Thermal Behavior Research Articles

Thermal and rheological behavior of aluminium-doped zinc oxide nanofluids: Experimental study and application of artificial neural network model

In this study, the influence of Al-doping concentration on the thermal and rheological characteristics of pristine zinc oxide (ZnO) nanofluids was investigated across a range of temperatures and nanoparticle concentrations. A multilayer perceptron (MLP) artificial neural network (ANN) with an optimized topology was employed to model the thermal conductivity and viscosity of nanofluids. The addition of 0.13 M of Al-doped zinc oxide nanoparticles at 1 % rate led to a remarkable 64 % increase in the thermal conductivity of the base fluid (50:50 ratio water + ethylene glycol mixture). Furthermore, incorporating 1 % of these Al-doped nanoparticles outperformed pure zinc oxide, resulting in a 44 % boost in thermal conductivity. The enhanced heat transfer capabilities of Al-doped zinc oxide were evident across different doping and nanoparticle concentrations. The viscosity of nanofluids increases with an increase in nanoparticle concentration and decreases with an increase in temperature. ZnO and Al-doped ZnO nanoparticles have been prepared and studied their structural, morphological and elemental properties using XRD, SEM and EDS respectively. The predicted thermal and rheological behaviours are in close agreement with the experimental values.

Water Sensitive Urban Design Construction Systems Performance Due to Water Retention

Objectives: The main goal of this research is to analyze and quantify reduction of surface temperatures (Ts) in systems which retain and especially harvest water with the focus on blue roofs and to check if just infiltrating water is enough to reduce surface temperatures. Theoretical Framework: ODS13, Climate action; ODS11 Sustainable Cities and communities; Water Sensitive Urban Design construction systems thermal behavior and Cooling water effect implemented by Governments and Municipalities. Method: it’s experimental, based on the quantification of different WSUD construction systems which infiltrate, retain and harvest water during a first year and focused on a blue roof prototype during a second year. Tools used are a thermal camera, a hygrometer and an anemometer. Results and Discussion: Surface temperatures gradients were from 5.3ºC at the infiltration basin, to 6ºC in the blue roof prototype to 14.6ºC in the built blue roof. Construction systems which could retain and harvest water had a Ts underneath the environmental one. They also retain less heat during the night contributing less to UHI than those which can’t retain water. Research implications: this research provides the information about water powerful effect in construction systems which infiltrate and harvest water. They contribute to the decrease of UHI. Originality/value: results demonstrate water cooling effect in infiltrating surfaces which can retain it. Results offer one more construction systems choice criteria in urban design.

Design of a New Catalyst, Manganese(III) Complex, for the Oxidative Degradation of Azo Dye Molecules in Water Using Hydrogen Peroxide.

In the current work, chloro(meso-tetrakis(phenyl)porphyrin) manganese(III) [Mn(TPP)Cl] was synthesized following two steps: the preparation of meso-tetraphenylporphyrin (H⁠2TPP) and the insertion of manganese into the free porphyrin H2TPP. The compounds were characterized using SEM, FT-IR, UV, TGA/DTA, and XRD analyses. Manganese(III) meso-porphyrins exhibited hyper-type electronic spectra with a half-vacant metal orbital with symmetry, such as [dπ:dxz and dyz]. The thermal behavior of [Mn(TPP)(Cl)] changed (three-step degradation process) compared to the initial H2TPP (one-step degradation process), confirming the insertion of manganese into the core of the free porphyrin H2TPP. Furthermore, [Mn(TPP)Cl] was used to degrade calmagite (an azo dye) using H2O2 as an oxidant. The effects of dye concentration, reaction time, H2O2 dose, and temperature were investigated. The azo dye solution was completely degraded in the presence of [Mn(TPP)(Cl)]/H2O2 at pH = 6, temperature = 20 °C, C0 = 30 mg/L, and H2O2 = 40 mL/L. The computed low activation energy (Ea = 10.55 Kj/mol) demonstrated the efficiency of the proposed catalytic system for the azo dye degradation. Overall, based on the synthesis process and the excellent catalytic results, the prepared [Mn(TPP)Cl] could be used as an effective catalyst for the treatment of calmagite-contaminated effluents.

Implementation of thermoelectric wall systems for sustainable indoor environment regulation in buildings through numerical and experimental performance analysis

With buildings representing a substantial portion of global energy consumption, exploring alternatives to traditional fossil fuel-based heating and cooling systems is critical. Thermoelectricity offers a promising solution by converting temperature differentials into electrical voltage or vice versa, enabling efficient indoor thermal regulation. This paper presents a comprehensive investigation into the integration of thermoelectric wall systems for sustainable building climate control through numerical simulations and experimental analyses. Numerical simulations using computational fluid dynamics (CFD) techniques were conducted to model fluid flow and heat transfer within the thermoelectric wall systems under various operating conditions. These simulations provided insights into the system’s thermal behavior, which were validated through experimental setups designed to measure temperature differentials, airflow rates, and power consumption. The results showed that power consumption is directly correlated with electrical current, ranging from 0.19 W to 77.4 W as the current increased from 0.1 A to 2 A. Additionally, the heat absorbed by the system increased significantly with electrical current, by 706–1044%, depending on the air velocity. The thermal energy released from the hot side of the thermoelectric modules also rose substantially, ranging from 9850 to 5285% with increasing electrical current, and from 275 to 51% with higher air velocities. Moreover, increasing air velocity led to a 6.78–9.37% reduction in power consumption for currents between 0.1 A and 2 A. The coefficient of performance (COP) analysis revealed that optimizing both electrical current and air velocity is essential for maximizing system efficiency. While fan power consumption reduces COP at higher air velocities, neglecting fan power consumption results in COP improvements ranging from 6.5 × 10⁻⁴ to 49.0%. These findings highlight the potential of thermoelectric wall systems to enhance indoor comfort and energy efficiency in buildings.

Enhanced Thermal and Flexural Properties of Alkalized Date Palm/Kenaf Fiber-Reinforced Epoxy Hybrid Composites: A Comparative Study of Untreated and Treated Fibers

ABSTRACT This study evaluates the thermal and mechanical behavior of hybrid composites made from date palm (DP) and kenaf fibers (KF) in an epoxy thermoset matrix. Both DP and KF fibers are abundant and renewable, reducing environmental impact. KF offers high tensile strength and stiffness, improving composite strength and rigidity, while DP fibers offer toughness and impact resistance, enhancing durability. The composites were developed in 30%, 50%, and 70% DP-KF compositions using layup and hot-pressing methods. Fiber treatment through alkalization was analyzed for its impact on mechanical and thermal properties to find the optimal fiber ratio. The hybrid composites were subjected to DMA, TGA, and flexural tests. The treated composites exhibited fewer impurities and increased cellulose content, resulting in enhanced flexural performance. This improvement was evident through higher storage modulus, lower loss modulus, and reduced tan δ when exposed to thermal stress. The 30% DP and 70% KF composites exhibited best performance. The treated 30DP-70KF exhibited improvement in the flexural strength and modulus by 13.8% and 2.7%, respectively. TGA demonstrated that treated 30DP-70KF composites had a higher glass transition temperature (Tg) and better thermal degradation resistance. These findings highlight the potential of natural fiber hybrids in creating sustainable, high-performance composite materials for construction and industrial applications.

Application of Sound Waves During the Curing of an Acrylic Resin and Its Composites Based on Short Carbon Fibers and Carbon Nanofibers.

Research into particulate polymer composites is of significant interest due to their potential for enhancing material properties, such as strength, thermal stability, and conductivity while maintaining low weight and cost. Among the various techniques for preparing particle-based composites, ultrasonic wave stimulation is one of the principal laboratory-scale methods for enhancing the dispersion of the discontinuous phase. Nevertheless, there is a scarcity of empirical evidence to substantiate the impact of stimulating materials with natural sound frequencies within the acoustic spectrum, ranging from 20 Hz to 20 kHz, during their formation process. The present work investigates the effect of acoustic stimuli with frequencies of 56, 111, and 180 Hz on the properties of an acrylic-based polymer and its discontinuous carbon-based composites. The results indicated that the stimulus frequency affects the cure time of the studied systems, with a notable reduction of 31% and 21% in the cure times of the neat polymer and carbon-nanofiber-based composites, respectively, after applying a frequency of 180 Hz. Additionally, the higher stimulation frequencies reduced porosity in the samples, increased the degree of dispersion of the discontinuous phase, and altered the composite materials' thermal, optical, and electrical behavior.

Multi-objective optimization of a novel hybrid battery thermal management system using response surface method

This study evaluates the thermal performance of a Z-type battery thermal management system (BTMS) designed for nine lithium-ion batteries discharged at a high rate of 5C, using Computational Fluid Dynamics (CFD) simulations. The investigation employs Response Surface Methodology (RSM) to optimize two critical thermal performance parameters: the maximum battery temperature (Tmax) and the maximum temperature difference between cells (ΔTmax). Various cooling strategies are explored to comprehensively assess the BTMS, including natural convection, forced convection, cooling fins, phase change material (PCM), and composite PCM. These methods are analyzed to determine their effectiveness in controlling the thermal behavior of the battery pack. The simulation results indicate that integrating different cooling techniques can significantly lower Tmax from 352.38 K to 309.14 K and reduce ΔTmax from 14.6 K to 3.31 K, depending on the method used. Under critical conditions, such as the failure of the active cooling system, the BTMS still maintained a Tmax of 310.64 K and a ΔTmax of 0.95 K, demonstrating its robustness and reliability. Further optimization identified the ideal configuration for the system, including an inlet air speed of 1.2 m/s, an inlet temperature of 297.15 K, and a PCM thickness of 3.8 mm, achieving optimal thermal performance with a Tmax of 303.97 K and ΔTmax of 3.17 K. This study offers valuable insights into the design and optimization of effective BTMS for enhanced battery safety and longevity.

Variability in thermal comfort and behavior of elderly individuals with different levels of frailty in residential buildings during winter

Research on the indoor thermal comfort of elderly individuals has become increasingly detailed, yet studies focusing on the impact of health levels on elderly thermal comfort are still relatively scarce. Due to aging and various chronic diseases, elderly individuals exhibit different physical states, affecting their physiological regulatory functions in response to thermal environmental changes. This study aimed to validate the impact of health levels on elderly thermal comfort and behavior during winter, by employing the Fried frailty assessment method. A survey was conducted in the HSCW regions of China, gathering 1437 valid questionnaires. The analysis revealed that frailty significantly impacts the winter thermal comfort and behavior of the elderly. Specific findings include: 1) Frailer elderly individuals express greater complaints about indoor environments; 2) Frailer elderly are more dependent on heating devices; 3) Frailer elderly have higher rates of closing windows with higher Tout prompting window closure. The Tout prompting non-frailty elderly to completely close windows is 8.1°C, while for pre-frail and frail elderly, it is 16.7°C and 16.0°C, respectively; 4) Frailer elderly individuals exhibit higher Icl, with median values of 1.56 clo for non-frail, 1.68 clo for pre-frail, and 1.71 clo for frail elderly; 5) Frailer elderly individuals have lower MR daily, with median metabolic rates of 1.71 met for non-frail, 1.42 met for pre-frail, and 1.17 met for frail. This study found that the level of frailty significantly impacts the winter thermal comfort and behavior of the elderly and should be considered in future elderly-friendly architectural designs.

Research on predicting the thermocompression deformation behavior of Mg-Li matrix composite using machine learning and traditional techniques

Artificial intelligence and machine learning (ML) technologies have emerged as powerful tools for analyzing the thermal compression deformation behavior of metal matrix composites, offering significant potential to optimize their plastic deformation processing techniques. In this study, the Al3La/LAZ532 composite based on in-situ self-reaction technology was successfully prepared by adding La2O3 particles. Then, the thermal compression flow behavior of the as-cast composite was comparatively researched using a traditional Arrhenius model and advanced machine learning methods (Linear Regression, AdaBoost, Random Forest, and XGBoost). The flow stresses were predicted under various thermal operating conditions, and the performance of all models was assessed using root mean square error (RMSE), coefficient of determination (R2) and mean absolute error (MAE). Analysis shows that the Random Forest model outperforms traditional models and other ML methods in predictive accuracy, achieving an R2 of 0.97, an MAE of 5.8, and an RMSE of 7.07. Additionally, the stable hot working zone for the composite at 300 °C and a strain rate of 0.001∼0.01 s⁻1 can be identified by combining the microscopic structure with the macroscopic hot working map. This zone is characterized by a uniformly distributed, fine-grained structure with high levels of dynamic recrystallization (DRX). The texture with the <0001> axis of the grains aligned parallel to the compression direction (CD) is formed in the thermally deformed microstructure, and the DRX mechanism is discontinuous dynamic recrystallization (DDRX).

The role of Ni minor additions on the mechanical characteristics of Sn-1.5Ag-0.5 wt.% Cu (SAC155) Pb-free solder alloy

AbstractMicrostructure analysis, thermal behavior, and tensile creep characteristics of the Sn-1.5Ag-0.5Cu-x wt.% Ni (SAC155-xNi, x = 0, 0.05, 0.1, 0.2, and 0.5 wt.%) solder alloys have been examined. The Ni additions have greatly modified the microstructure of Ni-free alloy into bulky fibrous eutectic regions and included the contemporary (Cu, Ni)6Sn5, and (Ni, Cu)3Sn4 IMCs. Ni additions slightly increased solidus temperature and melting temperature of them. The results of tensile creep resistance have shown dependence on Ni content and testing temperatures due to bulky fibrous eutectic regions and finer IMCs. Creep rates vary with Ni content across all temperatures and stresses. The SAC155-0.05Ni alloy has the lowest and the SAC-0.0Ni alloy has the highest creep rates at all tested conditions. The delicate dispersed IMCs of Ag3Sn and Cu–Ni–Sn resulted in a significant increase in stress exponent (n$$\approx $$ ≈ 5–8), enhancing its deformation resistance. The $$n$$ n values of alloys decrease as the testing temperature rises due to a change in the dominant creep mechanism. The average values of activation energy (Q) of SAC155-xNi alloy ranged from 60.20 to 68.02 kJ/mol. These Q values are coherent to the process of pipe self-diffusion through dislocation cores.

Improvement in the performance of indium free dye sensitized solar cell by the use of polyaniline composite

The photovoltaic study of the fabricated dye sensitized solar cells is revealed in this paper. To provide indium free approach, fluorine doped tin oxide (FTO) and aluminium doped zinc oxide (AZO) glass substrate were used as charge collectors for counter electrodes and photoanode respectively. Also, a novel and natural mixed dye was used as sensitizer and mixture of doped polymer (polyaniline with metallic oxides of tin, vanadium and cerium) and iodide-triiodide couple was utilized as electrolyte for the cell. Optical band gap and light absorption performance of dyes were studied by ultraviolet-visible (UV-vis) spectroscopy. Surface morphology and elemental composition of polymer composites was studied using scanning electron microscopic (SEM) with energy dispersive X ray (EDX) analysis. Phase analysis of the composites was determined by X-ray diffraction and thermal behavior with the help of thermo gravimetric analysis (TGA). Photovoltaic characteristics (I-V) and induced photon to current efficiency (IPCE) measurements were also investigated. Highest IPCE of 17.7% was observed when polyaniline was doped with oxide of vanadium. Hence an efficient, green, indium free and novel cell is fabricated by the usage of different charge collector substrate, natural dye sensitizer and quasi solid-state electrolyte.

Thermoluminescence characteristics of BeO doped with Si, Mg, and Cr: Density Functional Theory calculations and One Trap – One Recombination Center model simulations

The incorporation of first principles computational methods in Thermoluminescence (TL) enables the comprehensive investigation of the luminescent characteristics exhibited by solid materials. These calculations offer valuable insights into the electronic structures and thermal behavior, providing a deeper understanding of the underlying mechanisms. Density Functional Theory (DFT) is a powerful tool for predicting, among others, the electronic structure properties, like the Density of States (DOS) of materials. By theoretically depicting the electronic states arising from electron transitions, the present study focuses on the DFT study of undoped and of BeO with substitutional and doping, and the connection of TL emission caused by recombination of electrons in centers, as outlined in the One Trap – One Recombination (OTOR) center model. This approach offers essential details regarding the origins of electron traps, facilitating a deeper exploration of the intrinsic relationship between TL and DFT in Stimulated Luminescence (SL) analysis.

Unveiling the untapped potential of Hibiscus Rosa-sinensis lignocellulosic fiber: A multifaceted characterization for advancing sustainable biocomposite applications

In the pursuit of sustainable advancements in bio-inspired fiber reinforced polymer composite materials, the exploration of novel natural fibers has become a focal point of research. This experimental study aims to elucidate the unexplored potential of Hibiscus Rosa-sinensis fiber (HRF) as a versatile reinforcement material for high-performance composites. Through an integrated approach, this research offers a meticulous analysis of the HRF's physico-chemical properties, and single fiber tensile strength. The crystalline structure are revealed by X-ray diffraction (XRD), thermal behavior are characterized through thermo-gravimetric analysis (TGA), and surface morphology has been visualized using field emission scanning electron microscopy (FESEM) studies. From the results, it is found that the HRF contains a cellulose content of 79.50 %, positioning it as a prime bast fiber among its counterparts. This composition is complemented by hemicellulose (10.36 %), lignin (4.62 %), wax (0.84 %), and ash (2.96 %). The Fourier-transform infrared spectroscopy (FTIR) spectra unveils the intricate functional groups present in the fibers. XRD analysis highlights a crystallinity index (CI) of 66.93 %, confirming a well-organized and structured crystalline arrangement. The thermal stability established through TGA underscores HRF's resilience up to 284 °C, presenting it is an optimal reinforcement material for bio-inspired green composites operating within 280 °C. The surface morphology of HRF is examined through FESEM and three-dimensional profiling, showcasing its inherent morphological intricacies. The multidimensional characterization provided herein contributes significantly to the evolving landscape of biocomposite research, fostering a platform for future advancements and innovations in HRF-based composite materials.

C18‐DABCO‐AA: A Novel Brønsted Acidic Gemini Surfactant for the Environmental Benign Synthesis of 2,3‑Dihydroquinazolin‑4(1H)‑ones in Water at Ambient Temperature

AbstractWe have successfully synthesized a new acidic surfactant named C18‐DABCO‐AA, which contains octadecyl and acetic acid substituent on DABCO (1,4‐diazabicyclo [2.2.2] octane) unit, with an excellent yield. The synthesized surfactant was analyzed using FT‐IR, 1H NMR, and 13C NMR spectroscopic techniques. Its thermal behavior was analyzed by using the TGA–DTA technique. Our analysis indicates that the synthesized surfactant has excellent surfactant properties. Its critical micelle concentration (CMC) is 0.80 mM as determined by the conductivity method and UV–vis absorption measurement at 298.15 K. Surfactant also showed strong acidic properties with a pKa of 3.3. It is the best catalyst for the synthesis of 2,3‑dihydroquinazolin‑4(1H)‐ones (DHQs) in water at 40 °C. The synthesis is achieved via two‐component reactions of various aromatic aldehydes and anthranilamide in water at a CMC concentration of C18‐DABCO‐AA. The method was also extended for synthesizing DHQs via two‐component reactions of different ketones and anthranilamide under similar reaction conditions. The products were achieved in with yields ranging from good to excellent within 60–90 min. Additionally, the aqueous solution with C18‐DABCO‐AA was reused up to five times with a minor decrease in product yield. The present protocol is fast, energy‐efficient, and can be used on a large scale for synthetic purposes. Additionally, it boasts impressive environmentally friendly credentials.

Effects of mono- and dual-frequency ultrasounds on structure and physicochemical properties of faba bean proteins

Faba bean proteins are currently viewed as promising animal protein alternatives. However, certain functional properties e.g. relatively low solubility compared to whey protein isolates, can limit the application of faba bean protein isolates (FPIs) in certain food products. Therefore, it may be desirable to use modification approaches such as the application of ultrasound to alter such limiting physicochemical properties. In this study, Faba Bean Protein Isolates (FPI) were treated by ultrasound with different frequencies (20 kHz, 40 kHz and 20 + 40 kHz) prior to hydration (1 %) at different pH levels (3, 7, and 9). Then the structure and physicochemical properties (i.e. particle size, ζ-potential, surface hydrophobicity, thermal behavior, and solubility) of control and untreated FPIs were investigated. Ultrasound treatment had no obvious effect on the molecular weight of FPIs, whereas it changed the secondary structure of FPIs from a more ordered structure to a more disordered structure. The applied treatment resulted in an increase in surface hydrophobicity across all treatment levels and pHs. It also decreased the particle size of FPI at pH 3, while it increased the particle size at pH 7 and 9, compared to the untreated FPI. In addition, the solubility and thermal properties of FPI were modified through the ultrasound treatment. The higher solubility of FPI could improve its potential to be used as a functional ingredient for many food applications. Ultrasound treatment at 20 kHz and 20 + 40 kHz had more effects on the physiochemical properties of FPI compared to that at 40 kHz. Overall, ultrasound treatment with different frequencies (20 kHz, 40 kHz, and 20 + 40 kHz) modified the structure and physiochemical properties of FPI to different degrees and may be beneficial for the development of FPI for certain food applications.

Effect of B/Pb ion replacement in B2O3-PbO-SiO2 glasses: Structural, thermal, optical and electrical properties

Due to its easy manufacturing process and outstanding physical and chemical characteristics, boron lead silicate glass is widely used in electronic packaging, optical fields, and sensor technology. Herein, new glass samples with different proportions of B2O3/PbO are prepared by a combined melting and annealing process. The glasses undergo structural and thermal characterization to investigate its composition, thermal behavior, optical properties, and dielectric properties. The results show that the glass structure changes gradually as [SiO4] and [PbO4] units were replaced by [BO3] units with increasing B2O3 content. This transformation has an impact on coefficient of thermal expansion and characteristic temperature of the glass. Additionally, it is observed that alterations in structure resulted in a decrease in both optical band gap as well as dielectric constant and loss. These findings provide insights into how variations in the B2O3/PbO ratio influence structural evolution and enhance properties for boron lead silicate glasses. This provides a theoretical basis for further advances to improve material properties and expand optical and electronic applications.

Comprehensive Advanced Physicochemical Characterization and In Vitro Human Cell Culture Assessment of BMS-202: A Novel Inhibitor of Programmed Cell Death Ligand

Background/Objectives: BMS-202, is a potent small molecule with demonstrated antitumor activity. The study aimed to comprehensively characterize the physical and chemical properties of BMS-202 and evaluate its suitability for topical formulation, focusing on uniformity, stability and safety profiles. Methods: A range of analytical techniques were employed to characterize BMS-202. Scanning Electron Microscopy (SEM) was used to assess morphology, Differential Scanning Calorimetry (DSC) provided insights of thermal behavior, and Hot-Stage Microscopy (HSM) corroborated these thermal behaviors. Molecular fingerprinting was conducted using Raman spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy, with chemical uniformity of the batch further validated by mapping through FTIR and Raman microscopies. The residual water content was measured using Karl Fisher Coulometric titration, and vapor sorption isotherms examined moisture uptake across varying relative humidity levels. In vitro safety assessments involved testing with skin epithelial cell lines, such as HaCaT and NHEK, and Transepithelial Electrical Resistance (TEER) to evaluate barrier integrity. Results: SEM revealed a distinctive needle-like morphology, while DSC indicated a sharp melting point at 110.90 ± 0.54 ℃ with a high enthalpy of 84.41 ± 0.38 J/g. HSM confirmed the crystalline-to-amorphous transition at the melting point. Raman and FTIR spectroscopy, alongside chemical imaging, confirmed chemical uniformity as well as validated the batch consistency. A residual water content of 2.76 ± 1.37 % (w/w) and minimal moisture uptake across relative humidity levels demonstrated its low hygroscopicity and suitability for topical formulations. Cytotoxicity testing showed dose-dependent reduction in skin epithelial cell viability at high concentrations (100 µM and 500 µM), with lower doses (0.1 µM to 10 µM) demonstrating acceptable safety. TEER studies indicated that BMS-202 does not disrupt the HaCaT cell barrier function. Conclusions: The findings from this study establish that BMS-202 has promising physicochemical and in vitro characteristics at therapeutic concentrations for topical applications, providing a foundation for future formulation development focused on skin-related cancers or localized immune modulation.

Multiple-beam output, high-peak power passively Q-switched Nd:YAG/Cr4+:YAG laser for ignition application - Modeling of laser pulse characteristics and thermal behavior

In this work we report on the characteristics of a passively Q-switched Nd:YAG/Cr4+:YAG laser with four beams, developed for studies on the laser ignition of different combustible mixtures. The compact laser contains a Nd:YAG/Cr4+:YAG ceramic composite medium, with a monolithic optical resonator. A configuration in which each beam contains laser pulses with an energy of 3.1 mJ and a duration of 0.9 ns (i.e. with a peak power of 3.4 MW) is discussed; operation can be performed in pulse-burst mode, with up to five pulses per pumping pulse. The characteristics of the laser pulses are described by a model based on the rate equations for the photon flux and population inversions in the Nd:YAG gain medium and in the Cr4+:YAG medium with saturable absorption. In addition, the thermal effects are simulated for the operation up to 100 Hz repetition rate, considering the Nd:YAG/Cr4+:YAG laser medium with two geometries, the first of the rod type and the second of the annular type (i.e. cylinder with a central hole) for a good management of thermal effects. This work is an important advancement towards developing a compact laser device with multiple beams, featuring laser pulses and structural properties suitable for igniting combustible mixtures in real engines.

Elucidating synergistic effects during co-pyrolysis of plastics and paper in municipal solid waste: Thermal behavior and product characteristics

Elucidating synergistic effects during co-pyrolysis of plastics and paper in municipal solid waste: Thermal behavior and product characteristics

Investigation of battery safety states based on thermal propagation and expansion analysis: Experimental studies on different packaging forms

Lithium-ion batteries are highly susceptible to thermal runaway under harsh conditions, posing significant safety risks for electric vehicles. The differences in thermal runaway propagation across battery systems with varying manufacturing methods (including packaging and internal stacking) and the study of changes in expansion force within battery modules are crucial for improving safety and developing early warning systems for battery systems. This study investigates the thermal runaway and propagation behavior of lithium-ion batteries under various conditions, focusing on state of charge (SOC), internal manufacturing processes (electrode stacking and winding), and packaging types (pouch and prismatic) through a series of novel experiments. The results show that batteries at high SOC levels are at a greater risk of thermal runaway propagation, with winding pouch cells displaying more severe runaway behavior. In contrast, prismatic cells, despite experiencing intense explosions with an equivalent force of up to 42.3 g of TNT, exhibit relatively milder propagation. Furthermore, the study incorporates heat transfer analysis during thermal runaway propagation, identifying key phenomena such as the formation of negative pressure zones before explosions and changes in expansion forces at the module level. Based on these findings, a new safety evaluation method is proposed to assess the risk, hazards, and severity of thermal runaway, offering valuable insights for enhancing battery safety management and fire prevention strategies.