Journal of Thermal Analysis and Calorimetry最新文献

In view of the excellent C₂ hydrocarbon separation performance of the anionic layer-pillared porous coordination polymer, Cu(C₁₂H₁₀N₄)₂SiF₆ (NTU-65), the structure, composition, and synthetic phase purity of the material were comprehensively analyzed by elemental analysis, powder X-ray diffraction, and infrared spectroscopy. To address the actual demands of potential industrial applications, the molar heat capacity of NTU-65 in the temperature range of 193–393 K was accurately determined for the first time by temperature-modulated differential scanning calorimetry, and the corresponding enthalpy and entropy were calculated. The thermogravimetric analysis results of the material show that the crystal structure of NTU-65 can be maintained up to 600 K, confirming its excellent thermal stability and laying a solid foundation for the transition from the laboratory to practical applications.

This study explores the unconventional yet impactful flow of Reiner–Rivlin nanofluid flow over an upper horizontal paraboloid of revolution (UHSPR). This geometry finds applications in aerodynamic designs like car bonnets and aircraft noses. The said nanofluid flow is generated at the free stream owing to interlayer stretching surfaces and the surface's chemical reaction. The novelty of the anticipated model is enhanced, considering the effects of magnetohydrodynamics, viscous dissipation, temperature-dependent thermal conductivity, and activation energy. Through numerical and graphical analysis, we reveal how chemical reactions, thermal radiation, and free stream stretching interact with the fluid’s non-Newtonian behavior, offering insights for high-performance cooling and propulsion systems. Governing partial differential equations are nondimensionalized via appropriate similarity transformations, and the resulting boundary value problem is solved numerically using the bvp4c algorithm implemented in MATLAB. To analyze the effects of key parameters, graphical representations of temperature, velocity, and concentration fields are provided. The variations in Nusselt number, skin friction, and Sherwood number are summarized in tabular form. The results show that velocity increases with higher Reiner–Rivlin parameter values, which physically correspond to a decrease in viscous resistance. The augmentation in the activation energy parameter initially decreases temperature profiles, but as chemical reactions intensify, nanoparticle motion increases, leading to an escalation in temperature. Conversely, the heat of reaction parameter causes an elevation in temperature due to the exothermic reaction of the surface. Additionally, the mass transfer rate reduces as the reaction rate coefficient increases. The validation of the model is a part of this exploration.

Thermal management of lithium-ion batteries has become crucial due to their widespread use in electric vehicles (EVs), renewable energy storage, and consumer electronics. Given that conventional cooling methods are often energy-intensive and environmentally harmful, there is a pressing need for sustainable solutions. This study systematically explores passive, active, and hybrid alternatives, highlighting innovative materials and techniques such as phase change materials (PCMs) and nanofluids, which enhance heat transfer and energy absorption. The paper also emphasizes advanced approaches like liquid immersion cooling and energy-efficient designs, as well as the integration of renewable energy sources to power these systems. To optimize performance, we examine sophisticated tools like computational fluid dynamics (CFD) for thermal modeling and AI-driven systems for predictive maintenance, enabling real-time adjustments. Finally, the analysis addresses the inherent technical and economic challenges of each method, including the scalability of eco-friendly materials, the cost of high-performance nanofluids, and the design complexity of hybrid systems. Additionally, the review outlines current research gaps, including the need for durable, cost-effective PCM formulations and the limitations of current AI applications in cooling optimization, which must be addressed to achieve scalable, high-performance solutions. By providing a roadmap of emerging trends and potential breakthroughs, this paper aims to guide future research and development efforts toward achieving a new standard of reliability, sustainability, and economic feasibility in Li-ion battery thermal management, supporting the advancement of energy storage technology in diverse applications.

Formulations based on explosives with reduced vulnerability to mechanical stimuli and high thermal stability, e.g. nitrotriazolone, are used to produce insensitive munition. NTO has similar performance characteristics to commonly used explosives such as RDX and HMX, but is much less sensitive to accidental initiation due to heat, impact or spark. In order to forecast the thermal stability of explosives, as well as to determine for what period they can be safely operated, the accelerated ageing process is carried out, making it possible to predict changes in the initial properties of explosives during storage and to assess the impact of ageing on safety. This work aimed to obtain low-sensitive explosive compositions based on 3-Nitro-1,2,4-triazol-5-one and investigate the impact of accelerated ageing on their selected thermal and physicochemical properties. Two melt-cast compositions based on TNT and containing NTO were prepared and subjected to accelerated ageing. Samples were subjected to tests such as thermal analysis (including the kinetics of thermal decomposition), friction and impact sensitivity tests, as well as density measurements to determine the effect of ageing on, among others thermal properties, sensitivity to mechanical stimuli and density. As a result of accelerated ageing, all compositions changed colour. Sample submission to an ageing process did not adversely affect their sensitivity to friction and impact or thermal decomposition activation energy. Thermal decomposition of compositions is a complex process with an autocatalytic phase.

The thermal characteristics of natural fiber-reinforced polymer (NFRP) composites are crucial for real-world applications. The current study investigated the consequence of embedding human hair on the thermal attributes of NFRP hybrid composites. Two distinct polyester composites were developed by the hand lay-up method using 3–4 mm-long fibers and 20% (vol.) fiber loading. The first one is made of BNH and jute fibers with a 1:1 ratio (non-implanted) and the other is made of BNH (betel nut husk) and jute fibers and human hair with a 1:1:1 ratio (hair-implanted). Their thermal characteristics are investigated and compared. The thermal conductivity, thermogravimetric (TGA), differential thermogravimetric (DTG), and thermomechanical (TMA) analysis of composites are accomplished. The differential thermal analysis (DTA) explored the composite’s inflection points and endothermic peak temperature. TMA analysis unveiled the dimensional stability, coefficients of thermal expansion (CTE), and glass transition temperature (T_g) of both composites. The temperature for maximum mass loss is also predicted using the DTG curve. Human hair-implanted composites exhibit higher thermal stability, fire-deterrent properties, and glass transition temperature, and lower CTE than non-implanted ones. Outcomes are validated through mechanical characteristics and by investigating the morphological properties of composites. It revealed that human hair enhances the thermal characteristics of NFRP composites. It can be embedded in the NFRP composites as a low-cost, plentiful, and easily reachable constituent to prevent environmental contamination, enhance sustainability, and improve the composite’s thermal stability. Eventually, it will promote the adoption of NFRP composites over synthetic fiber-reinforced composites across various fields.

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Polydatin (PD) possesses a variety of pharmacological activities, but its poor aqueous solubility, stability, and bioavailability limit its application. To improve PD’s water solubility, PD/β-CD inclusion complexes were prepared by solution stirring method and characterized by infrared spectroscopy, X-ray diffraction spectroscopy, nuclear magnetic resonance hydrogen spectroscopy, and molecular docking. The results showed that PD and β-CD successfully generated an inclusion complex with a 1:1 host–guest ratio and a stabilization constant of 4362 M⁻¹. To further explore the beneficial potential, the antioxidant capacity of PD/β-CD after digestion and the pattern of change during digestion were evaluated in stages by simulated digestion and simulated fermentation in vitro. The simulated digestion process hardly changed the total sugar and reducing sugar contents (P > 0.05). During the simulated fermentation process, the pH value kept decreasing, and the short-chain fatty acid content in the fermentation products increased significantly (P < 0.05), with the acetic acid content showing the highest increment (1.90 ± 0.35 g L⁻¹). In addition, at the phylum level, PD/β-CD inclusion significantly increased the relative abundance of Firmicutes and Actinomycetes and significantly decreased the relative abundance of Proteobacteria, relative to the β-CD group. At the genus level, beneficial bacteria such as Bifidobacterium and Lactobacillus proliferated in the PD/β-CD group, and the relative abundance of potentially pathogenic bacteria such as Streptococcus, and Escherichia-Shigella was significantly reduced. The experimental results indicated that PD/β-CD inclusion complexes were a potential prebiotic with high potential in the field of medicine and health care.

The steady and incompressible two-dimensional flow of a hybrid nanofluid across a porous stretchable sheet is numerically analyzed in this study. To create a hybrid combination, copper (Cu) and alumina (Al2O3) nanoparticles are merged in water, which is regarded as the host fluid. The effects of suction, magnetic fields, porous media, thermophoresis, chemical reactions, Brownian motion, and activation energy have used in this work. Additionally, the molar concentration, velocity, and thermal slip constraints are used in this study. PDEs are used to illustrate the mathematical model, and with the use of suitable similarity variables, they are transformed into ODEs. After that, the transformed ODEs are numerically solved and verified using those reference studies. The velocity profile was observed to decrease with the increasing solid volume fractions of copper and alumina nanoparticles, as well as with higher magnetic, velocity slip, and porosity factors. Skin friction increased with the influence of porosity, magnetic, and suction factors, but decreased with the velocity slip factor. The temperature slip factor led to a reduction in the temperature profile, while higher solid volume fractions of copper and alumina nanoparticles, along with Brownian motion, thermophoresis, and magnetic factors, expressively enhanced it. The rate of heat transfer increased with radiation, Eckert number, Brownian motion, and thermophoresis effects, but decreased with the thermal slip factor. Furthermore, Brownian motion and the concentration slip factor reduced the mass transfer rate, whereas the Schmidt number, thermophoresis, and chemical reaction factors amplified it.

Enhancement in the heat transfer rate of the heat-exchanging fluid can significantly improve the efficiency of a thermal system. Nanofluids have emerged out to be a new promising fluid because of their unique heat-exchanging ability. However, most existing studies are restricted to single-component ferrofluids with limited control over thermal performance. To address this limitation, the present study experimentally investigates the parametric impact and tunability of the heat transfer coefficient (HTC) of a Fe₃O₄–Ag hybrid nanofluid, engineered to exploit the high thermal conductivity of silver nanoparticles and the magnetic responsiveness of magnetite nanoparticles. The experiments explore the influence of varying frequency (50–1 kHz) and field intensity of an alternating magnetic field (0–2.4 mT) on the heat transfer rate. Additionally, the effect of nanoparticles concentration (0.25–1 mass%) on HTC is analyzed. Results demonstrate that the HTC is highly susceptible to magnetic field parameters, exhibiting up to a 67.5% enhancement at a field intensity of 2.4 mT compared to the base fluid. To further optimize thermal regulation, a split-range fuzzy logic controller (FLC) is implemented to dynamically control fluid temperature by adjusting magnetic field strength and frequency. The FLC-based system achieves comparable cooling performance to the uncontrolled case while reducing heater energy consumption by 2.1% and electromagnetic energy input by 31.8%. The Fe₃O₄–Ag ferrofluid and control scheme establish a foundation for smart, magnetically tunable thermal management systems applicable to solar thermal devices and advanced heat exchangers.

This present investigation reports the measurement of thermally stimulated discharge current and contact angle to understand the role of surface properties in thermal relaxation in nanocomposite samples. The polysulfone (PSF)–ZnO nanocomposites thin film of thickness 40 µm was prepared by a solution-mixing method. TSDC is not only used to study the fine structure of polymeric materials, but it is an important technique for fine structure investigation of both solid polymers and additives of PSF nanocomposites, which were recorded at room temperature and 60 °C with different values of DC field. The nature of relaxation mechanisms in PSF nanocomposite was observed by the measurement of discharge current after polarization by DC field. The single relaxation peak was observed at around 180 °C. The high-temperature peak is associated with MWS relaxation mechanism. The PSF nanocomposite had mass ratio proportion of 3, 5, and 10 where the comparison of surface properties was made between the nanocomposites and the pure PSF.

Lignocellulosic biomass (LC) is a non-food-competing resource that can be converted into valuable products via pyrolysis. However, its complex polymeric structure makes this process challenging. Acetylation is a promising chemical treatment to enhance the efficiency of biomass pyrolysis. Furthermore, thermogravimetric analysis (TG) is a simple and low-cost technique that can be used to simulate pyrolysis, although dynamic TG curves may not be appropriate for LC. This work investigated the effects of acetylation on the chemical composition, thermal behavior, and catalytic thermo-degradation of three types of LC (wood sawdust, coconut husk, and cow manure). Acetylation was performed using acetic anhydride and sulfuric acid under microwave irradiation, and catalytic thermo-degradation was investigated by dynamic and isothermal TG analysis. Acetylation enhanced carbon content and total mass loss while decreasing residual mass in all biomass types. Interestingly, isothermal TG analysis revealed improved interaction between the catalyst and LC, surpassing dynamic analysis in catalytic thermo-degradation. Remarkably, the isothermal TG analysis showed greater mass loss in the presence of the catalyst. The combined effect of acetylation and the catalyst increased biomass thermo-degradation by 4.5% at 523 K compared to raw biomass. This suggests that acetylation combined with catalytic thermo-degradation can enhance the pyrolytic conversion of lignocellulosic biomass, with efficiency evaluated through isothermal TG analysis.

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