Papers by Keyword: Thermal

Abstract: The construction industry remains a major contributor to global CO₂ emissions, primarily due to its high consumption of non-renewable mineral resources and energy-intensive materials. In response to the growing need for sustainable alternatives, this study focuses on valorizing lignocellulosic biomass waste specifically Solid Olive Waste (SOW), a byproduct of olive oil production abundant in Mediterranean countries as a partial replacement for mineral aggregates in concrete. The main objective is to develop and evaluate an Innovative Solid Olive Waste Composite (ISOWC) as an eco-friendly material suitable for construction sector. The incorporation of SOW was optimized using the Talbot–Fuller–Thompson (T-F-T) semi-empirical method, which enabled the determination of ideal incorporation rates (10%, 20%, and 30% by aggregate volume) based on maximum packing density. Composite formulations were developed using the volumetric mix design method, incorporating both raw and water-saturated SOW. Comparative tests demonstrated that saturated SOW significantly improved the composite’s compressive strength and thermal conductivity, particularly as the SOW content increased. To further assess performance, a sensitivity analysis was conducted on ISOWC with 30% saturated SOW at varying cement dosages (200–350 kg/m³). The formulation with 200 kg/m³ cement achieved a compressive strength of approximately 6 MPa and thermal conductivity of 0.72 W/mK, meeting the criteria for insulating applications such as blocks and cladding panels. These results highlight the promising potential of ISOWC and support further investigation into the use of Solid Olive Waste as a full replacement for gravel in the development of eco-efficient, sand-based concretes.

Abstract: Graphene known as a groundbreaking nanomaterial for its outstanding mechanical strength, superior thermal conductivity, and excellent electrical properties, has gained recognition as an innovative additive for enhancing metal matrix composites. However, challenges such as agglomeration, uneven dispersion, and porosity limit its widespread application. This study aims to investigate the effects of varying graphene concentrations (0%, 0.5%, 1.0%, and 1.5%) on the microstructural, mechanical, and thermal properties of copper-graphene composites fabricated using the powder injection molding (PIM) method. The samples underwent systematic preparation and were analyzed through hardness and tensile testing, along with Scanning Electron Microscopy (SEM) for microstructural evaluation. Results revealed that incorporating 0.5% graphene significantly enhanced tensile strength (205.22 MPa), hardness (94.2 HRL), and thermal conductivity due to uniform dispersion, efficient load transfer, and reduced porosity. However, increasing graphene content to 1.0% and 1.5% led to agglomeration, increased porosity, and disrupted microstructures, resulting in reduced mechanical and thermal performance. SEM images corroborated these findings, showing a progression from smooth, well-bonded structures at 0.5% graphene to irregular, void-filled morphologies at higher concentrations, making it suitable for applications requiring efficient heat dissipation and mechanical reinforcement.

Abstract: Mechanical and thermal properties of composites reinforced with Banana fibre (BF) and Sisal fibre (SF) were investigated in this study. Benzoylation therapy was effective for Banana fibre /Sisal. The hybridised bio-composites (PP/BF/SF) with a total 10 weight percentage were produced using three different fibres ratios between Banana fibre - and Sisal-treated. The thermal stability experiments are performed using thermogravimetric analysis (TGA) and diffraction scanning calorimetry (DSC). According to flammability test results, the treated hybrid composite (BF / PP /SF) burned at the slowest rate (only 28 mm/min) and the stiffness damping factor (Tan δ). The loss modulus (E "the ideal (PP/BF/SF) hybrid composite, T-BF5SF5, has a damping factor of 0.058 and a modulus of 86.2 (MPa). Thermomechanical analysis (TMA) was also used to effectively record the dimensional coefficient (m) versus temperature studies, with T-BF5SF5 achieving the highest dimensional coefficient (m) of 30.11 at 110°C. Keywords: Sisal; biocomposites; Banana fibre ; dynamic mechanical analysis; thermal; benzoylation.

Abstract: This paper presents a comprehensive investigation into the thermal performance of microchannel heatsinks featuring varying geometries. The investigation was carried out utilizing computational fluid dynamics (CFD) simulations. Computational Fluid Dynamics (CFD) simulations have demonstrated potential as a viable method for prognosticating system performance. This study involved the modeling and analysis of three primary microchannel heatsink configurations, namely uniform, convergence, and divergence, utilizing ANSYS package v.22.1. The study examined the various parameters that affect microchannel heatsinks and evaluated their thermal performance. The investigated case involved laminar flow through microchannels of varying cross sections in a heat sink, where the Reynolds number is equal to 129. Steady state flow, incompressible fluid, neglecting radiation and natural convection, constant characteristics, and negligible viscous dissipation were assumed in the study. The results emphasize the significance of microchannel geometry and flow configurations in augmenting heat dissipation. The results were subjected to numerical validation, which demonstrated a high level of concurrence with prior research. The reliability of the numerical model was validated, thereby substantiating its suitability for utilization in simulations. The convergence microchannel, specifically in Case no.2, and the divergence microchannel, specifically in Case no.7, exhibited optimal performance. In the second case, there was a notable average improvement rate of 35%, which suggests that the heat dissipation capabilities were superior. Cases 3 through 11 demonstrated favorable outcomes, with improvement rates varying from 2.7% to 30%. Conversely, Cases 12 and 13 exhibited less satisfactory results. In conclusion, this research highlights the importance of microchannel heatsinks in effectively addressing thermal issues in electronic systems. The utilization of convergence and divergence microchannel configurations, in conjunction with carefully selected geometric parameters, exhibits the potential for efficient heat dissipation.

Abstract: Semiconductor devices rely on the incorporation of donor and acceptor atoms into the crystal lattice to form locally doped regions. For dopant atoms incorporated into SiC by ion implantation, a high-temperature annealing step is required to achieve electrical activation. This annealing step is accompanied by redistribution of the implanted atoms. The influence of the annealing parameters on dopant redistribution is crucial when aiming for ever smaller device dimensions. In this work, we present a consistent analysis of the diffusion of Al implanted in 4H-SiC after high-temperature annealing at 1650 °C and 1800 °C for different annealing times. We identify the equilibrium diffusion coefficient at long annealing times from Al profiles obtained by SIMS analyses for both annealing temperatures. The temperature dependence is determined using an Arrhenius representation. This allows to quantify the equilibrium diffusion lengths for the actual temperature profiles, including heating and cooling rates. We find that the measured diffusion lengths for short annealing times are larger than expected from equilibrium diffusion and attribute the excess length to transient enhanced diffusion. Comparing the transient diffusion lengths of room-temperature and 500 °C-implanted samples, we conclude that the transient behavior is likely related to residual crystal damage induced during the implantation process.

Abstract: In this paper, the cooling of a passenger car alternator’s stator winding is investigated with the help of computational fluid dynamics. The main heat sources are determined to be the stator winding and the diodes. Their respective heat loss is calculated and applied in the CFD software. In the first step, the CAD model is simplified in a way to enable a fine-quality numerical mesh generation, while keeping the important geometric features that could have significant effects on the results. In the next step, independence studies are carried out for the mesh, time-step size, and flow volume. A comparison is also presented between the steady “frozen rotor” approach and the transient “moving mesh” approach.After conducting the transient simulations at multiple operating points, the simulation results are evaluated with the help of contours and quantitative properties. An experimental comparison is presented which shows a good correlation between the simulated and the measured data, furthermore, the possible reasons for the deviations are eventually discussed. Finally, the benefits of the future applications of the simulation model are introduced briefly.

Abstract: This work presents a comparative finite element analysis of a 3-wheeler novel robot chassis used for uneven terrain robot applications. The chassis was modeled using SolidWorks and further analyzed in Ansys for its total deformation, equivalent stress, equivalent elastic strain and thermal strain. Two materials were taken into consideration for comparative analysis: Aluminium alloy and Structural steel. A load (force) of 500 N was distributed on the chassis uniformly and an acceleration of 5 mm/sec² was given. Thermal conditions were added by raising the temperature from 22°C to 50°C in 1 sec. The analysis performed was majorly divided into three parts: a) Only considering force, b) Considering force as well as acceleration, c) Considering force, acceleration and thermal conditions. Total deformation in Aluminium alloy was observed 1.51 to 2.79 times that of structural steel in all the cases. Both metals exhibited almost identical equivalent stress in absence of thermal effect and structural steel exhibit 1.5 times that of Aluminium alloy at elevated temperature. Aluminium alloy possess relatively more (1.86-2.63 times) equivalent elastic strain compared to structural steel. Although, distribution of thermal strain remained constant throughout the chassis for both the materials, its magnitude was 1.91 times high in Aluminium alloy. This type of analysis helps in evaluating the current design and decide whether it will sustain the required load and acceleration under given thermal conditions

Abstract: Chemical engineering frequently uses "process intensification" to consciously combine various phenomena or procedures. By treating the molecules in such a system in a way that every single molecule experiences the same processing, the selectivity is raised, enhancing productivity. For mass transfer limited reactions, the enhancement of the transport rates & the specific interfacial area are the typical approaches. These enable the reduction of diffusion path length, reduce hold-up and improve the controlling on temperature control, even for highly exothermic reactions. Micro reactor technology (MRT) is a subset of process intensification that aims to reduce the size of equipment, energy consumption, and waste generation. The research of peracetic acid (PAA) and perform acid (PFA) preparation is the focus of the current investigation. Amberlite IR-120H catalyst was used to study the synthesis of PAA and PFA in batch and micro-structured reactors while ultrasonic irradiations were present.. The current research describes a method for synthesizing both compounds in a batch and micro-structured reactors, with and without ultrasonic irradiation. Such a technology might be crucial in the online synthesis of these chemicals as it eliminates the need for harmful components to be transported and stored, assuring safety among other benefits. For these substances, various safety characteristics could be improved.

Abstract: When a pure liquid crystal is dispersed into a suitable polymer to form micron-sized droplet, then it is called Polymer-dispersed liquid crystal (PDLC). In the present study, PDLC of different concentrations were prepared by dispersing a conducting polymer poly (3, 4–ethylenedioxy thiophene): poly (styrene sulfonate) into a cholestryl palmitate. The differential scanning calorimetry and fabry perot scattering studies were employed to study thermal and optical properties. It was found that the phase transition for PDLC occurs at a temperature different than those exhibited by pure liquid crystal. The behaviour of PDLC for parallel and perpendicular electric field has been investigated and the dielectric constant is determined. The value of dielectric constant and conductivity were found to increase with increasing concentration of polymer. The bistability and reflective properties of pure cholesteric liquid crystal can be minimized by dispersing polymer which makes material suitable for high contrast at large viewing angles.

Abstract: In this paper, aiming at the heat resistance and thermal deformation process of titanium matrix composites 0 vol.%, 2.5.vol.%, 5.vol.%. Thermal simulation experiment of titanium matrix composites with different (TiB+TiC) strengthening phase content. The measurement accuracy of material displacement is 0.01 mm. The compression is 70%, and the strain rate is 0.1 mm/s and 0.01 mm/s respectively. Compression tests at different strain rates and temperatures were carried out. The experimental results show that when the (TiB+TiC) 5vol% titanium composite is deformed at 0.01mm/s low strain rate, the peak stresses corresponding to 25°C, 250°C,350 °C and 500°C are increased to 1096MPa, 835MPa, 646MPa and 416MPa respectively. Under the condition of high strain rate of 0.1mm/s, the peak stresses corresponding to 25 °C, 250 °C, 350 °C and 500 °C are increased to 1230 MPa, 896 MPa, 723 MPa and 471 MPa respectively. The deformation law of stress rheological curve is roughly the same, and the high temperature zone has good plastic deformation ability. The titanium matrix composite has high compression rheological mechanical properties and good high-temperature plastic deformation ability. It is the preferred material component for the preparation of titanium matrix composite and powder forging.