Journal of Thermal Analysis and Calorimetry最新文献

Behavior of progressive fluid motion under various physical circumstances and geometries must be predicted and understood to improve industrial thermal management systems. Furthermore, peristaltic motion of hybrid nanofluids is essential for temperature control, chemical manufacturing, environmental engineering and biological applications. The present research investigates peristaltic transport of hybrid nanoliquid within a nonlinear porous medium. Darcy–Forchheimer law is implemented to describe the nonlinear porous medium properties and convection. Dissipation and heat source/sink have been considered in energy expression. The copper (Cu) and silver (Ag) nanoparticles are taken. Maxwell thermal conductivity relation is used to explore the thermal features of hybrid nanomaterial. Brinkman viscosity model describes the viscous characteristics of mono and hybrid nanomaterials. Convective boundary constraints are imposed. Dimensionless systems for larger wavelength are chosen. System of equations and boundary conditions are numerically solved. Graphs and bar charts are drawn to study the velocity, pressure gradient, temperature and transfer rate.

To simulate the sodium fire phenomenon that is expected to occur in an accident of sodium-cooled fast reactor, it is necessary to obtain the thermodynamic parameters that describe the structural phase transition and melting of sodium peroxide (Na₂O₂). Nevertheless, the thermodynamic database and existing literature provide only limited information on this topic. The objective of this study was to ascertain the thermodynamic parameters associated with the phase transitions of Na₂O₂ through the use of differential scanning calorimetry (DSC). Due to the high chemical reactivity of Na₂O₂ at elevated temperatures, particular precautions were necessary for the DSC measurement, including the selection of an appropriate crucible material, the preparation of a custom-made crucible with a specialized geometrical configuration, and the meticulous calibration of the recorded temperature and enthalpy change. Furthermore, all experimental procedures for the DSC measurement were required to be conducted under controlled atmospheric conditions of inert gas. Despite the aforementioned difficulties, we were able to successfully determine the transition temperatures and enthalpy changes associated with the structural phase transition and melting of Na₂O₂ using DSC. The reliability of these thermodynamic parameters was validated by comparing them with previously reported values.

This work examines the thermal and flow characteristics of (left( {{text{TiO}}_{2} + {text{AgBr}} + {text{GO}}/{text{EG}}} right)) trihybrid nanofluid in the conical gap that exists between a disc and a cone. Effect of thermophoresis and particle deposition are examined to perceive the mass dissipation change on the surface. The governing equations of the problem are in the form of partial differential equations which are converted to nonlinear ordinary differential equations by applying proper scaling similarity transformations, and then the resultant equations are approximated numerically by using RKF45 technique. The interesting part of this research is to discuss the impact of various pertinent parameters on three cases namely: (1) rotating cone/disk (2) rotating cone/stationary disk and (3) stationary cone/rotating disk. The flow field, heat and mass transfer rates were analysed using graphical representations. Additionally, sensitivity analysis is performed on derived rate of heat transfer as a response function for input factors for different parameters. From the graph, it is perceived that flow field increases significantly with increase in the values of Reynolds numbers for both cone and disk rotations. Also, it is seen that temperature upsurges significantly for ascendent values of solid volume fraction of nanoparticles. It is also noticed that the sensitivity of the Nusselt number towards (n) is more for all the values of source/sink and for middle level values of (n).

During the rapid filling of hydrogen cylinders, the geometric parameters related to the cylinder configuration significantly influence the gas temperature rise and the final filling state. However, the existing literature still needs to sufficiently explore the internal structure of hydrogen cylinder injectors. Therefore, this study aims to address this gap by developing a numerical model for the rapid filling process of a 35 MPa, 74 L cylinder (includes both 2D axisymmetric and 3D models). The investigation focuses on analyzing the impacts of the internal length, diameter, and angle of the injector on the temperature rise and gas distribution within the cylinder. The results indicate that optimizing the injector angle can effectively mitigate the temperature increase, while improper angle configurations may exacerbate the temperature rise. Furthermore, this study introduces a novel time-divided filling strategy designed to control the maximum temperature within the cylinder while minimizing energy consumption. By optimizing both the injector configuration and the filling strategy, this research can enhance the efficiency of the hydrogen filling process, thereby contributing to the advancement of hydrogen energy utilization.

A comprehensive analysis is conducted on the magnetohydrodynamic (MHD) flow of a non-Newtonian Williamson fluid around a stretching cylinder, incorporating Hall current, heat generation, variable thermal conductivity, and convective boundary conditions in the presence of radial magnetic field. This study additionally examines the thermophoretic and Brownian motion characteristics with the selected non-Newtonian model. By employing appropriate physical assumptions, the problem is mathematically formulated as a system of nonlinear partial differential equations. To facilitate the analysis, these equations are further simplified by using the similarity transformations. The resulting equations are subsequently solved numerically utilizing the MATLAB bvp4c solver. The outcomes related to thermal, momentum, and mass transport are presented graphically, highlighting the influence of varying flow parameters. Additionally, key engineering quantities, such as the local skin friction coefficient, local Nusselt number, and Sherwood number, are summarized in a tabular format. The main findings of this study indicate that an increase in the Hall parameter enhances the momentum profiles, whereas the presence of a magnetic field parameter leads to a reduction in these profiles. Further, the thermophoretic parameter significantly enhances the distribution of heat and mass, whereas the Brownian motion parameter exhibits a counteractive effect, resulting in a reduction of mass distribution alongside an elevation in temperature. The skin friction coefficient is surged by (0.43% ) and dropped by (11%) by increasing Hall parameter from 0.1 to 0.5 and the magnetic field parameter raised by 0.3 – 0.7, respectively. Also, comparative analysis is conducted between the MATLAB-derived results and previously published data. Moreover, this study has significant implications for heat and mass transfer in Williamson nanofluids, with potential applications in chemical reactors, pollution control, fuel cells, and solar stills.

With the rapid growth of resource depletion, heat storage materials play a vital role in sustainable development. However, as a kind of heat storage material, phase change material (PCM) leaks easily when used, so anti-leak measures are crucial. In this study, microencapsulation phase change materials (MPCMs) were prepared by emulsifying first and then crosslinking, in which tetraethyl orthosilicate (TEOS) was used as the shell coating precursor, octadecane as the core and sodium dodecyl sulfonate (SDS) as the emulsifier. The grafted objects of Si–O bonds in TEOS were adjusted through different ratios of SDS/octadecane. The results showed that when the mass ratio of SDS/octadecane is 0.067, SDS is hydrolyzed to lauryl alcohol under acidic conditions and grafted with silica, and the phase transition temperature is − 20 °C. SDS gradually changed from graft to adhere with octadecane through sulfonic acid bond when the mass ratio of SDS/octadecane increased. Si–O bonds combine octadecane with sulfonic acid bonds through van der Waals forces and the indirect branches of Si–O bonds form an inorganic silica shell. When the mass ratio of SDS/octadecane is 0.15, the phase transition temperature was 23 °C and the phase transition enthalpy was 111.9 J g⁻¹. The obtained silica/octadecane MPCMs have small diameter, good thermal stability and the phase change enthalpy remains stable after 500 cycles, and the composite materials blended with polyvinyl alcohol also have good thermal properties. It is expected to be applied in the field of heat management textiles.

The combination of Maxwell fluids with hybrid nanostructures opens up the possibilities for novel energy-efficient systems that employ the advantage of hybrid nanofluids’ superior heat transfer capabilities, such as next-generation cooling systems for nuclear reactors or solar energy applications, advanced material development, improved process efficiency and innovation in thermal management and reaction control. Hence, the current article studies the effects of binary chemical reaction and multiple slips on MHD Maxwell hybrid nanofluid incorporating titanium dioxide and copper nanoparticles in water–ethylene glycol through a 2D stretching sheet with thermal radiation, viscous dissipation and non-uniform heat source or sink. A comprehensive behaviour of Maxwell hybrid nanostructure and Maxwell nanostructure is also investigated. Obtained dimensionless ordinary differential equations of the proposed model are solved by finite difference approach via bvp4c scheme in MATLAB. Computed numerical result revealed that Deborah number, magnetic parameter, thermal relaxation parameter, thermal radiation parameter, Eckert number, and space-dependent and time-dependent heat source/sink parameter tend to raise temperature profile. Maxwell hybrid nanostructure experiences more heat transfer, drag force and mass transfer than Maxwell nanostructure. The suspension of nanoparticles in the presence of magnetic field and slip condition on boundary has a significant application in enhancing the cooling system of electronics, sensors and drug delivery systems.

Previous studies indicate that nanotechnology can significantly enhance the effectiveness of enhanced oil recovery (EOR) techniques, particularly hot fluid injection. The efficiency of the injection process can be significantly influenced by the nanofluid's thermophysical properties (TPPs). However, laboratory examinations of TPPs on the performance of nanofluid-based EOR techniques are time-consuming and expensive, and theoretical models can also be inaccurate. To address this challenge, machine learning (ML) models can efficiently predict nanofluid TPPs and their impact on oil recovery performance. This study uses six ML algorithms: the K-Nearest Neighbors (KNN), the Theil-Sen regressor, the decision tree (DT), the lightGBM, the Bayesian ridge, and the LASSO. Using the VR-fluid thermal conductivity and temperature created the formula and the model for thermal conductivity of the VR-VGO nanofluid with 2 mass% CuAeg, and also by the VR-VGO nanofluid with 2 mass% CuAeg thermal conductivity and temperature created the formula and model for VR-fluid thermal conductivity. The maximum R-squared (R²) for the VR-VGO nanofluid with 2 mass% CuAeg for the formula and the model attained by the Theil-Sen regressor and the KNN, which respectively are 0.997 and 0.999 in linear formation, and the best R² for the VR-fluid for the formula and the model reached by the BR and the KNN respectively are 0.98 using the polynomial formation, and 0.995 using the linear form. The VR-fluid viscosity and temperature calculate the VR-VGO nanofluid with 2 mass% CuAeg viscosity and the VR-fluid viscosity are calculated using the VR-VGO nanofluid with 2 mass% CuAeg viscosity and temperature. The best R² for the VR-VGO nanofluid with 2 mass% CuAeg reached by the Theil-Sen regressor for the formula, the KNN for the model, and the R² score for the VR-VGO nanofluid with 2 mass% CuAeg viscosity respectively are 0.999 and 0.999 in linear form. The best R² value for the VR-fluid for the formula by the BR is 0.999, and for the model by the KNN is 0.999 in linear form.

This article introduces an advanced numerical method to simulate the unsteady freezing inside a curved porous container, enhanced with hybrid nanoparticles and porous foam. By integrating these components and accounting for radiation effects, the study significantly accelerates the freezing process. Replacing water with hybrid nanofluids decreases the solidification time by 6.26%, showcasing the superior thermal conductivity of the nanofluid. Additionally, the incorporation of porous foam is highly effective, reducing freezing time by 78.77%, while the inclusion of radiation cuts the time by 25.78%. In a base scenario using only water without porous foam or radiation, the freezing time extends to 700.12 s. However, the optimized configuration, which combines all these techniques, reduces the process to just 139.30 s, underscoring a marked improvement in cold energy storage performance.

Ibrutinib (IBR) is a Bruton's tyrosine kinase inhibitor, a potent drug used in the treatment of various B cell malignancies. The IBR has poor bioavailability due to low aqueous solubility and high first-pass metabolism. The current research aims to enhance the IBR aqueous solubility by complexation with substituted beta-cyclodextrins and characterize the inclusion complexes using isothermal titration calorimetry. The complexation rate constants calculated from phase solubility study and isothermal titration calorimetry range from 1000 to 6600M⁻¹, indicating stable inclusion complexes' formation. The driving forces for the formation of inclusion complexes in the solution state are characterized by isothermal titration calorimetry. The thermodynamic parameters such as negative Gibbs free energy change, negative change in enthalpy values, and positive change in entropy values indicate that the formation of inclusion complexes is a spontaneous reaction.