The electrical heating experiments on oil shale sample from Huadian of Jilin were carried out by the pyrolysis method at three different heating rate 2℃/min, 5 ℃/min and 10 ℃/min in the temperature range of 30℃ -...The electrical heating experiments on oil shale sample from Huadian of Jilin were carried out by the pyrolysis method at three different heating rate 2℃/min, 5 ℃/min and 10 ℃/min in the temperature range of 30℃ -750℃. Heating rate 2 ℃/rain is considered low, while intermediate one covers the range 5 ℃/min and high heating rate is 10℃/min. The controlling parameters studied were the final pyrolysis temperature and the influence of the heating rate as well as type. The heating rate has an important effect on the pyrolysis of oil shale and the amount of residual carbon obtained therefore. It is found that increasing the heating rate and py- rolysis temperature also increases the production of oil and the total weight loss. Higher heating rates resulted in higher rates of accumulation. The rate of oil and water collection passed through the maximum of different heat- ing rates at different pyrolysis temperatures. Heating rate affected density, oil conversion and oil yield.展开更多
Vapor deposition and three-dimensional(3D)printing technology are considered to be conventional methods to achieve patterned metal film preparation through the assistance of masks and high temperature.Therefore,there ...Vapor deposition and three-dimensional(3D)printing technology are considered to be conventional methods to achieve patterned metal film preparation through the assistance of masks and high temperature.Therefore,there are still some challenges in fabricating metal films in template-free and normal temperature environment.In this work,we report a flexible and rapid laser metal transfer(LMT)technique for fabricating the various metal films(Cu,Ni,Sn,Al,Fe,and Ag)with different patterns without templates on arbitrary substrates(glass,polyimide(PI)films,and aluminum nitride(AlN)ceramic).Especially,the obtained transparent conductive glass displays high transmittance(more than 90%)and adjustable resistances(≈5Ω).According to the Joule effect,the interface resistance between Cu particles and copper oxide coating produces the high temperature approximately 280℃ at 2 V in a short time(≈60 s)and remains stable at 120℃ over 12 h.At last,the multifunctional glass with Cu patterns also shows excellent bactericidal activity(≈95%).This work demonstrates that laser metal transfer is an exceeding effective means of fabricating the micro/nano structures with potential applications in functional devices.展开更多
To evaluate the thermal performance of a low-temperature electrical radiant floor heating system,an experimental facility equipped with a constant temperature chamber and different specimen floors is designed and buil...To evaluate the thermal performance of a low-temperature electrical radiant floor heating system,an experimental facility equipped with a constant temperature chamber and different specimen floors is designed and built.The heating cable is installed in the floor slab with a unit-rated power of 30 W/m.Twenty-four different schemes are worked out and tested,which include three kinds of composite floor structures and eight kinds of cable distances.The cable distances are 30,40,50,60,80,100,130,150 mm.The main affective factors of the thermal performance and their influencing regularity are discussed.The experimental results show that the system has good stability and reliability,and the ratio of the radiation heat-transfer rate to the gross heat-transfer rate is greater than 50%.When the floor structure and the cable distance are fixed,the gross heat-transfer rate of the upper floor surface has a maximum value at an optimal cable distance.Under the experimental conditions in this paper,the optimal cable distance is 50 mm.展开更多
A coupled electrical-thermal-mechanical analysis is conducted for electrical/laser heating assisted blanking. Two novel localized-heating methods, electrical heating and laser-heating, recently proposed for small-part...A coupled electrical-thermal-mechanical analysis is conducted for electrical/laser heating assisted blanking. Two novel localized-heating methods, electrical heating and laser-heating, recently proposed for small-part blanking, are investigated with FE simulations. Results show that electrical heating would result in an advantageous distribution of temperature in a 316 stainless steel work-material. A desired temperature distribution may also be achievable for a copper work-material, if laser beam is used. Both electrical heating and laser-heating enable to reduce the blanking force and increase the aspect ratio achievable by blanking. The simulation also demonstrates that both electrical heating and laser-heating can result in desired temperature-distributions at sufficiently high heating-rates, ease of implementation and application. Comparatively, electrical heating could generate more favorable temperature distribution for small-part blanking.展开更多
Modified electrically assisted(EA) rapid heating of Al–Si-coated hot stamping steel is suggested, and the intermetallic evolution in the coating during heating is experimentally investigated. In the modified EA rapid...Modified electrically assisted(EA) rapid heating of Al–Si-coated hot stamping steel is suggested, and the intermetallic evolution in the coating during heating is experimentally investigated. In the modified EA rapid heating, a continuous electric current for a suitable duration is applied to a specimen to heat it to a temperature slightly below the melting temperature of the coating. The temperature of the specimen is then kept constant for a specified dwell time. The result of the microstructural analysis shows that the modified EA rapid heating could effectively increase the thickness of the intermetallic layer between the coating and steel substrate much faster than conventional furnace heating and induction heating. The effectiveness of EA rapid heating may be due to the athermal effect of the electric current on the mobility of atoms, in addition to the well-known resistance heating effect. EA rapid heating also provides a technical advantage in that partial austenization can be easily achieved by properly placing the electrodes, as demonstrated in the present study.展开更多
At present, the main heating method for reducing crude oil viscosity is electric heating, and the all-day electric heating method has the problems of high energy consumption and high cost. In order to meet the needs o...At present, the main heating method for reducing crude oil viscosity is electric heating, and the all-day electric heating method has the problems of high energy consumption and high cost. In order to meet the needs of environmental protection and industrial production, a new type of phase change thermal storage electric heating device was designed by combining the crude oil viscosity reduction heating method with valley price and phase change materials. The results indicate that as the inlet flow rate of the working fluid increases, the outlet temperature continuously decreases. And when the outlet temperature rises to 10?C, the inlet flow rate of the device can meet the flow range of 1.413 - 2.120 m3/h. At the same time, the addition of foam nickel makes the internal temperature of PCM more uniform, and the internal temperature of PCM decreases with the decrease of porosity of foam metal. By increasing the number of electric heating rods and reducing the power of individual electric heating rods, the structure of the device was optimized to significantly improve local high-temperature phenomena. The use of this device can maintain high heat exchange efficiency and reduce production costs.展开更多
The design and fabrication of high toughness electromagnetic interference(EMI)shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem.Ternary MXene/ANF(ar...The design and fabrication of high toughness electromagnetic interference(EMI)shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem.Ternary MXene/ANF(aramid nanofibers)–MoS_(2)composite films with nacre-like layered structure here are fabricated after the introduction of MoS_(2)into binary MXene/ANF composite system.The introduction of MoS_(2)fulfills an impressive“kill three birds with one stone”improvement effect:lubrication toughening mechanical performance,reduction in secondary reflection pollution of electromagnetic wave,and improvement in the performance of photothermal conversion.After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 50:50),the strain to failure and tensile strength increase from 22.1±1.7%and 105.7±6.4 MPa and to 25.8±0.7%and 167.3±9.1 MPa,respectively.The toughness elevates from 13.0±4.1 to 26.3±0.8 MJ m^(−3)(~102.3%)simultaneously.And the reflection shielding effectiveness(SE_(R))of MXene/ANF(mass ratio of 50:50)decreases~10.8%.EMI shielding effectiveness(EMI SE)elevates to 41.0 dB(8.2–12.4 GHz);After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 60:40),the strain to failure increases from 18.3±1.9%to 28.1±0.7%(~53.5%),the SE_(R)decreases~22.2%,and the corresponding EMI SE is 43.9 dB.The MoS_(2)also leads to a more efficient photothermal conversion performance(~45 to~55℃).Additionally,MXene/ANF–MoS_(2)composite films exhibit excellent electric heating performance,quick temperature elevation(15 s),excellent cycle stability(2,2.5,and 3 V),and long-term stability(2520 s).Combining with excellent mechanical performance with high MXene content,electric heating performance,and photothermal conversion performance,EMI shielding ternary MXene/ANF–MoS_(2)composite films could be applied in many industrial areas.This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers.展开更多
This study addresses the issue of spray icing on the air intake grilles of ship power systems in cold maritime environments.Through numerical simulation methods,the influence of environmental parameters on icing chara...This study addresses the issue of spray icing on the air intake grilles of ship power systems in cold maritime environments.Through numerical simulation methods,the influence of environmental parameters on icing characteristics is revealed,and an energy-efficient zoned electric heating anti-icing strategy is proposed.A threedimensional grille model is constructed to systematically analyze the effects of environmental temperature(from−20℃to−4℃),droplet diameter(from 50μm to 500μm),and liquid water content(from 0.5 g/m³to 8 g/m³)on icing rates and blockage of the flow channel.The results indicate that low temperature and high liquid water content significantly exacerbate icing.Under the condition of an environmental temperature of−20℃,droplet diameter of 500μm,and liquid water content of 8 g/m³,the flow channel blockage ratio reaches 30.95%within 10 min.Additionally,as droplet diameter increases,the droplet impingement and icing regions become more concentrated toward the leading edge of blades.To mitigate grille icing in cold environments,an electric heating film configuration is employed for thermal protection.Optimization of the heating strategy reveals that the zoned heating approach,compared to the initial uniform heating scheme,effectively homogenizes surface temperature distribution while reducing total power consumption by 37.47%.This study validates the engineering applicability of the zoned electric heating anti/de-icing strategy,providing theoretical and technical support for the design of anti-icing systems in ship power systems operating in cold maritime regions.展开更多
Electric current heat treatment is an innovative technique to improve microstructures and mechanical properties of metallic materials.The microstructures and mechanical properties of a powder metallurgy high-speed ste...Electric current heat treatment is an innovative technique to improve microstructures and mechanical properties of metallic materials.The microstructures and mechanical properties of a powder metallurgy high-speed steel(PM-HSS)treated by electric current heat treatment and traditional heat treatment are comparatively investigated.Results showed that after austenitizing at 1130°C,the structure of PM-HSS sample composed of ferrite matrix,M6C,M23C6,and MC carbides,transformed into a martensite matrix accompanied by M6C and MC carbides.Compared to the traditional austenitizing at 1130℃ for 30 min,the electric current austenitizing at 1130℃ for 5 min dissolved more carbides,resulting in a greater solid solution of alloying elements in the matrix.Further traditional triple tempering led to carbide coarsening,whereas electric current triple tempering promoted the carbide dissolution.Notably,the dissolution of more carbides resulted in a higher C content in the martensite matrix of HSS treated by electric current,significantly promoting the formation of nanotwins(5-20 nm in width).The electric current triple tempering sample exhibited a yield strength of 3097 MPa,compressive strength of 5016 MPa,and a fracture strain of 30.0%,outperforming the traditional triple tempering sample by nearly 600 MPa in yield strength.Analysis revealed that this significant strengthening was primarily attributed to nanotwin formation and solid solution strengthening caused by carbide dissolution.展开更多
We are delighted to introduce this Special Issue of Acta Metallurgica Sinica(English Letters)dedicated to"Thermoelectric Materials and Devices."Thermoelectric materials and devices have emerged as a promisin...We are delighted to introduce this Special Issue of Acta Metallurgica Sinica(English Letters)dedicated to"Thermoelectric Materials and Devices."Thermoelectric materials and devices have emerged as a promising technology for sustainable energy solutions,enabling efficient conversion between heat and electricity.This special collection highlights the latest advancements in the field,showcasing cutting-edge research and fostering interdisciplinary collaboration among researchers worldwide.展开更多
Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical co...Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical conductivity,high solar absorptivity,and low infrared emissivity at the same time are rare in na-ture,which are highly anticipated and of great significance for highly efficient electric/solar heating.In this work,we demonstrate that Ti_(3)C_(2)T_(x) MXene with low IR emissivity(14.5%)fills the gap in the absence of the above materials,exhibiting a remarkable electric/solar heating performance.The saturated heating temperature of Ti_(3)C_(2)T_(x) film reaches a record-high value of 201°C at a low driving voltage of 1.5 V,and reaches 84.3°C under practical solar irradiation(750 W/m^(2))with a high solar to the thermal conversion efficiency of 75.3%,which is far superior to other reported materials.Meanwhile,the low IR emissivity endows Ti_(3)C_(2)T_(x) with a remarkable passive radiative heating capability of 7.0°C,ensuring zero-energy heating without electric/solar energy supply.The intrinsic characteristic of high electrical conductivity,high solar absorptivity,and low IR emissivity makes Ti_(3)C_(2)T_(x) unique existence in nature,which is highly promising for all-day and all-weather energy-saving heating.展开更多
Carbon nanotubes（CNTs） were synthesized by the electric heating catalytic chemical deposition method（CCVD） using acetylene（C2H2） as the carbon source and nitrogen（N2） as carrier gas,and nickel catalyst was loa...Carbon nanotubes（CNTs） were synthesized by the electric heating catalytic chemical deposition method（CCVD） using acetylene（C2H2） as the carbon source and nitrogen（N2） as carrier gas,and nickel catalyst was loaded by electroplating.The electric heating method,as a new method,electrifies the carbon fiber directly by using its conductivity.The morphology and structure of CNTs were characterized by SEM and TEM,and the surface properties of carbon fibers before and after the growth of CNT were characterized by Raman spectroscopy.The experimental results show that the electric heating method is a new method to produce CNT,and can grow a large number of CNTs in a short time,the crystallization degree and surface average crystallite size of carbon fiber increased after the growth of CNT on it.In addition,electroplating loading catalyst can also be used as an ideal loading way,which can control the number,shape,and distribution of nickel particles by controlling the plating time.展开更多
The transient plane source(TPS)method is developed recently to measure the thermal conductivity of materials.In the measurement,the heating power is influenced by the heat which is transferred via the probe electrical...The transient plane source(TPS)method is developed recently to measure the thermal conductivity of materials.In the measurement,the heating power is influenced by the heat which is transferred via the probe electrical leads.This fact further influences the measurement accuracy of thermal conductivity.To solve this problem,the influence of heat loss through the electrical leads on the heating power is studied theoretically.The mathematical formula of heat loss is deduced,and the corresponding correction model is presented.A series of measurement experiments on different materials have been conducted by using the hot disk thermal constant analyzer.The results show that the influence of the heat loss on the measurement is sensitive to different test materials and probes with different sizes.When the thermal conductivity of the material is greater than 0.2 W/(m·K),the influence of the heat loss is less than 0.16%,which can be ignored.As to the lower thermal conductivity materials,it is necessary to compensate the heat loss through the electrical leads,and the accuracy of thermal conductivity measurement can be effectively improved.展开更多
For heating systems based on electricity storage coupled with solar energy and an air source heat pump(ECSA),choosing the appropriate combination of heat sources according to local conditions is the key to improving e...For heating systems based on electricity storage coupled with solar energy and an air source heat pump(ECSA),choosing the appropriate combination of heat sources according to local conditions is the key to improving economic efficiency.In this paper,four cities in three climatic regions in China were selected,namely Nanjing in the hot summer and cold winter region,Tianjin in the cold region,Shenyang and Harbin in the severe cold winter region.The levelized cost of heat(LCOH)was used as the economic evaluation index,and the energy consumption and emissions of different pollutants were analyzed.TRNSYS software was used to simulate and analyze the system performance.The Hooke-Jeeves optimization algorithm and GenOpt software were used to optimize the system parameters.The results showed that ECSA systemhad an excellent operation effect in cold region and hot summer and cold winter region.Compared with ECS system,the systemenergy consumption,and the emission of different pollutants of ECSA system can be reduced by a maximum of 1.37 times.In cold region,the initial investment in an air source heat pump is higher due to the lower ambient temperature,resulting in an increase in the LOCH value of ECSA system.After the LOCH value of ECSA system in each region was optimized,the heating cost of the system was reduced,but also resulted in an increase in energy consumption and the emission of different pollutant gases.展开更多
A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon sour...A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon source with nitrogen as dilution gas, and the pyrolytic carbon started to deposit on the carbon fiber surface when the deposition temperature was reached. The morphology of pyrolytic carbon was characterized by SEM, and the surface properties of carbon fibers before and after CVD were characterized by Raman spectroscopy. The experimental results show that the electric heating method is a novel method to fabricate C/C composite materials, which can form a dense C/C composite material in a short time. The order degree and the average crystallite size of the carbon fiber surface were decreased after the experiment.展开更多
Boron has been considered a promising powdered metal fuel for enhancing composite propellants'energy output due to its high energy density.However,the high ignition temperature and low combustion efficiency limit ...Boron has been considered a promising powdered metal fuel for enhancing composite propellants'energy output due to its high energy density.However,the high ignition temperature and low combustion efficiency limit the application of boron powder due to the high boiling point of the boron oxide layer.Much research is ongoing to overcome these shortcomings,and one potential approach is to introduce a small quantity of metal oxide additives to promote the reaction of boron.This study prepared boron-rich fuels with 10 wt%of eight nano-metal oxide additives by mechanical ball milling.The effect of metal oxides on the thermo-oxidation,ignition,and combustion properties of boron powder was comprehensively studied by the thermogravimetric analysis(TG),the electrically heated filament setup(T-jump),and the laser-induced combustion experiments.TG experiments at 5 K/min found that Bi_(2)O_(3),MoO_(3),TiO_(2),Fe_(2)O_(3),and CuO can promote thermo-oxidation of boron.Compared to pure boron,Tonsetcan be reduced from 569℃to a minimum of 449℃(B/Bi_(2)O_(3)).Infrared temperature measurement in T-jump tests showed that when heated by an electric heating wire at rates from 1000 K/s to 25000 K/s,the ignition temperatures of B/Bi_(2)O_(3) are the lowest,even lower than the melting point of boron oxide.Ignition images and SEM for the products further showed that the high heating rate is beneficial to the rapid reaction of boron powder in the single-particle combustion state.Fuels(B/Bi_(2)O_(3),B/MoO_(3),and B/CuO)were mixed with the oxidant AP and ignited by laser to study the combustion performance.The results showed that B/CuO/AP has the largest flame area,the highest BO_(2) characteristic spectral intensity,and the largest burn rate for powder lines.To combine the advantages of CuO and Bi_(2)O_(3),binary metal oxide(CBO,mass ratio of 3:1)was prepared and the test results showed that CBO can very well improve both ignition and combustion properties of boron.Especially B/CBO/AP has the highest burn rate compared with all fuels containing other additives.It was found that multi-component metal-oxide additive can more synergistically improve the reaction characteristics of boron powder than unary additive.These findings contribute to the development of boron-rich fuels and their application in propellants.展开更多
Cascading faults have been identified as the primary cause of multiple power outages in recent years.With the emergence of integrated energy systems(IES),the conventional approach to analyzing power grid cascading fau...Cascading faults have been identified as the primary cause of multiple power outages in recent years.With the emergence of integrated energy systems(IES),the conventional approach to analyzing power grid cascading faults is no longer appropriate.A cascading fault analysis method considering multi-energy coupling characteristics is of vital importance.In this study,an innovative analysis method for cascading faults in integrated heat and electricity systems(IHES)is proposed.It considers the degradation characteristics of transmission and energy supply com-ponents in the system to address the impact of component aging on cascading faults.Firstly,degradation models for the current carrying capacity of transmission lines,the water carrying capacity and insulation performance of thermal pipelines,as well as the performance of energy supply equipment during aging,are developed.Secondly,a simulation process for cascading faults in the IHES is proposed.It utilizes an overload-dominated development model to predict the propagation path of cascading faults while also considering network islanding,electric-heating rescheduling,and load shedding.The propagation of cascading faults is reflected in the form of fault chains.Finally,the results of cascading faults under different aging levels are analyzed through numerical examples,thereby verifying the effectiveness and rationality of the proposed model and method.展开更多
Combined heat and electricity operation with variable mass flow rates promotes flexibility,economy,and sustainability through synergies between electric power systems(EPSs)and district heating systems(DHSs).Such combi...Combined heat and electricity operation with variable mass flow rates promotes flexibility,economy,and sustainability through synergies between electric power systems(EPSs)and district heating systems(DHSs).Such combined operation presents a highly nonlinear and nonconvex optimization problem,mainly due to the bilinear terms in the heat flow model—that is,the product of the mass flow rate and the nodal temperature.Existing methods,such as nonlinear optimization,generalized Benders decomposition,and convex relaxation,still present challenges in achieving a satisfactory performance in terms of solution quality and computational efficiency.To resolve this problem,we herein first reformulate the district heating network model through an equivalent transformation and variable substitution.The reformulated model has only one set of nonconvex constraints with reduced bilinear terms,and the remaining constraints are linear.Such a reformulation not only ensures optimality,but also accelerates the solving process.To relax the remaining bilinear constraints,we then apply McCormick envelopes and obtain an objective lower bound of the reformulated model.To improve the quality of the McCormick relaxation,we employ a piecewise McCormick technique that partitions the domain of one of the variables of the bilinear terms into several disjoint regions in order to derive strengthened lower and upper bounds of the partitioned variables.We propose a heuristic tightening method to further constrict the strengthened bounds derived from the piecewise McCormick technique and recover a nearby feasible solution.Case studies show that,compared with the interior point method and the method implemented in a global bilinear solver,the proposed tightening McCormick method quickly solves the heat–electricity operation problem with an acceptable feasibility check and optimality.展开更多
In situ thermal desorption(ISTD)technology effectively remediates soil contaminated by dense nonaqueous phase liquids(DNAPLs).However,more efforts are required to minimize the energy consumption of ISTD technology.Thi...In situ thermal desorption(ISTD)technology effectively remediates soil contaminated by dense nonaqueous phase liquids(DNAPLs).However,more efforts are required to minimize the energy consumption of ISTD technology.This study developed a laboratory-scale experimental device to explore the coupling merits of two traditional desorption technologies:steam-enhanced extraction(SEE)and electrical resistance heating(ERH).The results showed that injecting high-density steam(>1 g/min)into loam or clay with relatively high moisture content(>13.3%)could fracture the soil matrix and lead to the occurrence of the preferential flow of steam.For ERH alone,the electrical resistance and soil moisture loss were critical factors influencing heating power.When ERH and SEE were combined,preheating soil by ERH could increase soil permeability,effectively alleviating the problem of preferential flow of SEE.Meanwhile,steam injection heated the soil and provided moisture for maintaining soil electrical conductivity,thereby ensuring power stability in the ERH process.Compared with ERH alone(8 V/cm)and SEE alone(1 g/min steam),the energy consumption of combined method in remediating perchloroethylene-contaminated soil was reduced by 39.3%and 52.9%,respectively.These findings indicate that the combined method is more favorable than ERH or SEE alone for remediating DNAPL-contaminated subsurfaces when considering ISTD technology.展开更多
The application of electrical contact heating （ECH） in austenitic grain refining of ultra-pure 42CrMoVNb steel was introduced. The ECH equipment was designed to reach uniform heating of uniform heat transfer in the ...The application of electrical contact heating （ECH） in austenitic grain refining of ultra-pure 42CrMoVNb steel was introduced. The ECH equipment was designed to reach uniform heating of uniform heat transfer in the sample. The 42CrMoVNb steel treated possesses uniform microstructure with an average austenite grain size of 1.4 μm, higher strength （1 538 MPa） and impact toughness （81J/cm^2）.展开更多
文摘The electrical heating experiments on oil shale sample from Huadian of Jilin were carried out by the pyrolysis method at three different heating rate 2℃/min, 5 ℃/min and 10 ℃/min in the temperature range of 30℃ -750℃. Heating rate 2 ℃/rain is considered low, while intermediate one covers the range 5 ℃/min and high heating rate is 10℃/min. The controlling parameters studied were the final pyrolysis temperature and the influence of the heating rate as well as type. The heating rate has an important effect on the pyrolysis of oil shale and the amount of residual carbon obtained therefore. It is found that increasing the heating rate and py- rolysis temperature also increases the production of oil and the total weight loss. Higher heating rates resulted in higher rates of accumulation. The rate of oil and water collection passed through the maximum of different heat- ing rates at different pyrolysis temperatures. Heating rate affected density, oil conversion and oil yield.
基金supported by the Taishan Scholar Project of Shandong Province(No.tsqn201812083)the Natural Science Foundation of Shandong Province(Nos.ZR2021JQ15,ZR2020QE071,ZR2020LLZ006,and ZR2020MH191)+1 种基金the Innovative Team Project of Jinan(No.2021GXRC019)the National Natural Science Foundation of China(Nos.52022037,52102171,and 62174068).
文摘Vapor deposition and three-dimensional(3D)printing technology are considered to be conventional methods to achieve patterned metal film preparation through the assistance of masks and high temperature.Therefore,there are still some challenges in fabricating metal films in template-free and normal temperature environment.In this work,we report a flexible and rapid laser metal transfer(LMT)technique for fabricating the various metal films(Cu,Ni,Sn,Al,Fe,and Ag)with different patterns without templates on arbitrary substrates(glass,polyimide(PI)films,and aluminum nitride(AlN)ceramic).Especially,the obtained transparent conductive glass displays high transmittance(more than 90%)and adjustable resistances(≈5Ω).According to the Joule effect,the interface resistance between Cu particles and copper oxide coating produces the high temperature approximately 280℃ at 2 V in a short time(≈60 s)and remains stable at 120℃ over 12 h.At last,the multifunctional glass with Cu patterns also shows excellent bactericidal activity(≈95%).This work demonstrates that laser metal transfer is an exceeding effective means of fabricating the micro/nano structures with potential applications in functional devices.
文摘To evaluate the thermal performance of a low-temperature electrical radiant floor heating system,an experimental facility equipped with a constant temperature chamber and different specimen floors is designed and built.The heating cable is installed in the floor slab with a unit-rated power of 30 W/m.Twenty-four different schemes are worked out and tested,which include three kinds of composite floor structures and eight kinds of cable distances.The cable distances are 30,40,50,60,80,100,130,150 mm.The main affective factors of the thermal performance and their influencing regularity are discussed.The experimental results show that the system has good stability and reliability,and the ratio of the radiation heat-transfer rate to the gross heat-transfer rate is greater than 50%.When the floor structure and the cable distance are fixed,the gross heat-transfer rate of the upper floor surface has a maximum value at an optimal cable distance.Under the experimental conditions in this paper,the optimal cable distance is 50 mm.
基金This project is supported by National Natural Science Foundation of China (No.10272119)European Community(No.BRPR-CT98-0742).
文摘A coupled electrical-thermal-mechanical analysis is conducted for electrical/laser heating assisted blanking. Two novel localized-heating methods, electrical heating and laser-heating, recently proposed for small-part blanking, are investigated with FE simulations. Results show that electrical heating would result in an advantageous distribution of temperature in a 316 stainless steel work-material. A desired temperature distribution may also be achievable for a copper work-material, if laser beam is used. Both electrical heating and laser-heating enable to reduce the blanking force and increase the aspect ratio achievable by blanking. The simulation also demonstrates that both electrical heating and laser-heating can result in desired temperature-distributions at sufficiently high heating-rates, ease of implementation and application. Comparatively, electrical heating could generate more favorable temperature distribution for small-part blanking.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Ministry of Science,ICT and Future Planning(MSIP)(NRF-2015R1A5A1037627)the Technology Innovation Program(Industrial Strategic Technology Development Program,10044807.Development of technologies for vehicle body part made from UHSS and Al5000 by electrically assisted manufacturing)funded by the Ministry of Trade,Industry and Energy(MOTIE,Korea)
文摘Modified electrically assisted(EA) rapid heating of Al–Si-coated hot stamping steel is suggested, and the intermetallic evolution in the coating during heating is experimentally investigated. In the modified EA rapid heating, a continuous electric current for a suitable duration is applied to a specimen to heat it to a temperature slightly below the melting temperature of the coating. The temperature of the specimen is then kept constant for a specified dwell time. The result of the microstructural analysis shows that the modified EA rapid heating could effectively increase the thickness of the intermetallic layer between the coating and steel substrate much faster than conventional furnace heating and induction heating. The effectiveness of EA rapid heating may be due to the athermal effect of the electric current on the mobility of atoms, in addition to the well-known resistance heating effect. EA rapid heating also provides a technical advantage in that partial austenization can be easily achieved by properly placing the electrodes, as demonstrated in the present study.
文摘At present, the main heating method for reducing crude oil viscosity is electric heating, and the all-day electric heating method has the problems of high energy consumption and high cost. In order to meet the needs of environmental protection and industrial production, a new type of phase change thermal storage electric heating device was designed by combining the crude oil viscosity reduction heating method with valley price and phase change materials. The results indicate that as the inlet flow rate of the working fluid increases, the outlet temperature continuously decreases. And when the outlet temperature rises to 10?C, the inlet flow rate of the device can meet the flow range of 1.413 - 2.120 m3/h. At the same time, the addition of foam nickel makes the internal temperature of PCM more uniform, and the internal temperature of PCM decreases with the decrease of porosity of foam metal. By increasing the number of electric heating rods and reducing the power of individual electric heating rods, the structure of the device was optimized to significantly improve local high-temperature phenomena. The use of this device can maintain high heat exchange efficiency and reduce production costs.
基金supported by the Talent Fund of Beijing Jiaotong University(No,2023XKRC015)the National Natural Science Foundation of China(Nos.52172081,52073010 and 52373259).
文摘The design and fabrication of high toughness electromagnetic interference(EMI)shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem.Ternary MXene/ANF(aramid nanofibers)–MoS_(2)composite films with nacre-like layered structure here are fabricated after the introduction of MoS_(2)into binary MXene/ANF composite system.The introduction of MoS_(2)fulfills an impressive“kill three birds with one stone”improvement effect:lubrication toughening mechanical performance,reduction in secondary reflection pollution of electromagnetic wave,and improvement in the performance of photothermal conversion.After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 50:50),the strain to failure and tensile strength increase from 22.1±1.7%and 105.7±6.4 MPa and to 25.8±0.7%and 167.3±9.1 MPa,respectively.The toughness elevates from 13.0±4.1 to 26.3±0.8 MJ m^(−3)(~102.3%)simultaneously.And the reflection shielding effectiveness(SE_(R))of MXene/ANF(mass ratio of 50:50)decreases~10.8%.EMI shielding effectiveness(EMI SE)elevates to 41.0 dB(8.2–12.4 GHz);After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 60:40),the strain to failure increases from 18.3±1.9%to 28.1±0.7%(~53.5%),the SE_(R)decreases~22.2%,and the corresponding EMI SE is 43.9 dB.The MoS_(2)also leads to a more efficient photothermal conversion performance(~45 to~55℃).Additionally,MXene/ANF–MoS_(2)composite films exhibit excellent electric heating performance,quick temperature elevation(15 s),excellent cycle stability(2,2.5,and 3 V),and long-term stability(2520 s).Combining with excellent mechanical performance with high MXene content,electric heating performance,and photothermal conversion performance,EMI shielding ternary MXene/ANF–MoS_(2)composite films could be applied in many industrial areas.This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers.
基金supported in part by the Ship Preliminary Research Project (No.3020401020102)。
文摘This study addresses the issue of spray icing on the air intake grilles of ship power systems in cold maritime environments.Through numerical simulation methods,the influence of environmental parameters on icing characteristics is revealed,and an energy-efficient zoned electric heating anti-icing strategy is proposed.A threedimensional grille model is constructed to systematically analyze the effects of environmental temperature(from−20℃to−4℃),droplet diameter(from 50μm to 500μm),and liquid water content(from 0.5 g/m³to 8 g/m³)on icing rates and blockage of the flow channel.The results indicate that low temperature and high liquid water content significantly exacerbate icing.Under the condition of an environmental temperature of−20℃,droplet diameter of 500μm,and liquid water content of 8 g/m³,the flow channel blockage ratio reaches 30.95%within 10 min.Additionally,as droplet diameter increases,the droplet impingement and icing regions become more concentrated toward the leading edge of blades.To mitigate grille icing in cold environments,an electric heating film configuration is employed for thermal protection.Optimization of the heating strategy reveals that the zoned heating approach,compared to the initial uniform heating scheme,effectively homogenizes surface temperature distribution while reducing total power consumption by 37.47%.This study validates the engineering applicability of the zoned electric heating anti/de-icing strategy,providing theoretical and technical support for the design of anti-icing systems in ship power systems operating in cold maritime regions.
基金financially supported by the National Natural Science Foundation of China(Nos.52271034,52301058 and 52471042)China Postdoctoral Science Foundation(No.2023M732183)Postdoctoral Fellowship Program of CPSF(No.GZB20230399).
文摘Electric current heat treatment is an innovative technique to improve microstructures and mechanical properties of metallic materials.The microstructures and mechanical properties of a powder metallurgy high-speed steel(PM-HSS)treated by electric current heat treatment and traditional heat treatment are comparatively investigated.Results showed that after austenitizing at 1130°C,the structure of PM-HSS sample composed of ferrite matrix,M6C,M23C6,and MC carbides,transformed into a martensite matrix accompanied by M6C and MC carbides.Compared to the traditional austenitizing at 1130℃ for 30 min,the electric current austenitizing at 1130℃ for 5 min dissolved more carbides,resulting in a greater solid solution of alloying elements in the matrix.Further traditional triple tempering led to carbide coarsening,whereas electric current triple tempering promoted the carbide dissolution.Notably,the dissolution of more carbides resulted in a higher C content in the martensite matrix of HSS treated by electric current,significantly promoting the formation of nanotwins(5-20 nm in width).The electric current triple tempering sample exhibited a yield strength of 3097 MPa,compressive strength of 5016 MPa,and a fracture strain of 30.0%,outperforming the traditional triple tempering sample by nearly 600 MPa in yield strength.Analysis revealed that this significant strengthening was primarily attributed to nanotwin formation and solid solution strengthening caused by carbide dissolution.
文摘We are delighted to introduce this Special Issue of Acta Metallurgica Sinica(English Letters)dedicated to"Thermoelectric Materials and Devices."Thermoelectric materials and devices have emerged as a promising technology for sustainable energy solutions,enabling efficient conversion between heat and electricity.This special collection highlights the latest advancements in the field,showcasing cutting-edge research and fostering interdisciplinary collaboration among researchers worldwide.
基金support of the National Natural Science Foundation of China(Nos.52003248 and 82004001)the China Postdoctoral Science Foundation(Nos.2018M642780 and 2021T140613)+1 种基金the Open-ing Project of State Key Laboratory of Polymer Materials Engineer-ing(Sichuan University)(No.sklpme2019-4-31)the Key Research and Development and Promotion projects of Henan Province(No.202102210032)are gratefully acknowledged.
文摘Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical conductivity,high solar absorptivity,and low infrared emissivity at the same time are rare in na-ture,which are highly anticipated and of great significance for highly efficient electric/solar heating.In this work,we demonstrate that Ti_(3)C_(2)T_(x) MXene with low IR emissivity(14.5%)fills the gap in the absence of the above materials,exhibiting a remarkable electric/solar heating performance.The saturated heating temperature of Ti_(3)C_(2)T_(x) film reaches a record-high value of 201°C at a low driving voltage of 1.5 V,and reaches 84.3°C under practical solar irradiation(750 W/m^(2))with a high solar to the thermal conversion efficiency of 75.3%,which is far superior to other reported materials.Meanwhile,the low IR emissivity endows Ti_(3)C_(2)T_(x) with a remarkable passive radiative heating capability of 7.0°C,ensuring zero-energy heating without electric/solar energy supply.The intrinsic characteristic of high electrical conductivity,high solar absorptivity,and low IR emissivity makes Ti_(3)C_(2)T_(x) unique existence in nature,which is highly promising for all-day and all-weather energy-saving heating.
基金Funded by the National Natural Science Foundation of China(No.51165006)the Universities in Hubei Province Outstanding Young Scientific and Technological Innovation Team(No.T201626)
文摘Carbon nanotubes（CNTs） were synthesized by the electric heating catalytic chemical deposition method（CCVD） using acetylene（C2H2） as the carbon source and nitrogen（N2） as carrier gas,and nickel catalyst was loaded by electroplating.The electric heating method,as a new method,electrifies the carbon fiber directly by using its conductivity.The morphology and structure of CNTs were characterized by SEM and TEM,and the surface properties of carbon fibers before and after the growth of CNT were characterized by Raman spectroscopy.The experimental results show that the electric heating method is a new method to produce CNT,and can grow a large number of CNTs in a short time,the crystallization degree and surface average crystallite size of carbon fiber increased after the growth of CNT on it.In addition,electroplating loading catalyst can also be used as an ideal loading way,which can control the number,shape,and distribution of nickel particles by controlling the plating time.
文摘The transient plane source(TPS)method is developed recently to measure the thermal conductivity of materials.In the measurement,the heating power is influenced by the heat which is transferred via the probe electrical leads.This fact further influences the measurement accuracy of thermal conductivity.To solve this problem,the influence of heat loss through the electrical leads on the heating power is studied theoretically.The mathematical formula of heat loss is deduced,and the corresponding correction model is presented.A series of measurement experiments on different materials have been conducted by using the hot disk thermal constant analyzer.The results show that the influence of the heat loss on the measurement is sensitive to different test materials and probes with different sizes.When the thermal conductivity of the material is greater than 0.2 W/(m·K),the influence of the heat loss is less than 0.16%,which can be ignored.As to the lower thermal conductivity materials,it is necessary to compensate the heat loss through the electrical leads,and the accuracy of thermal conductivity measurement can be effectively improved.
基金This work was supported by the National Key Research and Development Program of China(No.2019YFE0193200 KY202001)Science and Technology Planning Project of Beijing(No.Z201100008320001 KY191004).
文摘For heating systems based on electricity storage coupled with solar energy and an air source heat pump(ECSA),choosing the appropriate combination of heat sources according to local conditions is the key to improving economic efficiency.In this paper,four cities in three climatic regions in China were selected,namely Nanjing in the hot summer and cold winter region,Tianjin in the cold region,Shenyang and Harbin in the severe cold winter region.The levelized cost of heat(LCOH)was used as the economic evaluation index,and the energy consumption and emissions of different pollutants were analyzed.TRNSYS software was used to simulate and analyze the system performance.The Hooke-Jeeves optimization algorithm and GenOpt software were used to optimize the system parameters.The results showed that ECSA systemhad an excellent operation effect in cold region and hot summer and cold winter region.Compared with ECS system,the systemenergy consumption,and the emission of different pollutants of ECSA system can be reduced by a maximum of 1.37 times.In cold region,the initial investment in an air source heat pump is higher due to the lower ambient temperature,resulting in an increase in the LOCH value of ECSA system.After the LOCH value of ECSA system in each region was optimized,the heating cost of the system was reduced,but also resulted in an increase in energy consumption and the emission of different pollutant gases.
基金Funded by the National Natural Science Foundation of China(51165006)
文摘A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon source with nitrogen as dilution gas, and the pyrolytic carbon started to deposit on the carbon fiber surface when the deposition temperature was reached. The morphology of pyrolytic carbon was characterized by SEM, and the surface properties of carbon fibers before and after CVD were characterized by Raman spectroscopy. The experimental results show that the electric heating method is a novel method to fabricate C/C composite materials, which can form a dense C/C composite material in a short time. The order degree and the average crystallite size of the carbon fiber surface were decreased after the experiment.
基金State Key Laboratory of Explosion Science and Safety Protection of China (Grant No.QNKT21-8)National Natural Science Foundation of China (Grant No.12302432)to provide financial support。
文摘Boron has been considered a promising powdered metal fuel for enhancing composite propellants'energy output due to its high energy density.However,the high ignition temperature and low combustion efficiency limit the application of boron powder due to the high boiling point of the boron oxide layer.Much research is ongoing to overcome these shortcomings,and one potential approach is to introduce a small quantity of metal oxide additives to promote the reaction of boron.This study prepared boron-rich fuels with 10 wt%of eight nano-metal oxide additives by mechanical ball milling.The effect of metal oxides on the thermo-oxidation,ignition,and combustion properties of boron powder was comprehensively studied by the thermogravimetric analysis(TG),the electrically heated filament setup(T-jump),and the laser-induced combustion experiments.TG experiments at 5 K/min found that Bi_(2)O_(3),MoO_(3),TiO_(2),Fe_(2)O_(3),and CuO can promote thermo-oxidation of boron.Compared to pure boron,Tonsetcan be reduced from 569℃to a minimum of 449℃(B/Bi_(2)O_(3)).Infrared temperature measurement in T-jump tests showed that when heated by an electric heating wire at rates from 1000 K/s to 25000 K/s,the ignition temperatures of B/Bi_(2)O_(3) are the lowest,even lower than the melting point of boron oxide.Ignition images and SEM for the products further showed that the high heating rate is beneficial to the rapid reaction of boron powder in the single-particle combustion state.Fuels(B/Bi_(2)O_(3),B/MoO_(3),and B/CuO)were mixed with the oxidant AP and ignited by laser to study the combustion performance.The results showed that B/CuO/AP has the largest flame area,the highest BO_(2) characteristic spectral intensity,and the largest burn rate for powder lines.To combine the advantages of CuO and Bi_(2)O_(3),binary metal oxide(CBO,mass ratio of 3:1)was prepared and the test results showed that CBO can very well improve both ignition and combustion properties of boron.Especially B/CBO/AP has the highest burn rate compared with all fuels containing other additives.It was found that multi-component metal-oxide additive can more synergistically improve the reaction characteristics of boron powder than unary additive.These findings contribute to the development of boron-rich fuels and their application in propellants.
基金supported by Shanghai Rising-Star Program(No.22QA1403900)the National Natural Science Foundation of China(No.71804106)the Noncarbon Energy Conversion and Utilization Institute under the Shanghai Class IV Peak Disciplinary Development Program.
文摘Cascading faults have been identified as the primary cause of multiple power outages in recent years.With the emergence of integrated energy systems(IES),the conventional approach to analyzing power grid cascading faults is no longer appropriate.A cascading fault analysis method considering multi-energy coupling characteristics is of vital importance.In this study,an innovative analysis method for cascading faults in integrated heat and electricity systems(IHES)is proposed.It considers the degradation characteristics of transmission and energy supply com-ponents in the system to address the impact of component aging on cascading faults.Firstly,degradation models for the current carrying capacity of transmission lines,the water carrying capacity and insulation performance of thermal pipelines,as well as the performance of energy supply equipment during aging,are developed.Secondly,a simulation process for cascading faults in the IHES is proposed.It utilizes an overload-dominated development model to predict the propagation path of cascading faults while also considering network islanding,electric-heating rescheduling,and load shedding.The propagation of cascading faults is reflected in the form of fault chains.Finally,the results of cascading faults under different aging levels are analyzed through numerical examples,thereby verifying the effectiveness and rationality of the proposed model and method.
基金This work was supported by the Science and Technology Program of State Grid Corporation of China(522300190008).
文摘Combined heat and electricity operation with variable mass flow rates promotes flexibility,economy,and sustainability through synergies between electric power systems(EPSs)and district heating systems(DHSs).Such combined operation presents a highly nonlinear and nonconvex optimization problem,mainly due to the bilinear terms in the heat flow model—that is,the product of the mass flow rate and the nodal temperature.Existing methods,such as nonlinear optimization,generalized Benders decomposition,and convex relaxation,still present challenges in achieving a satisfactory performance in terms of solution quality and computational efficiency.To resolve this problem,we herein first reformulate the district heating network model through an equivalent transformation and variable substitution.The reformulated model has only one set of nonconvex constraints with reduced bilinear terms,and the remaining constraints are linear.Such a reformulation not only ensures optimality,but also accelerates the solving process.To relax the remaining bilinear constraints,we then apply McCormick envelopes and obtain an objective lower bound of the reformulated model.To improve the quality of the McCormick relaxation,we employ a piecewise McCormick technique that partitions the domain of one of the variables of the bilinear terms into several disjoint regions in order to derive strengthened lower and upper bounds of the partitioned variables.We propose a heuristic tightening method to further constrict the strengthened bounds derived from the piecewise McCormick technique and recover a nearby feasible solution.Case studies show that,compared with the interior point method and the method implemented in a global bilinear solver,the proposed tightening McCormick method quickly solves the heat–electricity operation problem with an acceptable feasibility check and optimality.
基金supported by the National Key R&D Program of China(No.2019YFC1805700).
文摘In situ thermal desorption(ISTD)technology effectively remediates soil contaminated by dense nonaqueous phase liquids(DNAPLs).However,more efforts are required to minimize the energy consumption of ISTD technology.This study developed a laboratory-scale experimental device to explore the coupling merits of two traditional desorption technologies:steam-enhanced extraction(SEE)and electrical resistance heating(ERH).The results showed that injecting high-density steam(>1 g/min)into loam or clay with relatively high moisture content(>13.3%)could fracture the soil matrix and lead to the occurrence of the preferential flow of steam.For ERH alone,the electrical resistance and soil moisture loss were critical factors influencing heating power.When ERH and SEE were combined,preheating soil by ERH could increase soil permeability,effectively alleviating the problem of preferential flow of SEE.Meanwhile,steam injection heated the soil and provided moisture for maintaining soil electrical conductivity,thereby ensuring power stability in the ERH process.Compared with ERH alone(8 V/cm)and SEE alone(1 g/min steam),the energy consumption of combined method in remediating perchloroethylene-contaminated soil was reduced by 39.3%and 52.9%,respectively.These findings indicate that the combined method is more favorable than ERH or SEE alone for remediating DNAPL-contaminated subsurfaces when considering ISTD technology.
文摘The application of electrical contact heating （ECH） in austenitic grain refining of ultra-pure 42CrMoVNb steel was introduced. The ECH equipment was designed to reach uniform heating of uniform heat transfer in the sample. The 42CrMoVNb steel treated possesses uniform microstructure with an average austenite grain size of 1.4 μm, higher strength （1 538 MPa） and impact toughness （81J/cm^2）.
