Thermal High Temperature Research Articles

Numerical Study of a High-Temperature Latent Heat Thermal Energy Storage Device with AlSi12 Alloy

This paper explores the potential of thermal storage as an energy storage technology with cost advantages. The study uses numerical simulations to investigate the impact of adding porous material to the HTF side during solidification to improve the heat transfer effect of TES using AlSi12 alloy as the phase-change material. The research also examines the effects of adding porous dielectric materials and increasing air velocity on the discharge temperature, discharge power, and discharge time of high-temperature phase-change energy storage systems. The study found that the temperature difference of the PCM (increased), solidification time (reduced more than 85%), the outlet temperature of the air, and heat discharge power of the LHS did not vary significantly across different porous materials (copper foam, nickel foam, and silicon carbide foam) added to the HTF tube. These findings offer important information for the design of high-temperature phase-change energy storage devices and can guide future developments in this field.

Engineering Design Of Fuel Reactor Pirolysis Incinerator (IPFR) Processing Plastic Waste into alternative Fuel with Residual Oil Heating

In Indonesia, plastic waste has become an important problem at this time, because it causes environmental pollution problems. With this, further action is needed regarding the treatment of waste utilization, one of which is by converting waste into liquid fuel. Some types of rubbish that we often encounter are plastic bottles such as plastic cups, plastic bottle caps, children's toys and margarines and others, which is one of the types of PP (polypropylene) waste. The development of current plastic waste treatment technology is to convert plastic waste into fuel oil by utilizing plastic waste to be processed as plastic fuels such as premium fuel, diesel and kerosene. Polypropylene type plastic is the type of plastic that is most widely used in daily life because it has good mechanical properties with low density, heat and moisture resistance, and has good dimensional stability. Some of the technology used to convert plastic waste, among others, by using the method of high temperature (Thermal Cracking). In this study, researchers designed a Thermal cracking device, namely an Incinerator, a plastic waste smelter with high temperature, where the modification of this tool is to use used fuel oil or residual oil. In this study, the researcher analyzed the burning time, the amount of waste mass needed for the melting process in the Incinerator. In this research, a fuel equivalent of 1.5 liters of premium fuel was produced with 10 kg of plastic waste burned in the incinerator with a burning time of 125 minutes of the pyrolysis process, with a combustion temperature of 180-250 degrees Celsius.

Exploratory Process Development of a High-Temperature Thermal (3 + 2) Cycloaddition in Continuous Flow for the Synthesis of Seltorexant

Exploratory Process Development of a High-Temperature Thermal (3 + 2) Cycloaddition in Continuous Flow for the Synthesis of Seltorexant

The Heat-Dissipation Sintered Interface of Power Chip and Heat Sink and Its High-Temperature Thermal Analysis

The Heat-Dissipation Sintered Interface of Power Chip and Heat Sink and Its High-Temperature Thermal Analysis

Copper–Alumina Capsules for High-Temperature Thermal Energy Storage

High corrosivity, leakage, and oxidation of metallic phase-change materials (PCMs) have limited their applications in high-temperature thermal energy storage (TES) systems, regardless of their favorable benefits for high-temperature TES applications of over 1000 °C. To overcome these major challenges, this work presents a facile paraffin sacrificial layer approach for directly encapsulating copper (Cu) sphere PCMs with the alumina (Al2O3) shell, considering a buffer inner cavity. The cavity is formed by the decomposition of the paraffin layer through a pre-sintered process. It plays a key role in accommodating the volume expansion of the Cu core, thereby preventing the breakage of the shell and the leakage of the liquid PCM. A series of macrocapsules with different sizes (9.5–21 mm) containing the Cu core, cavity, and Al2O3 shell are successfully produced using the paraffin sacrificial layer method and deploying a two-step heat treatment. The experimental results show that the Al2O3 shell possesses a good structure, which can prevent the leakage of the Cu core. The Al2O3 shell also has strong compatibility with the Cu core without any chemical reaction between two materials. In a temperature range of 1000–1100 °C, the calculated mass and volume energy storage densities of the PCM macrocapsule with 21 mm outer diameter are found to be 222 kJ/kg and 745 J/cm3, which are 1.83 and 1.76 times, respectively, higher than those for the Al2O3 ceramic. After thermal cycle tests, the encapsulated Cu PCM shows superior shape stability, chemical stability, and thermal durability, which can be applied in long-term thermal storage systems for high-temperature TES systems.

Comparative Study of High-Temperature Cycling and Thermal Stability of LLOs and NCMs under Medium–High Voltage

Lithium-rich layered oxides (LLOs) are considered as one of the most potential layered cathode materials due to their high discharge specific capacity, low cost, and environmental friendliness. However, the decomposition of electrolytes at high voltages (4.7 V) limits the commercial application of LLOs. Furthermore, to meet the demand for high energy density, lithium nickel cobalt manganese oxides (NCMs) need to improve their working voltage. In limited conditions, all LLOs and NCMs need to be used under the medium–high (4.4–4.6 V) cutoff voltage. Herein, we compare the performance of LLOs and NCMs in the voltage window with a medium–high cutoff voltage. Results show that after 100 cycles at high temperature (45 °C), the capacity retention rate of LLO is 98.68%, while that of NCMs is 78.15–96.93%. Differential scanning calorimetry reveals that the exothermic temperature of LLO is increased by 60–100 °C, and thermal release is reduced by 33–93%. LLOs have obvious advantages under medium–high voltages and a promising application prospect. This work systematically analyzes and compares LLOs and NCMs under medium–high voltage, providing guidance for the industrialization of LLOs.

Wet-Oxidation-Assisted Chemical Mechanical Polishing and High-Temperature Thermal Annealing for Low-Loss 4H-SiC Integrated Photonic Devices

Wet-Oxidation-Assisted Chemical Mechanical Polishing and High-Temperature Thermal Annealing for Low-Loss 4H-SiC Integrated Photonic Devices

Wet-Oxidation-Assisted Chemical Mechanical Polishing and High-Temperature Thermal Annealing for Low-Loss 4H-SiC Integrated Photonic Devices

Silicon carbide (SiC) has become a promising optical material for quantum photonics and nonlinear photonics during the past decade. In this work, we propose two methods to improve the 4H-SiC thin film quality for SiC integrated photonic chips. Firstly, we develop a wet-oxidation-assisted chemical mechanical polishing (CMP) process for 4H-SiC, which can significantly decrease the surface roughness from 3.67 nm to 0.15 nm, thus mitigating the light scattering loss. Secondly, we find that the thermal annealing of the 4H-SiC devices at 1300 °C can help to decrease the material absorption loss. We experimentally demonstrate that the wet-oxidation-assisted CMP and the high-temperature annealing can effectively increase the intrinsic quality factor of the 4H-SiC optical microring resonators.

Developing meshing workflows in GMSH v4.11 for Geologic Uncertainty Assessment of the High-Temperature Aquifer Thermal Energy Storage

Developing meshing workflows in GMSH v4.11 for Geologic Uncertainty Assessment of the High-Temperature Aquifer Thermal Energy Storage

First-Principles Investigation on the High-Temperature Mechanical Properties and Thermal Properties of Pt-40Rh

First-Principles Investigation on the High-Temperature Mechanical Properties and Thermal Properties of Pt-40Rh

Experimental Study on Directional Fracturing of Granite by High-Temperature Thermal Shock

Experimental Study on Directional Fracturing of Granite by High-Temperature Thermal Shock

Multi-Scale Characterization of High-Temperature Properties and Thermal Storage Stability Performance of Discarded-Mask-Modified Asphalt

In the context of the global pandemic of COVID-19, the use and disposal of medical masks have created a series of ethical and environmental issues. The purpose of this paper is to study and evaluate the high temperature properties and thermal storage stability of discarded-mask (DM)-modified asphalt from a multi-scale perspective using molecular dynamics (MD) simulation and experimental methods. A series of tests was conducted to evaluate the physical, rheological, thermal storage stability and microscopic properties of the samples. These tests include softening point, rotational viscosity, dynamic shear rheology (DSR), Fourier transform infrared (FT-IR) spectroscopy and molecular dynamics simulation. The results showed that the DM modifier could improve the softening point, rotational viscosity and rutting factor of the asphalt. After thermal storage, the DM-modified asphalt produced segregation. The difference in the softening point between the top and bottom of the sample increased from 2.2 °C to 17.1 °C when the DM modifier admixture was increased from 1% to 4%. FT-IR test results showed that the main component of the DM modifier was polypropylene, and the DM-modified asphalt was mainly a physical co-blending process. MD simulation results show that the DM modifier can increase the cohesive energy density (CED) and reduce the fractional free volume (FFV) of asphalt and reduce the binding energy between base asphalt and DM modifier. Multi-scale characterization reveals that DM modifiers can improve the high temperature performance and reduce the thermal storage stability of asphalt. It is noteworthy that both macroscopic tests and microscopic simulations show that 1% is an acceptable dosage level.

Flame Characteristics of Gasoline and a Water-in-Gasoline Mixture under a Controllable High-Temperature Thermal Atmosphere.

This study explores the flame characteristics of gasoline and a water-in-gasoline mixture and provides some optimization suggestions for the control strategy of water-in-gasoline mixture injection in the internal combustion Rankine cycle engines. The influences of co-flow temperature, injection pressure condition, and water content on the flame characteristics were investigated under a controllable high-temperature thermal atmosphere, including flame pattern, liftoff height, brightness, and local peak temperature distribution. Results obtained show that the water content has the most significant effect on the flame characteristics. The flame pattern gradually changes from slender to lumpy as the water content rises, while the high-temperature zone increases and becomes uniform. There is an appropriate water content range of 10-20% in which the flame characteristics are generally better. Furthermore, as the water content increases from 20 to 30%, the flame characteristics deteriorate, with a sharp decrease in the maximum flame temperature and brightness.

Preparation and Thermoelectric Properties of Nano-Bismuth Telluride Film by High-Temperature Thermal Shock

Thermoelectric materials can directly convert thermal energy into electrical energy, realizing the recovery of waste heat. Bismuth Telluride (Bi-Te) is considered as a perfect candidate thermoelectric material which has great potential in the field of refrigeration and temperature sensor. However, in the field of intelligent wearable devices and integrated circuits, traditional Bi-Te block material is difficult to be directly used due to its poor flexibility. In this paper, a series of Bi-Te thin films were prepared by a self-designed high-temperature thermal shock equipment. This equipment can heat up the reduced graphene oxide strip to 1750 K in 20 ms, which features both high heating rate (8.2 × 104 K/s) and cooling rate (1.5 × 104 K/s). Thermoelectric films on different substrates were prepared via high-temperature thermal shock. Through regulating the temperature of evaporation source, the particle size and composition of Bi-Te thin films can be precisely modulated, thus optimizing the Seebeck coefficient of the films. The Seebeck coefficient of copper foil (Cuf)-based Bi-Te film can reach 345.41 μV/K, which was prepared by thermal-shocking the Bi-Te powders for 30 s at 900°C.

A High-Temperature Thermal Simulation Experiment for Coal Graphitization with the Addition of SiO2

The effect of SiO2 on coal graphitization was investigated by adding SiO2 as an additive to vitrinite in coal from the Gemudi mining area in Guizhou province (SW China) via a high-temperature heating treatment. The graphitization products of the samples were analyzed by X-ray diffraction (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM), and the influence of the SiO2 additive on the process of coal graphitization was investigated. The results showed that, with the temperature increases, the graphitization degree of all samples was promoted, and the orderliness of the microcrystalline structure in the vitrinite increased. Compared with the samples without additives, the graphitization degree, graphite lamellae ductility, and stacking degree of the samples with SiO2 additives were higher, and the carbon layer spacing reached 0.3379 nm at 3000 °C, entering the graphite stage. The Raman spectra showed that the peak intensities of the defect structures (D1 and D2) in the samples with SiO2 were lower than those of the samples without additives, exhibiting fewer in-plane and interlayer defects in the samples with SiO2. The microstructures of the experimental samples were observed by HRTEM; at the same temperature, the carbon layer stacking degree of the samples with the SiO2 additives was higher than that of the samples without SiO2, and large graphite lamellae with smoother and clearer edges were observed.

Effect of Initial Molecular Weight on the Structural Evolution of Polyamide 1012 during High-Temperature Thermal Treatments as Revealed by Successive Self-Nucleation and Annealing

Effect of Initial Molecular Weight on the Structural Evolution of Polyamide 1012 during High-Temperature Thermal Treatments as Revealed by Successive Self-Nucleation and Annealing

Characterization of High-Temperature Tensile Properties and Thermal Stability in Gas Tungsten Arc Welds of Ti-added Reduced Activation Ferritic/Martensitic Steel

In this study, the effects of Ti addition on the microstructure, the tensile properties at 550 ℃, and the thermal stability in gas tungsten arc (GTA) welds of reduced activation ferritic/martensitic (RAFM) steel were studied. Ti was added to promote precipitation of MX in order to enhance high-temperature properties. For reference, Ti-free RAFM (reference RAFM steel with the composition of 9Cr-1W-0.2V-0.1Ta-0.1C) was compared with 0.013 wt% Ti added RAFM steel (Ti-added RAFM). The addition of Ti contributed to the increase in the area fraction of MX precipitates (2.0 → 4.6 %) and a decrease in the average size of M23C6 (149 → 119 nm) in the base metal. After the cross-weld tensile test at 550 ℃, the tensile properties of Ti-added RAFM steel were superior to that of Ti-free RAFM steel. Both steels were fractured at inter-critical heat-affected zone (ICHAZ) showing the lowest hardness due to over-tempering. However, the higher area fraction of MX precipitates in the Ti-added RAFM produced more significant strengthening, compared to the Ti-free RAFM steel. After heat exposure at 550 ℃ for 500 h, Ti-added RAFM steel was highly resistant to degradation; hardness distribution and tensile properties were almost similar before and after thermal exposure. ICHAZ exhibited the substantial retention of fine laths and high density of dislocation with marginal recovery even after thermal exposure. It is conceivable that excellent thermal stability of Ti-added RAFM steel can be attributed to the high fraction of MX particles by suppressing lath boundary migration.

Axial Chirality in the Sotorasib Drug Substance, Part 2: Leveraging a High-Temperature Thermal Racemization to Recycle the Classical Resolution Waste Stream

Axial Chirality in the Sotorasib Drug Substance, Part 2: Leveraging a High-Temperature Thermal Racemization to Recycle the Classical Resolution Waste Stream

Using multiple partially-penetrating wells (MPPWs) to improve the performance of high-temperature ATES systems: Well operation, storage conditions and aquifer heterogeneity

The occurrence of free thermal convection negatively affects thermal recovery efficiencies of High-Temperature Aquifer Thermal Energy Storage (HT-ATES) systems. In this study the potential of applying a Multiple Partially Penetrating Well (MPPW) configuration to counteract the impact for seasonal HT-ATES is tested through numerical modeling with SEAWATv4. For scenarios where the thermal front is close to the HT-ATES well-screen and free thermal convection has considerable effect on the thermal recovery efficiency, the use of a MPPW configuration has great potential. Storage at a moderate temperature contrast (ΔT = 40 °C) between the hot injection volume and cold ambient groundwater in a high-permeability aquifer resulted in significant improvement of the thermal recovery efficiency with a MPPW configuration targeting injection in lower parts of the aquifer and recovery in the upper parts. For conventional, fully screened HT-ATES a thermal recovery efficiency of 0.43 is obtained while this is 0.59 with the MPPW scheme in the first recovery cycle. This recovery efficiency of 0.59 is only 0.11 less than a theoretical case with no buoyancy effects. For seasonal HT-ATES cases that face severe free thermal convection, rapid accumulation of heat in the upper part of the aquifer is observed and the MPPW configuration is less effective due to the long period between injection and recovery. Especially for HT-ATES cases that require a cut-off temperature, thermal recovery can be significantly improved and prolonged. For storage temperatures of 60 and 80 °C in a high-permeability aquifer, approximately 4 times more abstracted usable heat is obtained with the MPPW setup while considering a cut-off temperature of 40 °C. Moreover, the present study shows that the use of MPPW configurations in heterogeneous aquifers should be carefully planned. Improper application of MPPW is particularly vulnerable for simplification of the aquifer characteristics, and therefore proper site heterogeneity investigation and operational monitoring are required to benefit from optimal MPPW operation during HT-ATES.

Characterizing Drift Behavior in Type K and N Thermocouples After High Temperature Thermal Exposures

Although of the widespread use of base metal thermocouples in the industry, many previous relevant researches have shown that the accuracy and stability of thermocouples are clearly influenced by any physical or chemical changes in their thermoelements. Among the most important of these changes are the inhomogeneity, pollution, oxidation and microstructure changes of the thermoelements, all of these changes and more leads to thermocouples drift after a prolonged thermal exposure. To study how these changes affect the drift and thermoelectric properties of thermocouples, in this work we subjected the base metal thermocouples of types K and N to successive thermal exposure periods at their maximum temperatures. Scanning electron microscopy (SEM) and Energy Dispersive X-ray (EDX) systems were used to monitor the change in the crystal structure and chemical composition of the thermocouple wires after each stage of the thermal heating, and then we studied the changes in the thermoelectric properties of thermocouple wires. The results showed type N thermocouples are more stable at high temperatures (up to 1050 ͦ C), even if used for long periods (for more than 1200 hours) at those temperatures, but K type thermocouples showed a rapid drift with first exposure to high temperatures and completely failed after 600 hours due to devastating corrosion.