Quick Temperature Rise Research Articles

Explosive Leidenfrost-Droplet-Mediated Synthesis of Monodispersed High-Entropy-Alloy Nanoparticles for Electrocatalysis.

High-entropy-alloy nanoparticles (HEA NPs) exhibit promising potential in various catalytic applications, yet a robust synthesis strategy has been elusive. Here, we introduce a straightforward and universal method, involving the microexplosion of Leidenfrost droplets housing carbon black and metal salt precursors, to fabricate PtRhPdIrRu HEA NPs with a size of ∼2.3 nm. The accumulated pressure within the Leidenfrost droplet triggers an intense explosion within milliseconds, propelling the carbon support and metal salt rapidly into the hot solvent through explosive force. The exceptionally quick temperature rise ensures the coreduction of metal salts, and the dilute local concentration of metal ions limits the final size of the HEA NPs. Additionally, the explosion process can be fine-tuned by selecting different solvents, enabling the harvesting of diverse HEA NPs with superior electrocatalytic activity for alcohol electrooxidation and hydrogen electrocatalysis compared to commercial Pt (Pd) unitary catalysts.

Investigation on mechanical bending caused thermal runaway of lithium-ion cell

Lithium-ion batteries are widely used in electronics, and are susceptible to thermal runaway from mechanical abuse, which poses a threat to consumer safety and the development of new batteries. This work conducts both experimental and numerical simulation to study thermal runaway caused by varying degrees of mechanical bending of commercial mobile phone batteries. The results show that batteries with greater degrees of deformation have a higher thermal runaway maximum temperature with quick temperature rise rate. Simulated results provide in-depth analysis towards correlation between temperature and heat generation, it is found that the two significant increases in temperature rise rate are attributed to the heat generated by SEI decomposition and the heat released by the cathode and electrolyte reaction. In order to effectively reduce or even eliminate the hazards of thermal runaway, it is necessary to lengthen the interval between the two heat releases or to reduce the amount of heat released. This study further develops a theoretical framework for battery bending abuse and provides guidance to prevent thermal runaway.

Changes in Glaciers and Glacial Lakes in the Bosula Mountain Range, Southeast Tibet, over the past Two Decades

Glaciers and glacial lakes in the Bosula Mountain Range need special attention, because their instability may cause disastrous consequences to the downstream settlements and the Sichuan-Tibet Road. The latter is a pivotal traffic line in the Southeast Tibetan Plateau. In order to investigate the state of glaciers and glacial lakes in the Bosula Mountain Range, we estimated the changes in glacier/glacial lake boundaries, glacier surface elevation, and glacier flow velocity between 2000 and 2021 based on multisource remote sensing data. Our results showed that, from the period 2000–2013 to the period 2013–2021, the average shrinking rate of glacier area increased from 0.99 km2/a to 1.74 km2/a, and the average expanding rate of glacial lake area increased from 0.04 km2/a to 0.06 km2/a. From the period 1990–2011 to the period 2015–2019, the average thinning rate of glaciers increased from 0.83 m/a to 1.58 m/a. These results indicate the Bosula Mountain Range is one of the fastest melting glacierized regions in the High Mountain Asia, and the factors that account for this may include quick temperature rise, abundant summer rainfall, and thin debris cover. In spite of strong ice melting, the observed changes in glacier boundaries, surface elevation, and flow velocity show no sign of surge activity, and the frequency of glacier lake outburst has not increased since 1989. Currently, three proglacial lakes that expanded quickly during 2000–2021 are now prominent hazards. They are directly threatened by accidental ice calving and ice avalanche, and their outburst could cause considerable damage to the downstream settlements and the Sichuan-Tibet Road.

Fast Prediction of RF-induced Heating for Sacral Neuromodulation System Exposed to Multi-Channel 2 RF Field at 3T MRI.

This paper presents a fast method to predict the radiofrequency (RF) induced heating for Sacral Neuromodulation System (SNM) under multi-channel 2 (MC-2) RF field of 3 Tesla (T) magnetic resonance imaging (MRI) system by using the artificial neural network (ANN). The raw computational model for the SNM was based on the transfer function approach. The MC-2 parallel transmission RF field at 3T MRI exposure was considered for 2 independent channels, which have an exposure space of -15 dB to 15 dB magnitude difference and -180 degrees to 170 degrees phase difference. A total number of 535,680 study cases that cover all possible shimming conditions and the corresponding temperature rises are collected from raw calculation data. The ANN was used as the surrogate model to predict the temperature rises against the incident electromagnetic field distributions. 40320 cases were used for training while the rest data sets were used for testing. The ANN can estimate the temperature rises for each human model in a small exposure sampling space. The testing performance of the ANN has a correlation coefficient higher than 0.99 and the mean absolute error was less than 0.12°C. It is demonstrated that the ANN can be used as an efficient tool for quick temperature rise estimation under MRI 3T shimming.

Effect of microwave heating on thermo-mechanical behavior of cemented tailings backfill

Cemented tailings backfill (CTB), which is a mixture of tailings, binder and water, is used to fill underground mined-out areas. Once placed, the CTB is required to provide enough ground support as soon as possible, in order to improve the mining efficiency. A relatively high temperature can accelerate the consolidation of CTB, and microwave radiation can afford a quick temperature rise. Therefore, this study proposed an experimental program incorporating the microwave heating into the conventional curing of the CTB samples. The thermal behavior and strength development of the CTB was investigated, and the CTB deformation under gravity and compression was also evaluated. The obtained results showed that the microwave radiation could significantly increase the CTB temperature. Besides, the microwave heating could either enhance or reduce the mechanical performance of the CTB samples with different curing ages, depending on when the microwave radiation was applied (delay time) and how long it lasted (heating time). This study demonstrates that the microwave technique can definitely be used in mine backfill, for improving the thermo-mechanical performance of the backfill.

Overcharge investigation of degradations and behaviors of large format lithium ion battery with Li(Ni0.6Co0.2Mn0.2)O2 cathode

Abstract Overcharge is considered to be one of the most severity safety problems for large format lithium ion battery (LIB), understanding of correlation between overcharge states and associated degradations is still a challenging issue. Here overcharge features of 51Ah prismatic LIBs were studied by charging the LIBs to various state of charge (SOC). When the SOC reaches up to 125%, lithium plating and lithium involved side reactions have taken place accompanied by capacity fade, internal resistance increase and LIB swelling. Meanwhile, the interlayer spacing of graphite anode is enlarged as indicated by shift of (002) diffraction peak to lower angle. When the SOC reaches up to 140%, additional to above reactions aggravation, structural damage of cathode materials was found. With further increase of SOC, internal side reactions became more violent as indicated by obvious self-heating at 146% SOC. Moreover, effects of charging current and initial temperature on overcharge behaviors were also discussed. Large charging current (4C) can lead to more severity thermal runaway as supported by higher maximum surface temperature of 413.34 °C compared to that of 187.90 °C at 1C. LIB overcharged at initial low temperature shows quick temperature rise but lower maximum surface temperature of 143.15 °C at 160% SOC compared to that of 187.90 °C at 159% SOC for LIB overcharged under ambient temperature

A stepwise microwave synergistic pyrolysis approach to produce sludge-based biochars: Feasibility study simulated by laboratory experiments

A stepwise microwave synergistic pyrolysis (SMSP) approach is proposed as a new way to relieve disposal problems of the sewage sludge. Here the sludge is first pre-pyrolyzed by a conventional heating stage, and then rapidly pyrolyzed by a microwave-induced heating stage without any extra microwave absorbers or blending needed. Under simulated process pyrolysis conditions, the dried sludge, intermediate and final sludge-based biochar samples were prepared in the laboratory. Their chemical composition, microstructure and morphology, and leaching toxicity of heavy metals were carefully characterized and analyzed by various techniques such as proximate and ultimate analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), and scanning electron microscope equipped with energy-dispersive x-ray spectroscopy (SEM-EDX). Results showed that the pre-pyrolytic biochar can be rapidly heated up to 1100 °C within 5 min under microwave irradiation. The pre-pyrolytic stage increased the carbonization and ash enrichment degree of the sludge which itself acted as a good microwave absorber while achieving a quick temperature rise under microwave irradiation. The ash remaining ratio and the specific surface area of the biochar derived from the SMSP approach (labelled as SBC2) are increased by 6.46% and 16.17% respectively, compared with the conventional biochar sample (SBC1). And SBC2 still had diverse surface functional groups kept after SMSP. The residual ratios of Ni, Cu, Zn, Pb, Cr and Cd in SBC2 was more noticeable than in SBC1 but the leaching ratios quite the contrary. Vitrification is also well proved by the increment of quartz peak detected by XRD tests, and the formation of melted glassy spheres with elemental composition of Si, Ca, Al observed by SEM-EDX. It can favorably increase solidification level and decrease leaching toxicity of heavy metals in the SBC2. The feasibility of this proposed SMSP concept has been positively supported by our experimental results. The properties of the sludge-based biochar produced from the SMSP approach also show great potential to be utilized as precursors to produce various adsorbents.

Application of the best-estimate model calibration and prediction through experimental data assimilation methodology to the tests performed on a helium cooled First Wall Mock-up

Abstract Experiments are under progress at the Karlsruhe Institute of Technology (KIT) as part of the general strategy for the development of the DEMO Helium Cooled Pebble Bed (HCPB) design. These experiments are part of the program on the qualification of components and on the validation of system codes. In 2018, thermal-hydraulic investigations have been performed looking into the transient response of a helium-cooled blanket First Wall Mock-Up under Loss Of Flow Accident (LOFA) conditions. The results obtained through these investigations captured the quick temperature rise on the surfaces exposed to heat loads (such as those coming from the plasma), and provided a robust set of data for the validation of system codes such as RELAP5-3D. Then, the present work describes the validation activities performed on the RELAP5-3D code. This validation was performed employing also a Best-Estimate methodology called “Best-Estimate Model Calibration and Prediction through Experimental Data Assimilation methodology”. In a previous work, the same methodology was used to calibrate a RELAP5-3D model of the HELOKA-HP electrical heater under normal operation. In this regard, the present work marks the first application of this methodology to fast transients in the field of fusion reactors.

Investigation on mechanical and microwave heating characteristics of asphalt mastic using activated carbon powder as electro-magnetic absorbing materials

Activated carbon, one of carbon-based materials with developed pore structure and favourable microwave radiation absorption, was added in asphalt to investigate its possibility as microwave heating enhancement in asphalt materials. Effect of activated carbon powder (ACP) on mechanical performance of asphalt mastic was firstly studied. Mechanical tests including multiple stress creep and recovery (MSCR) test, temperature sweep test, time sweep test, and linear amplitude sweep (LAS) test were conducted to evaluate rutting resistance, liner viscosity, and fatigue resistance. Interactions between fillers and asphalt were then observed by scanning electron microscope (SEM). Besides, microwave heating capacity of asphalt mastic with different amount of ACP was investigated to ensure its potential in microwave heating acceleration. Cost of activated carbon powder in asphalt mixture was roughly estimated and compared with other microwave absorbing materials. Results showed that addition of ACP slightly influenced physical properties of mastic, permanent deformation at high temperature of asphalt mastic decreased and creep recovery increased. Increase of complex shear modulus and rutting factor suggested that asphalt was stiffened by adding ACP and rutting resistance was also improved. Fatigue resistance was improved and fatigue life was extended most when ACP replacement was 100% volume fraction of fillers. Wetting surface between ACP and asphalt was smooth with less folds and voids which means it had good contact and interaction with asphalt. Mastic with larger amount of ACP had a quick temperature rise under microwave radiation and heating rate (HR) defined as temperature increment per seconds was applied. It is found that surface temperature increased firstly fast and then slowly when dividing heating process as two stage. Results basically ensured the feasibility of ACP in enhancing mechanical performance and microwave heating capacity of asphalt materials. The extra cost from ACP is relatively lower. Partial substitution of ACP in fillers and reused ACP from pollution treatment factories may further reduce the amount and cost from ACP application.

Erratum to: Effects of rapid temperature rising on nitrogen removal and microbial community variation of anoxic/aerobic process for ABS resin wastewater treatment.

ABS resin wastewater is a high-temperature nitrogenous organic wastewater. It can be successfully treated with anoxic/aerobic (A/O) process. In this study, the effect of temperature on nitrogen removal and microbial community after quick temperature rise (QTR) was investigated. It was indicated that QTR from 25 to 30 °C facilitated the microbial growth and achieved a similar effluent quality as that at 25 °C. QTR from 25 to 35 °C or 40 °C resulted in higher effluent concentration of chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen (TN), and total phosphorus (TP). Illumina MiSeq pyrosequencing analysis illustrated that the richness and diversity of the bacterial community was decreased as the temperature was increased. The percentage of many functional groups was changed significantly. QTR from 25 to 40 °C also resulted in the inhibition of ammonia oxidation rate and high concentration of free ammonia, which then inhibited the growth of NOB (Nitrospira), and thus resulted in nitrite accumulation. The high temperature above 35 °C promoted the growth of a denitrifying bacterial genus, Denitratisoma, which might increase N2O production during the denitrification process.

Effects of rapid temperature rising on nitrogen removal and microbial community variation of anoxic/aerobic process for ABS resin wastewater treatment.

ABS resin wastewater is a high-temperature nitrogenous organic wastewater. It can be successfully treated with anoxic/aerobic (A/O) process. In this study, the effect of temperature on nitrogen removal and microbial community after quick temperature rise (QTR) was investigated. It was indicated that QTR from 25 to 30°C facilitated the microbial growth and achieved a similar effluent quality as that at 25°C. QTR from 25 to 35°C or 40°C resulted in higher effluent concentration of chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen (TN), and total phosphorus (TP). Illumina MiSeq pyrosequencing analysis illustrated that the richness and diversity of the bacterial community was decreased as the temperature was increased. The percentage of many functional groups was changed significantly. QTR from 25 to 40°C also resulted in the inhibition of ammonia oxidation rate and high concentration of free ammonia, which then inhibited the growth of NOB (Nitrospira), and thus resulted in nitrite accumulation. The high temperature above 35°C promoted the growth of a denitrifying bacterial genus, Denitratisoma, which might increase N2O production during the denitrification process.

Chaos embedded particle swarm optimization algorithm-based solar optimal ReflexTM frequency charge

The battery temperature rise and charge efficiency during the long-term charge in the sun are a very important topic. The traditional common constant current and constant voltage result in quick temperature rise and influence the charge efficiency indirectly. Therefore, the Reflex TM charge is adopted, the chemical reaction of electrolyte is buffered during discharge, so that the battery temperature rises slightly during charge. However, there is no optimum frequency for switching loss and charge efficiency during Reflex TM charge. Therefore, this paper proposes using chaos embedded particle swarm optimization algorithm (CPOS) to minimize the switching loss of battery in charge and discharge conditions. The battery module in Matlab/Simulink environment is used for solar charge, multiple charge modes are compared with traditional common methods. The simulation results show that the Reflex TM method has improved the battery temperature in Matlab/Simulink, and the State of Charge (SOC) is equivalent to other charge modes. It is proved that the method proposed in this paper has significant effect on switching loss and oscillation, and its charge efficiency is equivalent to traditional quick charge. All Rights Reserved © 2015 Universidad Nacional Autonoma de Mexico, Centro de Ciencias Aplicadas y Desarrollo Tecnologico. This is an open access item distributed under the Creative Commons CC License BY-NC-ND 4.0.

In Situ Monitoring of Temperature Rise in Friction Surface Using Ultrasonic Technique

Abstract In this work, the feasibility of the use of ultrasonic thermometry for in situ monitoring of temperature rise in friction surface has been examined. The ultrasonic thermometry that is a method providing internal temperature measurements by ultrasound is applied to temperature measurements of a friction surface at which temperature rise occurs due to friction, and an attempt is made to demonstrate in situ monitoring of transient variations in the friction surface temperature and temperature distribution beneath the surface. Those temperatures near the friction surface are quantitatively determined by an effective method consisting of ultrasonic pulseecho measurements and a finite difference calculation for estimating a one-dimensional temperature distribution along the direction of ultrasound propagation. The advantage of the method is that no boundary condition at the friction surface is needed. To demonstrate the practical feasibility of the method, the ultrasonic pulse echo measurements at 5 MHz are performed for a steel plate of 30 mm thickness whose single side is being rubbed with a felted fabric plate. The temperature at the friction surface and internal temperature distribution of the steel plate are measured during the rubbing process and the transient variations of the measured temperatures are obtained. Quick temperature rise of approximately 30 K at the friction surface is observed within a few seconds after the rubbing starts. It is noted that the temperatures measured by the ultrasonic method almost agree with those measured using thermocouples inserted into the steel plate. Thus, it has been demonstrated that the ultrasonic thermometry is a promising sensing means for in situ monitoring of temperatures at friction surface as well as beneath the surface.

Maskless direct micro-structuring of PDMS by femtosecond laser localized rapid curing

Polydimethylsiloxane (PDMS) is widely used to build biomedical microdevices because of its excellent properties. Prototyping 2D and 3D PDMS microdevices normally requires a long curing time and must go through multiple steps. In this paper, we propose femtosecond laser stereolithography for the rapid prototyping of PDMS 2D and 3D microstructures. This work presents a new way of rapid curing of PDMS resin on a microsecond timescale using femtosecond laser pulses of megahertz pulse frequency. The proposed technique permits single-step curing and is capable of fabricating 2D and 3D structures in micro-scale. The rapid localized curing can be explained by the volume-constrained quick temperature rise due to the accumulated heating at repetitive irradiation. The rapid cooling following the curing limits the decomposition and, therefore, the PDMS retains its mechanical strength.

Thrust and Thermal Characteristics of Electromagnetic Launcher Based on Permanent Magnet Linear Synchronous Motors

Compared with steam catapult system, electromagnetic launcher (EML) system is highly integrated, and it has high and well matching performance. It will be widely used aircraft carriers ejection, rocket launchers etc in future. Double-side tabular permanent magnet linear synchronous motor (PMLSM) for electromagnetic launcher can meet the requirements of big thrust and high efficiency etc. It can accelerate the launcher at the expected speed in short time. The thrust characteristic of the launcher is essential to the whole electromagnetic launcher system. Large thrust and small thrust ripple are both expected. This paper studies thrust characteristic of different pole arc coefficients, compares the series and parallel magnetic circuit structures, and analyses the method of staggering a certain distance between poles on both sides. In order to achieve the goal of large thrust, the launcher is often designed with high current density. As a result, it is of great loss and has quick temperature rise. This paper establishes numerical model of the two-dimensional (2D) primary transient temperature field. The temperature field of the short-term system is analyzed. The calculated and experimental results of the electromagnetic launchers can provide a basis for optimum design.

半導体封止用エポキシ樹脂の発熱挙動の解析 第２報 金型内での流動・硬化挙動の解析

A method for predicting the mold-filling and curing dynamics associated with heat generation caused by the chemical reaction of epoxy compounds has been developed. To verify this method, transient temperature profiles were measured during the mold-filling and curing process for two kinds of compounds used for encapsulation of semiconductor devices. After the completion of fill, temperature exceeded the mold temperature. The calculated temperature profiles for both compounds fit well with the experimental data. Calculated cure profiles showed that the cure was faster near the wall than at the center due to a quick temperature rise produced by heat conduction from the mold. On the other hand, within the usual filling time, the degree of cure remained very small. Calculated viscosity profiles were compared between this new model and the conventional model, which neglects heat generation, for two kinds of circular flow channels. Differences in the viscosity profiles were not found under several molding conditions due to the small curing advancement up until gelation.

The cooling apparatuses especially reffering to radiative cooling

Some properties of frost action on a plant may be studied experimentally in the laboratory by means of the most easy way of cooling by conduction in contact with the freezing mixture. In this case however the temperature on the frost forming surface of the plant is higher than in the inside tissue of the plant when cooled down under the clear night sky. It is a matter of great difficulty to realize the noctual cooling passage taking place in the open field by introducing radiative cooling process in the closed chamber. The nuisance to get rid of arises from the frost formation on the outer wall of the cooling apparatus which prevents the cooling surface from frost deposition, our object really wished for.The 1st type of our apparatuses worked out consists of 2 concave aluminium mirrors facing each other at a little distance and the freezing mixture (or dry ice) and the surface to be frosted are put on each focus of the mirrors as shown in fig. 3, (or a hollow ellipsoid coated inside with gold is possibly better). The experimental test of this apparatus is not mostly satisfactory principally owing to the small scale apparatus as well as imperfectly refecting surfaces.The second type consists of 4 glass cylinders of different diameters as shown in fig. 4, CC cylinder being protected by means of thermally insulating wool cloth and humid or dry air flows into its enclose space through 4 small holes EE……and flows down through G, G. The middle part of the innermost cylinder is used as the cooling surface mape evident by the figure of a plant leaf. The cooling curves obtained by this cooling apparatus are shown in fig. 5 in which a fine lined cooling curve is due to the inflowing humid air and a quick temperature rise marked A arises from the sudden freezing of the supercooled drop of dew, and that marked B from that of the plant sap. The other thick lined curve is due to the inflowing dry air in which only one quick temprature rise B is noticeable there because owing to the sudden freezing of the supercooled plant and also owing to no formation of dew. Thus the 2nd type of our cooling apparatus meets demand most sufficiently and may be recommended to some worker in need of the frost investigation.