Article
Thermodynamics
Jun Li, Pega Hrnjak
Summary: This study investigates the phase separation efficiency in microchannel condensers using Computational Fluid Dynamics simulations. The results show a linear trend between liquid and vapor separation efficiency within the experimental range.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2021)
Article
Multidisciplinary Sciences
Pawel Dabrowski
Summary: The aim of the study is to compare various methods for quantifying flow maldistribution using different parameters. An experimentally validated numerical study was conducted on a heat exchanger with 34 semi-circular channels. Different heat flux and inlet velocities were tested, and flow maldistribution coefficients were calculated based on velocity, pressure, and temperature profiles. The study found that different methods yielded different results, leading to ambiguities in fluid distribution conclusions in the literature. A normalized flow maldistribution coefficient that gives consistent results for all parameters was proposed.
SCIENTIFIC REPORTS
(2023)
Article
Thermodynamics
Amrendra Kumar, Nirmal K. K. Manna, Sandip Sarkar, Nirmalendu Biswas
Summary: In micro-scale sensitive medicinal and biochemical systems, the improvement of mixing efficiency is crucial despite small velocity limitations. This study investigates the key parameters and their impact on mixing efficiency in a new two-dimensional electroosmotic micromixer. The results demonstrate the significance of electrode polarity configuration and an increase in electrode pairs in optimizing fluid mixing.
NANOSCALE AND MICROSCALE THERMOPHYSICAL ENGINEERING
(2023)
Article
Physics, Multidisciplinary
Ferhat Koca, Mustafa Zabun
Summary: In this study, the numerical simulation of coolant flow in the CPU heat sink with micro-pin fins was conducted using ANSYS-Fluent. Different inlet-outlet configurations were studied, showing that an increase in Reynolds number leads to higher Nusselt number and lower skin friction along the heat sink surface.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Energy & Fuels
Wen-Jenn Sheu, Yu-Ting Chen, Aristotle T. Ubando, Yen-Cho Chen, Chin-Tsan Wang
Summary: This study proposed a 3D numerical model of dual-chamber MFCs to improve performance by redesigning and changing the inlet and outlet locations, addressing uneven biomass distribution and acetic concentration. Results showed a 5% increase in total current density with appropriate changes in input and output locations.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Article
Engineering, Chemical
Ali Monavari, Jafar Jamaati, Mehdi Bahiraei
Summary: The study investigates the effects of different particle shapes on the thermohydraulic performance of a boehmite nanofluid in a microchannel heat sink with various cross-sections. Results show that microchannels with triangular cross-sections exhibit the highest heat transfer coefficient and best temperature distribution, while nanofluids with platelet particles cause the highest pressure loss. Uniformity of temperature distribution and thermal resistance decrease with increasing Reynolds number, while heat transfer coefficient, pressure drop, and pumping power increase. Additionally, nanofluids with platelet particles demonstrate the highest heat transfer coefficient among all shapes tested.
JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS
(2021)
Article
Thermodynamics
Raghav Singupuram, Tabish Alam, Masood Ashraf Ali, Saboor Shaik, Naveen Kumar Gupta, Nevzat Akkurt, Mukesh Kumar, Sayed M. Eldin, Dan Dobrota
Summary: This paper presents a novel design of microchannel heat sinks (MHS) that can effectively cool electronic components and maintain its temperature in the safe range. Circular extruding ribs were added on the side wall of the passage to enhance heat transfer. The study found that the maximum Nusselt number was observed at sector angles of 80 degrees, with values ranging from 7.26 to 64.11. The thermohydraulic performance parameter (THPP) values were greater than one, indicating the proposed design is reasonable and effective for thermal management of MHS.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Engineering, Chemical
Mehdi Bahiraei, Ali Monavari
Summary: The thermal-hydraulic efficacy of boehmite nanofluids with different particle shapes was evaluated inside a microchannel heat sink, showing that nanofluids with platelet-shaped nanoparticles have the best heat transfer performance, while those with oblate spheroid particles have the lowest heat transfer performance and smallest pressure loss. Overall, the study found that heat transfer capabilities were influenced by particle shape, with platelet-shaped nanoparticles showing the most promising results.
CHINESE JOURNAL OF CHEMICAL ENGINEERING
(2021)
Article
Materials Science, Ceramics
M. Satheeshkumar, M. R. Thansekhar, R. Pandiyarajan
Summary: This study explored the flow performance of nanofluids with different inlet header geometries, finding that the heat transfer performance was optimal with coolant fluids based on aluminum oxide and silicon dioxide. The highest local Nusselt number and heat transfer rate were observed with high concentrations of SiO2 and Al2O3, indicating better performance with these coolant fluids.
JOURNAL OF CERAMIC PROCESSING RESEARCH
(2021)
Article
Engineering, Chemical
Mohammed R. A. Alrasheed
Summary: In this study, the microchannel heat sink with a Boron Nitride Nanotube-based nanofluid as a coolant is optimized using the evolutionary algorithm MOMVO. The optimization results in the optimal thermal resistance and pumping power values. The study shows that the optimal results can be achieved with a population size of 50 and within 100 iterations.
Article
Chemistry, Analytical
Tao Wu, Lizhi Wang, Yicun Tang, Chao Yin, Xiankai Li
Summary: Liquid metal-based microchannel heat sinks are proposed to address high-density heat dissipation challenges. Among different working fluid types and microchannel cross-section shapes, lithium and circle were found to be the most appropriate choices. Inlet velocity significantly influences flow and heat transfer performances, with pressure drop increasing by up to 65 times and heat transfer coefficient enhanced by about 74.35% from 1 m/s to 9 m/s.
Article
Thermodynamics
Saban Unal, Ertugrul Cihan, M. Tahir Erdinc, Mehmet Bilgili
Summary: The performance of vapor compression cooling systems can be increased thanks to the ejector, but the impact of refrigerant velocities has been neglected in some previous studies. By considering velocities, the study calculated the performance of a system using R600a/R290 refrigerant mixture, finding higher cooling performance and lower exergy efficiency when velocities are taken into account.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2022)
Article
Thermodynamics
Saban Unal, Ertugrul Cihan, M. Tahir Erdinc, Mehmet Bilgili
Summary: This study investigated the impact of refrigerant velocities at the mixing section inlet and diffuser outlet on the performance of an ejector-expansion refrigeration system. By considering these velocities in the mathematical model, it was found that the cooling performance of the system using a R600a/R290 refrigerant mixture increased by 5.8%-7%. The neglect of these velocities also resulted in a lower exergy efficiency of around 4.6%.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Jianyu Du, Yuchi Yang, Huaiqiang Yu, Han Xu, Deyin Zheng, Qi Wang, Jiajie Kang, Wei Wang
Summary: This paper investigates the influence of different shapes of liquid inlets and outlets of embedded microchannel chips during the flip-chip bonding process using finite element simulation technology, and validates the simulation predictions through experiments. The results show that optimizing the design of the liquid inlets and outlets can effectively reduce the stress performance of the chips. This work is of great significance in promoting the practical application of microfluidic chips.
IEEE 72ND ELECTRONIC COMPONENTS AND TECHNOLOGY CONFERENCE (ECTC 2022)
(2022)
Article
Multidisciplinary Sciences
Yousef Alihosseini, Mohammad Reza Azaddel, Sahel Moslemi, Mehdi Mohammadi, Ali Pormohammad, Mohammad Zabetian Targhi, Mohammad Mahdi Heyhat
Summary: Research shows that the circular cross-section is the most efficient shape for the microchannel heat sink, with a 25% increase in heat transfer compared to the square shape at Reynolds number of 1150. Additionally, placing the circular cross-section microchannel below the PCR device can cool saliva samples in 16.5 seconds, saving 157.5 seconds for the whole amplification procedure compared to conventional air fans. Another advantage of using the microchannel heat sink is its small space requirements compared to other common cooling methods.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Multidisciplinary
Jun-Jie Su, Jun Wang, Guo-Dong Xia
Summary: This study investigates the influence of particle temperature on the shear lift of nanoparticles and derives corresponding formulas based on gas kinetic theory. The findings reveal the significant impact of particle temperature on nanoparticle transport properties, especially in cases where the gas-particle temperature equality assumption may lead to significant errors.
Article
Engineering, Chemical
Junjie Su, Jie Cui, Jun Wang, Guodong Xia
Summary: This paper theoretically investigates the effect of particle temperature on the thermophoresis of nanoparticles in the free molecule regime. Theoretical formulas for thermophoretic force and velocity are derived based on gas kinetic theory. The study reveals that the particle temperature has a significant influence on the thermophoresis of nanoparticles, and the error caused by assuming equal gas-particle temperature can be neglected as the particle size increases.
Article
Thermodynamics
Jun Wang, Chunrui Shao, Haiyang Li, Guodong Xia
Summary: This paper introduces the thermal rectification effect and its application in a bi-segment thermal rectifier. By introducing zigzag-structure interfaces into the system, the thermal rectification ratio can be improved, enhancing the thermal rectification effect. The finite element method is used for numerical calculations, and the heat flux through the system is calculated based on Fourier's law. The results show that the zigzag interface can increase the thermal rectification ratio by more than 36% compared to a flat interface.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Li Fan, Li Haiyang, Wang Jun, Xia Guodong, Gisuk Hwang
Summary: This study investigates tailored nanoscale thermal transport by using a gas-filled nanogap structure with mechanically-controllable nanopillars. The results show that both thermal rectification and negative differential thermal resistance effects can be significantly enhanced by controlling the nanopillar height. These mechanisms provide insights for the design of thermal management systems.
JOURNAL OF THERMAL SCIENCE
(2022)
Article
Mechanics
Kexue Zhang, Liyuan Xu, Yunyun Li, Fabio Marchesoni, Jun Wang, Guodong Xia
Summary: This study investigates the self-propulsion of a Janus particle suspended in a dilute gas at equilibrium and confirms the analytical results through numerical simulations.
Article
Thermodynamics
Haiyang Li, Jun Wang, Guodong Xia
Summary: This paper studies the mechanism of heat transfer through solid-liquid interfaces. It is found that the interfacial heat transfer can be enhanced by increasing interfacial coupling strength or introducing nanostructured surfaces. The underlying mechanism of the interfacial thermal transport is analyzed based on various calculation results.
JOURNAL OF THERMAL SCIENCE
(2022)
Article
Physics, Multidisciplinary
Haiyang Li, Jun Wang, Guodong Xia
Summary: Thermal rectification, the phenomenon where the heat flux is much larger in one direction than in the opposite direction, is implemented in an asymmetric solid-liquid-solid sandwiched system with a nano-structured interface. Non-equilibrium molecular dynamics simulations reveal that the thermal rectification effect is due to the difference in interfacial thermal resistance between Cassie and Wenzel states when reversing the temperature bias. The effects of liquid density, solid-liquid bonding strength, and nanostructure size on thermal rectification are also examined, providing new insights for the design of thermal devices.
Article
Thermodynamics
Haiyang Li, Jun Wang, Guodong Xia
Summary: In this study, the phenomenon of negative differential thermal resistance effect is observed in a solid-liquid-solid sandwiched system with a nanostructured cold surface. Non-equilibrium molecular dynamics simulations reveal that the heat flux initially increases with temperature bias for low temperature bias, but decreases counter-intuitively for high temperature bias. The negative differential thermal resistance effect at high temperature bias is attributed to the suppressed solid-liquid interfacial thermal conductance with decreasing temperature, as analyzed based on interfacial thermal resistance and density depletion length at the solid-liquid interface.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Mechanics
Wangwang Liu, Jie Cui, Jun Wang, Guodong Xia, Zhigang Li
Summary: In this study, the negative thermophoresis of nanoparticles in liquids, which is usually from low to high temperature, is investigated using molecular dynamics simulations. The strength of solid-liquid intermolecular coupling was found to have a significant effect on the direction and magnitude of the thermophoretic force. Negative thermophoresis is induced by a density gradient that pushes the particles from high to low density. The sign change of the averaged potential mean force for the interfacial layer can be used as a criterion to predict the occurrence of negative thermophoresis. These findings provide insights for the microscopic manipulation of nanoparticles.
Article
Mechanics
Ran Li, Ziqing Yan, Guodong Xia
Summary: This study reports a novel investigation of the inter-pore interference effect in nano-porous evaporation, elucidating the changes in the net evaporation rate from individual nanopores when the inter-pore distance, neighboring nanopore diameter, or liquid temperature were varied. Molecular simulation results reveal that reducing inter-pore distance can enhance evaporation rate by increasing vapor convection effect and suppressing condensation flux. This interference effect is more pronounced at lower evaporation intensity, with the evaporation flux differing by up to 25% from the one-dimensional case.
Article
Mechanics
Wangwang Liu, Jun Wang, Guodong Xia, Zhigang Li
Summary: The thermophoresis of nanoparticles suspended in gas in the transition regime was investigated through molecular dynamics simulations. It was found that there was a significant discrepancy between the simulation results and theoretical predictions for the thermophoretic force, which was attributed to the adsorption of gas molecules on nanoparticles and the gas-particle non-rigid body collisions. By using the effective particle radius, the simulation results and Talbot et al.'s equation were found to agree with each other. The investigation presented in this paper provides guidance for the application of nanoparticles in aerosol science.
Article
Physics, Multidisciplinary
Shao Chun-Rui, Li Hai-Yang, Wang Jun, Xia Guo-Dong
Summary: This study investigates the enhancement of thermal rectification effect by applying porous structure on bulk materials, finding that porous structure can effectively increase the thermal rectification ratio. The influence of porosity is weak under low temperature bias, but becomes significant under high temperature difference.
ACTA PHYSICA SINICA
(2021)
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)
