Journal of Thermal Analysis and Calorimetry最新文献

Information about the structure-property relationship can be useful for the synthesis of compounds with desired properties, analysis of the role of intermolecular interactions in various physicochemical processes and separation of the synthesis product from impurities. In the present work, the influence of the position of the carbonyl group on the saturated vapour pressure and enthalpy of vaporization of ketones was studied. The saturated vapour pressures of isomeric decanones, undecanones and isophorone were measured by the transpiration method. The enthalpies of vaporization of isomeric ketones were determined using various methods: solution calorimetry, transpiration and correlation gas chromatography. The obtained values agree with each other within 1 kJ mol⁻¹. It was shown that 2-alkanones have higher enthalpies of vaporization and lower vapour pressures than 3-, 4-, 5-, 6-alkanones, which can be explained by the stronger intermolecular interactions existing between the molecules of 2-alkanones compared to others isomers.

Bioheat transfer is pivotal in a range of medical and daily applications, contributing to health and well-being. In hyperthermia treatment, it facilitates the elevation of temperatures in malignant tissues, thereby increasing their sensitivity to interventions such as radiation and chemotherapy, as well as in wearable monitoring devices, rehabilitation methods like heating pads and wraps, and electric blankets. This paper investigates the effects of thermal memory and dynamic linear thermal shocks on heat transfer within biological tissues. The research utilizes an advanced form of the Pennes equation for this analysis. The mathematical framework is based on an innovative time fractional generalized Fourier’s law, which can clarify particular aspects of atypical thermal diffusion phenomena. In the model being analyzed, the temperature gradient and its historical context influence the thermal flux. Additionally, at a specific location within the tissue, the thermal source induces a linear thermal shock at every instant. For both graphical and numerical simulations, Mathcad is employed to assess how the thermal memory parameter influences heat transfer.

In this study, an attempt has been made to develop a different design for a gray cast iron rear brake disk used in the automotive industry, which can serve as an alternative to traditional designs. The designs were created to enable the production of this brake disk on the Disamatic vertical molding machine. The purpose of this study is to prevent casting defects that may occur in traditional designs. The simulation parameters were clearly explained and the correctness of the mesh structure was stated. These are the necessary parameters to show how reliable our study is. In order to minimize air bubble and sand inclusion defects encountered in the casting of a 4.5-kg automobile brake disk, different runner system simulations were performed and optimized instead of traditional runner system designs. Three different models were evaluated. The result of this study showed that the newly developed designs might be more useful than the traditional design. The resulting different filling profiles were directly associated with the gating system. The Reynolds number was used to indicate whether the liquid metal flow was turbulent or not, making it easier to make a sensible choice between designs. The designs were compared in terms of possible casting defects. The results revealed that the new designs had a more homogeneous filling profile and a lower risk of casting defects. It was found that design 2 was the most suitable option among the proposed models.

High flame retardancy and thermal conductivity are key performances for advanced electronic packaging materials. Herein, boron nitride (BN) and epoxy curing agent were chemically bonded with highly flame retardant DOPO moieties to obtain BN-DOPO thermal conductive filler and DOPO-PA curing agent with flame retardancy. The effect of BN-DOPO and DOPO-PA on the thermal stability, flame retardancy, combustion behavior and thermal conductive performance of EP composites were analyzed in detail. Compared with EP/Al(OH)₃, up to 32.5% in LOI, V0 rating in UL-94, prolonged 125 s of TTI, 22% reduction of PHRR and 29% reduction of THR in cone test were observed when both BN-DOPO and DOPO-PA were incorporated into EP cross-linking network. According to the residual char morphology, the excellent flame retardancy of EP/Al(OH)₃ composite containing BN-DOPO and DOPO-PA was attributed to the formation of compact front char covered by fluffy porous carbon and thick continuous back char with tiny aluminum oxide particles. Moreover, the introduction of a small amount of BN-DOPO and DOPO-PA could also greatly improve the thermal conductivity of EP/Al(OH)₃ by 107% due to the better compatibility resulting in lower interface thermal resistance and more effective thermal transfer caused by the participation of BN-DOPO and DOPO-PA into epoxy curing reactions.

Viscoelastic liquids are of great interest for industrial and engineering applications due to their unique properties. This research presents a comparative examination of tri-nanomaterial Darcy-Forchheimer flow, involving Oldroyd-B, Maxwell, and Jeffrey (OMJ) nanofluids, over a permeable stretching sheet. The analysis integrates the influences of quadratic thermal radiation, activation energy, magnetic field, and heat source. Additionally, Buongiorno’s model has been utilized along with convective thermal boundary conditions. By leveraging local non-similar approach (LNSA), the modelled highly nonlinear partial differential equations (PDEs) are transformed into a set of ordinary differential equations (ODEs) which are further solved using the finite-difference-based bvp5c solver. It is determined that a rise in the Forchheimer parameter reduces the velocity field. The least and highest temperature profile is observed for Maxwell and Oldroyd-B nanofluids, respectively. It is further noted that per-unit increase in the Forchheimer parameter declines the drag coefficient by 15.43%, 23.87%, and 14.49% for Oldroyd-B, Maxwell, and Jeffrey nanofluid, respectively. As the temperature ratio raises, the heat transfer rate and mass transfer rate increase. Additionally, it is seen that the Oldroyd-B has the highest transfer rates followed by Jeffrey and Maxwell nanofluid.

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The increasing demand for hydrogen as an energy carrier requires the development of efficient and sustainable production strategies. Methane reforming is a widely used method for hydrogen production, and catalysts play a crucial role in optimizing this process. This paper provides a comprehensive review of the catalytic aspects of methane reforming, highlighting significant progress and recent advancements. After reviewing various research works, it was seen that the conversion of methane and carbon dioxide is influenced by the specific surface area of catalysts. It is observed that the catalysts with larger surface areas exhibit higher methane conversion rates, although exceptions are observed in the case of perovskites, which demonstrate good conversion efficiency despite their smaller size. Cobalt (Co) and nickel (Ni) are commonly employed in catalysts for achieving higher conversion rates. Other than that, various rare-earth catalysts were also evaluated in the paper. To further optimize the production strategy, several crucial points are identified. These include a comprehensive understanding of the reaction mechanisms for catalyst design, the integration of in situ characterization techniques for studying catalyst changes and active species, collaboration between theoretical calculations and experimental studies, and the development of highly efficient and stable catalysts. Emphasis is placed on exploring cost-effective options, such as nickel and other non-noble metal catalysts, while assessing their performance at low temperatures and in advanced reforming systems. With the increasing importance of hydrogen and syngas production, upgraded reforming systems are expected to flourish soon.

Nanoparticle coatings present a highly effective method for significantly enhancing the performance of solar distillers by improving heat transfer, evaporation, and condensation processes. This review provides a comprehensive examination of the current research on nanoparticle-coated solar stills, highlighting how nanoparticles improve thermal conductivity, absorb solar energy more efficiently, and promote dropwise condensation to increase freshwater productivity. Various nanoparticles, including metal oxides and carbon-based materials, have been studied for their ability to optimize solar still performance. However, challenges such as nanoparticle stability, cost, and environmental impact remain. This paper consolidates research efforts, analyses key findings, and outlines future directions for advancing the application of nanoparticle coatings in sustainable water purification technologies.

In this study, thermophysical properties of MWCNT (15%)-ZnO (85%)/ethylene glycol hybrid nanofluid (HNF) have been investigated statistically and experimentally. Understanding thermal behavior of nanofluid (NF) in different laboratory conditions and also determining the correlation between process factors and how the factors affect the thermal behavior are the most important objectives of this study. This study is performed under laboratory conditions (T = 28–55 °C, SVF = 0.05–1.85%). Experimental results show with increasing SVF and temperature; thermal conductivity (TC) of NF increases due to increasing collisions number, increasing kinetic energy and increasing energy transfer between fluid layers. The Maximum increase and minimum increase in TC occur in laboratory conditions of SVF_max = 1.85% and SVF_min = 0.055 % which was equal to 27% and 2.5%, respectively. To predict and determine the correlation between process variables, RSM is used with a second-order model with R-squared = 0.9854 and − 1.5% < MOD <  + 1.5%. Also, the price performance factor (PPF) has been studied for two different HNFs.

This study delves into the computational exploration of the impact of magnetic intensity, magnetic nanofluid, flow rates and heat transfer coefficient in the form of Nusselt number on inclined ribbed channels with both parallel and staggered configurations for the cooling of sodium-ion and lithium-ion batteries in electric vehicles. Employing Fe₃O₄ + H₂O as the working fluid, within a minichannel with multiple magnets at different locations, namely 15 mm, 25 mm and 15 mm and 25 mm, the parallel and staggered inclined ribbed channel Nusselt number (Nu) increased with magnetic field intensity, reaching maximum of 152.81% for staggered ribbed minichannel configuration at 2000 Gauss (G). Similarly, the skin friction experienced an increment with magnetic field intensity for staggered ribbed minichannel configuration and for parallel ribbed minichannel when both the magnets were placed at the location of 15 mm and 25 mm from the inlet but decreased with increasing Reynolds number. Notably, the thermal enhancement factor (TEF) consistently surpassed greater than unity for all investigated cases. These findings carry significant implications, particularly in EV cooling, offering valuable insights for developing more efficient and tailored cooling solutions for advanced EV battery thermal management.

The utility of micropolar nanofluid presents challenges nowadays in various industrial sectors as well as biomedical areas due to its higher thermal properties. Generally, these are useful in electronic cooling devices, drug delivery processes, hyperthermia treatment, etc. The current problematic model aims at the behavior of particle concentration of copper nanoparticles on the motion of micropolar fluid via two parallel plates packed within a porous matrix. The conducting fluid, with the interaction of radiative heat and dissipation energy, energies the flow and heat transport phenomena. The modeled problem equipped with aforesaid properties is transmuted to ordinary for the suitable choice of similarity rules, and then, numerical technique is adopted to handle the governing equations. The simulation of the characterizing parameters is presented through graphs followed by the comparative analysis with the existing results in particular case. The main conclusions are as follows: The thickness is greatly increased by the Reynolds number, while it is attenuated by the magnetization provided by the interplay of the applied magnetic field and the medium's permeability. As a result of amplified radiating heat, the fluid temperature moves toward the top plate region, indicating a greater fluid temperature and a greater cooling impact at the bottom region.