Heat Generation Research Articles

Application of inverse heat transfer to fatigue fracture

Cyclic actuation tends to cause self-heating in the material as the structure experiences fatigue, where the movement and coalescence of defects lead to crack formation, propagation, and eventual fracture. This study explores the modeling aspects of the self-heating phenomenon using a one-dimensional inverse heat problem to analyze heat generation and dissipation to quantify the plastic work rates needed for predicting fatigue life. The approach is based on analyzing the surface thermography obtained using an infrared camera and numerically solving an inverse Fourier heat conduction equation. Formulation of the inverse problem via constrained optimization and method of solution for analyzing the fatigue behavior of CS 1018 flat dog bone specimens subjected to fully reversed bending fatigue are presented. The proposed model demonstrates superior accuracy in predicting the location of maximum heat generation and identifying potential fracture zones compared to traditional methods.

Influence of tool traverse speed on mechanical properties and fracture morphology of friction stir welded pure copper butt joints

The key goal of this research was to study the effect of the traverse speed of a tool on microstructural changes, mechanical properties and fracture morphology of pure copper butted weld joint by friction stir welding technique. In this study, other parameters like tool rotational speed (1000 rpm), axial force (4.2 kN), tilt angle (0˚) and tool offset (0 mm) were fixed. A cylindrical tool with a non-threaded tapered pin was used to fabricate the weld joints. All the weld joints produced by varying the traverse speeds (11, 20 and 24 mm min−1) were defect-free. It was noticed that the grains in the stir zone were tiny, well distributed and homogeneous at 24 mm min−1 owing to the adequate heat generation and complete intermixing of material in the stir zone. The utmost tensile strength of 187 MPa was achieved by the welded joint attained at 24 mm min−1. It was observed that a densely populated dimple structure enhances the joint ductility in the case of 24 mm min−1.

Radiative MHD Casson Non-Newtonian Nanofluid Slip Flow Induced by Stretching Cylinder: A Numerical Approach

Objectives: This article investigates the continuous magnetohydrodynamics slip flow across an extending cylinder, including heat radiation and free stream velocity. The proposed model incorporated the Brownian motion parameter and thermophoresis. Methods: Applying the similarity transformation to a system of partial differential equations yields an ordinary differential equation of first order. Since, there is the nonlinear nature of the modified equations, these ordinary differential equations are addressed by employing mathematical modeling. The shooting process has been embraced to solve changed equations by implementing the following Runge-Kutta Fehlberg method. Findings: Graphical representations are used to show how several fluid factors, such as Casson fluid parameter, free stream velocity, thermophoresis, magnetic parameter, Brownian motion parameter, heat generation parameter, Lewis number, radiation parameter, chemical reaction and curvature parameter affect concentration, temperature and velocity. Results for physical quantity of interest are also computed and reported in tabular form. The study's main findings showed that nanoparticle temperatures rise with greater Brownian motion parameter values, whereas nanoparticle concentration falls with higher heat radiation parameter values. Additionally, it is found that with rise in Lewis number rises as 0.1, 0.4, 0.7, 1.0, 1.3, heat transfer rate falls down by 21.19%. The outcomes are calculated using the MATLAB software. Novelty: This technique's validity is defended by comparing its most recent findings to previously published results and successfully meeting the convergence criteria. The present work emphasizes the analysis of free stream flow in the cylindrical area, specifically in the existence of partial slip and heat radiation, under convective circumstances. This study has significant implications for electronic devices such as processors as well as many businesses and the field of biological and medical sciences. The present investigation aims to support production businesses in achieving the desired level of quality of their products by effectively managing the transport phenomena. Keywords: Stretching cylinder, Heat radiation, Brownian motion, Thermophoresis, Non-Newtonian nanofluid, Shooting technique

Deformation Heat in Tension of Steel Elements

The purpose of the work is an approximate computational and experimental assessment of the specific energy intensity and heat generation at various stages of the material’s operation when the sample is stretched. The paper discusses an approximate method for estimating the specific energy intensity and heat generation at four stages of tensile deformation of a steel sample. Finite element modeling of the work of the manufactured sample under elastic-plastic tension was performed in the ANSYS multifunctional software package. The load in the digital model of the sample was applied according to the full-scale test program. The experiment used flat samples in accordance with GOST 1497, a WAW-1000 testing machine with a 100T microcomputer, and a testo 875i thermal imager with a temperature sensitivity of 0.05 °C at 30 °C. We compared the obtained values on graphs of full-scale tests and a digital model of the samples, identifying critical points and deviation values. Phased loading revealed that the development of destruction occurs on the descending branches and is accompanied by the gradual development of local instability of plastic deformation in the form of a “neck”. It is shown that the heating temperature of the tensile metal can be calculated using the formulas proposed in the paper or by calculation using the ANSYS software package. The test results showed that the surface temperatures of the samples at each stage differ significantly. Four main areas were identified on the graph of changes in the sample surface temperature at a point. An analysis of the existing database of measuring instruments and the ability to obtain and process data was carried out. Experimental values of surface temperatures during continuous quasi-static deformation exceed their calculated values (up to 5 times). The kinetics of changes in the temperature field of the sample surface was carried out using thermographic instruments.

Interfacial energy conversion mechanism between 3003 aluminum alloy and 321 stainless steel in vaporizing foil actuator welding process

Conventional welding methods encounter significant challenges, including poor weldability, low joint strength, and the formation of brittle intermetallic compounds, primarily due to the substantial disparities in the physical and chemical properties of aluminum and iron. To mitigate these issues, the vaporizing foil actuator welding (VFAW) process has emerged as a highly promising solid-phase welding technology, particularly suitable for joining dissimilar metals with pronounced differences in properties, such as aluminum alloys and stainless steels. The present study provides an innovative quantitative analysis of the interfacial impact energy conversion mechanisms within the VFAW process. The analysis reveals that the energy responsible for accelerating the flyer workpiece comprises burst vaporization energy (Ed\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_d$$\\end{document}) and continuous vaporization energy (Ep\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_p$$\\end{document}), with Ed\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_d$$\\end{document} identified as the primary energy source, contributing approximately 65–80% of the total energy required for acceleration. Further examination elucidates the mechanisms underlying heat generation and transfer during the interface collision. The investigation identifies the formation of an overheating zone at the interface, attributed to the combined effects of plastic deformation energy and adiabatic shear energy within the flyer workpiece. Consequently, the interface temperature can rise significantly, reaching up to 1394 K, with impact velocities as high as 925 m/s. The analyses contribute to establishing a theoretical foundation for understanding the interface bonding mechanisms characteristic of the vaporizing foil actuator welding method.

Theoretical Study on Transverse Mode Instability in Raman Fiber Amplifiers Considering Mode Excitation

Raman fiber lasers (RFLs), which are based on the stimulated Raman scattering effect, generate laser beams and offer distinct advantages such as flexibility in wavelength, low quantum defects, and absence from photo-darkening. However, as the power of the RFLs increases, heat generation emerges as a critical constraint on further power scaling. This escalating thermal load might result in transverse mode instability (TMI), thereby posing a significant challenge to the development of RFLs. In this work, a static model of the TMI effect in a high-power Raman fiber amplifier based on stimulated thermal Rayleigh scattering is established considering higher-order mode excitation. The variations of TMI threshold power with different seed power levels, fundamental mode purities, higher-order mode losses, and fiber lengths are investigated, while a TMI threshold formula with fundamental mode pumping is derived. This work will enrich the theoretical model of TMI and extend its application scope in TMI mitigation strategies, providing guidance for understanding and suppressing TMI in the RFLs.

ELECTRIC VEHICLE POWERTRAIN DESIGN: INNOVATIONS IN ELECTRICAL ENGINEERING

The electrification of vehicles is reshaping transportation, with electric vehicle (EV) powertrain design playing a key role in this shift. This review focuses on recent innovations in electrical engineering that have enhanced EV powertrains, particularly in areas like electric motors, power electronics, energy storage, and thermal management. Advances in motor technology, such as permanent magnet synchronous motors (PMSM), and the integration of silicon carbide (SiC) and gallium nitride (GaN) semiconductors have improved efficiency and reduced heat generation. Battery innovations, including solid-state technologies and advanced battery management systems, along with regenerative braking, have extended EV range and efficiency. Power electronics, including inverters and onboard chargers, now utilize wide-bandgap semiconductors to minimize energy losses and improve thermal performance. Additionally, novel cooling solutions are addressing thermal challenges in EV systems. Looking forward, modular powertrain architectures and AI-driven control strategies offer promising advancements for various vehicle types. This review provides an overview of how electrical engineering innovations are driving the future of EV powertrain design and sustainable transportation.

Natural convection and variable fluid properties of tangent hyperbolic nanofluid flow with Cattaneo-Christov theories and heat generation

The main aim behind this work is that we have to determine the enhancement that happens in thermal conductivity by using the Buongiorno model of nanofluid when the nanofluid particles are added to the tangent hyperbolic base fluid moving above the stretched surface. The viscosity of tangent hyperbolic nanofluid is assumed to be temperature-dependent. The modified form of the Fourier law of heat conduction motivated us; therefore, the Cattaneo-Christov heat and mass flux model is considered to observe its significance for heat and mass transport. The chemical reaction and heat generation are also considered to determine their influence on temperature and concentration gradients. This study is crucial because of its application in industrial manufacturing processes such as the coating of wire, the thinning of copper, the production of paper, photographic films, hot rolling, and the purification of crude oil. In electronic cooling systems, the efficient dissipation of heat in smartphones, computers, and data centers is critical to preventing overheating. Nanofluids, with their enhanced thermal properties, can significantly improve heat transfer rates, ensuring better performance, stability, and energy savings. The partial governing equations arising from fluid flow, mass, and heat transfer are transformed into ordinary differential equations via appropriate similarity variables. The obtained ordinary differential equations are solved numerically by using the Runge-Kutta Fehlberg method in the MATLAB software. The effects of the emerging parameters are represented through graphs. According to the results, the velocity profile upsurges due to the natural convection parameters and curvature parameter, while the power law index declines the velocity profile. As the Brownian motion coefficient rises, the concentration profile diminishes while the temperature profile increases. Both the concentration and temperature profiles increase for larger values of the thermophoresis parameter. The concentration profile declines for larger values of chemical reaction parameters, and enhancement happens in the temperature region.

Closing the Loop between Plastic Waste Management and Energy Cogeneration: An Innovative Design for a Flexible Pyrolysis Small-Scale Unit

This study proposes a simplified unit that can be employed in an industrial facility for the utilization of its own abundant plastic waste, primarily from discarded packaging, to achieve full or partial energy autonomy. By converting this waste into synthetic pyrolysis oil equivalent to 91,500 L, the industry can power a combined heat and power generation unit. The proposed unit was designed with a focus on maintaining high temperatures efficiently while minimizing oxygen exposure to protect the integrity of hydrocarbons until they transform into new compounds. Pyrolysis stands as a foundational procedure, paving the way for subsequent thermochemical transformations such as combustion and gasification. This study delves into the factors affecting pyrolysis and presents analytically the mathematical formulations and relevant calculations in order to effectively design and apply a real-life system. On this basis, fuels from plastic waste can be produced, suitable for utilization in typical equipment meant to produce heat, estimated for six months’ operation and 800 MWh of electricity. This study enhances the transition towards a more circular and resource-efficient economy with technologies that unlock the latent energy contained within the discarded matter. Additionally, it demonstrates the feasibility of a moderate investment in a co-generation system for industries utilizing 568 tonnes of plastic waste per year. The design and accurate calculations of this study highlight the theoretical potential of this technology, promoting environmental sustainability and resource conservation.

Flexible polyester-embedded thermoelectric device with Bi2Te3 and Te legs for wearable power generation

This study presents an approach for powering wearable sensors by integrating nanostructured bismuth telluride (Bi2Te3 and Te legs) into flexible polyester substrates. The choice of polyester as the substrate is because it is widely used in clothing, especially in items such as shirts, blouses, dresses, and sportswear. This enables seamless integration with wearable devices. By capturing wasted body heat, our small and flexible thermoelectric generators (TEGs) offer long-term operation without the need to plug the batteries. We demonstrate the feasibility of using commercially available polyester for reproducible electrochemical deposition of highly oriented Bi2Te3 and Te material. Through electrodeposition, we embed Bi2Te3 and Te legs within the flexible polyester, creating a cost-effective and easily scalable hybrid system for wearable energy harvesting.Our optimized TEG design, which can be worn on the arm or forehead, achieves impressive power density compared to existing state-of-the-art solutions. With a mere 3.5 °C temperature difference, only two pairs of p- and n-type legs, and a thickness of approximately 15 µm, our TEG generates a maximum open circuit voltage of ∼0.1 mV and a maximum power density of ∼0.04 mW·K-1·cm−2. With 250 pairs, 10 mV can be reached. This cost-effective design also integrates electrical contacts, surpassing previous flexible TEG performances. These advancements make our TEGs suitable for driving microwatt-level electronic sensors and open new avenues for efficient energy harvesting in wearable applications.

Implementation of stacking regressor model on the flow induced by TiO2‐H2O and Ti6Al4V‐H2O nanofluid with waste discharge concentration

AbstractThe present investigation examines the circulation of and based nanofluids while considering the concentration of waste discharge. An innovative stacking regressor model is used to increase prediction accuracy. Using Shooting and Runge Kutta Fehlberg's fourth and fifth‐order schemes, the governing equations are converted into ordinary differential equations using similarity transformation and then numerically solved. The findings are represented graphically, and the model's correctness is assessed using Gaussian Process Regression, Categorical Boost, Extreme Gradient Boosting, and Random Forest, with linear regression acting as a meta‐model. The closely related testing and training data show the model's consistency and stability. Magnetic field and inclination angle will decline the velocity, space, and temperature‐dependent internal heat generation factors will enhance the temperature. Raising the pollutant external source parameter raises concentration. In all the cases, shows better performance than based nanofluid. The work's application ranges from fluid dynamics to waste management. By offering precise forecasts of nanofluid concentration, the proposed prediction model may aid in designing and optimizing waste discharge systems.

7690 Acute hormonal signaling-induced 3D genome organization controls transcriptional dynamics during adipocyte thermogenesis

Abstract Disclosure: Y. Zhang: None. R. Zheng: None. T. Tsuji: None. Y. Xing: None. C. Wang: None. J. Darcy: None. K. Chen: None. Y. Tseng: None. Brown adipose tissue (BAT) maintains body temperature by dissipating energy as heat, presenting a promising target against obesity and its associated metabolic disorders. When exposed to cold, the β3-adrenergic receptor (β3-AR) in brown adipocytes is stimulated, initiating a sequential signaling cascade and activating a thermogenic gene program essential for heat generation. Despite remarkable progress has been made towards understanding the engagement of transcriptional and epigenetic regulators during thermogenesis in response to β3-AR stimulation, the precise impact of three-dimensional (3D) genome organization, an increasingly important modulator of gene expression, on the activation of thermogenic gene program remains elusive. In this study, we employed high-resolution Micro-C in murine brown adipocytes to interrogate the rapidity of 3D genome reorganization in response to β3-AR hormonal signaling and its impact on transcriptional dynamics during thermogenesis. Our findings unveiled substantial rewiring of chromatin loops within 4 hours of β3-AR stimulation. These dynamic changes in chromatin loops, particularly enhancer-promoter (E-P) interactions, were coupled with gene activation during thermogenesis. Furthermore, we uncovered the mechanisms by which β3-AR hormonal signaling mediates 3D chromatin reorganization to regulate the thermogenic gene program. We found that β3-AR hormonal signaling induced the phosphorylation of p18Hamlet, a subunit of the SRCAP complex, facilitating the deposition of the histone variant H2A.Z into regulatory DNA regions. This nucleosome incorporation of H2A.Z further mediated nucleosome rearrangement, favoring the formation of nucleosome-depleted regions (NDRs) and enhancing the accessibility of regulatory DNA regions. As a result, H2A.Z chromatin incorporation facilitated interactions between cis-regulatory regions and gene promoters, such as E-P interactions, thereby activating thermogenic gene expression in response to β3-AR stimulation. Loss of H2A.Z disrupted loop dynamics, impeding gene activation and BAT thermogenic capacity. The conserved role of H2A.Z in human thermogenesis was validated, and we identified adiposity-related SNPs in human homologous loop anchors that could potentially be targeted for treating obesity. Taken together, our results unveil a previously underappreciated aspect of acute hormonal signaling-induced chromatin dynamics in orchestrating the thermogenic program in brown adipocytes. These findings not only enhance our understanding of molecular regulation of thermogenesis but also shed light on the role of rapid and dynamic chromatin reconfiguration in regulating the cellular response to external stimuli. Our study bridges a critical gap between 3D genome organization and gene activation in the thermogenic program mediated by acute β3-AR hormonal signaling. Presentation: 6/2/2024

Facilely Achieving Near-Infrared-II J-Aggregates through Molecular Bending on a Donor-Acceptor Fluorophore for High-Performance Tumor Phototheranostics.

Constructing J-aggregated organic dyes represents a promising strategy for obtaining biomedical second near-infrared (NIR-II) emissive materials, as they exhibit red-shifted spectroscopic properties upon assembly into nanoparticles (NPs) in aqueous environments. However, currently available NIR-II J-aggregates primarily rely on specific molecular backbones with intricate design strategies and are susceptible to fluorescence quenching during assembly. A facile approach for constructing bright NIR-II J-aggregates using prevalent donor-acceptor (D-A) molecules is still lacking. In this study, we present a facile method that transforms D-A molecules into J-aggregates by simply bending the molecule through introducing a methyl group, enabling high-performance NIR-II phototheranostics. The TAA-BT-CN molecule exhibits hypsochromic-shift absorption upon forming H-aggregated NPs, while the designed mTAA-BT-CN with a bent structure demonstrates a bathochromic shift of over 100 nm in absorption upon forming J-aggregated NPs, leading to much enhanced NIR-II emission beyond 1100 nm. With respect to its H-aggregated counterpart with the aggregation-caused quenching (ACQ) phenomenon, the J-aggregated mTAA-BT-CN NPs exhibit a 7-fold increase in NIR-II fluorescence owing to their aggregation-induced emission (AIE) property as well as efficient generation of heat and reactive oxygen species under 808 nm light excitation. Finally, the mTAA-BT-CN NPs are employed for whole-body blood vessel imaging using NIR-II technology as well as imaging-guided tumor phototherapies. This study will facilitate the flourishing advancement of J-aggregates based on prevalent D-A-type molecules.

Defect identification of nano-cementitious composites, using statistical analysis of thermal images

Carbon-based nanomaterials have diverse applications, including in electronics, energy storage, and environmental remediation. Current research aims to enhance the multifunctionality of construction materials by integrating cement with carbon-based nanomaterials known for their high thermal and electrical conductivity. However, nano-cementitious composites may develop internal defects due to the agglomeration of nanomaterials during fabrication. This study aims to utilize the heat characteristics of nano-cementitious composites for detecting internal defect. Test specimens were prepared by incorporating 1 wt% Multi-Walled Carbon Nanotubes (MWCNTs) into the cement paste. Internal defect sizes were defined from 5 % to 25 % of the specimen's area and were positioned in the center of the specimen. A heat generation test was conducted to capture thermal images and temperature data. Quantitative analysis followed, examining the correlation between defect size and temperature through statistical analysis of the thermal images, using skewness to assess this correlation. The results of the skewness analysis indicated a linear correlation with defect size. A parametric study was conducted to analyze the impact of the number of pixel data on skewness, and it was derived that at least 1500 pixel data are required. Consequently, this study concludes that internal defects in nano-cementitious composites can be detected and their sizes can be inferred through the linear relationship between defect size and skewness.

Temperature Analysis of Single busbar With Variation of Total Harmonic Distortion in Current

Typically, busbars are used to transmit and distribute currents in a bus duct system. The alarming use of nonlinear loads in the industrial sector or at residentials, such as arc welding, computers, ballast lighting, variable speed drives, and so on, has resulted in the generation of harmonics in current distortion, which are uncontrolled and thus increase heat generation within the system. The research conducted in this paper focuses on the prediction of the heat distribution as well as the analysis on operating temperature of a single busbar with compliance to the British National and International Standard (BS 159: 2014) using the Finite Element Method (FEM) in COMSOL Multiphysics software. The copper busbar dimension used for this research was 20mm x 6mm x 300mm, and the fundamental Root Mean Square (RMS) current was 419.1 A. The size of this busbars can withstand the maximum current of 430 A at a maximum operating temperature of 90°C, which complies with the standard requirement. The fundamental current is injected with variation of total harmonic distortion in current up to 55% with an interval of 5%. According to the findings, the operating temperature increases in direct proportion to the increase in total harmonic distortion with the current injections. With the presence of 55% of total harmonics in the current, the current was increased up to 57.73 A from the fundamental current, while the operating temperature was increased up to 140C from the fundamental temperature. The total harmonics in current produced by the nonlinear loads could affect the operating temperature of the busbars, and this continuous operation of current flow will affect the busbars' lifespan due to the occurrence of overheating.

A Numerical Framework of Simulating Flow-Induced Deformation during Liquid Composite Moulding

Fibre deformation (or shearing of yarns) can develop during the liquid moulding of composites due to injection pressures or polymerisation (cross-linking) reactions (e.g., chemical shrinkage). On that premise, this may also induce potential residual stress–strain, warpage, and design defects in the composite part. In this paper, a developed numerical framework is customised to analyse deformations and the residual stress–strain of fibre (at a micro-scale) and yarns (at a meso-scale) during a liquid composite moulding (LCM) process cycle (fill and cure stages). This is achieved by linking flow simulations (coupled filling–curing simulation) to a transient structural model using ANSYS software. This work develops advanced User-Defined Functions (UDFs) and User-Defined Scalers (UDSs) to enhance the commercial CFD code with extra models for chemorheology, cure kinetics, heat generation, and permeability. Such models will be hooked within the conservation equations in the thermo-chemo-flow model and hence reflected by the structural model. In doing so, the knowledge of permeability, polymerisation, rheology, and mechanical response can be digitally obtained for more coherent and optimised manufacturing processes of advanced composites.

Energy dataset of Frontier supercomputer for waste heat recovery

The Hewlett Packard Enterprise–Cray EX Frontier is the world’s first and fastest exascale supercomputer, hosted at the Oak Ridge Leadership Computing Facility in Tennessee, United States. Frontier is a significant electricity consumer, drawing 8–30 MW; this massive energy demand produces significant waste heat, requiring extensive cooling measures. Although harnessing this waste heat for campus heating is a sustainability goal at Oak Ridge National Laboratory (ORNL), the 30 °C–38 °C waste heat temperature poses compatibility issues with standard HVAC systems. Heat pump systems, prevalent in residential settings and some industries, can efficiently upgrade low-quality heat to usable energy for buildings. Thus, heat pump technology powered by renewable electricity offers an efficient, cost-effective solution for substantial waste heat recovery. However, a major challenge is the absence of benchmark data on high-performance computing (HPC) heat generation and waste heat profiles. This paper reports power demand and waste heat measurements from an ORNL HPC data centre, aiming to guide future research on optimizing waste heat recovery in large-scale data centres, especially those of HPC calibre.

Numerical study on Prandtl number dependence of thermal convection in an internally heated pool

Large-eddy simulations have been conducted to study natural convection in a corium pool. The study focuses on a hemispherical pool with uniform volumetric heat generation, complemented by isothermal cooling on all exterior surfaces. The internal Rayleigh number (Rai), correlated with the internal heat generation, is fixed at 1015. The Prandtl numbers (Pr) examined vary from 0.32 to 10. While previous experimental studies have explored internally heated pool convection primarily in the Pr≥3 range using liquids, the present research extends the investigation to the Pr<3 range, including the value for corium of about 0.5. The simulation results indicate that the overall Nusselt number (Nu), defined as the volume averaged pool temperature relative to the total heat flux adheres to power laws of Nu∼Pr0.073 for 0.32≤Pr≤1 and Nu∼Pr0.021 for 3.2≤Pr≤10. Consequently, the Nu at the Pr of 0.32 is observed to be 17% lower than that at the Pr of 10. A correlation for Nu is proposed as Nu=1+0.0636Rai0.231+1.39Pr−1.18−0.0847 using a generalized logistic function that combines theoretical scaling laws of Nu∼Pr0.1 for Pr≪1 and Nu∼Pr0 for Pr≫1. This study also includes theoretical analyses, elucidating dependencies of Pr on various parameters, such as the Nusselt number, Reynolds number, the proportion of the heat flux at the upper cooling wall relative to the total generated heat, and the height of the stratified zone.

Effect of filer content on the thermal characteristics of underfill materials for Ball-Grid-Array component package

High-density integration and fast processing speed in the semiconductor industry have increased heat generation in electronic devices. Underfill materials, known for their high thermal conductivity and low coefficient of thermal expansion (CTE), offer a potential solution to dissipate heat and improve device reliability. In this study, we investigate the effect of filler content on the thermal reliability of underfill materials for ball grid array (BGA) component packaging. Mainly, we investigate the thermal conductivity, CTE, and mechanical properties of different filler contents of Al2O3 and Al2O3–BN hybrid underfills to facilitate heat dissipation and improve device reliability. The thermal conductivity of the underfill materials was evaluated by measuring the surface temperatures of underfill molded flip-chip light-emitting diodes (FCLEDs). The mechanical properties and thermo-mechanical reliability of the underfill materials were evaluated via a three-point bending test of the underfill packaged BGA components after the thermal shock test. The results showed that optimizing underfill properties based on specific application environments is crucial for obtaining enhanced thermal reliability and mechanical properties of underfill packaged BGA components.

Thermal transport analysis for ternary hybrid nanomaterial flow subject to radiation and convective condition

Ternary nanomaterials are now recognized as useful not only for thermal efficiency importance but also to enhance physical characteristics of liquids. Insertion of three nanoparticles in base liquid is characterized as ternary hybrid nanomaterial. Such materials have better magnet properties, electrical conducting and mechanical resistance. Here we discuss three-dimensional magnetized stretched flow of ternary nanofluid through porous space is addressed. Porous space is scrutinized by Darcy-Forchheimer relation. Convective condition is imposed. Nanoparticles here include copper, polyphenol coated and aluminum oxide and water as conventional liquid. Energy equation consists of radiation, magnetohydrodynamics, dissipation and heat generation. Resulting dimensionless system is computed by Newton built in-shooting technique. Outcomes of velocity, temperature, skin friction and Nusselt number for emerging parameters of interest are organized. Comparison of results for ternary nanofluid , hybrid and nanofluid is examined. It is found that temperature and velocity against Hartman number have reverse trends. Temperature and Nusselt number for radiation have increasing features. Similar characteristics for temperature through heat generation and Eckert number is noticed. Larger thermal Biot number corresponds to rise the Nusselt number and temperature. An increase in temperature through Forchheimer number is witnessed while reverse trend holds for velocity.