Journal of Thermal Analysis and Calorimetry最新文献

This work presents a comprehensive analysis of thermofluidic characteristics for a radiation-absorbing hybrid nanofluid within an electromagnetically driven rotating vibrator channel, considering coupled pressure gradients, Hall/ion-slip phenomena, and porous medium effects. The configuration features a stationary right boundary and an oscillating left wall with three distinct excitation modes (impulsive, cosinusoidal, and sinusoidal) for both velocity and thermal boundary conditions. The governing time-dependent PDE system is solved analytically through Laplace transform techniques, yielding exact solutions for all flow variables. Parametric studies reveal that: (i) Main flow velocity is attenuated by the Coriolis force, which concurrently amplifies cross-flow velocity, (ii) Hall currents alter velocity profiles, enhancing streamwise flow while diminishing cross-stream motion, (iii) higher oscillation frequencies promote a stabilization of the flow field, and (iv) modified Hartmann numbers exhibit dual effects—strengthening primary wall shear while weakening secondary shear components. Thermal radiation parameters consistently enhance the rate of heat transfer at the vibrating boundary. The artificial neural network model achieves remarkable prediction accuracy, with training/validation scores of 99.307%/99.40% for primary shear stress, 96.202%/98.762% for secondary shear stress, and perfect 100%/98.64% agreement for rate of heat transfer, demonstrating exceptional reliability in capturing the complex thermofluidic interactions.

The suggested thermo-bioconvection model for CNTs+TiO₂/water-based trihybrid nanofluid with gyrotactic microbes has potential applications in enzyme biosensors and bacteria-powered micromixers. The trihybrid nanofluid's increased thermal conductivity and mass transfer capabilities improve biosensor sensitivity and stability, allowing for the effective detection of biological and chemical species. Meanwhile, the regulated bioconvection of gyrotactic bacteria aids in the development of self-driven micromixers, which are essential in lab-on-a-chip systems, biomedical devices, and microfluidic platforms that demand precise and energy-efficient mixing. This study examines the properties of thermal radiation on gyrotactic microorganisms and thermophoretic particle deposition in a water-based trihybrid nanofluid across a surface with Soret and Dufour characteristics was described. The properties of Hall current and magnetic fields are all taken into consideration when analyzing fluid flow. A nonlinear set of PDEs is reduced to a dimensionless system of ODEs by the similarity variables. We have used the bvp4c approach to numerically estimate the reduced set of nonlinear ODEs. As the Soret and Dufour numbers rise, consequently increase the thermal and concentration profiles.

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In this study, an artificial neural network (ANN) approach is employed to analyze the thermal and fluid behavior of gold–blood Casson nanofluid flow over a heated stretching sheet, incorporating Joule heating and viscous dissipation. The analysis is based on the advanced Cattaneo–Christov heat flux model, which captures several essential physical effects, including Brownian motion, thermophoresis, chemical reactions, activation energy, Eckert number, Joule heating, and viscous dissipation. The governing nonlinear PDEs are reduced to ODEs via similarity transformations and solved using an intelligent backpropagation neural network with Levenberg–Marquardt optimization in conjunction with the bvp4c solver. A comprehensive dataset was generated by varying critical parameters and partitioned into 80% training, 10% testing, and 10% validation subsets. The ANN model exhibited excellent predictive performance, with regression coefficients approaching unity and mean squared errors ranging from (E^{ - 7} {text{to}};E^{ - 3}). Model reliability was further confirmed through error histograms and fitness curves. Numerical and graphical results were benchmarked against existing literature and showed strong agreement. The findings reveal that fluid velocity decreases under stronger magnetic fields and higher stretching rates, while porous media enhance flow. Thermal transport is significantly improved by Joule heating and viscous dissipation. Furthermore, nanoparticle concentration increases with thermophoresis but diminishes with higher chemical reaction rates.

The main source of the significant environmental problem of pesticide pollution in wastewater is the widespread use of these chemicals in agriculture. This study emphasizes creating three effective adsorbents, potassium carrageenan (CA), flaxseed mucilage powder (FM), and composite of flaxseed mucilage/carrageenan beads (FMC), with strong adsorption abilities to remove the organophosphorus pesticide chlorpyrifos from wastewater. The fabricated adsorbents were assessed employing a diversity of physicochemical techniques. Physicochemical tools revealed that FMC had an appropriate surface area of 44.6 m² g⁻¹, a mesoporous nature (2.9 nm as pore diameter), acceptable thermal stability, and various functional groups on its surface that originated. The optimal adsorption conditions were identified at a temperature of 15 °C, adsorption time of 90 min, initial solution pH 6, and solid dose of 3 g L⁻¹ with maximum adsorption capacity of 189.19 mg g⁻¹. Different mathematical models were implemented to evaluate isothermal, thermodynamic, and kinetic parameters, conveying that the adsorption on all solid adsorbents follows a pseudo-second order mechanism, spontaneous, exothermic, and physisorption. After eight rounds of adsorption/desorption, the adsorption potential of CA, FM, and FMC reduced by 8.9%, 12.7%, and 4.1%, respectively. This study highlights the efficacy of the fabricated flaxseed mucilage/carrageenan for the effective and large-scale pesticide removal in polluted water bodies.

Theoretical study on heat and mass transport in tangent hyperbolic fluid using mathematical modeling and numerical simulations has been the cheapest means for exploring the phenomenon. Physical laws and boundary conditions under some realistic assumptions are solved numerically. Convergence and grid-independent analysis are performed under a specified computational tolerance. Several numerical experiments are done to explore the behaviors and trends of field variables against related parameters. Bar graphs are a quick review of the trend in quantities related to the data size. Therefore, the trend of the Nusselt number and wall shear stresses is identified through bar graphs. The comparison between the wall heat transfer rates for nano, di-nano, and tri-nano-fluids is provided. The thermal relaxation parameter has shown a decreasing effect on the temperature of the fluid. This decreasing behavior is noted in all three types of fluid considered in the study. The highest wall heat flux is noticed in the case of tri-nanofluid. Thus, in non-Fourier heat transfer, the Nusselt number has the highest value compared to that in Fourier heat transfer. Thus, in a thermal system, the efficiency of a fluid subjected to non-Fourier heat transfer is much better than that of a fluid subjected to Fourier heat transfer. The presence of a porous medium in the fluid results in a decrease in wall heat flux (the Nusselt number). The Ohmic dissipation and viscous dissipation both provide heat to the fluid. This results in increasing its overall energy and, consequently, its temperature increases. Thus, the thermal performance of the fluid is reduced. It means that the heat dissipation due to viscous dissipation and Joule heating (Ohmic dissipation) undermined the thermal efficiency of the fluid.

Melamine particleboard (MFPB) is extensively utilized in the construction and decoration industries. However, when exposed to natural environmental conditions, its flame-retardant properties gradually deteriorate due to humidity-related factors. This study investigates the aging mechanisms and flame-retardant characteristics of MFPB under dry and wet aging conditions. The findings indicate that the volatile matter content in MFPB exhibits a negative correlation with aging duration, whereas fixed carbon demonstrates a positive correlation with ash content. The stability of cellulose, hemicellulose, and melamine–formaldehyde resin (MF) is relatively poor, and aging induces the decomposition of volatile components within MFPB, thereby diminishing its flame-retardant performance. The limiting oxygen index (LOI) of MFPB shows an overall declining trend, transforming it from a flame-retardant material into a combustible one. After 60 days of exposure to alternating dry and wet aging conditions, the time-to-ignition (TTI) of MFPB decreased by 23 s compared to unaged samples. Nevertheless, the aging process exerts an inhibitory effect on the heat release rate, potentially increasing the risk of secondary hazards associated with fires. These research outcomes provide a theoretical foundation for predicting the effective service life of engineered wood products and advancing the development of flame-retardant materials.

Analyzing heat transfer and fluid dynamics of ternary hybrid nanomaterials in confined cavities is vital for improving thermal performance in wide-ranging engineering applications. The current investigation employs finite element technique to explore natural convection and thermal transport of ternary hybrid nanomaterials ((Fe_{3} O_{4} - Cu - TiO_{2 } - H_{2} O)) inside an undulant-wall enclosure enclosing a heated fin. The integration of fins in confined cavities emerged as a highly effective strategy for enhancing the efficiency of thermal systems. Impacts of heat generation and horizontal magnetic field are invoked. The finite element technique is utilized to solve coupled nonlinear PDE’s governing fluid motion and heat transport under steady and laminar flow conditions. Key variables, such as Rayleigh number, heat generation parameter and Hartmann number, are systematically varied to analyze their impacts on fluid flow patterns and thermal performance. Results reveal that enhancing Rayleigh number and heat generation parameter significantly improves heat transfer rate up to 58% and 25%, respectively. Furthermore, invoking magnetic field within the enclosure influences the heat distribution up to 18%, leading to a suppression of convective flow. Enhancement of fin’s length in the enclosure leads to a notable enhancement in thermal transport up to 20% due to increased surface area for convective flow. Nusselt numbers are computed to evaluate heat transfer performance. Temperature and velocity profiles are found to increase with high Rayleigh numbers and heat generation parameter. This analysis provides valuable insights into optimizing enclosure design using ternary hybrid nanomaterials for improved thermal system performance.

This study investigates the heat and mass transfer in the cross-nanofluid model. It holds great importance in numerous applications such as jet engine coatings, thermal storage, fuel efficiency, heat exchangers, spacecraft thermal control, drug delivery, and electronic cooling. Entropy expression is explored by examining heat source/sink, nonlinear thermal radiation, and viscous dissipation. Temperature and concentration are considered in terms of thermal and solutal slip conditions. Thermophoretic and Brownian motion aspects are considered in the nanofluid model. Appropriate similarity transformations are utilized to reduce the governing partial differential equations into ordinary differential equations and are tackled numerically by employing MATLAB’s built-in BVP4C solver. The effect of various parameters on temperature, friction drag, entropy generation, velocities, Bejan number, heat, and mass transport rate is discussed graphically. Furthermore, the optimization of the thermal transport rate is performed via sensitivity evaluations using the response surface methodology. The opposite behavior is noticed for entropy generation and Bejan number via higher values of the Hartman number and Eckert number. The thermal transport rate is more sensitive to the thermophoretic parameter than the temperature difference parameter and the Eckert number, particularly when the Eckert number and temperature difference parameter are at a high level.

This study explores the impact of transient laminar fossil fuel thermophoretic convective heat transfer on climate change. To achieve this, a physical model is designed in which three regions are connected through trans-boundaries via temperature and concentration differences. Fossil fuel combustion emits thermophoretic particles in a rectangular coordinate source region. These particles travel through the plume region, represented in a cylindrical coordinate system, and then reach the atmospheric region, described mathematically using a spherical coordinate system. The main aim of this investigation is to analyse the time-dependent impacts of these thermophoretic particles on climate change. For this purpose, the non-dimensional model of all the three regions is separated into steady and unsteady (real and imaginary) part. These models are reduced to algebraic equations employing the finite difference technique. The solutions are achieved by applying a numerical method of differentiation to suitably chosen values of dimensionless parameters. The results, presented as graphs and contours, depict the effects on transient skin friction, transient heat transfer and transient behaviour of thermophoretic concentration. The contour graphs reveal that at (alpha = 1.5) rad, transient heat transfer is greater due to increased heat transfer, whereas transient behaviour of thermophoretic concentration indicates weaker particle deposition. At (alpha = 3.14) rad, transient heat transfer is weak and widely distributed while transient behaviour of thermophoretic concentration is greater indicating more particle deposition in horizontal directions suggesting increased pollutant accumulation in these directions. The main reason of this investigation is to analyse the transient impact of fossil fuels emission on climate change numerically and graphically.

This study investigates the influence of external parameters on thermal runaway propagation (TRP) in a prismatic LiFePO₄ (LFP) battery module using a coupled electro-thermal abuse model combined with statistical multi-parameter analysis. Four key factors—insulation thickness, trigger cell position, convective heat transfer coefficient, and internal short-circuit (ISC) location, were analyzed through a Taguchi L9 orthogonal design and gray relational analysis (GRA). Results revealed that insulation thickness had the strongest effect on delaying TRP, increasing the thermal runaway (TR) delay by up to 145 s when increased from 0.5 mm to 1.5 mm. The trigger cell position also played a dominant role, delaying TR initiation by 120–138 s when shifted from a central to boundary location. The internal short-circuit position influenced TR severity, with a bottom-edge ISC initiating TR 37 s earlier than a central ISC. In contrast, increasing the natural convection coefficient from 10 to 20 Wm⁻² K⁻¹ produced only a marginal TR delay of 1–3 s. GRA-ANOVA confirmed the parameter influence ranking as insulation thickness as the dominant factor, followed by trigger cell position and ISC location, while heat transfer coefficient ranked lowest. The findings enable the identification of the dominant factor controlling the delay of thermal runaway propagation, thereby providing strategies for enhanced battery safety.