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In recent years, attention to the realization and characterization of wetsuits for scuba diving and other sea sports or activities has increased. The research has aimed to establish reliable and standardized measurement methods to objectively assess wetsuit quality, particularly focusing on their mechanical and thermal properties. In this work, we describe and compare two different measurement methods for the characterization of neoprene wetsuit thermal resistivity. The first method follows the existing regulations in the field, while the second one, which we are originally proposing in this paper, offers an alternative yet accurate way based on a simplified experimental set-up and easier measurements. In both cases, the wetsuit sample under testing was shaped in the form of a cylindrical sleeve of proper dimensions and wrapped around a phantom containing water at a higher temperature and surrounded by water at a lower temperature. The wetsuit's cylindrical surface allows heat flow from the warmer water on the inside to the colder water on the outside through the wetsuit area. In the first case, a thermal steady state was achieved, with constant heat flow from the phantom to the exterior. This was obtained with a power balance between two homogenous quantities. Electrically supplied thermal heating within the phantom was used to balance the thermal energy naturally flowing through the wetsuit's surface. In this first case, a stable and fixed temperature difference was obtained between the inner and the outer surfaces of the wetsuit sample. In the second case, a thermal transient was analyzed during the cooling process of the phantom, and the thermal time constant was measured, providing the sample thermal resistance once the phantom thermal capacity was known. In both cases and methods, the heat flow and thermal resistance of other elements than the wetsuit must be evaluated and compensated for if they are not negligible. Finally, the thermal resistivity per unit area of the wetsuit material was obtained with the product of the wetsuit sample's thermal resistance and the wetsuit area. The measurements, conducted until now by immersing the phantom in a free surface tank, show that both methods—under stationary and under transient temperature conditions—were valid to assess the wetsuit's thermal resistivity. The stationary method somehow provided better accuracy while involving less well-known parameters but at the expense of a more complicated experimental set-up and additional energy consumption. The transitory method, on the other hand, is quite easy to implement and, after careful characterization of the phantom's parameters, it provided similar results to the stationary one. An uncertainty budget was evaluated for both methods, and they did provide highly compatible measurement results, with resistivity values of 0.104(9) m2·K/W (stationary method) and 0.095(9) K·m2/W (transient method) for the same wetsuit sample under testing, which is also consistent with the values in the literature. We finally propose that the novel method is a valid alternative for characterization of the thermal insulation properties of a scuba diving wetsuit. [ABSTRACT FROM AUTHOR]

This study investigates the thermal conductivity (λ) and volumetric heat capacity (C) of sandy soil samples under a variety of conditions, including freeze-thaw cycles at temperatures both above and below zero and differing moisture levels. To estimate these thermal properties, a novel predictive model, EFAttNet, was developed, which utilizes custom-designed embedding and attention-based fusion networks. When compared to traditional de Vries empirical models and other baseline algorithms, EFAttNet demonstrated superior accuracy. Preliminary measurements showed that λ values increased linearly with moisture content but decreased with temperature, whereas C values exhibited a rising trend with both moisture content and freezing temperature. Following freeze-thaw cycles, both λ and C were positively influenced by moisture content and freezing temperature. The EFAttNet-based model proved highly accurate in predicting thermal properties, particularly effective at capturing nonlinear relationships among the influencing factors. Among these factors, the degree of saturation had the most significant impact, followed by the number of freeze-thaw cycles, subzero temperatures, porosity, and moisture content. Notably, dry density exerted minimal influence on thermal properties, likely due to the overriding effects of other factors or specific soil characteristics, such as particle size distribution or mineralogical composition. These findings have significant implications for construction and engineering projects, especially in terms of sustainability and energy efficiency. The demonstrated accuracy of the EFAttNet-based model in estimating thermal properties under various conditions holds promise for practical applications. Although focused on specific soil types and conditions, the insights gained can guide further research and development in managing soil thermal properties across diverse environments, thereby enhancing our understanding and application in this field. [ABSTRACT FROM AUTHOR]

Lunar meteorites are the most diverse and readily available specimens for the direct laboratory study of lunar surface materials. In addition to informing us about the composition and heterogeneity of lunar material, measurements of their thermo‐physical properties provide data necessary to inform the models of the thermal evolution of the lunar surface and provide data on fundamental physical properties of the surface material for the design of exploration and resource extraction hardware. Low‐temperature data are particularly important for the exploration of low‐temperature environments of the lunar poles and permanently shadowed regions. We report low‐temperature‐specific heat capacity, thermal conductivity, and linear thermal expansion for six lunar meteorites: Northwest Africa [NWA] 5000, NWA 6950, NWA 8687, NWA 10678, NWA 11421, and NWA 11474, over the range 5 ≤ T ≤ 300 K. From these, we calculate thermal inertia and thermal diffusivity as functions of temperature. Additionally, heat capacities were measured for 15 other lunar meteorites, from which we calculate their Debye temperature and effective molar mass. [ABSTRACT FROM AUTHOR]

The growing interest of human skin thermal properties is motivating the development of new instruments, either by contact or by remote sensing. In this work, we show the ability of a skin calorimeter to monitor the temporal evolution of the heat capacity and the equivalent thermal resistance of the skin, in two small skin lesions. The first one consists of a forehead wound of 10 × 2 mm2. The other injury consists of a second degree burn on the volar wrist area, of 10 × 20 mm2. We studied the temporal evolution of the thermal properties of both injuries. The variation of heat capacity was significant. For first injury, heat capacity decreased by 21% and full recovery was achieved after ten days. For the second case, the heat capacity decrease was 55% and recovery was achieved after 3 weeks. These skin recoveries are monitored by the measured heat capacity value. The returning of the heat capacity to its normal value coincides with the recovery from the injury. [ABSTRACT FROM AUTHOR]

The use of iron waste in concrete is now of considerable importance, mainly because of the benefits for the environment and for improving the strength of concrete. The increased and unused of this industrial byproducts represents a challenge for the environment and human health. This article experimentally explores the influence of utilizing iron powder waste and iron fibers in concrete in order to enhance the thermophysical properties of concrete and reduce the environmental impact resulting from iron waste. The aim of this work is to study the thermophysical properties (thermal conductivity, volumetric heat capacity, thermal diffusivity and thermal effusivity) of concrete with waste iron powder and iron fibers for application in building construction. The iron powder waste was added to the concrete with different percentages of 0%, 5%, 15%, 20% and 25% respectively as a partial replacement of sand. The iron fibers were added with mix proportions including 1.0%, 1.5%, 2.0% and 2.5% by volume of concrete, and in two different arrangements, uniform and random. The thermal conductivity and the volumetric heat capacity of these samples were measured experimentally in the dry state at ambient temperature (20 °C), and at 28 days of age. The effect of the integration of iron powder and fiber on thermal properties was analysed. [ABSTRACT FROM AUTHOR]

Advanced electronics technology is moving towards smaller footprints and higher computational power. In order to achieve this, advanced packaging techniques are currently being considered, including organic, glass, and semiconductor-based substrates that allow for 2.5D or 3D integration of chips and devices. Metal-core substrates are a new alternative with similar properties to those of semiconductor-based substrates but with the added benefits of higher flexibility and metal ductility. This work comprehensively compares the thermal properties of a novel metal-based substrate, molybdenum, and silicon and fused silica glass substrates in the context of system-on-foil (SoF) integration. A simple electronic technique is used to simulate the heat generated by a typical CPU and to measure the heat dissipation properties of the substrates. The results indicate that molybdenum and silicon are able to effectively dissipate a continuous power density of 2.3 W/mm2 as the surface temperature only increases by ~15 °C. In contrast, the surface temperature of fused silica glass substrates increases by >140 °C for the same applied power. These simple techniques and measurements were validated with infrared camera measurements as well as through finite element analysis via COMSOL simulation. The results validate the use of molybdenum as an advanced packaging substrate and can be used to characterize new substrates and approaches for advanced packaging. [ABSTRACT FROM AUTHOR]

The rapid development of micro-electronics has a growing demand on the heat dissipation performance of devices, especially thermal management materials. However, recent researches focus on the improvement of single ability, such as thermal or mechanical properties. Herein, a strategy that simultaneously improves thermal and mechanical performance of thermal manager material was proposed, which was achieved by preparing Cu-SiC w composites via the co-electrodeposition technology. The influence of electroplating parameters, such as temperature, current density and reinforcement contents, on the microstructure evolution, mechanical and thermal conductivity were investigated systematically. The fabricated SiC w composite displayed excellent shear strength up to 420 MPa, which is resulted from the Orowan strengthening and load transferring. Additionally, the thermal conductivity of 340 W/(m·K) was obtained, owing to the uniform distribution of whiskers and good interface between the Cu matrix and whiskers. Therefore, the presented work provided an effective method for fabricating comprehensive thermal-mechanical properties and homogeneous heat dissipation capacity Cu-SiC w composites and paved the way for the practical application in the field of the connector between the power devices and heat sinks. [ABSTRACT FROM AUTHOR]

The most important thermal and rheological properties of water-based CaCO3/SiO2 dual hybrid nanofluid (DHNF) at overall volumetric concentrations of the nanoparticles from 0.1 to 0.5 and different volume fractions at temperatures of 15–60 °C have been studied. Prepared DHNFs consisted using SDS and ultrasonic homogenizer. Stability analysis of the DHNFs performed by changing ultrasonication time and power. The optimum consistency conditions and volume fractions of the nanoparticles determined for the prepared DHNFs. Specific heat capacity, thermal conductivity and resistivity, usual viscosity and density of the DHNFs studied, experimentally, compared with preexisting models, and finally, theoretical models with 99% precisions suggested. Maximum augmentation in thermal conductivity attained to 21.8% for 80:20 corresponding volume ratio and 0.5 vol% total concentration. At these conditions, maximum reduction in heat capacity occurred as 1.08%, and the greatest reduction in thermal resistivity got about 22.2% at 60 °C. Usual viscosity and density increased as 36.9 and 1.2%, respectively. [ABSTRACT FROM AUTHOR]

Transient vehicle dynamics are deeply affected by the spatial distribution of tire temperature, heat generation, and heat dissipation capacity. However, the tire testing process involves numerous parameters, adding the complexity to monitoring the tire's thermal properties variation. To address this issue, this paper proposes a data-driven framework that combines the well-known Magic Formula with scaling factors and a long- and short-term memory (LSTM) neural network. The framework forecasts tire thermal properties and functionality under given conditions by learning from time-series data on tire operating conditions and mechanical characteristics. It predicts future spatially varying thermal properties of the tire, including temperatures, heat generation, and heat dissipation. This is achieved with a high degree of forecasting ability quantified by train size/test size ratios equaling 22 and 38% with an impressive Relative Root Mean Square Error (RRMSE) around 1−2%. Here, this framework is applied to quantify the impacts of various operating conditions, including vertical load, slip angle, and vehicle speed, on heat transfer for three crucial radial positions on the tire. Our results show that the vertical load is the primary influencing parameter among all operating conditions. The knowledge about transient tire dynamics will be advantageous to their performance optimization. [ABSTRACT FROM AUTHOR]

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As ceramics based on magnesium aluminum oxynitrides solid solutions are promising materials as refractories, windows/armors, phosphors, and so forth, it is essential to explore their thermal and thermomechanical properties, owing to the physical requirements on application. In this study, Mg5xAl23−5xO27+5xN5−5x were chosen for the investigation on composition‐dependent thermal and thermomechanical properties by the theoretical calculations. Though the binary system with octahedral bonds contributes more to the thermal expansion coefficient of Mg5xAl23−5xO27+5xN5−5x, the binary system with tetrahedral bonds plays an important role in the variation of the thermal expansion coefficient. The change of heat capacity with the rise of x is mainly attributed to the variation of covalent character of Mg5xAl23−5xO27+5xN5−5x. Moreover, the thermal conductivity is mainly affected by the scattering from atoms in 8a sites. Both thermal and mechanical properties contribute to the variation of thermomechanical properties of Mg5xAl23−5xO27+5xN5−5x. This study can provide guidance to designing spinel materials with desirable thermal and thermomechanical properties for application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Upcycling materials were produced composite using clothing waste and PCMs. • Clothing waste, without sorting, was utilized in specimens via a physical process. • The composites demonstrated enhanced latent heat storage capacity. • Clothing waste is valuable for building due to its high insulation. The current volume of clothing waste reached 115 million tons in 2021 and is projected to increase to approximately 150 million tons by 2030. This significant surge in clothing waste has prompted heightened discussions regarding environmentally friendly recycling methods. Clothing presents complex properties, posing substantial challenges to recycling and usually resulting in environmental pollution when disposed. In this study, our recycling approach capitalizes on the differing melting points of textiles. This transformation was achieved through a physical process that included an opening procedure and high temperature heat compression. Textile materials exhibit exceptional thermal properties. Through experimentation on 50 g fiber specimens, thermal conductivities similar to commercial insulation materials were observed, registering an average of 0.0592 W/m·K at 20 °C and 0.06053 W/m·K at 40 °C. This study explores the impregnation of phase change materials (PCMs) into clothing waste-based specimens, equipping them with heat storage capabilities. During the experimental phase, we employed three distinct types of PCMs to evaluate their thermal properties and heat storage capacities in relation to their respective melting temperatures. Through thermal properties analysis, we determined the latent heat capacity of each specimen, ranging from a minimum of 6.63 J/g to a maximum of 75.81 J/g. Our observations indicated a reduction in peak temperature and time-leg effects attributable to the use of PCMs for surface heat flow. This research underscores the superior thermal performance of construction and building materials derived from clothing waste, enhanced by the integration of PCMs, when compared to traditional materials and other waste-derived alternatives. [ABSTRACT FROM AUTHOR]

This study introduces a novel (Al0.8Si0.2)100−xBix (x = 1, 2, 3, 4, and 5 at.%) phase change energy storage alloy, showcasing high heat capacity for energy regulation and heat management applications. We investigated the influence of Bi content on the alloy’s microstructure, thermal properties, high-temperature stability, and container compatibility using optical microscopy, DSC, XRD, SEM, and EDS. Adding 4 wt.% Bi significantly refines the microstructure, evidenced by reduced eutectic silicon size and increased grain boundaries. The (Al0.8Si0.2)96Bi4 alloy achieved a maximum enthalpy change of –397 J g−1 and exhibited phase change temperatures of 500–600◦ C, suitable for diverse high-temperature applications. The phase composition remained stable after 100 thermal cycles at high temperatures. Static corrosion tests at 560◦ C for 240 h revealed enhanced compatibility with SS304 containers, attributed to a dense oxide layer formed by accelerated Cr and Ni atom diffusion through increased grain boundaries. This layer effectively prevents further diffusion of Al and Fe atoms, demonstrating the alloy’s improved suitability for practical applications. [ABSTRACT FROM AUTHOR]

In this work, the thermoforming potential of PS/perlite composites was investigated. Compositions with amounts of 10% and 20% of the mineral filler were processed in a twin-screw extruder with two different screw configuration profiles, followed by compression molding. The influence of perlite content and screw configuration profiles on the flow behavior and heat capacity of the composites was evaluated through morphological, rheological, and thermal properties. The micrographs indicated that most of the perlite broke during the processing and the ones that remained intact were not bigger than 50 µm. The rheological assessment and the evaluation were decisive for the thermoforming properties characterization. The most pronounced elastic behavior identified for the composite processed in low shear conditions and with higher perlite content (P(20%wt)2:2), even in the fragments form, indicated that this composite was the one with the highest potential thermoforming. The low heat capacity value identified for P(20%wt)2:2 composite when compared to the neat-PS:2:2 reinforced that this was the most suitable composite for thermoforming considering its rapid cooling capability after molded. [ABSTRACT FROM AUTHOR]

Conducting in-situ measurements of planetary environments is a key scientific goal in the geoscience field for the extraterrestrial exploration, such as the Moon or Mars. Among these measurements, determining the thermal properties of regolith is particularly challenging due to the material's inhomogeneities. In this paper, an active thermal probing technique is proposed, utilizing a transient hot-wire technique with a needle-like probe structure integrated with temperature sensors and a heater. It is capable of measuring in-situ temperature variations and inner heat flux without disturbing the surrounding regolith. In addition, a machine-learning-based method is proposed for inverting in-situ thermophysical properties, including density, thermal conductivity, and heat capacity. An embedded artificial neural network model has been developed and trained with data sets from both finite element simulations and experiments. This machine learning model is capable of efficiently predicting temperature responses for different lunar regolith simulants. For total 12 parameters, the errors of ten cases are less than 10%, and other two cases are 12.23% and 13.17%. Finally, the proposed method is verified by heat measurement experiments under normal pressure and vacuum, and the variation of thermal properties with different compactness is obtained. The proposed probing technique provides novel ideas to measure the in-situ thermal properties of extraterrestrial regolith. [ABSTRACT FROM AUTHOR]

Reliable information about the properties of the processed materials has a significant impact on the effects of their processing. In induction heating processes, this also applies to information about the influence of temperature T on these properties. These are both thermal and electro-magnetic properties. Based on previous studies, a comprehensive experimental method is presented for estimating the temperature characteristics of thermal diffusivity, volumetric heat capacity and resistivity on one measurement station, with particular attention to ferromagnetic materials. The estimation process is carried out on an induction heating stand using forcing signals from an inverter generator. In a computer-controlled cycle that changes the base temperature level, basic measurements of thermal and electrical properties are carried out on a material sample in the form of a cylindrical disk. They are the results of the analysis of the temperature and electromagnetic responses of a material sample to short- and long-term step pulses of a sinusoidal excitation signal with a frequency of approximately 40 kHz. The presented estimation method can be treated as a final method or a preliminary procedure for radically narrowing the variability in decision variables inthe optimization process of simultaneous determination of the sought material characteristics. [ABSTRACT FROM AUTHOR]

This study focused on an important global issue containing both environmental pollution control and energy storage. Polyaniline has been utilized as a supporting material to load paraffin in order to form highly thermal conducting and shape-stable phase change material (PCM). Three different weight percentages (wt%), i.e., 10, 15, and 20 wt%, of polyaniline have been used to obtain shape-stable composite materials. The paraffin leakage of the prepared samples PPCM1, PPCM2, and PPCM3 has been examined by 500 thermal cycles in a hot air oven at 80 °C. Among three samples, the PPCM3 composite with 20 wt% of polyaniline in paraffin has shown excellent leakage-bearing properties with only ~ 0.06% leakage after 500 thermal cycles. Further, the chemical, structural, and morphological analyses of the PPCM3 composite have been carried out by FTIR, XRD, and FESEM. The thermal performance of the prepared sample has been studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis, which revealed that the impregnation of polyaniline polymer has improved the thermal stability and thermal conductivity of paraffin with a small decrement in latent heat capacity of the PPCM3 composite. The latent heat of the composite decreased by 18.36% and thermal conductivity increased by ~ 65.45% for a 20 wt% concentration of polyaniline in paraffin with the maximum latent heat capacity. To check the thermal reliability of the formulated PPCM3 composite, the composite has been subjected to thermal cycling of 500 thermal cycles. With increased thermal conductivity, high latent heat capacity, good shape stability, excellent leakage-bearing capability, and improved thermal reliability, paraffin/polyaniline composite PCMs look promising for application in thermal energy storage areas. [ABSTRACT FROM AUTHOR]

Solid–liquid organic phase-change micro/nanocapsules are potential candidates for energy storage. Recently, significant progress has been made regarding phase-change micro/nanocapsules in terms of their synthesis, properties, and applications. Extensive research has been conducted to enhance their thermal properties, such as thermal storage capacity, thermal conductivity, and thermal reliability. However, factors that influence the thermal properties of micro/nanocapsules have received little attention. This study presents a comprehensive review of phase-change micro/nanocapsules focusing on their thermal properties and their influencing factors. In addition, the thermal properties of the major solid–liquid organic pure phase-change materials are summarized. Furthermore, common micro/nanoencapsulation methods and their influence on the thermal properties were analyzed. Finally, the potential applications of these phase-change micro/nanocapsules were also investigated. This study was devoted to enhancing the thermal properties of micro/nanocapsules, which play a crucial role in their practical applications. [ABSTRACT FROM AUTHOR]

In transportation applications, filling high pressurised hydrogen tanks within a few minutes implies a fast and large temperature increase that can compromise the structural integrity of the storage system and the safety of the process. Common approaches to control this temperature increase mainly involve hydrogen pre-cooling using complex and energy-demanding refrigeration systems. This study proposes and assesses alternative and energy efficient thermal management strategies for fast filling of hydrogen tanks including the modification of the liner's thermal properties and the use of existing on-board refrigeration systems. The analysis is performed by means of a Computational Fluid Dynamics model validated against experimental observations. Results show that proposed solutions provide a robust and efficient alternative to hydrogen pre-cooling, potentially simplifying the hydrogen supply system, reducing its associated energy demand, maintaining the hydrogen temperature below admissible limits and increasing the state of charge of the tank. • Strategies are based on liner pre-cooling and its thermal properties modification. • Similar H 2 temperature is achieved when pre-cooling it or changing liner properties. • Energy consumption of liner pre-cooling is up to 42–68% lower than H 2 pre-cooling. • Liner heat capacity increase is more effective than thermal conductivity increase. • Strategies increase the SOC up to 3.5% points compared to H 2 pre-cooling. [ABSTRACT FROM AUTHOR]

Deep coaxial borehole heat exchanger (DCBHE) is a promising kind of ground heat exchanger for geothermal exploitation. In this study, effects of stratified ground thermophysical properties (GTP) are considered, and then an improved semi-analytical heat transfer model is developed and validated to analyze the DCBHE performance. Then, influences of stratified GTP on the DCBHE performance are investigated. Finally, thermal response test (TRT) of DCBHE with stratified GTP is simulated by a numerical model, and by using the simulated TRT data, the improved model is combined with a parameter estimation method to identify the effective values of GTP, which are compared with actual values. The results show that stratified ground thermal conductivities have an important influence on the DCBHE performance, and that stratified volumetric heat capacities of ground have a small influence on the DCBHE performance. The DCBHE performances based on the effective values and actual values of GTP match well with each other for different cases and geothermal gradients, indicating that for stratified thermal conductivities or volumetric heat capacities of ground, the effective GTP are reliable and can be used for accurately predicting the DCBHE performance. [ABSTRACT FROM AUTHOR]

The physical properties of CdS is calculated by using the first principles pseudopotential plane wave method based on density functional theory (DFT). The calculated lattice parameters and elastic constants agree well with other theoretical values, and the crystal is determined to be structurally stable by the Born mechanical stability condition. The Debye temperature, Grüneisen parameters, heat capacity and thermal expansion coefficient of CdS under high temperature and high pressure were studied successfully by using the quasi-harmonic Debye model. The influence of pressure on thermal expansion coefficient and Debye temperature is greater than that of temperature. The heat capacity decreases with the increase of pressure. At high temperature and high pressure, the heat capacity approaches the Dulong-Petit limit. [ABSTRACT FROM AUTHOR]

The thermal energy properties in any material affect the substance’s capacity to store or transfer heat. This study investigated the effect of the polymeric chains’ tacticity on the thermal properties of polypropylene related directly to the thermal power, i.e., the heat capacity and thermal conductivity. The study selected different commercial polypropylene groups with two steric modes: isotactic and syndiotactic. The aim is to determine the parameters: isotacticity index, degree of crystallinity, glass-transition temperature, melting point, heat capacity, and thermal conductivity. The data were collected using gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC). The results showed that methyl groups randomly distributed within the homo-polypropylene changed the overall content of meso diads, i.e., less isotacticity index. The differences between isotactic and syndiotactic polypropylene groups were 20-40% the degree of the crystallinity, 5-10°C the glass-transition temperature, and 10-20°C the melting point. Using suitable mathematical models, these parameters can be related directly to specific heat capacity and thermal conductivity.

The black appearance of asphalt pavement easily absorbs a large amount of solar radiation in hot summer to lower its anti-deformation ability, and asphalt pavement cools down quickly in cold winter to cause cracks. To solve these problems, thermochromic core material (TCM) was encapsulated by the shell material of urea-formaldehyde (UF) resin to prepare thermochromic microcapsule (TM) using situ-polymerization. Then the surface morphology, particle size distribution, chemical composition, phase change property and thermal stability of TM were characterized. After that, emulsified asphalt and acrylic emulsion were selected as film-forming substances to prepare thermochromic asphalt-based composite coating (TACC) after adding different dosages of TM. The surface morphology, chemical composition, thermal storage capacity, phase change property and spectral reflectance of TACC were studied. The results show that TCM is successfully encapsulated by shell material which restricts the thermal conductivity of TCM, making heat transfer process of TM become gentler. Also, the phase change property of TM is still better due to excellent phase change property of TCM. Further, TM particles with the size range of 3.2–4.8 μm are uniformly distributed on TACC surface and show better dispersion in emulsified asphalt. Additionally, TM enhances the thermal storage capacity and thermal stability of TACC. The heat exchange efficiency between asphalt pavement and surrounding environments is increased by added TM particles, improving the thermal stability of TACC. Finally, the increased spectral reflectance in the near-infrared region reflects more solar radiation in hot season because of high reflectivity of TACC on asphalt pavement, which lowers asphalt pavement temperature to improve its anti-deformation ability. [Display omitted] • TACC is developed after adding prepared TM in emulsified asphalt and acrylic emulsion. • The shell material limits thermal conductivity of TCM to enhance thermal stability of TM. • Prepared TM obviously improves thermal storage capacity and thermal stability of TACC. • Heat exchange efficiency between asphalt pavement and environments is increased by TM. • Developed TACC reflects more solar radiations to regulate asphalt pavement temperature. [ABSTRACT FROM AUTHOR]

The structural stability as well as the mechanical, magnetoelectronic and thermal properties of the quaternary Heusler KMgNZ (Z = O or S) were studied using first principles approach based on the DFT implemented in Wien2k code. The exchange-correlation potential is treated by PBE-GGA. The calculated negative formation energies for both materials corroborate their thermodynamic stability. Moreover, the derived elastic constants support the mechanical stabilities of the latter compounds. On the other hand, the density of states of the studied materials shows that both compounds are half-metallic ferromagnets. The total magnetic moments for both compounds are mainly originated from N atom, and its integer value followed the Slater-Pauling rule. The calculated half-metallic gaps are found for two systems. The three-dimensional plots of different mechanical moduli exhibit that the bulk modulus is isotropic, whereas Young's modulus, Poisson's ratio and shear modulus of both compounds are highly anisotropic. The effects of temperature and pressure on the heat capacity, thermal expansion coefficient and Debye temperature are also studied. [ABSTRACT FROM AUTHOR]

MgCl 2 –NaCl–KCl ternary melts hold great promise as thermal energy storage and heat transfer fluid for the next generation of concentrating solar power (CSP), offering major advantages such as high-temperature storage capacity, adjustable temperature ranges, and renewable usability. However, a critical challenge is the lack of an accurate model to analyze the structural and property aspects of this complex melt. In response, a machine learning-based model with high accuracy and applicability has been developed for this purpose. Based on DPMD techniques, the trained model is used to investigate the structure information, transport and thermal properties of the melt. Temperature and composition effects are introduced. Radial distribution functions, coordination numbers, and angular distribution functions are applied to investigate the microscopic ionic environment within the melt. Transport properties studied include density, self-diffusion coefficient, ionic conductivity, and viscosity, while thermal properties include heat capacity at constant pressure and volume and thermal conductivity. Our model accurately reproduces the results obtained from FPMD simulations and accurately predicts the macroscopic properties of the melt through validation. The high stability of the Mg2+-Cl- interactions is introduced, which remains relatively unaffected by temperature and concentration changes. The presence of MgCl 5 3− species in the melt was observed. We are devoted to the development of AI for the CSP science field. Due to the application of machine learning strategies, our models have proven to have exceptional accuracy and ease of study for MgCl 2 –NaCl–KCl ternary melts, and they can provide valuable insights into their properties and ionic behaviors. • A potential model is rapidly generated through a novel method based on density function theory and hybrid machine learning strategies, incorporating both the Bayesian-learning algorithm and Deep Potential. • Large-scale ion simulations (about 8000 ions), similar to density functional theory, are conducted. • The model is applied to investigate the structure of MgCl 2 –NaCl–KCl melts and introduces strange characteristics. • Through experiment validation, the effective generalization ability of the model is demonstrated, allowing accurate prediction of thermal and transport properties for the melts with different components. [ABSTRACT FROM AUTHOR]

Binder Jetting technology is well established for the production of sand molds and cores for foundry use, owing to its flexibility and expansive design capabilities. A wide array of sand, aggregate, and binder combinations is commercially available. Utilizing these types of refractory materials in the casting process presents both technical and economic benefits and drawbacks. For intricate cast components, foundry technologists must assess the thermophysical properties of the mold material systems. With this knowledge, specialized high-performance material combinations may be employed in specific areas of the mold, while more economically viable systems are used for shaping the external mold support. This study primarily focuses on determining the heat capacity and thermal diffusivity and consequently the thermal conductivity using a specially developed analytical method. It investigates three different fundamental aggregates: silica, cerabeads®, and chromite. The result’s range provides an overview of relevant characteristics for the selected material systems. Given that the properties of sand affect heat flow during casting and solidification, these newly determined values can be utilized in future simulations. Consequently, these findings aid in maintaining and enhancing the quality of critically stressed cast parts. [ABSTRACT FROM AUTHOR]

Integration of phase change materials (PCMs) into buildings contributes to mitigating indoor temperature fluctuations, offering opportunities for alleviating energy crisis. However, prevalent PCM integration methods commonly suffer from shortcomings in mechanical properties, compatibility, and environmental sustainability, restricting their applications. This study developed a novel shape-stabilized PCM (SSPCM) using cenospheres from coal-fired power waste and bio-based PCMs from vegetable oil by-products, subsequently sealed with silica coatings to inhibit PCM leakage and improve thermal stability, termed as SCS@PCM, exhibiting melting enthalpy up to 103.9 J/g. SCS@PCM was then integrated into cement mortars by replacing fine sand to fabricate thermal storage cement-based materials (TSCM), followed by assessments of their microstructural, mechanical, and thermal properties. The results showed that the silica coating helps to lowrer adverse impact of SCS@PCM on the compressive strength and thermal conductivity of TSCM. TSCM containing 30.0 vol% SCS@PCM reached a 28-day compressive strength of 45.3 MPa, exhibiting only a 17.4 % reduction compared to the control group, notably less than reductions observed for other SSPCMs reported in literature. Moreover, integration of SCS@PCM improved thermal storage capacities and decreased thermal fluctuation rates of TSCM, evidenced by a 4.7 ℃ decrease in peak temperature at dosage of 30.0 vol%. This study endeavors to develop an eco-friendly TSCM with excellent thermal and mechanical properties, providing insights for applications in improving the thermal regulation and energy efficiency in building roofs. • An eco-friendly, compatible, and robust shape-stabilized PCM was developed using cenospheres and bio-based PCMs. • Effective inhibition of PCM leakage and improved thermal stability of SCS@PCM was achieved by the SiO 2 coating. • SCS@PCM replaced up to 30 % by volume of fine sand without noticeable reduction in the mechanical strength of cement mortar. • SCS@PCM significantly improved the heat storage and temperature regulation capabilities of cement mortar. [ABSTRACT FROM AUTHOR]

[Display omitted] • BNNS/ANF thermal conductivity insulating fibers were prepared via sol–gel wet spinning. • BNNS and ANF are connected to form a stable three-dimensional network structure. • The fibers have excellent mechanical properties and thermal conductivity. With the intensification of global warming and the occurrence of extremely hot weather, there is an urgent need for textiles that can effectively regulate temperature. Using amino-functionalized boron nitride nanosheets (K-BNNSs) and aramid nanofibers (ANFs) as materials, the well-oriented thermally conductive insulating textile fibers with "lotus root" structure were directly prepared by sol–gel wet spinning process. The axial thermal conductivity of a single fiber can be as high as 22.4 W/(m·K), and has an excellent tensile fracture strength (176.6 MPa). Thermal infrared imaging revealed that the fibers woven into textiles had a more significant heat dissipation capacity than commercial cotton fabrics. The fiber obtained by this low-cost preparation method provides a cooling textile with excellent heat-dissipation ability and has wide application prospects in emerging textiles. [ABSTRACT FROM AUTHOR]

The most currently used ionic liquids (ILs) are protic ionic liquids (PILs), subject to extensive investigation regarding their physical properties. These compounds along with their mixtures with other substances such as salts and solvents, serve as electrolytes in next generation electrochemical smart devices, and emerge as viable candidates to replace conventional Heat Transfer Fluids (HTFs) in various energy applications. Despite the extensive number of studies, important information about this kind of compounds is still unknown, such as the effect of alkyl chain length on thermal and thermophysical properties, as well as toxicity. This work, extending previous studies of our group, summarizes the liquid range, heat capacity and acute toxicity level of six ammonium ILs: specifically, n-alkyl-ammonium nitrate ILs with increasing alkyl chain length (n = 2, 3, 4, 5, 6, 8). For this study, the synthesis of the three ILs with the longest alkyl chain was performed, along with DSC, TGA and toxicity measurements. It was observed that an increase in alkyl chain length resulted in a decrease in short-term thermal stability and an increase in melting temperature, indicating a reduction in the liquid range. A compensation effect between enthalpy and entropy of melting was observed for the studied chain lengths. The isobaric specific and molar heat capacities increase with temperature for all the compounds studied here, and good correlations were obtained between molar heat capacity and the number of carbon atoms in the alkyl chain for every temperature. Finally, most of the ILs are non-toxic, although toxicity increases with alkyl chain length. [ABSTRACT FROM AUTHOR]

• Critical properties, heat capacities, and thermal diffusivities were measured. • The thermal conductivities of the compounds under study were calculated. • Thermal properties were determined for liquid phase at atmospheric pressure. • Glymes are used for capture of CO 2 , H 2 S, and other gases. The critical temperatures, critical pressures, and thermal diffusivities have been measured for mono-, di-, tri-, and tetraglymes, compounds that are used for pre- and post-combustion capture of CO 2 , H 2 S and other gases. The critical properties have been measured using the pulse-heating method applicable to thermally unstable compounds. The combined relative expanded uncertainties with the 0.95 level of confidence are 0.01 and 0.03 for the critical temperature and pressure, respectively. The acentric factors of the compounds have been calculated based on the experimental data. The critical properties of these compounds have also been calculated by the group contribution methods of Wilson and Jasperson, Nannoolal et al., and Hukkerikar et al. in two variants. The Wilson/Jasperson technique provides the best estimation of the critical temperature and the Hukkerikar et al. one gives the best results for the critical pressure. The thermal diffusivities of glymes have been measured at atmospheric pressure in the temperature range from 303.15 to 353.15 K. The thermal conductivities of glymes have been calculated from the experimental data. The temperature dependence of the thermal diffusivities and thermal conductivities has been approximated by linear polynomials. The experimental thermal conductivities of glymes have been compared with those estimated by the methods of Govender et al. and Liu et al. The method of Govender et al. provides a good estimation of the thermal conductivity of glymes. [ABSTRACT FROM AUTHOR]

While battery researchers often focus on optimizing device performance to improve, for example, battery capacity or charging rate, thermal effects have often been relegated to a secondary concern. The evolution of the thermal properties with aging and cycling impacts the temperatures within the battery cell and, in turn, the performance and reliability of the battery cell. This work focuses on quantifying the change in thermophysical properties of lithium-ion battery cells subject to various aging conditions. The effective thermal diffusivity of the electrode stack and thermal conductivity of the active materials are significantly impacted by the aging conditions, while the volumetric heat capacity remains relatively constant. Aging below room temperature results in relatively stable thermal transport, while aging above room temperature degrades thermal transport by up to ∼75% after 8200 equivalent full cycles at 50 °C. For the cathode, the reduction in transport properties corresponds to visual observation of breakage of the particles. For the anode, solvent co-intercalation and exfoliation, along with growth of the solid electrolyte interphase (SEI) and loss of contact between active particles, may explain the reduction. Ultimately, the changes in thermophysical properties with aging will increase temperatures and reduce the electrochemical performance and reliability. [Display omitted] • Thermal transport properties reduce with increasing temperature during aging. • Degradation in properties correlates with observed microstructural changes. • Reduced thermal transport leads to higher temperatures during operation. • Higher temperatures reduce performance, reliability, and safety. [ABSTRACT FROM AUTHOR]

A systematic study of the thermal properties of an artificial molecule formed by a single electron embedded in two laterally coupled quantum rings under external probes: magnetic and static electric fields was carried out. The eigen-states and eigen-values of the Hamiltonian in the effective mass approximation were obtained numerically. By varying the distance between the centers of the rings, it was possible to establish the equilibrium length required by the formation of a giant stable artificial molecular complex and its dissociation energy. These features were corroborated by studying the effects of the distance between centers of the rings, the magnetic and electric field on the entropy and heat capacity of the system. At low temperatures, the equilibrium condition of the artificial molecule is linked to the formation of a minimum value of the entropy and a peak in the heat capacity. The temperature's rising modifies substantially these conditions. • Artificial molecule quantum rings. • Entropy and heat capacity of two laterally coupled quantum rings. • Electric and magnetic field effects on artificial molecule thermal properties. • Geometrical effects on artificial molecule thermal properties. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the thermal behavior of composite building materials comprised of silt and flax fibers, considering various initial conditions. The experiments were conducted on flax fibers alone, examining factors such as moisture content variation, fibers arrangement, and density. Subsequently, the thermal properties of the earth-flax fiber composite were studied, taking into account the influence of water content and fibers mass content. The thermal properties of both flax fibers and raw earth-flax fibers composite specimens were determined using the experimental unsteady-state method. The results indicate that the thermal conductivity and heat capacity of flax fibers increase with density, temperature, and moisture content. Regardless of fibers density and arrangement of fibers, linear relationships have been established for both thermal conductivity and heat capacity as functions of temperature. Additionally, it was demonstrated that the heat capacity and the thermal conductivity increase with water content, regardless of the percentage of added fibers. Moreover, mixing randomly flax fibers with compacted raw earth material has improved the thermal properties of the composite. This improvement pertains to its insulating capacity, ability to store heat, and, subsequently, its contribution to the thermal comfort provided by such earth composite material when used as a building material. • Thermal conductivity enhances by increasing the moisture content and density. • The arrangements of fibers have highly influenced the thermal properties. • Linear relationships were established for the thermal conductivity and heat capacity. • The addition of flax fibers to raw earth improved the thermal properties. [ABSTRACT FROM AUTHOR]

A comprehensive inspection on thermo-physical and flow assets of aqueous CuO/CaCO 3 /SiO 2 ternary hybrid nanofluid (THNFs) was conducted. All investigates accomplished at the temperatures of 15 to 60 °C and 0.1–0.5 vol% of nanoparticles concentrations. Experimental data demonstrated that all THNFs presented Newtonian behavior at the studied concentrations. Development of temperature and volume concentration of the nanoparticles cause to increase usual viscosity and thermal conductivity. Maximum development of thermal conductivity relative to distilled water (DW) was achieved to 78.6% at 0.5 total vol% and 15 °C with the volume ratios of 60:30:10, respectively. Thermal resistivity act as the reverse of the thermal conductivity. Moreover, specific heat of the nanofluids decreased with volume fraction. Also, temperature augmentation led to the reduction of heat capacity followed by increasing. With the purpose of prediction of the significant thermos-physical properties of the THNFs, mathematical correlations with 99% precision have been derived and suggested. Activation energy of a typical THNF with 60:30:10 vol ratios determined from linearized Arrhenius equation as 15838 (± 63.5) J/mol. [Display omitted] [ABSTRACT FROM AUTHOR]

U-bend deep borehole heat exchanger (DBHE) is a new promising kind of ground heat exchanger, but nowadays there are lack of accurate efficient models to simulate U-bend DBHE. This paper has developed a semi-analytical model of U-bend DBHE, which considers the unsteady heat transfer of borehole, heterogenous soil thermal properties and geothermal gradient. A 2D numerical model and an analytical model based on infinite line-source theory are also developed, and the three models are compared with experimental data for different boundary conditions. Based on the soil thermal properties estimated by logging data and rock identification, the three models have large errors when compared with experimental data. Based on a soil thermal conductivity λ s estimated by matching experimental data, the three models match better with experimental data, and it is inferred that λ s should be measured by thermal response test instead of rock identification. The semi-analytical model and 2D numerical model match very well for all the time, but the analytical model has large differences with 2D numerical model, which is because the analytical model ignores borehole heat capacity and time-varying heat flows at the borehole wall. This paper could provide a cost-effective semi-analytical model and some advices for U-bend DBHE. [ABSTRACT FROM AUTHOR]

Ab-initio calculations of lattice heat capacity and phonon thermal conductivity have been performed for CrN of rock-salt structural type (paramagnetic) and for the orthorhombic antiferromagnetic (AFM) phase below T N ≈ 285 K. The comparison with experimental data below ≈30 K unveils that in contrary to the theoretically calculated heat capacity following the βT3 term with Debye temperature Θ D = 830 K, a large excess of experimental heat capacity in a form of δT2 is observed. This additional heat capacity is ascribed to magnons in the specific layered-type AFM arrangement of CrN. The experimental thermal conductivity shows a similar low-temperature excess of T2-dependence. Considering that mean free path of heat carriers is essentially limited by the grain size and calculated phonon conductivity itself is very low below ≈30 K, such additional contribution can be ascribed again to AFM magnons though theoretical model of such conductivity is still to be assessed. In spite of this complexity, our model of phonon thermal conductivity reproduces well the maximum of 7.2 Wm−1K−1 at 150 K followed by a decline tied to phonon-phonon scattering (Umklapp process). Nonetheless at higher temperatures, the experimental data evidence sudden drop at T N to ≈2 Wm−1K−1 with only slightly varying thermal conductivity at elevated temperatures, which reminds rather a behavior of amorphous or defective solids. It is proposed that atomic displacements that stabilize spin-parallel and spin-antiparallel Cr pairs in the orthorhombic AFM phase persist partially as fluctuating ones in the cubic paramagnetic state above T N , which gives rise to dynamic strain fields that cause strong phonon scattering. [Display omitted] [ABSTRACT FROM AUTHOR]

Recycled concrete powder (RCP) is a promising supplementary cementitious material, its application in thermal insulation materials is however very limited. In this study, the influence of RCP substitution on the properties of insulation mortars was investigated. The results showed that as the RCP content increased, the compressive strength and thermal conductivity of insulation mortars decreased by 39.8% and 16.8%, owing to the increasing volumes of porous paste and internal air voids. Note that the mortar containing a high content (50 wt%) of RCP struggled to meet the strength requirements of the specification. Therefore, CO 2 curing was further employed here to alleviate the strength loss and successfully increased the compressive strength by 11%∼38%. It was found that since the CaCO 3 particles formed and densified the microstructure (confirmed by the porosity test), the strength reduction derived from the RCP substitution was compensated for. Consequently, insulation mortars incorporating 50% RCP after CO 2 curing for 7 days exhibited satisfactory compressive strength (∼ 0.22 MPa) and relatively low thermal conductivity (∼ 0.048 W/(m∙K)). The mortars showed improved aesthetic appearance and excellent thermal insulation capacity in both hot and cold environments. This study proposed a successful approach to combining reutilization of RCP and CO 2 curing in insulation mortar generation, which effectively improved the sustainability of materials. • A novel and sustainable EPS insulation mortar is developed for energy-efficient buildings. • The synergistic influence of the RCP substitution and CO 2 curing duration is studied. • Remarkably low thermal conductivity is attained through the incorporation of RCP. • Excellent aesthetic appearance and thermal performance are achieved simultaneously. [ABSTRACT FROM AUTHOR]

Thermodynamic properties of ternary ceramic TiCN are studied by first-principles calculation combined with the Debye Einstein model, which considers the contribution of 3n−3 optical frequencies at the Γ point; Debye Grüneisen model, which treats optical frequencies as acoustic ones; and quasiharmonic approximation(QHA), which is the most prevalent method in prediction of phonon dispersion and thermal properties. No imaginary frequency shows that TiCN has dynamic stability, and negative formation energy indicates the thermodynamic stability. Particularly, TiCN has low thermal expansion coefficient, which rises quickly firstly and then gradually as temperature rises. The study of bulk modulus shows that TiCN possess excellent resistance to the volume thermal deformation. For temperature effects of thermal expansion coefficient, heat capacity and entropy, the obtained results show that Debye Einstein model are apparently closer to the QHA at low temperatures. Our present results provide guideline for exploration of thermal properties of multicomponent materials. [ABSTRACT FROM AUTHOR]

• New analytical solution for vertical streambed fluxes and streambed thermal properties developed. • The time-variant vertical streambed fluxes could be estimated using the Particle Swarm Optimization method. • The model can be recommended as an alternative to the traditional isotope-based method during extreme hydrologic events. As a natural tracer, heat has some remarkable advantages over competing test methods and has become a popular and widely used tool for quantifying streambed fluxes. In recent decades, extreme hydrological events have become intense and frequent, resulting in irregular or complex temperature changes at the stream-streambed interface. During extreme hydrological events, most existing analytical models with periodic changing top boundary conditions are inapplicable. In this study, we present a heat-based analytical model that accounts for the arbitrary top boundary and initial conditions to estimate time-variant vertical streambed fluxes (VSFs) and streambed effective thermal diffusivity using temperature–time series from streambed sediments during extreme hydrologic events. The particle swarm optimization is used to estimate the time-variant VSFs. The Morris global sensitivity analysis method is used to test the impacts of the input parameters on heat transport in the streambed. Results show that the output temperature data is most sensitive to VSFs, followed by the volumetric heat capacity of the streambed, thermal conductivity and thermal dispersivity. The performance of the new model is tested using a numerical model with time-variant VSFs associated with extreme hydraulic events such as hurricanes and dam-controlled river conditions. Results demonstrate that despite oscillations in the estimated VSFs and fluctuations being stronger when the VSFs begin to reverse and at the peak of the VSFs, the new model of this study captures changes in VSFs under extreme hydraulic events. In addition, the frequency domain model, LPMLEn, performs satisfactorily in estimating VSFs in hurricane conditions. Application to field data demonstrates that the temperature distribution can be effectively remodeled based on the estimated VSFs and streambed effective thermal diffusivity. Both the present model and LPMLEn model could be considered as alternatives to the traditional isotope-based method in estimating VSFs during extreme hydrologic events. [ABSTRACT FROM AUTHOR]

Despite its wide range of real-life applicability, the combined effect of the thermal properties and thickness of a heater on the Leidenfrost temperature (T L) of the system has not been explored. Thus, this study investigates the effects of thermal properties and thickness on the T L using four different metal specimens (Inconel 718, AISI 304 stainless steel, brass, and aluminum). Our experimental results show that the T L decreases with an increase in the thickness of the specimens up to a threshold value. Herein, this varying T L , which varies with thickness, is called transient Leidenfrost temperature (T L,TR) in this study. When the thickness of the sample exceeds the asymptotic thickness, T L became constant, which is termed as the asymptotic Leidenfrost temperature (T L,ASY) in this study. The dependency of the Leidenfrost phenomenon on the thermal properties and thickness can be described by simultaneously considering the heat capacity and heat propagation characteristics; however, in case of the thick specimens, the T L,ASY is mainly considered to be resultant of the speed of heat propagation, including the heat-transfer performance. Consequently, two different trends of the Leidenfrost phenomenon can be predicted. • Leidenfrost temperatures decrease as the thickness of specimens increases to an asymptotic thickness. • Transient Leindenfrost temperature is simultaneously affected by both heat capacity and thermal conductivity. • Asymptotic Leindenfrost temperature is mainly affected by thermal conductivity. • Leidenfrost temperatures are predicted from a transient heat conduction analysis based on the droplet dynamics. [ABSTRACT FROM AUTHOR]

Thermal Response Tests (TRT) have been extensively studied in the past decades and is an important area of research belonging to ground heat exchanger design. The most important thermal property inferred in a TRT is the equivalent subsurface thermal conductivity. Previous studies were presented where the thermal diffusivity was estimated but with limited success. In this paper, a TRT with an oscillatory excitation (OTRT) is used to obtain a better uncoupling between thermal conductivity found from constant heat injection and thermal diffusivity. The method was already used in the past with a simplified ground model. It is presented here with a better model that takes into account the ground and the borehole thermal response. The method is based on the concept of concentric composite cylinder where the equivalent radius is used for the U-tube arrangement. Results obtained with this method were successfully correlated to those obtained with numerical simulations and the method was then used to analyze an experimental field test. • New Thermal Response Test with Oscillatory heat injection. • Estimation of soil diffusivity or volumetric capacity. • Numerical and Experimental Verification. [ABSTRACT FROM AUTHOR]

Thermal transport properties play a critical role in the performance of lightweight foams used as shock-absorbing layers in helmets, sports gear, and electronic packaging. We report superior tailored thermal properties achieved at lightweight in vertically aligned carbon nanotube (VACNT) foams by introducing mesoscale hexagonally close-packed cylindrical architecture. We measure thermal diffusivity (α) using a laser flash technique and specific heat capacity (C p) by differential scanning calorimetry at varying temperatures from 25 °C to 200 °C from which we determine the thermal conductivity and the thermal resistance as functions of temperature. The architected VACNTs exhibit similar α and C p as non-architected VACNTs but exhibit higher intrinsic thermal conductivity (k i) and lower intrinsic thermal resistance (R i) compared to the non-architected VACNTs. This improvement in k i and R i arises due to the higher intrinsic density of VACNTs achieved by exploiting a synthesis size effect—the geometrically confined CVD synthesis which leads to higher vertical alignment and number density of CNTs. The effective thermal conductivity k e f f of VACNT foams follows a desirable sub-linear scaling with the density—which is tailored by the architecture—in contrast to the higher order scaling observed in other materials. The superior thermal transport properties of architected VACNTs enable lightweight protective materials for extreme engineering applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Nanofluid has emerged as a promising heat transfer fluid (HTF) due to their significant thermophysical, and optical characteristics enhancement over base fluids. Hybrid nanofluids with multiple nanomaterials have the advantage of synergistic properties in comparison to monocomponent nanofluids. The present study proposes an energy-efficient and cleaner synthesis method for developing carbon quantum dot (C-dot), MXene, and a hybrid MXene/C-dot hybrid nanofluids, for heat transfer application. In-situ microwave pyrolysis technique and two-step method were adopted for nanomaterial and nanofluid synthesis. The morphological, phase structural, chemical, and elemental compositional analysis of the nanomaterials was performed. The material characterization confirms the hybridization of C-dot on MXene nanosheets. The thermal conductivity and volumetric heat capacity of the nanofluids were measured using the transient plane source (TPS) method. Thermal conductivity was observed to increase with nanofluid concentration and temperature. Results indicate that MXene has the highest thermal conductivity enhancement (50 %) over water, followed by hybrid (42.2 %) and C-dot nanofluid (33.2 %). The volumetric heat capacity of nanofluids decreased with concentration and temperature. A semi-empirical correlation, as a function of nanofluid concentration and temperature, was coined for predicting thermal conductivity and volumetric heat capacity. Optical property characterization study shows that C-dot nanofluid exhibited considerable absorption along the UV range, while MXene nanofluid showed absorption in the visible and near-infrared (NIR) region. Hybrid nanofluids demonstrated complementary absorption properties of C-dot and MXene nanofluids. [Display omitted] • Novel MXene/C-dot hybrid nanofluid was synthesized for heat transfer applications. • Study reveals the material and thermal-optical properties of C-dot, MXene and hybrid nanofluids. • Semi-empirical correlation were coined to predict thermal properties of nanofluids. • Highest thermal conductivity enhancement was exhibited by 0.2 wt% MXene nanofluid. • Hybrid nanofluid showed complementary absorption property of component nanofluids. [ABSTRACT FROM AUTHOR]

• Foundations of experimental geothermic studies were significantly improved. • Advanced technique was applied to study the Volga-Ural oil and gas basin. • Field experiment included 7 cycles of temperature logging during 186 days of well shut-in. • Unique data on temperature and its gradient behavior after drilling were obtained. • A significant increase in heat flow with depth was established. • The necessity for new, special experimental estimations of heat flow is demonstrated. • Thermal core profiling is needed for estimation the detailed variations of heat flow. • One more prove that heat flow data obtained with common technique are unreliable. The paper describes the results of experimental geothermal studies of the formation surrounding Savitskaya-300 well (depth 3555 m) drilled in the Volga-Ural oil and gas basin (Orenburg region, Russia). The work was aimed, firstly, at obtaining geothermal data for basin modeling and, secondly, at improving the instrumental and methodological foundations of experimental studies. Continuous core profiling of the rock thermal conductivity, volumetric heat capacity, and thermal anisotropy was performed on all 2886 recovered core samples with the total length of 329.1 m. Additional measurements were conducted at fluid saturation and elevated temperatures. For non-cored intervals, the rock thermal properties were determined from well-logging data and via measurements on rock cuttings. The studied formation is characterized by high thermal heterogeneity at both the level of strata (horizons) and individual samples. Significant thermal anisotropy up to 1.50–1.66 in the lower part of the well has been observed. To obtain data on vertical variations of equilibrium temperature and its gradient, temperature logging was performed 7 times within the 2 to 186 days of well shut-in. New data on the recovery of temperature and its gradient after drilling are important for the practice of applied and fundamental geothermal surveys. A significant increase in heat flow with depth was established based on the results of temperature gradient and rock thermal conductivity determination for 34 depth intervals. The observed general vertical variation in the whole depth range of the well up to ∼3.3 km depth can be attributed to paleoclimatic effect in the Late Pleistocene-Holocene, while the sharp increase in heat flow at ∼3.3 km within Fransian sediments is possibly due to advective heat transfer by fluid filtration. The apparent heat flow was established to be 84.3 mW⋅m−2 in the lower section of the well, below 3.3 km. The value may be close to the steady-state heat flow value, which is 84% higher than the previous published average data for the studied area. [ABSTRACT FROM AUTHOR]