Interface Temperature Research Articles

IMPACTS OF USING POROUS CORNER PARTITIONS AND BLADE SHAPED NANOPARTICLES IN BASE FLUID ON THE PERFORMANCE IMPROVEMENT OF THERMOELECTRIC GENERATOR MOUNTED VENTED CAVITIES AND INTERFACE TEMPERATURE ESTIMATION WITH PROPER ORTHOGONAL DECOMPOSITION

Numerous technical applications, such as solar power, refrigeration, waste heat recovery, thermal management, and many more, employ thermoelectric devices because of the numerous advantages they offer. Techniques are required to improve their effectiveness in usage. In this study, a unique technique for improving the performance of a thermoelectric generator (TEG) positioned between vented cavities is proposed. The method combines the effects of blade-shaped nanoparticles in the base fluid and corner porous partitions. A numerical study using the finite element method is conducted for different values of Darcy number of upper and lower cavity (10<sup>-6</sup> ≤ Da<sub>1</sub> ≤ 10<sup>-2</sup>, 10<sup>-6</sup> ≤ Da<sub>2</sub> ≤ 10<sup>-2</sup>), opening ratio (SR between 0.5 and 2.5), and nanoparticle loading amount (SVF between 0 and 0.03). By adjusting the permeability of the partitions and opening ratio of the cavities, significant changes in the flow field can be obtained. TEG power increases with greater opening ratios and lower partition permeabilities. By changing the permeability, the TEG power can increase by up to 27.5 percent, while increasing the opening ratio from SR = 0.5 to SR = 1 can increase the TEG power by up to 140 percent. Using blade-shaped nanoparticles results in additional improvements, with values of 32.7% at SR = 0.5 and 20.26% at SR = 2.5. Using 180 parametric computational fluid dynamics cases, a POD-based low-cost reconstruction model is created for the interface temperatures at the hot and cold sides using five-POD modes. The method may be used for other complicated geometries where 3-D computations are costly and allows for the rapid computation of coupled TEG-vented cavity systems with corner partitions.

Solar power conversion: CuI hole transport layer and Ba3NCl3 absorber enable advanced solar cell technology boosting efficiency over 30.

Researchers are becoming more interested in novel barium-nitride-chloride (Ba3NCl3) hybrid perovskite solar cells (HPSCs) due to their remarkable semiconductor properties. An electron transport layer (ETL) built from TiO2 and a hole transport layer (HTL) made of CuI have been studied in Ba3NCl3-based single junction photovoltaic cells in a variety of variations. Through extensive numerical analysis using SCAPS-1D simulation software, we investigated elements such as layer thickness, defect density, doping concentration, interface defect density, carrier concentration, generation, recombination, temperature, series and shunt resistance, open circuit voltage (V OC), short circuit current (J SC), fill factor (FF), and power conversion efficiency (PCE). The study found that the HTL CuI design reached the highest PCE at 30.47% with a V OC of 1.0649 V, a J SC of 38.2609 mA cm-2, and an FF of 74.78%. These findings offer useful data and a practical plan for producing inexpensive, Ba3NCl3-based thin-film solar cells.

Effects of in-process surface finishing on part strength in polymer material extrusion additive manufacturing

Material extrusion additive manufacturing suffers from limitations in surface finish, dimensional accuracy, and part strength. Hybrid manufacturing, which in this context integrates material extrusion with in-process surface finishing, offers a potential solution to address these issues. This study presents two critical aspects of a polymer-based hybrid manufacturing process. First, it quantifies the impact of the interfacial temperature drop during the finishing cycle on part strength. Secondly, it investigates the influence of surface finishing on part strength, considering two finishing methods: machining and a combination of machining and chemical polishing. The results reveal that temperature plays a major role in influencing the part strength and must be regulated to preserve interfacial bonding. An interfacial temperature drop beyond the material’s glass transition temperature can lead to a 50% reduction in part strength. However, slowing down the printing speed at the interface could induce localized heating, partially offsetting this loss. Furthermore, in-process surface finishing can mitigate potential sites for crack initiation, thereby increasing part strength. The results indicate that the machining-only scenario increases the part strength by 70.6% compared to the as-printed condition, while the combined machining and chemical polishing further increase part strength by 163.3%. This research underscores the multifaceted benefits of surface finishing in a polymer hybrid manufacturing setting while highlighting the potential challenge of temperature management.

Investigation of thermal effects on the saturated shear behaviour of a clayey sand-structure interface

The mechanical behaviour of soil-structure interfaces at various temperatures plays a key role in predicting the performance of energy piles, such as their ultimate bearing capacity and settlement under heating and cooling. The experimental data was limited in the literature, and previous studies used clay and clean sand. In this study, a modified direct shear apparatus that can control temperature was developed. To control interface temperature, a refrigerated/heated circulating bath is connected to channels in the lower shear box and then heated/cooled water is circulated. The interface can be heated/cooled through heat exchange with circulating water. Three series of tests were conducted at various temperatures of 8, 20 and 42 °C and effective normal stress levels of 50, 150 and 300 kPa. The soil specimen was recompacted clayey sand with a 95% degree of compaction. The results indicate that the shear strength of saturated soilstructure interfaces decreases with increasing temperature. This is likely because temperature elevation results in a reduction of interface roughness and a partial increment of void ratio in the shear zone.

Machine-learning based process monitoring for automated composites manufacturing

AbstractAutomated fibre placement (AFP) is an advanced robotic manufacturing technique which can overcome the challenges of traditional composite manufacturing. The interlaminar strength of AFP-manufactured composites depends on the in-situ thermal history during manufacturing. The thermal history is controlled by the choice of processing conditions and improper interfacial temperatures may result in insufficient bonding. Being able to better predict such maintenance issues in real-time is an important focus of smart manufacturing and Industry 4.0 to improve manufacturing operations. The data analysis of real-time temperature measurements during AFP composites manufacturing requires the temperature profiles from Finite Element Analysis (FEA) based simulations of the AFP process to better predict the quality of layup. However, the FEA simulations of the AFP process are computationally expensive. This study focuses on developing a digital tool enabling real-time process monitoring and predictive maintenance of the AFP process. The digital tool constitutes a machine learning-based surrogate model based on results from Finite Element Analysis (FEA) simulations of the AFP process to predict the in-situ thermal profile during AFP manufacturing. Multivariate Linear Regression, Multivariate Polynomial Regression, Support Vector Machine, Random Forest and Artificial Neural Network (ANN)-based models are compared to conclude that ANN based surrogate model performs best by predicting the important parameters of thermal profiles with a mean absolute percentage error of 1.56% on additional test data and reducing the time by four orders of magnitude as compared to FEA simulations. The predicted thermal profile can be compared with the real-time in-situ temperatures during manufacturing to predict the quality of the layup. A GUI application is developed to provide predicted thermal profiles data for analysis in conjunction with real-time temperatures during manufacturing enabling monitoring and predictive maintenance of the AFP process and paving way for the development of a digital twin of the AFP composites manufacturing process.

Atomistic insights into the influence of Y element on the amorphization behavior of dual-phase Mg alloys

Molecular dynamics simulations are performed to investigate the effect of the interface structure, diffusion time and diffusion temperature on the diffusion behavior and amorphization mechanism of the dual-phase Mg alloys. The results indicate that there is a critical concentration of Y element in the amorphous/crystalline interface (ACI), which depends on the interface structure and temperature. And when the concentration of Y atoms in the ACI is higher than the critical concentration, the ACI will migrate towards the crystalline side, accompanied by the amorphization of the crystalline layer. In addition, it is found that the presence or absence of Y element in the amorphous layer has a significant impact on the amorphous layer thickness of the alloys. For the alloys containing Y atoms, the amorphous layer thickness increases with the increase of diffusion temperature and diffusion time.

An embedded machine learning strategy for analyzing interfacial characteristics in impact welding of dissimilar alloys

ABSTRACT In this study, a novel embedded machine learning (ML) framework was employed to analyze interfacial characteristics in dissimilar-alloy impact welding. While keeping the substrates constant, i.e., stainless steel and Ti alloy, the influence of interlayer types on the resultant morphology of impact-welded bonds was also highlighted. The dataset was meticulously generated through numerical simulations, utilizing materials properties and processing parameters as primary inputs. These inputs were used to predict various interfacial features, including the extent of wave formation (L), specific welding zone area (S), average waveform amplitude (A), and maximum interface temperature (Tmax). Impressively, exceptional predictive capabilities were demonstrated by the ML model, with determination coefficients of 0.938, 0.924, 0.967, and 0.909 for S, L, A, and Tmax, respectively. Based on the results, strong dependencies between interfacial features and the weight functions of materials properties and processing parameters were unveiled. Intriguingly, as the weight function of materials properties for a specific output objective increased, a corresponding decrease in the weight function of processing parameter inputs was observed. These findings emphasize the complex connection between input parameters and output characteristics, revealing previously unexplored intricacies in the impact welding process, facilitated by our advanced ML methodology.

Theoretical Analysis on Thermo-Mechanical Bending Behavior of Timber–Concrete Composite Beams

In this study, an analytical approach is introduced for predicting the bending behavior of a timber–concrete composite (TCC) beam subjected to a mechanical load and a non-uniform temperature field, in which the orthotropy of timber as well as interfacial slip are taken into consideration. The analytical model addresses the non-uniform temperature field using Fourier series expansion based on the heat transport theory. The stresses and displacements of the TCC beam under the thermo-mechanical condition are governed by the thermo-elasticity theory, and the corresponding solution is derived analytically by solving a group of non-homogeneous partial differential equations. The proposed solution is in good agreement with the finite element solution and exhibits higher accuracy compared to the Euler–Bernoulli beam solution that relies on the assumption of transverse shear deformation and isotropy. An extensive investigation is carried out to analyze how the bending behavior of TCC beams is influenced by variations in interfacial shear stiffness and temperature field.

Coaxial one-side resistance spot welding for cross-lap joints of Al5052 and CFRP: Thermal process and strength evaluation

Coaxial one-side resistance welding (COS-RSW) is an advanced joining technology for the metal-plastic hybrid structure, which has great application potential in the lightweight design of body-in-white. In the present research, the Al5052-CFRP cross-lap joints were fabricated by COS-RSW with different welding conditions. The author-developed finite element (FE) code JWRIAN-RSW was employed to reproduce the multi-physics coupled phenomena of COS-RSW and predict thermal history. The influence of welding current and welding time on molten zone generation and joining strength was discussed in detail. The results showed that the developed FE model can predict temperature distribution and variation effectively, which were verified by the bonding zone observation and infrared thermal image measurement. Both welding current and welding time had a significant contribution to the Joule heat generation. While their influence on the molten zone growth during heating and cooling stage was distinct. The maximum joining strength of COS-RSW cross-lap joints can reach about 1380 N. The static tensile strength was improved significantly when the maximum interface temperature exceeded 340 °C and the failure mode altered into staged fracture. The strength degradation induced by significant CFRP decomposition was appeared when the predicted interface temperature reached 410 °C. For the COS-RSW joint of Al5052 and CFRP, it was better to improve the joining strength using longer welding time rather than higher welding current, which led to sufficient heat generation, persistent thermal conduction and elongated melting duration for sound joining.

Power law exponents for single bubbles growth in nucleate pool boiling at zero gravity

Nucleate pool boiling is an important boiling mode used in various fields of application. Bubble detachment and new bubble generation at the nucleation site is an important aspect of the process under terrestrial conditions. This sequence prevents prolonged observation of bubble growth phenomena. The problem can be circumvented by performing single bubble growth experiments under zero gravity conditions. Many experiments of this type are performed in a specially designed cell on board the International Space Station. Several combinations of boiling experimental parameters (pressure, heat flux, waiting time, degrees of subcooling) are tested. The bubble size evolution curve was found to represent the influences off the individual parameters best. Fitting attempts show that the experimental bubble growth curves can be nicely described by power law correlations. An analytical solution is given for the evolution of the liquid temperature field within the experimental test cell, in the absence of boiling incidents. It is shown that the time evolving difference between the solid/liquid interfacial temperature and the liquid saturation temperature is the basic factor that determines the bubble growth exponent. As an outcome, the whole experimental information on the bubble growth curves of 160 different boiling conditions is compressed in the form of tables that include the corresponding power law factors. These tables not only allow the reconstruction of the examined boiling curves but can also generate boiling curves in a dense grid of boiling conditions through interpolation of existing boiling data. The latter offers coherence and continuity in boiling computer codes over a broad range of conditions.

Ultra-high pulse pressure induced particle surface thermal field assisted preparation of W–Al composite

Particle surface thermal field (PSTF) is an inhomogeneous thermal field that concentrates the heat effect on the surface of particles, and it can be utilized to fabricate composite materials with large differences in physical properties. However, it is difficult to form PSTF with large temperature gradients to meet the preparation requirement of materials with extreme differences in physical properties. In our work, a PSTF is proposed and realized by an ultra-high pulse pressure (UHPP) to prepare W–Al composite, the PSTF has a heating effect on the powder interface with a low-temperature interior of the powders. The combination of ex-situ microstructural observation and in-situ molecular dynamic simulation microstructural snapshot is used to demonstrate the densification mechanism. The PSTF is characterized as the temperature higher than 1200 °C on the W–Al powders interface but lower than 200 °C interior of the powders. The densification mechanisms are explained as interfacial jet penetration, interfacial friction welding and interfacial melting. In addition, interfacial temperature distribution creating gradient pressure on the W–Al interface illustrated the generation of gradient Al grains on the W surface, thus creating a high mechanical micro-hardness of 249.8 Hv and compressive strength of 473.2 MPa for the W–Al composite.

Investigation of hetero gate oxide hetero stacked triple metal vertical tunnel FET with variable interface trap charges and temperature

The performance of the hetero gate oxide hetero stacked triple metal vertical tunnel FET (HGO-HS-TMG V-TFET) in both dc and analog/RF is examined in this work. GaSb (a low bandgap material) and Si are layered in the source area. The reliability of the device is also examined by analyzing the consequence of interface trap charges (ITC) like donor (positive ITC) and acceptor (negative ITC) at diverse temperature values on DC, analog/RF and linearity performance of the device by dint of Silvaco ATLAS. Simulation shows Shockley-Read-Hall (SRH) phenomena predominate at reduced gate voltage, causing IOFF deterioration that, at high temperatures, results in ION/IOFF degradation. Whereas the band-to-band tunneling (BTBT) phenomenon—which is weakly influenced by temperature changes—is common at high gate voltages. As a result, IOFF degrades at elevated temperatures about a magnitude of 102, going from 10−19 A (200 K) to 10−17 A (400 K). Additionally, at elevated temperature values, it becomes apparent that the cut-off frequency (fT) increases and the threshold voltage (Vth) decreases, which leads to an improvement in device performance. Moreover, ITC alters flat band voltage and gate control, which impacts the device's performance. Device performance is improved when ITC is positive, while it is decreased when ITC is negative.

CFD modelling of the non-isobaric evaporation of cryogenic liquids in storage tanks

A new CFD model relevant to non-isobaric cryogen evaporation has been developed. It considers the heat influx, from the surroundings to the liquid and vapour phases, and the heat transfer between the phases. The phase change is modelled considering two contributions: an interfacial energy balance far from the tank wall, and by direct wall-to-liquid conduction near the wall. The model provides well resolved liquid and vapour temperature and velocity profiles, as well as pressure build-up and evaporation rates. It shows that below the vapour-liquid interface, liquid natural convection is dampened by thermal stratification, which is driven by the increase of the interfacial temperature due to increase in pressure. The pressure build-up is mainly governed by the heating of the vapour, particularly at the beginning of the evaporation. The model was used to analyse liquid velocity profiles for two different sets of experimental data for evaporation of liquid nitrogen by optimizing empirical parameters, namely the wall heat partitioning fraction and the overall heat transfer coefficients. The results show that a large fraction of the vapour heat ingress is not transferred to the vapour phase bulk. Instead, it is transported through the walls and transferred to the liquid at the liquid-vapour-wall contact point, driving phase change. Heat conduction from the walls to the interface has a significant effect, even for low heat fluxes, and cannot be neglected.

Decision Tree-Supported Analysis of Gallium Arsenide Growth Using the LEC Method

In this study, an axisymmetric Czochralski furnace model for the LEC growth of gallium arsenide is presented. We produced 88 datasets through computational fluid dynamics simulations. Among the many parameters that affect crystal growth, a total of 13 input parameters were selected, including the geometry and material parameters of the hot zone (crucible, heaters, radiation shield, and crystal), as well as the process parameters (such as pulling and rotation rates, heating power, etc.). Voronkov criteria (v/Gn), interface deflection, and the average interface temperature gradient were selected as the output parameters. We carried out a correlation analysis between the variables and used decision trees to study the impact of the 13 input variables on the output variables. The results indicated that in the growth of gallium arsenide, the main factor affecting interface deflection and the average interface thermal gradients is the crucible rotation rate. For v/Gn, it is the pulling rate.

Full-field vapor concentration and temperature field measurement of an evaporating ethanol–water binary sessile drop by tomographic laser absorption spectroscopy

Quantitative measurement of full-field, spatially resolved temperature and concentration field of pure water and ethanol–water binary evaporating drop is realized, in which the gas-phase and interfacial temperature and concentration are accurately captured. By studying the vapor field of evaporating drop under different heating temperatures, it is demonstrated that the method can achieve a spatial resolution below 100 μm and a time resolution of <10 s. Simultaneous gas-phase temperature and concentration field measurements reveal the occurrence of buoyancy convection in the gas phase. Through the analysis of interfacial temperature and concentration distribution, it is observed that in the process of pure water drop evaporation, both buoyancy-driven convection and thermal Marangoni convection exist, while in the ethanol–water binary drop evaporation, the solutal Marangoni flow convection and thermal Marangoni convection are coupled, and the buoyancy convection is suppressed. The interfacial temperature and gas-phase water vapor concentration can be obtained from the water vapor measurement, and combined with the activity coefficient models. The liquid-phase mole fraction of water at the interface and its distribution are also obtained, such that the liquid-phase mole fraction distribution of ethanol at the interface can be obtained, and finally, the concentration of ethanol vapor near the interface is obtained. The full-field, high-resolution measurement of evaporated drops is of substantial significance for in-depth understanding of the evaporation process. The measurement of ethanol–water binary drop evaporation provides a new research perception and method exploiting the spectral dimension, providing both quantitative and qualitative observations for the study of multi-component drop evaporation.

Nonequilibrium liquid-vapor interfaces: Linear and nonlinear descriptions.

While it is often assumed that liquid-vapor interfaces in nonequilibrium processes are in states of local thermodynamic equilibrium, this might not be the case for strong deviations from equilibrium. Clausius-Clapeyron equations for bulk properties yield a consistently defined temperature of the interface that is close to the liquid bulk temperature. The alternative interface temperature defined through the surface tension will be different for stronger nonequilibrium processes. Structural variables are introduced to extend the thermodynamic description of interfaces to a wider range of processes. Interfacial resistivities will depend on interface temperature as well as mass and heat flux through the interface.

Development of Computational Approach for Analyzing In-Process Thermal-Mechanical Condition during Friction Stir Welding for Prediction of Material Bonding Defect

Unlike the conventional fusion welding process, friction stir welding (FSW) relies on solid-state bonding (SSB) to join metal surfaces. In this study, a straightforward computational methodology is proposed for predicting the material bonding defects during FSW using quantitative evaluation of the in-process thermal-mechanical condition. Several key modeling methods are integrated for predicting the material bonding defects. FSW of AA2024 is taken as an example to demonstrate the performance of the computational analysis. The dynamic sticking (DS) model is shown to be able to predict the geometry of the rotating flow zone near the welding tool. Butting interface tracking (BIT) analysis shows a significant orientation change occurring to the original butting interface, owing to the material flow in FSW, which has a major impact on the bonding pressure at the butting interface. The evolution of the interfacial temperature and the interfacial pressure at the butting interface was obtained to analyze their roles in the formation of material bonding. Four bonding-quality indexes for quantifying the thermal-mechanical condition are tested to show their performance in characterizing the bonding quality during FSW. When the BQI is below a critical value, a bonding defect will be generated. The paper indicates that the simulation-based prediction of a material bonding defect is highly feasible if the developed methodology is extended to quantitatively determine the critical value of the bonding quality index for successful SSB for various alloys.

Optimizing joint structure and performance in friction spot joining of aluminum alloy AA6061 and poly-ether-ether-ketone (PEEK)

This study investigated the challenge of joining poly-ether-ether-ketone (PEEK) to aluminum alloy AA6061 through friction spot joining (FSpJ), by examining the impact of surface treatment of AA6061 sheets and analyzing various process parameters' effects on joint interface morphology, tensile-shear strength, and failure. Results indicated a peak interface temperature may reach 400 °C during FSpJ, with a 0.5–0.9 mm molten PEEK layer containing sealed bubbles. Notably, Boehmite treatment significantly improved joint strength, although the primary failure occurred in the PEEK base material. An optimization through response surface method (RSM) analysis identified plunging depth as the most influential factor in joint strength, and a peak load of 4576 N with an optimized combination of pin rotation speed, plunging depth, and dwell time was achieved. Using optimized process parameters, strong PEEK-AA6061 joints can be formed, and the approach is extendable to joining other metallic and polymeric materials.

Ultrasonic assisted pecking drilling process for CFRP/Ti laminated materials

Carbon fiber reinforced polymer (CFRP)/titanium alloy (Ti) laminated materials are widely used in aerospace and marine industries because of their excellent physical and electrochemical properties. The extensive demand requires a higher level of hole making technology to reduce the material damage caused by hole making. In this paper, we adopt a novel machining method, which combines Ultrasonic Assisted Drilling (UAD) and pecking drilling to generate a new machining method, Ultrasonic Pecking Drilling (UPD). Based on this, this study compares Conventional Drilling (CD), UAD and UPD in terms of thrust using orthogonal test method. In this paper, CFRP exiting delamination damage is investigated for three processing methods, and indirect measurement of interface temperature as well as detection of CFRP entrance delamination damage are carried out for UPD process. In addition, the tool wear and the exit burr of titanium alloy are analyzed for the three processes under different parameters. The test results show that UPD performed better in terms of thrust, the lowest thrust force is reduced by 35.1 % and 14.8 % at low feeds, respectively. CFRP exit delamination and tool wear are also good compared to both CD and UAD. Compared to CD, the maximum delamination damage decreased by 6.37 %. Besides, UPD results in better hole surface quality, where the roughness can be reduced by up to about 40 %. The obtained results show that UPD is a worthwhile option for drilling CFRP/Ti laminated materials.

A Review on Nanofluids: Synthesis, Stability, and Uses in the Manufacturing Industry

Abstract: Nanofluids are a new class of nanomaterials suspended in a base liquid. Nanofluids have shown extremely distinctive properties that give tremendous opportunities for a wide range of applications. Nanofluids are a novel group of heat transfer fluids that have attracted the attention of researchers from various fields due to their intensive thermal properties. This systematic review highlights the synthesis, stability, physical treatment, and applications of nanofluids in various sectors. Applications of nanofluids in different sectors like the coolant in machinery, cooling of electronics, in chillers, cooling of diesel electronics generators, in a boiler cool gas reductions, and the manufacturing industry. The manufacturing process is one of the most fundamental and well-proven industrial processes in product-based industries. Cutting fluids play a critical function in lowering manufacturing cycle time as well as cutting costs during the machining process. A review of the importance of the machining process, as well as the use of nanofluids as cutting fluids, has been investigated in this work. To achieve these goals, cutting force, surface quality, tool and workpiece interface temperature, tool geometry, and the impacts of environmental situations were studied. Various vital specifications, such as the type of nanoparticle, a cutting tool used, work material type, and machining processes like turning, milling, drilling, and grinding were studied and thoroughly summarised in this work. If the machining parameters were used correctly, a greater heat transfer rate would be observed due to changes in lubricating characteristics and physical parameters.