Journal of Thermal Analysis and Calorimetry最新文献

With the widespread adoption of electric vehicles, thermal runaway safety incidents have become increasingly frequent. The battery thermal management system (BTMS) plays a critical role in ensuring the safe and efficient operation of batteries. Phase change material (PCM)-based BTMS, as a passive thermal management approach, offers advantages such as low operating costs and excellent temperature uniformity. This paper primarily reviews the development of hybrid liquid and PCM cooling BTMS. Focusing on lithium-ion batteries, the study analyzes their structure, working principles, heat generation mechanisms, and heat transfer characteristics. Subsequently, the working principles and theoretical models of liquid cooling systems and PCM cooling systems are examined separately. Finally, the paper summarizes advancements in hybrid PCM cooling-based thermal management systems, including the application of PCM in BTMS and the development of BTMS integrating PCM. The liquid-PCM cooling BTMS serves as the main focus of this study, categorized by cooling channel structures into three types: parallel-channel, serpentine-channel, and cross-flow-channel liquid-PCM hybrid systems. The results demonstrate that the cooling performance of hybrid PCM cooling-based BTMS depends on superior PCM properties and an optimized system structure. Leveraging their advantages in temperature control, battery protection, and structural design, liquid-PCM BTMS exhibits broad application prospects in the field of electric vehicle battery thermal management. They provide a reliable and efficient technical solution to address battery thermal safety challenges and are expected to emerge as a mainstream direction for future electric vehicle thermal management systems.

This study reviews the literature on vinyl ester matrix samples hardened with rockwool fibers and fumed silica, focusing on its flammability, thermal, and mechanical characteristics. The load bearing behavior was greatly improved using the insertion of rockwool fibers, which increased the structural strength and reduce the stress concentration. With a flexural strength of 156 MPa and a tensile strength of 146 MPa, sample VRS2 demonstrated the best mechanical performance among the different formulations. With a decomposition threshold of 381 °C, the composite delivered an outstanding thermogravimetric residue of 98%, slashed the flame spread rate to a mere 5.33 mm min⁻¹, and achieved its best-in-class low heat conductivity of 0.28 W m⁻¹ K⁻¹. The enhanced thermal insulation and flame-retardant behavior were mainly caused by the higher fumed silica content. SEM investigation revealed even more details about the internal architecture of the composites. Sample VRS2 showed low signs of fiber pull-out and robust fiber-matrix adhesion in addition to excellent filler dispersion. While VRS2 exhibited excellent thermal and flammability properties, sample VRS3 showed indications of filler agglomeration, which could account for its marginally worse mechanical performance. In sum, the findings highlight the possibility of composites in situations requiring a harmony between thermal stability, flame resistance, and mechanical strength.

With the increasing demand for fresh water and the need for sustainable energy solutions, solar desalination technologies have emerged as a promising alternative. Traditional solar desalination systems often face challenges such as low evaporation rates, high-energy consumption, and slow desalination processes. This study aims to optimize solar desalination systems using vacuum-assisted heat exchangers. By applying a vacuum, the boiling point of water is reduced, which increases evaporation rates and accelerates the desalination process. The experimental setup involves circulating saline water through the vacuum chamber, where solar energy heats the water, promoting evaporation at lower temperatures. The evaporated water vapor is captured by a condenser unit and converted back to freshwater. The system’s performance is evaluated under various conditions to identify optimal parameters. Data analysis, employing deep learning techniques such as convolutional neural networks (CNNs) combined with long short-term memory (LSTM) models, aims to refine operating conditions for maximum efficiency. Multivariate adaptive regression splines (MARS) will be integrated to model the nonlinear and complex relationships between these variables in a more interpretable and flexible way. The findings indicate that vacuum-assisted heat exchangers at 50 Torr significantly enhance evaporation rates to 3.15 kg m⁻² h⁻¹ compared to traditional systems, achieving improved desalination performance. The study demonstrates the potential for substantial energy and cost savings while increasing sustainability in water purification processes. Future research will focus on scaling up the technology, improving material durability, and integrating advanced control systems for real-time optimization, offering potential solutions to global water scarcity issues.

Azobisisobutyronitrile (AIBN) is extensively utilized as an initiator and foaming agent in polymerization processes. Upon thermal decomposition, AIBN releases toxic nitrogen gas and organic cyanides, posing significant hazards. This study investigates its thermal stability and associated risks using TG-MS, DSC, and ARC methodologies. The decomposition process comprises two stages: crystalline phase transition followed by simultaneous solid-phase melting and decomposition. Mass loss occurs across three temperature ranges: preheating (< 86 °C), rapid decomposition (86–133 °C), and subsequent decomposition (133–180 °C). Adiabatic tests reveal decomposition between 70.95–125.66 °C. Hazard assessments classify decomposition heat as level 3, thermal runaway potential as level 2, and severity as level 2, highlighting notable exothermic potential and explosion risks. Activation energies are determined as 97.27 kJ mol⁻¹ (nonadiabatic) and 142.54 kJ mol⁻¹ (adiabatic), with reaction mechanisms described as G(α) = (1 − α)⁻1–1 and f(α) = (1 − α)2. These findings offer essential safety data for AIBN's production, handling, and storage.

This study investigates the thermal performance enhancement of parabolic trough collectors (PTCs) through nanoparticle-enriched Syltherm 800, addressing the critical yet underexplored challenge of achieving uniform heat distribution in solar thermal systems. Computational fluid dynamics (CFD) simulations using ANSYS Fluent and ray-tracing analysis with Tonatiuh were conducted under 968.2 W m⁻² irradiance to evaluate CuO, Fe₃O₄, and MWCNTs nanoparticles at a 5% concentration. Among the tested nanoparticles, CuO exhibited the highest enhancement, increasing volumetric specific heat capacity by 8%, compared to 7.6% for Fe₃O₄ and 1.5% for MWCNTs. Thermal efficiency improved from 70.73 to 80.70%, representing a 14.1% gain, with Fe₃O₄ and MWCNTs achieving increases in 13.6% and 12.5%, respectively. Additionally, CuO uniquely reduced absorber tube temperature gradients by 4.2% at the bottom surface, surpassing reductions of 3.2% for Fe₃O₄ and 0.4% for MWCNTs, effectively mitigating thermal stress beyond conventional efficiency-focused improvements. These findings highlight CuO’s superior potential in enhancing specific heat capacity, improving thermal efficiency, and minimizing temperature gradients, offering a promising approach to optimizing PTC performance.

This study aims to examine the mixed convective flow and heat transport of a pentahybrid nanofluid over an exponentially stretching surface under nonlinear thermal radiation effects. By employing non-similar solutions, the study explores how stretching, convection, radiation, and nanoparticles influence the pentahybrid nanofluid motion. The methodology involves formulating flow equations under boundary layer approximations in a Cartesian coordinate system. Scaling transformations are applied to non-dimensionalize the governing equations. The resulting non-similar equations are then solved using the finite difference method to analyze the hydrothermal flow characteristics of pentahybrid nanofluid. The mixed convection parameters significantly influence pentahybrid nanofluid flow and heat transfer. Higher ({beta }_{text{t}}) strengthens buoyancy forces, enhancing temperature, streamlines, and heat transfer, while (delta) increases velocity. Thermal radiation parameters intensify heat transfer by elevating temperature gradients. Temperature shows a rise–fall–rise behavior under the collective aspects of nonlinear thermal radiation and mixed convection. The originality of the study lies in analyzing the mixed convective flow of a novel pentahybrid nanofluid over an exponentially stretching surface under the influence of nonlinear thermal radiation. Unlike previous works that often use simpler nanofluid models or linear radiation assumptions, this study develops a non-similar formulation, capturing more general and realistic flow behavior. The combination of pentanary nanoparticles, nonlinear radiation, and non-similar solutions makes the study highly innovative and unique.

Hybrid nanofluids demonstrate superior thermophysical properties compared to pure nanofluids, offering enhanced thermal conductivity, mechanical strength, and stability. This investigation examines the thermal and magnetic characteristics of both pure (text {Al}_2text {O}_3)/engine oil (EO) and hybrid (text {Al}_2text {O}_3)-(text {Fe}_3text {O}_4)/EO nanofluids under the influence of applied and induced magnetic fields. The analysis incorporates the effects of activation energy and chemical reaction kinetics. We develop an innovative numerical solution approach employing order reduction techniques implemented via the bvp4c solver. Validation against established results demonstrates excellent agreement, confirming the method’s robustness. Key findings reveal that increasing Grashof numbers enhances both vertical and horizontal velocity components, while the induced magnetic field parameter exhibits an inverse relationship with fluid velocity in both pure and hybrid systems. Furthermore, nanoparticle volume fraction shows a positive correlation with temperature distribution. The results suggest that hybrid (text {Al}_2text {O}_3)-(text {Fe}_3text {O}_4) nanofluids present significant advantages for thermal management applications, combining improved heat transfer performance with inherent corrosion resistance properties. These characteristics position hybrid nanofluids as promising candidates for advanced thermal engineering systems.

Internal pressure in solids or liquids is theoretically studied, and cannot be measured directly by experiments. A new heat capacity model is created for general materials in the wide temperature range recently, and shows that heat capacity is dependent on both the temperature and the volume. In this study, we further analyzed the parameters in the heat capacity model, and first established a relation between heat capacity and internal pressure in materials. The potential heat capacity-dependent cohesive energy induces the internal pressure P_c in solids or liquids. The internal pressure in matters reflects the existence of strong intermolecular attractive forces, and can be determined by experimental heat capacity, which is helpful to further understand the nature of the internal pressure or heat capacity in condensed matter physics.

Solar energy fluctuations prevent the current solar integrated thermal cycle (SITC) power generation system from functioning efficiently under its intended design conditions, and thermal energy storage (TES) can efficiently mitigate the impact of solar energy fluctuations. Cascaded TES is considered a superior option for solar heat storage over two-tank TES. This study investigates a thermal power plant boasting a capacity of 210 MW, incorporating a solar system based on integrated thermal storage devices and LFR technology. Solar-integrated thermal cycle performance is analyzed using MATLAB to simulate dual-tank and cascade thermal storage systems. The results indicate that (i) Molten salt as HTF stores 36.75 MW of energy when charging, compared to 29.18 MW with oil. Molten salt exhibited 4.7% better thermal storage efficiency than oil. (ii). Two FWH can be replaced in cascade TES compared to two-tank TES. The coal consumption rate with cascade TES was decreased by 2.09% compared two-tank. Also, the fuel saving rate of cascade TES can be increased by 17.90% than two-tank TES.

This study presents a numerical analysis of magneto-radiative mixed convection in a Casson fluid confined within a wavy square enclosure containing a centrally heated circular cylinder. The combined effects of inclined magnetic fields, thermal radiation, and geometric waviness are examined to understand their influence on flow circulation, heat transfer, and entropy generation. The governing equations are solved using the finite element method (FEM) with appropriate grid independence and convergence verification. Results are expressed through detailed streamlines, isotherms, and Nusselt number variations for a wide range of dimensionless parameters. The findings reveal that increasing the Casson parameter, Darcy number and Reynolds number enhances flow circulation, whereas higher Hartmann numbers suppress it. Lid inclination markedly alters flow topology, thermal fields and entropy distribution. Enlarging the heated cylinder radius broadens isothermal zones and elevates total entropy. Notably, the average Nusselt number increases by a factor of 8.4 when the radiation parameter rises from 0.5 to 10 and the lid inclination changes from 0° to 90°. Furthermore, average kinetic energy grows with the Casson parameter but declines as radiation effects intensify. These results offer new insights into magneto-radiative transport in complex geometries, with potential applications in energy systems, materials processing and thermal management technologies.