石蜡/改性硅藻土复合相变储能材料的制备及性能研究

以石蜡为相变储能材料,改性硅藻土为载体,无水乙醇为溶剂采用溶液插层法制备了石蜡/改性硅藻土复合相变储能材料,利用综合热分析仪(TG-DSC)测定了复合材料的相变温度、相变潜热及复合材料的热稳定性,通过扫描电镜(SEM)、FT-IR分别对复合材料的微观结构及兼容性进行了表征,结果表明:复合相变储能材料中石蜡的适宜含量为65%,此时相变温度为53.7℃,相变潜热为147.93J/g,复合材料具有良好的热稳定性和兼容性。     

粉煤灰-硅藻土复合相变储能材料制备及导热强化

固废资源化利用是实现节能减排的重要途径,以月桂酸为相变工作介质,以粉煤灰-硅藻土二元载体为封装材料,碳纳米管为导热剂,采用直接熔融共混法制备出月桂酸/粉煤灰-硅藻土/碳纳米管复合相变储能材料。采用热扩散渗透测试、傅里叶红外光谱仪(FTIR)、差示扫描量热仪(DSC)、热重分析仪(TGA)、无纸记录仪等分别考察了定形复合相变储能材料的承载性能、微观结构和热物性。结果表明:粉煤灰-硅藻土二元载体可有效防止月桂酸的泄漏,当二元载体中月桂酸的质量分数为28%时可制得无泄漏复合相变储能材料,且原样粉煤灰利用率为55%;FTIR结果表明复合材料中各组分之间相容性好;DSC测得其熔化相变温度为45.79℃,相变潜热为51.06 J/g;TGA分析显示月桂酸/粉煤灰-硅藻土/碳纳米管热稳定性较好;储/放热性能曲线显示加入质量分数为5%的碳纳米管时,复合相变储能材料的熔化与凝固时间分别减少60%和62.5%,传热效率得到显著改善。     

豆蔻酸-棕榈酸/皂土复合相变储能材料的制备及储热性能研究

利用溶液插层法制备了豆蔻酸-棕榈酸/皂土复合相变储能材料,并用X射线衍射、红外光谱分析对复合材料的结构进行了表征,以差热分析法研究了材料的储热性能和储热稳定性.结果表明,皂土经过十六烷基三甲基溴化铵(CTAB)改性后,层间距变宽,且随着CTAB量的增加而变宽;豆蔻酸-棕榈酸进入改性皂土的纳米层间,形成了稳定的复合体系,这种复合材料具有优良的结构性能和良好的储放热性能,经过800次储放热循环后,材料的相变温度和相变潜热变化都不大,表现出较好的储热稳定性,有望在储能方面得到实际应用.     

石墨烯导热增强相变储能材料的制备及性能

为了提高复合相变储能材料的导热性能,以N,N,N-三甲基-1-十六烷基溴化铵(CTAB)改性剂,氧化石墨烯(GO)经有机化改性、还原反应制得功能化石墨烯(CTAB-RGO),并作为强化传热载体对癸酸-十二醇(CA-LA)共混物(相变储能材料)进行导热增强改性,获得新型石墨烯导热增强相变储能材料。结果表明,CTAB-RGO的加入提高了CA-LA相变复合材料的相变潜热、导热系数、热稳定性能等。添加1%CTAB-RGO复合材料的相变潜热为164.7 J/g,相对CA-LA混合物提高了22%;导热系数为高达0.94 W/(m·K),导热增强率为184%。     

石蜡-硬脂酸/石墨复合相变材料的储热性能研究

由二元相图确定出石蜡-硬脂酸二元低共熔物的质量配比为m(石蜡)∶m(硬脂酸)=17∶8,按上述配比通过熔融共混法制备出石蜡-硬脂酸复合相变材料,将石蜡-硬脂酸复合相变材料与石墨通过熔融共混法制备出石蜡-硬脂酸/石墨复合相变材料,通过储/放热实验和差示扫描量热法(DSC)对石蜡-硬脂酸和石蜡-硬脂酸/石墨复合相变材料的热性能进行了测试和表征。结果表明,石蜡-硬脂酸复合相变材料的相变储热性能好;随着石墨含量的增加,石蜡-硬脂酸/石墨复合相变材料的储/放热时间明显缩短,导热性能大幅度提高,但相变潜热逐渐降低,相变温度保持不变。制备的石蜡-硬脂酸/石墨复合相变材料具有合适的相变温度、较高的相变潜热,导热性能优良,可用于低温储能领域。     

潜热储能石膏基建筑材料的制备及其储(放)热行为研究

以膨胀石墨为吸附介质,硬脂酸丁酯为吸附对象,可以制得有机/无机复合相变材料,将这种复合材料掺入石膏中制备潜热储能石膏建材.DSC的测试结果显示,复合相变材料的相变焓值与纯硬脂酸丁酯的相变焓值基本相当,体现了良好的热物理性能.考虑到浆体的和易性,复合相变材料在石膏试样中的掺量不宜超过5%.在石膏硬化浆体中,复合相变材料与石膏浆体间的界面具有一定的缺陷,但是对石膏试样的强度影响不大.温度循环试验显示,复合相变材料掺量5%的潜热储能石膏具有良好的储(放)热效果,这种特性将有助于增加环境温度波动的惰性,实现热量在不同时间上的迁移,从而在建筑节能领域中加以应用.     

膨胀石墨/硬脂酸丁酯复合相变储热脱硫石膏板的研究

以多孔膨胀石墨(EG)为载体、硬脂酸丁酯(BS)为相变材料制备了相变储热复合材料,将所得材料与脱硫石膏和高分子乳液BASF400混合制备了相变储能石膏板.利用差示扫描量热法(DSC)研究了温度(45～50℃)和高分子乳液BASF400对石膏板相变潜热的影响,分析结果表明,复合相变储热石膏板经长时间烘烤后相变潜热未出现明显变化,所得相变石膏板在建筑节能领域具有广阔的应用前景.     

肉豆蔻酸-硬脂酸/改性粉煤灰复合相变储能材料的制备及性能研究

以肉豆蔻酸(MA)和硬脂酸(SA)的二元低共熔混合物为相变储能基材、改性粉煤灰为复合基底,采用熔融混合法制备了MA-SA/改性粉煤灰的复合相变储能材料(CPCM)。利用TG/DTA与FT-IR分析研究了CPCM的热性能与结构。结果表明,MA-SA低共熔物可均匀的嵌入改性粉煤灰的多孔结构中。经过800次的吸放热循环后,CPCM的相变温度和相变焓变化都不大,表现出较好的储热稳定性,有望在储能方面得到实际的应用。     

硬脂酸-月桂酸/蒙脱土复合相变储能材料的合成及性能研究

采用溶液插层法合成硬脂酸-月桂酸/蒙脱土复合相变储能材料,通过X射线衍射、红外光谱等手段对复合材料的结构进行分析,以差示扫描量热法研究了材料的储热性能,并对其热稳定性进行研究。结果表明:十六烷基三甲基溴化铵(CTAB)改性后,蒙脱土的层间距变宽;硬脂酸-月桂酸进入改性蒙脱土的纳米层间,形成了稳定的复合体系,这种复合材料具有优良热稳定性,可在建筑节能领域得到实际应用。     

癸酸-棕榈酸-硬脂酸/膨胀石墨蓄能复合相变材料的制备与热性能研究

癸酸、棕榈酸、硬脂酸形成的三元低共熔物与膨胀石墨通过真空浸渍法制备出新型癸酸-棕榈酸-硬脂酸/膨胀石墨储能复合相变材料,适宜的质量比为m(癸酸)∶m(棕榈酸)∶m(硬脂酸)=77.0∶11.5∶11.5,m(癸酸-棕榈酸-硬脂酸)∶m(膨胀石墨)=13∶1。采用DSC、FT-IR、TG、SEM、冷热循环实验和蓄/放热实验研究了材料的结构和热性能。SEM和FT-IR分析结果表明低共熔物与膨胀石墨是通过物理吸附方式结合。DSC结果表明复合材料融化和凝固时的相变温度为28.93℃和16.32℃,相变潜热为137.38J/g和141.51J/g。TG结果表明复合相变材料在100℃以下具有良好的热稳定性。500次热循环和蓄/放热实验表明循环前后复合相变材料的热可靠性好,且使用寿命长。膨胀石墨的添加改善了复合材料的热性能和热导率。研究表明制备的新型复合相变材料具有合适的相变温度、较高的相变潜热和热导率,热性能稳定可靠,可用于低温蓄能领域。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.