondary austenite and chromium nitride in the HAZ.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Multidisciplinary
Ming Zhai, ChuanSong Wu, Lei Shi, GaoQiang Chen, QingYu Shi
Summary: Understanding the effect of ultrasonic vibration on process variables is of great significance for optimizing the ultrasonic vibration enhanced friction stir lap welding (UVeFSLW) process of dissimilar Mg/Al alloys. In this study, the dislocation strain energy in both grain interior and grain boundary is taken into consideration to improve the formula for determining threshold thermal stress, and the modified constitutive equation is used to develop a model for the Mg/Al UVeFSLW process. The quantitative analysis reveals that ultrasonic vibration reduces the flow stress, decreases interfacial heat generation and viscous dissipation heat generation, resulting in lower interface temperature, intensified material flow, and larger material intermixed region in Mg/Al UVeFSLW.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Engineering, Manufacturing
Yuwen Wang, Ji Chen, Xiangyang Wu, Maoai Chen, Hao Su, Lin Wang, Chuansong Wu
Summary: This study employed an external compound magnetic field to enhance the efficiency and forming accuracy of the DED process. The results showed significant improvements in deposition rate, surface roughness, and grain size, leading to high forming accuracy and acceptable mechanical properties. This novel method allows for high deposition rate in the DED process with good formability and performance.
ADDITIVE MANUFACTURING
(2023)
Article
Engineering, Manufacturing
Najib Ahmad Muhammad, Peihao Geng, ChuanSong Wu, Ninshu Ma
Summary: An in-depth study was conducted on the residual stress in dissimilar ultrasonic vibration-assisted friction stir welding (UVaFSW) of aluminium (Al)/magnesium (Mg) alloys. The use of ultrasonic vibration resulted in predominantly compressive stress in the UVaFSW welds, improving the mechanical properties. The ultrasonic effect reduced the thickness of intermetallic compounds (IMCs), resulting in more homogeneous hardness distributions. Additionally, it mitigated residual tensile stresses and distortion, thus showing potential for co-optimizing residual stress and microstructure in dissimilar Al/Mg welds.
INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE
(2023)
Article
Engineering, Mechanical
Lei Shi, Jie Chen, Chunliang Yang, Gaoqiang Chen, Chuansong Wu
Summary: In this study, a novel integrated thermal-fluid-structure coupling model of the friction stir welding process was proposed to study the non-uniform distribution model of the tool-workpiece contact pressure and the void defect formation mechanism. The tool service life was also predicted. This research provides important theoretical guidance for optimizing welding parameters.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Materials Science, Multidisciplinary
Junjie Zhao, ChuanSong Wu, Lei Shi, Hao Su
Summary: A complete understanding of the evolution behaviors of microstructures and intermetallic compounds (IMCs) in friction stir welding (FSW) of dissimilar Al to Mg alloys is crucial. This study conducted conventional FSW and ultrasonic vibration enhanced FSW (UVeFSW) experiments on Al/Mg alloys. The results showed that ultrasonic vibration could suppress the growth of IMCs and lead to a thinner IMC thickness in UVeFSW.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)
Article
Mechanics
Yan Li, Ze Yun, Xiang Zhou, Chuansong Wu
Summary: The keyhole arc welding technique improves welding efficiency by utilizing a stable keyhole mode. Understanding the keyhole effect is crucial for enhancing welding quality. A three-tier sandwiched model based on multiphysics and multiphase effects was developed to demonstrate open keyhole mode welding. The model fully includes multiphysics phenomena and calculates gas-liquid-solid interactions using the Volume of Fluid technique and the Enthalpy-porous technique.
Article
Materials Science, Multidisciplinary
Yichen Xiao, Yang Li, Lei Shi, Chuansong Wu, Huijie Liu, Zhen Sun
Summary: Friction stir additive manufacturing (FSAM) is a novel solid-phase additive manufacturing method. A finite element model (FEM) of FSAM was proposed to quantitatively study the thermal processes and mechanical properties of FSAM components. The results show that the volume of the additive zone in FSAM increases with the tool rotation speed and decreases with the transverse speed. The height and width of the hook structure decrease with the transverse speed. The tensile strength of FSAM components initially increases with the transverse speed and reaches its maximum at 90 mm/min, then decreases. The maximum value of the thermal cycle decreases with the transverse speed, while the high-temperature residence time increases with the decrease in transverse speed.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Xue Wang, Yichen Xiao, Lei Shi, Ming Zhai, Chuansong Wu, Gaoqiang Chen
Summary: Experiments have confirmed that tool tilting in friction stir welding (FSW) can effectively prevent void defects. However, the mechanism of this suppressive effect is still unknown. In this study, a CFD model that considers tool tilting is established, and a non-uniform distribution of normal pressure is proposed to explain the relationship between tool tilt angle and tool-workpiece contact interfaces. The results show that tool tilting leads to higher heat flux and temperature near the pin side in the middle and low parts of the workpiece, which helps to heal voids on the advancing side of the FSW joints. The model is validated by experimental results.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Multidisciplinary
Guanlan Zhang, Jinqiang Gao, Chuansong Wu
Summary: This paper investigates the numerical prediction and understanding of ultrasonic vibration-assisted friction stir welding (UVaFSW) of dissimilar Al/Mg alloys. By redefining the calculation method of acoustic stress work and developing a modified acoustic-plastic constitutive equation, the quantitative analysis of the acoustic effects on heat generation, material flow, and intermixing in the welding process is conducted. The results show that the ultrasonic vibration has a minor effect on the total heat, but promotes material flow and intermixing.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Multidisciplinary
Faliang He, Chuansong Wu, Lei Shi
Summary: This study developed a numerical simulation method to investigate the dynamic recrystallization behavior during friction stir welding of dissimilar Al/Mg alloys. The results show significant changes in grain size and dislocation density during the welding process, with the final grain size on the Al side being lower.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(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)
