Heating Rate Research Articles

Metaheuristic optimizing energy recovery from plastic waste in a gasification-based system for waste conversion and management

In an era where sustainable waste management and clean energy production are paramount, this study presents an innovative integration of plastic waste gasification with solid oxide fuel cell (SOFC) technology, optimized through metaheuristic particle swarm optimization (PSO). The research explores the conversion of polypropylene (PP) waste into syngas via gasification, which is then utilized as a fuel for SOFCs to generate electricity. The optimization process focuses on maximizing power and heating outputs while minimizing carbon dioxide emissions. The study's findings demonstrate the potential of integrating gasification and SOFC technologies to create a sustainable energy system that addresses the challenges of plastic waste. Key findings from the metaheuristic PSO multi-objective optimization reveal that optimal power production, approximately 360 kW, is achieved at temperatures exceeding 1140 K, irrespective of the steam/PP waste ratio. Heating production peaks at 1000 kW with temperatures above 1120 K and utilization factors over 0.765, while the minimum heating output is 700 kW. Emission analysis indicates a significant reduction in carbon dioxide emissions with increased temperatures and utilization factors, achieving a minimum of 700 kg/MWh at temperatures above 1120 K. The study's results demonstrate the effectiveness of the PSO optimization in fine-tuning the operational parameters of the integrated system, leading to improved energy efficiency and reduced environmental impact. Power production of 366.37 kW, a significant heating rate of 995.20 g/s, and emissions of 714.06 kg/MWh are the optimum performances. The research provides valuable insights into the potential of plastic waste-to-energy technologies as sustainable solutions for energy production and waste management.

Combustion reactivity of sewage sludge hydrochar derived from hydrothermal carbonization via thermogravimetric analysis

Wastewater treatment plant sludge contains a high concentration of organic compounds that can be used to produce fuel viahydrothermal carbonization (HTC). This study investigated the combustion reactivity and kinetic parameters of hydrochars produced to understand the combustion behavior of the solid fuel derived from HTC. The hydrochar was produced at various temperatures ranging from 150 to 300 °C, reaction times ranging from 30 to 150 min, and solid loadings ranging from 10% to 30%. The combustion behavior of sewage sludge (SS) and hydrochar was evaluated using thermogravimetric analysis with a constant air flow rate (100 mL/min) and heating rate (10 °C/min) from ambient temperature to 900 °C. It was observed that the HTC temperature, reaction time, and solid loading influenced the combustion characteristics and kinetics of the hydrochar. Additionally, the hydrochar exhibited higher ignition and burnout temperatures and a lower peak temperature than SS, indicating superior performance and reactivity in combustion. The combustion kinetic analysis also revealed that the hydrochar had a range of lower activation energy (29.12–41.60 kJ/mol) than SS (52.95 kJ/mol). Therefore, hydrochar derived from SS has the potential to be used as a substrate for solid fuel production for future renewable energy sources.

Effect of fullerene (C70) on the structural, morphological optical and thermal properties of poly(butyl methacrylate) (PBMA)

Poly(butyl methacrylate) (PBMA)/Fullerene (C70) nanocomposites were successfully prepared by solvent removal method and characterized by different techniques. Structural characterization showed an interaction between PBMA and C70 nanofiller. Morphological features showed that C70 was homogeneously distributed in the PBMA matrix. Optical analysis confirmed the formation of nanocomposites with wavelength shift in PBMA/C70 nanocomposites compared to pure PBMA. Photoluminescence spectra showed that the emission bands of PBMA/C70 nanocomposites shifted from blue to red and the presence of new emission spectra in the red region. The data obtained from thermal analysis showed that the Tg of the nanocomposites increased by about 10 °C compared to pure PBMA and the maximum decomposition temperatures improved by about 65–70 °C, confirming the increased thermal stability. The data obtained from thermogravimetric analyses performed at different heating rates were analyzed by Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) equations to calculate the activation energy values. According to the regression coefficient values, the experimental results were in good agreement with the FWO method (R2 PBMA=0.937 and R2 PBMA/C70 (5 wt%)=0.953). The activation energy of PBMA and fullerene doped nanocomposite were calculated as 48 kJ/mol and 104 kJ/mol, respectively and the results showed that the Ea value of nanocomposite was higher than PBMA.

Ion-chain sympathetic cooling and gate dynamics

Sympathetic cooling is a technique often employed to mitigate motional heating in trapped-ion quantum computers. However, choosing system parameters such as number of coolants and cooling duty cycle for optimal gate performance requires evaluating trade-offs between motional errors and other slower errors such as qubit dephasing. The optimal parameters depend on cooling power, heating rate, and ion spacing in a particular system. In this study, we aim to analyze best practices for sympathetic cooling of long chains of trapped ions using analytical and computational methods. We use a case study to show that optimal cooling performance is achieved when coolants are placed at the center of the chain and provide a perturbative upper bound on the cooling limit of a mode given a particular set of cooling parameters. In addition, using computational tools, we analyze the trade-off between the number of coolant ions in a chain and the center-of-mass mode heating rate. We also show that cooling as often as possible when running a circuit is optimal when the qubit coherence time is otherwise long. These results provide a roadmap for how to choose sympathetic cooling parameters to maximize circuit performance in trapped-ion quantum computers using long chains of ions. Published by the American Physical Society 2024

An Overview of Biochar Utilization Strategies for Screen-Printed Electrochemical Sensors

In this review, we address the utilization of biochar, a cost-effective material derived from renewable resources (biomass), for the construction of printable electrochemical devices. Key parameters influencing the final properties of biochar, including pyrolysis temperature, pyrolysis duration, heating rate, and activation treatments, are detailed. The role of biochar in the fabrication of electrochemical (bio)sensors is highlighted with emphasis on advancements in screen-printed electrochemical devices. Furthermore, this review showcases examples of using biochar in the construction of portable and flexible screen-printed electrodes, as well as humidity sensors. Future perspectives and challenges in the field of biochar-based electrochemical sensors and biosensors are also discussed, providing a comprehensive outlook on this promising area of research.

Constraints on dark matter from dynamical heating of stars in ultrafaint dwarfs. I. MACHOs and primordial black holes

We place limits on dark matter made up of compact objects significantly heavier than a solar mass, such as MACHOs or primordial black holes (PBHs). In galaxies, the gas of such objects is generally hotter than the gas of stars and will thus heat the gas of stars even through purely gravitational interactions. Ultrafaint dwarf galaxies (UFDs) maximize this effect. Observations of the half-light radius in UFDs thus place limits on MACHO dark matter. We build upon previous constraints with an improved heating rate calculation including both direct and tidal heating, and consideration of the heavier mass range above 104M⊙. Additionally we find that MACHOs may lose energy and migrate in to the center of the UFD, increasing the heat transfer to the stars. UFDs can constrain MACHO dark matter with masses between about 10M⊙ and 108M⊙ and these are the strongest constraints over most of this range. Published by the American Physical Society 2024

Enhancing Iron Ore Grindability through Hybrid Thermal-Mechanical Pretreatment

Grinding is an important process of ore beneficiation that consumes a significant amount of energy. Pretreating ore before grinding has been proposed to improve ore grindability, reduce comminution energy, and enhance downstream operations. This paper investigates hybrid thermal mechanical pretreatment to improve iron ore grinding behavior. Thermal pretreatment was performed using conventional and microwave approaches, while mechanical pretreatment was conducted with a pressure device using a piston die. Results indicate that conventional (heating rate: 10 °C; maximum temperature: 400 °C), microwave (2.45 GHz, 1.7 kW, 60 s), and mechanical (14.86 MPa, zero delay time) pretreatments improved the studied iron ore grindability by 4.6, 19.8, and 15.4%, respectively. Meanwhile, conventional-mechanical and microwave-mechanical pretreatments enhanced the studied iron ore grindability by 19.2% and 22.6%, respectively. These results suggest that stand-alone mechanical pretreatment or microwave pretreatment may be more beneficial in improving the grinding behavior of the studied fine-grain iron ore sample. The results of the mechanical pretreatment obtained in this study may be used in a simulation of the HPGR system for grinding operations of similar iron ore

Thermogravimetric study on thermal degradation kinetics and polymer interactions in mixed thermoplastics

AbstractPotential interactions during thermal degradation of polymer blends significantly influence product yields and their composition. Therefore, chemical recycling of plastic waste requires fundamental understanding of feedstock dependency for effective process design. This study investigates the pyrolysis of polymer blends (HDPE, LDPE, PP, PS, ABS, PET, PA6, PVC) through thermogravimetric experiments at different heating rates. Sample homogeneity’s impact on interactions is analyzed using particles, powder, coextruded blends, and samples in crucibles with separated compartments. A kinetic model is presented to support the experimental findings, assuming linear superposition of individual polymer kinetics. A proposed grouping of thermoplastics, reflecting their degradation behavior and potential interactions, correlates with the polymer structure. Observed interactions, particularly in blends of heteroatom-containing polymers (N, O, Cl), are accelerated reactions and coke formation. Hence, the model accurately predicts the degradation of heteroatom-free polymer mixtures but encounters challenges with more complex blends. This comprehensive study emphasizes the importance of feedstock composition for future pyrolytic polymer recycling. Graphical abstract

Tuning Na Occupation and Annealing Temperature on Na Diffusion Pathways in P2-Type NaxNi0.25Mn0.75O2 for Sodium-Ion Batteries by Ab Initio Calculations.

The NaxNi0.25Mn0.75O2 cathode material draws ongoing interest owing to its considerable specific capacity along with its elevated average operating voltage. However, its application is limited by weak rate performance and quick capacity fading. In this study, a series of NaxNi0.25Mn0.75O2 (x = 0.65, 0.70, 0.75, 0.80) cathode materials are prepared by the solid-phase method based on an orthogonal experiment. The optimum preparation process is investigated by optimizing factors such as Na content, calcination temperature, calcination time, and heating rate. The Nae/Naf ratio is adjusted, and the Na+ at different sites are rearranged to reduce the Na+/vacancy ordering by changing the Na content on the basis of process optimization. Owing to the fast migration kinetics of Nae sites, experimental results indicate that the P2-Na0.75Ni0.25Mn0.75O2 cathode material, which has Na+ occupying more thermodynamically stable Nae sites, demonstrates superior battery performance. High initial discharge specific capacity (157.2 mAh g-1) along with favorable cycle performance of the Na0.75Ni0.25Mn0.75O2 cathode material can be achieved by modifying the Nae site occupancy and optimizing the experimental conditions. Together with the microscopic control of Na+ occupancy, this novel orthogonal experiment design offers a fresh perspective and approach to a thorough comprehension of cathode materials for sodium-ion batteries.

Development of a novel bio char for CO2 capture and biogas upgrade: Static and dynamic testing

The optimization of the pyrolysis of the spruce sawdust was conducted based on the yield, textural properties, and static capture capacity of the chars to generate a new micro porous char for biogas upgrade. The nature of the precursor (C: 45.68 %, H: 6.08 %, N: 0.15 %, and 0.34 % ash content) helped to tune the porosity of the char for capturing CO2 from gas streams and biogas. The optimization of the pyrolysis at 700 °C, a heating rate of 10 °C / min and holding time of 1 hour, produced a microporous char with high yield, CO2 capture capacity and CO2/CH4 selectivity. The presence of the oxygen and nitrogen-containing functional groups in the optimum char help in the selective capture of CO2. The static CO2 capture capacity of the optimum char was 1.98 mmol/g at atmospheric pressure and 25 °C (90 % CO2 stream). The CSD (700−10−60) have capture capacity of 1.50 mmol/g (at a feed gas stream of 50 % CO2 and adsorption temperature of 25 °C and 120 kPa) which is equivalent to Norit C and Calgon BPL. Hence, spruce sawdust can be used to produce efficient biochar for biogas upgrade (CO2 capture) owing to high capture capacity and CO2/CH4 selectivity (around 3) and easy regeneration of the biochar for 10 consecutive cycles.

The Impact of Activated Carbon–MexOy (Me = Bi, Mo, Zn) Additives on the Thermal Decomposition Kinetics of the Ammonium Nitrate–Magnesium–Nitrocellulose Composite

This research investigates the impact of additives such as activated carbon (AC) combined with metal oxides (Bi2O3, MoO3, and ZnO) on the thermal decomposition kinetics of ammonium nitrate (AN), magnesium (Mg), and nitrocellulose (NC) as a basic AN–Mg–NC composite. To study the thermal properties of the AN–Mg–NC composite with and without the AC–MexOy (Me = Bi, Mo, Zn) additive, a differential scanning calorimetry (DSC) analysis was conducted. The DSC results show that the AC–MexOy (Me = Bi, Mo, Zn) additive catalytically affects the basic AN–Mg–NC composite, lowering the peak decomposition temperature (Tmax) from 534.58 K (AN–Mg–NC) to 490.15 K (with the addition of AC), 490.76 K (with AC–Bi2O3), 492.17 K (with AC–MoO3), and 492.38 K (with AC–ZnO) at a heating rate of β equal to 5 K/min. Based on the DSC data, the activation energies (Ea) for the AN–Mg–NC, AN–Mg–NC–AC, and AN–Mg–NC–AC–MexOy (Me = Bi, Mo, Zn) composites were determined using the Kissinger method. The results suggest that incorporating AC and AC–MexOy (Me = Bi, Mo, Zn) additives reduce the decomposition temperatures and activation energies of the basic AN–Mg–NC composite. Specifically, Ea decreased from 99.02 kJ/mol (for AN–Mg–NC) to 93.63 kJ/mol (with addition of AC), 91.45 kJ/mol (with AC–Bi2O3), 91.65 kJ/mol (with AC–MoO3), and 91.76 kJ/mol (with AC–ZnO). These findings underscore the potential of using AC–MexOy (Me = Bi, Mo, Zn) as a catalytic additive to enhance the performance of AN–Mg–NC-based energetic materials, increasing their efficiency and reliability for use in solid propellants.

Comprehensive Review of Biomass Pyrolysis: Conventional and Advanced Technologies, Reactor Designs, Product Compositions and Yields, and Techno-Economic Analysis

Pyrolysis is an environmentally friendly and efficient method for converting biomass into a wide range of products, including fuels, chemicals, fertilizers, catalysts, and sorption materials. This review confirms that scientific research on biomass pyrolysis has remained strong over the past 10 years. The authors examine the operating conditions of different types of pyrolysis, including slow, intermediate, fast, and flash, highlighting the distinct heating rates for each. Furthermore, biomass pyrolysis reactors are categorized into four groups, pneumatic bed reactors, gravity reactors, stationary bed reactors, and mechanical reactors, with a discussion on each type. The review then focuses on recent advancements in pyrolysis technologies that have improved efficiency, yield, and product quality, which, in turn, support sustainable energy production and effective waste management. The composition and yields of products from the different types of pyrolysis have been also reviewed. Finally, a techno-economic analysis has been conducted for both the pyrolysis of biomass alone and the co-pyrolysis of biomass with other raw materials.

Nonlinear mechanical response of UHSS rectangular plate under thermo-mechanical-metallurgical coupling

The mechanical properties of ultrahigh-strength steel (UHSS) produced through the gradient thermoforming process (GTP) are significantly influenced by residual stress and deformation. However, the precise distribution of these factors during GTP remains unclear. To address this issue, a detailed thermal model is developed, incorporating key heat transfer mechanisms, including coupled heat conduction and radiation, using the method of separation of variables. Furthermore, the displacement and stress fields of UHSS rectangular plates are derived using the differential quadrature method (DQM), accounting for phase transitions and external load. The combination of the separation of variables and DQM methods significantly improves computational efficiency. Furthermore, this study presents the first analysis of the combined effects of thermal load, phase transitions, and external forces on UHSS rectangular plates. Finally, through a combination of theoretical analysis, experimental validation, and case studies, the influence of material properties, geometric parameters, and external load on the temperature, stress, and displacement fields is examined. The findings reveal that heating rate, phase transitions, and external load play a critical role in the stress and displacement distribution in UHSS plates during GTP. This research provides a theoretical foundation for optimizing GTP process parameters and material design, ultimately enhancing the quality and performance of UHSS components.

The Effects of Super-Fast Heating Rate and Holding Time on the Microstructure and Properties of DP Fe-0.16C-1.4Mn Sheet Steel.

This study investigates the influence of super-fast heating rate and holding time on the microstructure and mechanical properties of dual-phase (DP) Fe-0.16C-1.4Mn sheet steel. Super-fast heating and cooling rates were achieved via induction heating and gas quenching. The results were also compared with those for a conventional low-speed heat treatment. The microstructures were characterized in detail using X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, and electron probe microanalysis. The results showed that the layered structure of the DP Fe-0.16C-1.4Mn steel after super-fast heating was mainly composed of recrystallized ferrite, martensite clusters, and a small amount of residual austenite. Compared with the conventional method, super-fast heating significantly refined the grains and improved yield and tensile strength, but it slightly reduced the elongation. The fraction of martensite, which depends on the nucleation and growth behavior of austenite, was significantly affected by the heating rate and holding time. The DP structure of Fe-0.16C-1.4Mn steel had an atypical layered heterogeneous structure, with an uneven plastic strain between the two phases occurring during the deformation process, which is something that can improve fracture elongation.

Rapid synthesis and enhanced microwave absorption of carbon-supported high-entropy metal oxide

Complex preparation process and long annealing time of high-entropy metal oxide (HEO) limit its extensive application as microwave absorber at civil and military fields. Herein, a rapid synthesis method of mesocarbon microbeads (MCMB)-loaded spinel structure (FeCoCrNiMnCu)O is studied via plasma flow. In the presence of extreme plasma heating rate, a nanoscale high-entropy phase can be formed while modifying the surface activity of carbon. Simultaneously, due to the short synthesis time, gaseous conversion of carbon under high temperature aerobic conditions is avoided. By appending of carbon, the dual-media absorber exhibits better absorption performance with a maximum peak (-44.7 dB), which achieves over 90 % absorption in 11.2–15.5 GHz with a thickness of only 1.9 mm. Interestingly, the real and imaginary parts of complex permittivity increase remarkably. The former change is attributed to the expansion of heterogeneous hole carrier region and the latter dues to the interfacial polarization of the strongly coupled interface. The increase of dielectric loss and conductance loss leads to great improvement of microwave absorption. Our study injects new vitality into the preparation of HEO for advanced applications and the as-prepared HEOM is promised to be high-efficient microwave absorber based on robust stability and excellent absorbing performance.

Experimental performance of avocado seed oil as a bio-based phase change material for refrigeration applications

Bio-based phase change materials (BPCMs) derived from agro-industrial residues represent an ecofriendly alternative for refrigeration applications. In this work, a BPCM was obtained by steam extraction from avocado seed and studied as a suitable cold thermal energy storage system. First, differential scanning calorimetry was used to determine that the solid-liquid phase transition occurred from -27°C to 15°C. This temperature range is of interest for the conservation different food products. The study aimed to determine the best distribution of the material, which was stored in plastic packaging bags, and placed in an insulated polystyrene thermal container. Two configurations were evaluated: (i) four bags of 75 mL, (ii) two bags of 75 mL and one of 150 mL. The temperatures of the avocado seed oil, and of the air inside the container, were measured during 6 to 8 h. It was concluded that, despite working with the same amount of avocado seed oil (300 mL) in different experiments, there was a better performance when the same volume of material was distributed in each wall. Furthermore, the utilization of avocado seed oil allowed to maintain low temperatures, suitable for food preservation during two additional hours. In the same way, in a yogurt storage experimentation of 8 h, the utilization of the avocado oil enhanced the temperature preservation by 6°C on the phase change range from 4°C to 14°C. While compared to water, the temperature difference was evaluated showing a good performance of the BPCM and an important stability on the temperature heating rate.

Microwave Ablation Therapy for Hepatocellular Carcinoma: The Effect of Metabolic Heat on Temperature Distribution

Hepatocellular carcinoma is the main cause of liver cancer and one of the most occurring cancers worldwide. Microwave Ablation (MWA) is a method to destroy cancer cells by heating tumours above 50°C. Cancerous tissues can have high metabolic heat rates and affect temperature gain and distribution in thermal therapies. This research clarifies the metabolic heat effects in MWA therapy of liver cancer. Using Pennes Bioheat transfer equation with finite element numerical method, this research simulates temperature distribution with metabolic heat value ranging from 368,1 W/m3 to 29000 W/m3. The heat generated by metabolic heat is lower than the MWA heat source. However, the temperature increase should be considered as it can increase healthy surrounding tissue temperature to dangerous levels.

In Situ Raman Spectroscopy as a Valuable Tool for Monitoring Crystallization Kinetics in Molecular Glasses

The performance of in situ Raman microscopy (IRM) in monitoring the crystallization kinetics of amorphous drugs (griseofulvin and indomethacin) was evaluated using a comparison with the data obtained via differential scanning calorimetry (DSC). IRM was found to accurately and sensitively detect the initial stages of the crystal growth processes, including the rapid glass–crystal surface growth or recrystallization between polymorphic phases, with the reliable localized identification of the particular polymorphs being the main advantage of IRM over DSC. However, from the quantitative point of view, the reproducibility of the IRM measurements was found to be potentially significantly hindered due to inaccurate temperature recording and calibration, variability in the Raman spectra corresponding to the fully amorphous and crystalline phases, and an overly limited number of spectra possible to collect during acceptable experimental timescales because of the applied heating rates. Since theoretical simulations showed that, from the kinetics point of view, the constant density of collected data points per kinetic effect results in the smallest distortions, only the employment of the fast Raman mapping functions could advance the performance of IRM above that of calorimetric measurements.

Entropy generation of Williamson hydromagnetic non-linear radiative nanofluid flow near a stagnation point over a porous stretching sheet

Purpose This study aims to analyze the multi-slip effects of entropy generation in steady non-linear magnetohydrodynamics thermal radiation with Williamson nanofluid flow across a porous stretched sheet near a stagnation point. Also, the qualities of viscous dissipation, Cattaneo–Christove heat flux and Arrhenius activation energy are taken into account. Thermophoresis, Brownian motion and Joule heating are also considered. Design/methodology/approach The Navier–Stokes equation, the thermal energy equation and the Solutal concentration equations are the governing mathematical equations that describe the flow and heat and mass transfer phenomena for fluid domains. By using the proper similarity transformations, a set of ordinary differential equationss are retrieved from boundary flow equations. The classical Runge–Kutta fifth-order algorithm along with the shooting technique is implemented to solve the obtained first order differential equations. Findings The study concludes that the temperature distribution boosting for thermal radiation, magnetic field and Eckert number where as the velocity and entropy generation escalate for the Williamson parameter, diffusion parameter and Brinkman number. The skin-friction and heat and mass transfer rate increases with the fluid injection. In addition, tabulated values of friction drag and rate of heat and mass transfer for various values of constraints are provided. Originality/value The comparison of the present results is carried out with the published results and noted a good agreement.

Thermoluminescence and kinetic parameters of irradiated dopant calcium aluminate nanophosphors

CaAl2O4:0.1% La nanoparticles doped with different concentrations of Mg were prepared using the sol–gel method and annealed at 400 °C, 500 °C, and 800 °C, respectively. The prepared nanophosphors show a highly crystalline orthorhombic structure with a crystallite size of about 81.2 nm. The optimum concentration of Mg dopants is about 0.7 mol%. The thermoluminescence (TL) glow curve of 11 Gy of beta-ray irradiated CaAl2O4:0.1% La:0.7% Mg measured at heating rates of 5 K/s has 16 overlapping glow peaks. The TL kinetic parameters for the prepared nanoparticles were evaluated using two different methods and they exhibited good agreement. Moreover, the linearity dose response of dosimetric peaks follows a good linearity up to 220 Gy in nanophosphor. The minimum detectable dose of the prepared nanophosphor was 125.7 mGy. The results of the prepared nanophosphors suggest good candidates for dosimetric applications.Graphical abstract