Thermal Conductivity Resistance Research Articles

Simultaneous measurement of thermal conductivity and interfacial thermal resistance of Sub-10 nm SWCNT bundle via Raman-probing of distinct energy transport states

Simultaneous measurement of thermal conductivity and interfacial thermal resistance of Sub-10 nm SWCNT bundle via Raman-probing of distinct energy transport states

Optimization of silver/graphene composite coating for GIL touch spring based on cyanide-free electroplating technology

Abstract The GIL spring contact finger, as the primary component connecting the units of the Gas Insulated Line (GIL), is subject to displacement over time due to factors such as equipment vibration. This displacement leads to inevitable friction and wear between the contact finger and the current-carrying conductor. Such friction alters the contact state, increasing the contact resistance and subsequently affecting the transmission of electrical power. Additionally, metal debris generated by friction can cause partial discharge inside the GIL equipment, potentially leading to insulation breakdown and significant damage to the equipment. To address this issue, this study proposes the incorporation of graphene into the existing silver-plated layer of the contact finger to improve its wear resistance and optimize its overall performance. A silver/graphene composite coating was prepared using a cyanide-free silver-plating technique based on a thiosulfate system. The coating performance was optimized by varying both the coating thickness and the graphene content. The overall performance of the coatings was evaluated using radar charts, which helped identify the optimal coating parameters. Results indicated that when the cathodic current density ranged from 0.4 to 0.6 A/dm², the coating surface was smooth, the graphene was evenly distributed, and the adhesion was good. Furthermore, when the coating thickness was 10μm and the graphene content was 8.23%, the friction coefficient remained stable around 1, a reduction in contact resistance of approximately 100μΩ compared to pure silver was observed, the hardness increased by 7.08 HV, and the thermal conductivity and corrosion resistance remained largely unchanged. In conclusion, the addition of graphene to the silver coating significantly enhances wear resistance, and an appropriate coating thickness effectively improves the overall performance. The optimal coating parameters, with a thickness of 10μm and a graphene content of 8.23%, meet the performance optimization requirements for the contact finger coating.

Effect of Aloe binder on green properties of dry pressed copper compact: a comparative study

ABSTRACT The present study used Aloe (0–4 wt%) as a binder for dry compaction of copper metal powder. The properties of copper compacts were investigated as a function of compaction pressure (130 MPa, 140 MPa, 150 MPa) and moisture content. The maximum compact density of samples was achieved using 3.5 wt% of Aloe binder at 150 MPa compaction pressure. The maximum achievable green and sintered density of the copper samples was 68.04% and 88.25%, respectively. The corresponding samples exhibited a 4.5-fold and 2.1-fold increase in their green and sintered flexural strength. Copper compacts with the optimal amount of Aloe binder were sufficient for green machining. The density and strength of green compacts were affected by plasticising effect of binder due to functional groups such as hydroxyl (−OH), carbonyl (C=O), and ester groups present in Aloe gel. Samples with the optimal amount of Aloe binder show minimum porosity with negligible residue, as validated by the SEM and thermal analysis. The examined results were compared with the green properties of dry-pressed copper compacts using 0–4 w % polyvinyl acetate binder. Copper has been selected due to its excellent electrical and thermal conductivity and corrosion resistance, making it valuable for electronics, heat exchangers, manufacturing components, etc.

Control of Silver Micro-Flakes Sintering and Connection Properties of Epoxy-Based Conductive Adhesives by the Effectiveness of Binder Chemistry.

Bonding materials with high thermal and electrical conductivity and reliable resistance to thermal stress are required. The authors have been conducting fundamental research on sintering-type bonding, in which metal micro-fillers are low-temperature sintered in the resin-bonded type electrically conductive adhesives (ECAs), as a new bonding technology, with the aim of easing thermal stress through the resin binder. This study investigated the influence of the kind of additive diluent in epoxy-based ECAs containing silver (Ag) micro-flakes on the microstructure development in the adhesives and the connection properties to metal electrodes. As a result, the sintering of Ag micro-flakes was observed to proceed in the adhesive once cured at 150 °C and by post-annealing at 250 °C. Furthermore, the sintering behavior varied greatly depending on the kind and composition of the binder additive diluent, with corresponding changes in electrical conductivity and connection characteristics with metal electrodes. Additionally, electrode surface conditions affected the connection performance. These findings are valuable for designing sintering-type bonding using resin-bonded ECAs, optimizing interfacial interactions between binder chemicals and metals.

Efficiency improvement in silicon and perovskite solar cells through nanofluid cooling using citrate and PVP stabilized silver nanoparticles

This study investigates the enhancement of solar cell efficiency using nanofluid cooling systems, focusing on citrate-stabilized and PVP-stabilized silver nanoparticles. Traditional silicon-based and perovskite solar cells were examined to assess the impact of these nanofluids on efficiency improvement and thermal management. A Central Composite Design (CCD) was employed to vary nanoparticle concentration (0.2–0.8 wt%), coolant flow rate (0.5–1.5 L/min), and solar irradiance (800–1000 W/m²). Efficiency improvements were measured using Ordinary Least Squares (OLS) regression. The experimental setup integrated nanofluid cooling systems with the solar cells, facilitating efficient heat dissipation. Results showed significant efficiency gains: silicon-based cells improved from 15 to 17% with PVP stabilization, and perovskite cells increased from 18 to 21.1%. PVP-stabilized nanofluids exhibited superior thermal conductivity (0.7 W/m K) and lower thermal resistance (0.008 K/W) compared to citrate-stabilized nanofluids, leading to notable reductions in operating temperatures. For silicon cells, temperatures dropped from 50 °C to 40 °C with PVP, and for perovskite cells, from 55 °C to 40 °C. Response Surface Methodology (RSM) identified optimal conditions for maximum efficiency improvement at 0.8 wt% nanoparticle concentration and 1.5 L/min flow rate. These findings underscore the potential of PVP-stabilized nanofluids in enhancing solar cell performance and longevity. Future research should refine the experimental design, increase sample size, and explore other nanoparticle types and stabilization methods to optimize solar cell efficiency and thermal management. This study contributes to the broader goal of promoting the widespread adoption of solar energy as a sustainable alternative to conventional energy sources.

The Utilisation of Coconut Shell (Cocos Nucifera) as a Partial Aggregate Replacement on the Properties of Concrete in Terms of Thermal Behaviour

Green environments or environmentally friendly buildings have increasingly captured the attention of researchers. This concept involves the reuse of waste materials to enhance or create new products. Accordingly, this study aims to investigate the utilization of fine coconut shell (FCS) as a partial substitute for sand, focusing on its applications with varying percentages from 10% to 100% on the properties of concrete in terms of thermal conductivity. The initial phase of the research concentrated on characterizing the properties of fine coconut shell and sand using methods such as sieve analysis, laser diffraction sieve technique, specific gravity tests, bulk density measurements, scanning electron microscopy (SEM), and water absorption tests. Subsequently, the mechanical properties of fine coconut shell in concrete, replacing sand partially, were evaluated through slump tests, compressive strength tests, flexural strength tests, modulus of elasticity tests, splitting tensile strength tests, water absorption tests, and water permeability tests. The second phase of the study focused on exploring the low thermal conductivity applications of fine coconut shell concrete, assessed through thermal conductivity tests (k-value) and thermal resistance (r-value) calculations. Upon collecting data, a relationship analysis was conducted to determine the optimal percentage of fine coconut shell replacement. Using this optimal percentage, wall panels were constructed to assess heat penetration into buildings, and the temperature data was validated using Autodesk Ecotect software. The findings indicated that fine coconut shell particles were finer (≤ 600 μm) compared to sand (4.25 mm - 150 μm). In terms of mechanical properties, concrete containing fine coconut shell as a partial replacement for fine aggregate demonstrated superior performance to normal concrete. Moreover, the thermal conductivity values of specimens containing coconut shell were lower than those of normal concrete. In conclusion, the study determined that replacing 50% of fine aggregate with fine coconut shell was optimal, meeting British Standard requirements and aligning with previous research findings.

Strength and Thermal Properties of Hollow Foamed Concrete Blocks considering Various Parameters

Hot weather is one of the main problems the residential building construction field faces, especially in the southern hemisphere. Therefore, there is an increasing need to produce materials capable of reducing the high temperature impact. These materials should be characterized by thermal insulation properties without, though, their mechanical properties and load resistance being affected. In this research, cuboid and hexagonal hollow concrete blocks were produced from lightweight foam concrete with different hole shapes and a hole ratio of 30%. An analytical study was conducted for 8 models using the ANSYS v16 program, while the compression behavior and thermal performance of the selected models were studied. Ordinary Portland Cement (OPC), water, sand, and foaming agents were deployed in the production of foamed concrete. In addition to the use of admixtures, materials, such as Superplasticizer (SP), Class F Fly Ash (FA), and Silica Fume (SF), were also utilized. Moreover, the effect of the hole’s shape and the method of bonding were studied. The compressive strength of the concrete blocks, bond shear strength, thermal conductivity, and thermal resistance were tested. It was found that the cuboid shape of the hole block H7 was the most acceptable compared to the other shapes, with a compressive strength of 3.75 MPa, thermal conductivity of 0.149 W/m.k, and a bond shear strength of 0.157 MPa. At the same time, it was found that using bonding adhesive material gave the best results, with the cuboid blocks being compared to using mortar and mechanical bonding.

A review of organic phase change materials and their adaptation for thermal energy storage

Organic phase change materials (O-PCMs) such as alkanes, fatty acids, and polyols have recently attracted enormous attention for thermal energy storage (TES) due to availability in a wide range of temperatures and high latent heat values. However, low thermal conductivity and leakage problems during the phase transition of O-PCMs are of great concern. To overcome the long-standing drawbacks of O-PCMs, we critically discussed the preparation techniques of macro encapsulation phase change (MaPCM), microencapsulation phase change materials (MPCM), shape stabilized phase change materials (SSPCM), eutectic phase change materials (EPCM), nano-enhanced phase change materials (NePCM) along with the morphological insights, thermal property enhancements & molecular dynamics (MD) simulation of the prepared composite PCMs. The article also discusses fundamental thermal property increments in phonon interaction, Van der Waals forces of attraction, aspect ratio, thermal conductive path, temperature agglomeration, surfactant effect, and thermal resistance of O-PCMs. The current ongoing review manuscript consolidates the variation in thermal properties with different concentrations of nanoparticles, considering the variety of references to provide valuable insight to the researchers. Carbon-based nanoparticles dispersed with the O-PCMs are the best way to reduce the low thermal conductivity problem. The π-π stack interaction between the O-PCMs and the nanoparticles decreased the leakage problems of O-PCMs during encapsulation and shape stabilization. The authors observed that the highest increment in the thermal conductivity and the latent heat of the OPCMs is 1008.33% and 60%, respectively. Finally, the present review provides a new vision and draws more attention to the material reliability of O-PCMs-based applications in the future, particularly regarding TES.

Harnessing the potential of coal-derived graphene oxide/epoxy nanocomposites: Enhancing thermal conductivity and fracture toughness

The choice of precursor material significantly influences the properties of graphene oxide (GO), thereby providing its adaptability across diverse applications. Coal, with its distinctive molecular structure characterized by graphene-like domains and aliphatic side chains, as well as abundant impurities and heteroatoms featuring specific functional groups, emerges as a promising precursor. Employing a recently developed facile one-pot process for synthesizing semianthracite coal-derived GO (AC-GO), we have, in this study, explored its potential as a nanofiller in an epoxy matrix, resulting in AC-GO-enriched nanocomposites. The main purpose of the project was to introduce AC-GO within the epoxy matrix to enhance its thermal conductivity and fracture resistance by enhancing interfacial interactions. Our findings indicate remarkable enhancements in thermal conductivity (0.646 Wm-1K-1 at 1.0 wt% loading) and fracture toughness (6.7 MPam1/2 at 0.8 wt% loading) within AC-GO loaded nanocomposites, with these improvements being 255 % and 215 %, respectively, over those for the epoxy matrix. Remarkably, they surpass those achieved with graphite-derived GO (Gr-GO) by approximately 112 % and 76 %, respectively. Enhancing thermal conductivity and fracture toughness in epoxy nanocomposites is vital for effective heat dissipation and durability, making them ideal for high-performance electronics, aerospace, and automotive applications. These improvements can be attributed to the enhanced interactions between oxygen moieties located at the periphery of AC-GO and the fundamental epoxy-amine hardener system within the resin formulation, fostering electron acceptor–donor interactions. Furthermore, we introduce a new figure of merit (FOM) that accurately captures the combined role of thermal conductivity and fracture toughness. It is shown that this FOM can serve as a useful design tool for selecting an optimal nanofiller loading for targeted applications. The findings of our paper highlight the versatility and unique attributes of AC-GO, offering promising opportunities for applications in the industrial engineering, owing to their outstanding interfacial properties.

Atmospheric Corrosion of Aluminum and Aluminum/Gold Thin Films

Aluminum and its alloys are extensively utilized in various applications due to their high thermal and electrical conductivity and inherent resistance to corrosion, primarily due to the formation of a protective oxide layer. However, the strength, durability and electrical properties of many aluminum-based materials and aluminum/gold contacts tend to diminish in humid environments. Therefore, a thorough understanding of the mechanistic aspects of atmospheric corrosion reactions over time in pure Al and galvanic Al/Au couples is crucial for predicting degradation and optimizing performance. Presently, much of our knowledge regarding atmospheric aluminum corrosion is derived from empirical correlations based on extensive corrosion data, typically involving a simplistic relationship between corrosion rates and environmental factors. However, the mechanistic understanding of corrosion processes, particularly during in the presence of electrolytes like sodium chloride found in the environment is not fully elucidated.Here we propose a new surface approach to obtain mechanistic insights into atmospheric corrosion of Al and Al/Au thin films in the presence of NaCl. The corrosion rate is investigated through a combination of experimental and theoretical approaches, correlating corrosion kinetics with electrolyte chemistry, mass changes, and corrosion byproducts. Quartz crystal microbalance with dissipation (QCM-D) electrodes coated with aluminum and aluminum/gold contacts and sodium chloride serve as the experimental platform. The structure, composition, and surface morphology of the samples are analyzed using various techniques including grazing-incidence X-ray diffraction, FTIR spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, transmission electron microscopy, and electron energy loss spectroscopy. Operando data with nanogram resolution provided by the QCM-D technique allows real-time monitoring of corrosion product formation, facilitating the derivation of rate constants for corrosion surface reactions. It is observed that the reaction rate in dry air is negligible, but a significant acceleration occurs at relative air humidity levels of 50% and above. Additionally, this study delves into the impact of sodium chloride on the corrosion rate and reaction products, the influence of surface termination on aluminum oxide/hydroxide formation, and the temperature-dependent acceleration of electrochemical corrosion rates. Finally, by integrating theoretical insights with experimental findings, preliminary understanding of the rate-limiting steps has been achieved, paving the way for the development of validated computational models to simulate early-stage atmospheric corrosion processes.

(Corrosion Division H. H. Uhlig Award) The Remarkable Versatility of Copper: From its Corrosion Resistance to Antibacterial Properties

Copper is one of the most important metals known from the prehistoric Copper Age and is still essential to our everyday lives and industrial applications today. Its remarkable properties include high ductility, malleability, thermal and electrical conductivity, mechanical strength, corrosion and biofouling resistance, fungicide and antibacterial properties. Copper is non-magnetic and easily alloyed with other metals, forming hundreds of copper alloys. It is one of the critical alloying elements of other alloys, increasing strength and facilitating precipitation hardening. In addition, copper is an essential nutrient in the human body. This lecture will explore through the many faces of copper, and selected examples of our studies will be presented, concentrating on three aspects: i) the corrosion resistance of copper and its alloys, ii) the role of copper-containing intermetallics in aluminium alloys, and iii) the role of copper-containing phases in titanium alloys (Figure 1).1.) The corrosion resistance of copper in neutral and slightly alkaline solutions is based on forming a duplex layer containing an inner cuprous and outer cupric oxide layer. The oxide's thickness and structure depend on the electrode potential, electrolyte, and the presence of aggressive anions, such as chloride, which initiates pitting corrosion. Corrosion inhibitors are commonly used to protect copper alloys. Our experimental studies on organic inhibitors include about thirty formulations based on azoles, benzimidazoles and mercapto-based compounds. Various functional groups were explored; some were pinpointed as efficient, while others were not. One approach to address the challenges of poor or moderate inhibition is to search for synergistic combinations of inhibitors.2.) In contrast to copper alloys, which are homogeneous mixtures, aluminium alloys are heterogeneous, consisting of numerous intermetallic particles (IMPs), constituent particles and phases. Such systems generally exhibit selective dissolution in aggressive solutions, with Cu-based particles as one of the main culprits for initiating this process. Dealloying Mg and Al from IMPs leads to Cu enrichment, thus contributing to a stronger cathodic character and intensive dissolution of the surrounding aluminium matrix. The mitigation of selective dissolution was tackled in our studies using rare earth, zirconium and chromium conversion coatings, sol-gel coatings and their combinations.3.) Finally, the role of copper as an antibacterial agent is considered. The scientific challenge is to develop a new class of alloys for implants with long-term inherent antibacterial ability to reduce implant infection rates without jeopardising other biomaterial properties. Using novel additive manufacturing technology, modifying Ti-6Al-4V alloy by adding copper is possible. Scientific challenges include developing the Ti-6Al-4V-xCu alloy with an optimised content of copper, appropriate microstructure, minimum porosity and defined roughness, suitable mechanical properties, high corrosion resistance, antibacterial activity against clinically relevant bacterial strains and biocompatibility.Studying copper's corrosion and corrosion protection mechanisms and other functional abilities remains challenging in future research.Figure 1: Images of copper corrosion in slightly alkaline solutions containing (a) iodide, (b) fluoride and (c) corrosion products formed in the presence of chloride ions. (d) Corrosion of Cu-based intermetallic particles in aluminium alloy in sodium chloride solution. (e) Microstructure of additively manufactured Ti-6Al-4V-xCu alloy. Figure 1

Homeostatic Microfiber-Composed Synthetic Leathers with Chemical Robustness and Undercooling Self-Regulation.

Homeostatic microfiber leathers with temperature self-regulation promise broad applications, ranging from the apparel and automotive interior industries to the home furnishing and healthcare industries. Temperature self-regulation is achieved by phase-change materials containing microcapsules introduced within the leathers. The introduction of phase change microcapsules (PCMs) into microfiber leather faces two formidable challenges: (1) the shell of microcapsules must remain chemically stable against alkalis and organic solvents; (2) PCMs possess the ability to reduce supercooling during which latent heat is released, allowing for the precise and controllable release of latent heat. Here we present a high-performance homeostatic microfiber-composed synthetic leather containing PCMs that can address these two challenges, which not only demonstrate exceptional chemical robustness under alkaline conditions but also offer efficient and precise control over temperature fluctuation and latent heat release by reducing supercooling. Titanium carbide (TiC) known for its high thermal conductivity and alkali resistance has been selected as the shell material for the microcapsules, which can effectively resolve chemical stability issues. Meanwhile, the high thermal conductivity of TiC can be leveraged to enhance heterogeneous nucleation, thus narrowing the temperature range for latent heat release. The resultant microfiber leather shows outstanding capabilities for adjustable thermal energy storage. Our studies offer an effective approach to create homeostatic microfiber-composed synthetic leathers with chemical robustness and undercooling self-regulation, which would be useful in the fields of the textile, biomedical, and healthcare industries.

Novel ultralight carbon foam reinforced carbon aerogel composites with low volume shrinkage and excellent thermal insulation performance

Lightweight carbon aerogels are attractive for thermal insulation due to their low thermal conductivity and excellent high-temperature resistance under extreme environments. However, the preparation of monolithic carbon aerogels from phenolic resin precursor always faces the problem of large volumetric shrinkage during the drying and carbonization processes, thus resulting in the increasing density and thermal conductivity of aerogels. Here, to solve such issues, ultralight and rigid carbon foam was designed and synthesized as the reinforcement to fabricate carbon aerogel composites (CACs), which could significantly enhance the shrinkage resistance of monolithic carbon aerogels. The high rigidity of the carbon foam reinforcements (CFRs) was achieved through a pre-carbonization process, which also endowed the CFRs with a matched shrinkage with the monolithic carbon aerogels. As a result, the obtained CACs reinforced by the rigid CFRs showed not only crack-free structures, but also quite low shrinkage, which was about 5.9 % after carbonization. The low shrinkage of CACs then endowed them with quite low density (21.5 mg cm−3) and excellent thermal insulation performance (25.9 mW m−1 K−1). Furthermore, due to a highly rough nanostructure, the CACs also possessed outstanding hydrophobicity. These merits make the CACs a promising thermal insulation material even in humid environments.

Conformal cooling channels with composite layers

ABSTRACT Conformal cooling channels (CCCs) are a cooling method used in injection molding. According to the literature review, CCCs can reduce cooling time by 2%–70%, with the average reduction being 30%, and they can improve warpage by 5%–90%, with the average improvement being 37%. But the present study found that previous research has ignored the effect of the solidified skin layer in CCCs. This study posits that during the design of cooling channel positions, the plastic solidified layer exhibits distinct thermal properties. Heat transfer involves conduction thermal resistance, which affects the effectiveness of heat conduction. Ignoring the solidified layer can lead to inaccurate predictions of cooling channel positions. Accordingly, this study developed a novel calculation formula for determining the cooling channel positions while considering the existence of the solidified layer, leveraging the concept of steady one-dimensional conduction in composite layers. The results of this study indicated that in the uniform-thickness scenarios, optimal cooling efficiency and quality were obtained when the thickness of the solidified layer was 0.10 mm. However, in the variable-thickness scenario, the cooling efficiency decreased by approximately 2%. Regarding quality, higher deformation control in three dimensions but poorer warpage control in the z-dimension was observed.

Corrugated veneer panel thermophysical properties

The article substantiates the need to develop new mechanisms for the hardwood use in modern conditions of Republic of Karelia timber industry. One of the potential uses of birch wood in wooden house construction is building materials production from veneer and slab materials based on it. A large amount of associated waste from processing birch wood into veneer stands out as one of the key problems. A new slab joinery and construction material made of corrugated birch veneer is considered. The purpose of this study is to evaluate the thermophysical properties of a corrugated board made of birch wood. To achieve this goal, the tasks and methods of research are defined. An experimental device has been developed to conduct an experiment to determine the values of thermophysical characteristics. DS18B20 temperature sensors were used to measure the surface temperature, as well as to monitor device operation and the room air temperature. The sensors are connected to the Arduino microcontroller platform, which was used to record and transmit sensor readings. Additionally, the course of the experiment was monitored using a thermal imager Testo 875-1i. During the experiment, more than 1000 measurements were carried out. As a result of data processing, a diagram of the dependence of the density of the heat flux passing through the sample on time, as well as diagrams of the dependence of thermal conductivity and thermal resistance on the temperature difference on the sample surfaces, was obtained. The diagrams show the regression dependences of changes in heat flux density, thermal conductivity and thermal resistance during measurements. The values of the heat flux density, thermal conductivity coefficient and thermal resistance calculated on the basis of regression equations and the values obtained experimentally are determined. The directions of further research of the material under consideration are determined.

Improving thermal conductivity of phthalonitrile composite through constructing three-dimensional graphene networks and interfacial engineering

Achieving high thermal conductivity for polymer composite with low filler loading is still a challenge. Here, phthalonitrile (APN)/few-layer graphene (FLG) composite with high thermal conductivity was successfully prepared by constructing three dimensional (3D) thermally conductive pathways. Such 3D structure was formed by hot compressing APN@FLG core-shell structures. The results showed that the thermal conductivity of APN@FLG composites with only 30 wt% of FLG was up to 11.4Wm−1K−1, which was 57 times to that of the pristine resin (0.2 Wm−1K−1). Such high thermal conductivity was attributed to the 3D connected thermally conductive networks. Furthermore, benefited from the high thermal stability of APN matrix, the as-prepared composite also showed high T5 (temperature of mass losing 5 %) of higher than 500 °C. The composite with both high thermal conductivity and heat resistance are expected to be an idea candidate for high temperature thermal management applications.

A detailed optical thermo-electrical model for better thermal analysis of bifacial PV systems

Converting sunlight into electricity through photovoltaic (PV) technology is an effective solution to address the challenges of energy shortage and environmental protection. Bifacial (bPV) is a new type of solar cell that has advantages over monofacial (mPV) generation in that it can receive energy from both sides and produce more electrical energy, which has given rise to hope for PV. Thermal analysis, optical and electrical analyses are essential for bPV modeling. As temperature increases, the performance of a solar module decreases. The purpose of this study is to evaluate the performance of a 550 W bPV panel in Tehran, Iran through optical, thermal, and electrical evaluations. In addition to the produced power and bifacial gain for the electrical measurement of the panel and comparing it with the mPV, thermal resistance has also been studied to investigate the importance of conductive, convective, and radiant heat transfer. It was discovered that the bPV produces 13.90 % more energy per year than the mPV. In terms of heat transfer, radiative thermal resistance contributes 63.08 % while conductive thermal resistance contributes only 0.57 %. This exhibits that the solar panel can be viewed as an integrated layer to simplify modeling.

Optimization of polishing fluid composition for single crystal silicon carbide by ultrasonic assisted chemical-mechanical polishing

Silicon carbide (SiC) is renowned for its exceptional hardness, thermal conductivity, chemical stability, and wear resistance. However, the existing process is difficult to meet the high standards of uniform corrosion in its polishing process and surface roughness and flatness after polishing, new polishing fluids and technique optimization are crucial for development. The study optimized and validated the composition of the polishing fluid used in ultrasonic-assisted chemical-mechanical polishing (UACMP). Abrasives significantly influenced the material removal rate (MRR) and surface roughness (Ra), contributing 67.63% and 56.43%, respectively. Organic bases and pH buffers significantly affected Ra, accounting for 19.66% and 21.44%, respectively. The optimum composition was determined, consisting of triethylamine (3wt%), potassium hydrogen phthalate (1wt%), a composite of silica and alumina abrasive particles (5wt%), and hydrogen peroxide (6wt%), which reduced the Ra from 95 nm to 3 nm. The MRR achieved 25.96 nm/min. In comparison to the 7 nm minimum roughness from the orthogonal test, the optimal scheme’s Ra was reduced by 57.14%, leading to a significant enhancement in overall surface quality. In this paper, a new type of additive is added to prepare the polishing liquid, which provides a new idea for the UACMP of SiC and has a great impact.

Comparison between new enhanced thermal response test methods for underground heat exchanger sizing

For the efficient design and implementation of a Ground Source Heat Pump (GSHP) system, the local subsoil stands as the core element. Alongside the conventional Thermal Response Test (TRT), recent research has developed improved approaches that garner more detailed information about ground thermal properties. One such technique is the fiber optic-based distributed thermal sensing. It relies on copper wires to thermally stimulate the ground, while optical fibers collect temperature variations over time along the cable. Another pioneering technology, the enhanced GEOsniff (produced by enOware GmbH), enables high-resolution, spatially-distributed representation of subsoil thermal properties along the Borehole Heat Exchanger (BHE) via wireless data transmission. This study compares and discusses data acquired through these two innovative techniques at the new campus for the humanities of the University of Padova, situated in Northern Italy's Eastern Po river plain. The findings are further juxtaposed with conventional TRT results, in terms of thermal conductivity and borehole thermal resistance. The thermal conductivity vertical profiles are also compared with direct measurements conducted on samples. These advanced techniques show promise in aiding the optimization of borehole length design, particularly in geological settings of heightened complexity.

Photothermal Infrared Radiometry and Thermoreflectance-Unique Strategy for Thermal Transport Characterization of Nanolayers.

Thermal transport properties for the isotropic and anisotropic characterization of nanolayers have been a significant gap in the research over the last decade. Multiple studies have been close to determining the thermal conductivity, diffusivity, and boundary resistance between the layers. The methods detailed in this work involve non-contact frequency domain pump-probe thermoreflectance (FDTR) and photothermal radiometry (PTR) methods for the ultraprecise determination of in-plane and cross-plane thermal transport properties. The motivation of one of the works is the advantage of the use of amplitude (TR signal) as one of the input parameters along with the phase for the determination of thermal parameters. In this article, we present a unique strategy for measuring the thermal transport parameters of thin films, including cross-plane thermal diffusivity, in-plane thermal conductivity, and thermal boundary resistance as a comprehensively reviewed article. The results obtained for organic and inorganic thin films are presented. Precise ranges for the thermal conductivity can be across confidence intervals for material measurements between 0.5 and 60 W/m-K for multiple nanolayers. The presented strategy is based on frequency-resolved methods, which, in contrast to time-resolved methods, make it possible to measure volumetric-specific heat. It is worth adding that the presented strategy allows for accurate (the signal in both methods depends on cross-plane thermal conductivity and thermal boundary resistance) and precise measurement.