Article
Thermodynamics
G. E. Lau, J. Mohammadpour, A. Lee
Summary: Numerical investigations were conducted on the heat transfer enhancement in a three-dimensional micro-channel using Al2O3-water, CuO-water and TiO2-water nanofluids with a single synthetic jet. Different types of nanoparticles at various concentrations were examined to assess their effects on thermal performance. The study found that the overall thermal performance was greatly influenced by the thermal conductivity and dynamic viscosity of the nanofluids, and the convective cooling effectiveness of the synthetic jet decreased with higher nanofluid viscosity, although this could be offset by an increase in thermal conductivity depending on the Peclet number.
APPLIED THERMAL ENGINEERING
(2021)
Article
Mechanics
Udaysinh S. Bhapkar, Abhishek Mishra, Harekrishna Yadav, Amit Agrawal
Summary: This experimental study investigated the flow characteristics of synthetic jets emitted from different orifice shapes. The results showed that the wall jet from the elliptical orifice had higher energy-containing vortices and a delayed self-similarity compared to other orifice shapes. The elliptical orifice also had relatively higher normal and shear stresses. In addition, for a larger nozzle to surface spacing, the rectangular orifice shape resulted in a shifting of the self-similarity location.
Article
Thermodynamics
Yuan-wei Lyu, Jing-zhou Zhang, Jun-wen Tan, Yong Shan
Summary: Based on experimental studies, this research investigates the heat transfer characteristics of a single synthetic jet emitted from planar lobed orifices. It is found that the planar lobed orifices enhance heat transfer significantly compared to the baseline round orifice, depending on the shapes of the lobes and targets. The N=6 petal-shaped orifice is identified as the most promising configuration among the petal-shaped orifices, while a moderate lobe aspect ratio is shown to be superior in the arch-shaped orifices.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Pin Chen, Nidhal Ben Hassine, Safouene Ouenzerfi, Souad Harmand
Summary: In this study, impinging jet was used as an efficient cooling technology to reduce the end-winding temperature of an electric machine stator. Infrared imaging and numerical simulation were utilized to analyze the heat dissipation efficiency of silicone oil jet on a real stator. The results showed that the configuration with an internal surface exhibited the best cooling performance, and the minimum and most cost-effective oil flow rates were determined for this configuration.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
R. J. Talapati, V. V. Katti, N. S. Hiremath
Summary: The experimental study focuses on the local heat transfer characteristics of synthetic air jet impinging on convex surface. The results show that the local heat transfer is strongly influenced by actuator frequency and jet to plate distance. The combination of an actuator frequency of 200 Hz and a lower jet to plate distance of 2 is observed to be effective across all conditions.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Thermodynamics
Liang Xu, Di Ren, Lei Xi, Tao Yang, Jianmin Gao, Yunlong Li
Summary: In this paper, a composite cooling structure with grooved target surface is proposed for the cooling of combustion chamber. Experimental and numerical simulation results show that using grooved target surface can significantly reduce temperature, increase Nusselt number, and decrease friction factor. The comprehensive heat transfer performance of the grooved target surface is better with F greater than 1.06.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Abdolvahab Ravanji, Mehran Rajabi Zargarabadi
Summary: The study demonstrates that elliptical pin-fins are the most effective in cooling a heated flat plate, significantly decreasing local temperatures and increasing heat transfer efficiency.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Thermodynamics
Philipp Golda, Noah Lettner, Robert Schiessl, Ulrich Maas
Summary: This work presents an experimental setup to study cryogenic impingement cooling performance under given inflow conditions, examining the relationship between heat flux and heat transfer coefficients. Important conclusions regarding heat flux and its governing physical phenomena are drawn.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Alex Li, Rui Zhu, Terrence Simon
Summary: This study investigates the cooling performance of an impinging synthetic jet on a normal plane. The research is supported by experiments, numerical simulation, and flow visualization. The results are validated by both experiment and numerical analysis. The local, time-average Nusselt numbers are measured using thermochromic liquid crystal technique.
ASME JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Engineering, Multidisciplinary
JunWen Tan, YuanWei Lyu, JingZhou Zhang, JingYang Zhang
Summary: A novel concept of improving square-array jet impingement heat transfer by integrating a synthetic jet actuator into the array unit is proposed and experimentally investigated. The results show that the synthetic jet has minor influence on the stagnation heat transfer of square-array jet but significantly improves the local heat transfer at the central zone of the array unit. Its potential is closely related to the array layout, Reynolds number, and impinging distance.
SCIENCE CHINA-TECHNOLOGICAL SCIENCES
(2023)
Article
Thermodynamics
Stephen Adeoye, Anatoly Parahovnik, Yoav Peles
Summary: This study investigated the characteristics of microm jet impingement heat transfer with supercritical CO2, revealing that high heat transfer coefficients can be achieved under certain conditions. Additionally, a Nusselt number correlation for micro jet impingement with sCO2 was proposed.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Energy & Fuels
Jinpeng Hua, Jianfeng Pan, Feiyang Li, Baowei Fan, Zhongjia Li, Abiodun Oluwaleke Ojo
Summary: This study experimentally and numerically investigated the heat transfer characteristics of a premixed methane-air flame jet impinging on a hemispherical surface. The effects of mixture equivalence ratio, burner to plate distance, mixture Reynolds number, and curvature ratio on heat transfer characteristics were studied. CFD simulations were performed to analyze the heat flux distribution and average heat flux on the impingement surface. Heat transfer efficiency was used to evaluate the thermal performance of the impinging flame jet. The results showed that equivalence ratio had a significant effect on flame height, which influenced heat transfer efficiency. The burner-to-plate distance played a decisive role in heat transfer characteristics, and the best thermal performance was achieved when the flame premixed cone just touched the impingement surface.
Article
Mechanics
Wenwu Zhou, Kechen Wang, Tangjia Yuan, Xin Wen, Di Peng, Yingzheng Liu
Summary: The spatiotemporal distributions of coolant coverage behind the 777-shaped hole, sweeping jet, and compact SJ were comprehensively quantified and compared. It was found that the compact SJ had the highest cooling effectiveness, but its flow structure coherence was reduced.
Article
Thermodynamics
Naseem Uddin, Sven Olaf Neumann, Bernhard Weigand, Bassam A. Younis
Summary: The study found that using a cylindrical insert in the impingement pipe results in enhanced heat transfer rates for cooling applications. The insert is placed just before where the jet issues from the circular pipe to passively excite the jet's velocity field. Large Eddy Simulations showed that this method can improve heat transfer performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Stephen Adeoye, Yoav Peles
Summary: Flow boiling of carbon dioxide with a micro impinging jet was experimentally studied. The effects of heat flux, radial position, mass flux, and pressure on the heat transfer coefficient were investigated. Results showed an increase in the heat transfer coefficient with heat flux, mass flux, and pressure up until the critical heat flux condition. In contrast, the heat transfer coefficient declined with radial position characterized by a pronounced influence of the jet hydrodynamics.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
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)