降低裸露电气接头热故障的理论研究与热设计

从产生裸露电气接头热故障的机理入手,分析了引起接头温升的主要原因,以及裸露电气接头表面对太阳辐射的吸收率αｓ和在长波区的发射率ε对接头温升的影响,从而得出结论：在裸露电气接头表面,涂敷一种αｓ／ε比值较小的光谱选择性辐射涂层,将大大降低裸露电气接头的温升,这对降低裸露申气接头的热故障率、保证电力系统安全、经济地运行,有着非常积极的意义。     

热辐射纺织品辐射载体的热性能研究

从理论上分析了具有热辐射功能的纺织品所使用的选择性辐射载体的热辐射性能。通过对几种实际辐射材料的测试，并结合它们各自的光谱发射率图对实验结果进行分析，得出了它们在实际应用中的看法。最后应用理想光谱发射率图提出了几个产品热设计方案。     

电气接头红外检测的研究

本文首先利用 Hagen-Rubens 关系式计算了纯铜和铝材料的法向光谱发射率,并用加权纵坐标法计算了它们在233～773K 温度范围内占98%以上的总辐射和法向全发射率,得到了这两种材料发射率随辐射波长及温度的理论变化规律。进一步通过对不同类型红外辐射测温方法的误差分析,得到了辐射温度及亮度温度与其真实温度相对偏差的变化曲线。最后根据取得的上述变化规律和曲线,提出了应用单片微型计算机的电力系统专用智能化红外测温仪的设计构思和原理方框图,并对这种新型专用智能化红外测温仪做了初步讨论。     

基于辐射传输方程的稀土辐射器厚度优化分析

对以碳化硅为基底、氧化镱为表面涂层的选择性辐射器进行优化分析,基于热辐射传输方程和能量平衡方程建立数学模型,研究带内、带外光谱发射率与涂层厚度的变化关系.结果表明:涂层内外温差对发射率有削弱作用,而且涂层厚度越大这种削弱作用越明显.以0.98μm为典型波长的带内辐射,在涂层厚度为0.25mm时发射率有最大值;以1.8μm为典型波长的带外辐射,发射率随涂层厚度增加而单调增大.依据高性能辐射器应同时具备较高的带内发射率和较低的带外发射率的原则,综合分析得出稀土辐射器氧化镱涂层的最优厚度为0.25mm.     

高发射率节能涂层的制备及性能研究

在耐火材料表面成功制备出新型高发射率节能涂层，涂层的发射率达到0．90，厚度约为300μm。涂层与基体间有3mm左右渗透层，基体到涂层的连续过渡层结构保证了涂层与基体间良好的黏结性能和优异的抗剥落能力。涂层在1750m。高炉热风炉上应用。结果表明，涂层能提高热风温度28℃，同时减小送风温度的波动。高发射率涂层强化了气一固相间辐射传热，提高了炉窑的热效率，从而缩短了加热时间、提高加热温度和降低燃料消耗。     

应用高发射率涂层改善燃气红外辐射器性能的研究

分析了提高燃气红外辐射器表面辐射性能的途径,提出在燃气红外辐射器多孔陶瓷板表面应用高发射率涂层改善辐射器性能。选择涂料并制作了涂层。对比实验获得的数据,采用高发射率涂层的陶瓷板板面温度下降10～60℃,可增大灶具调节范围,烟气中CO含量大大降低,NOx含量减少4.9×10-6,改善了燃气灶具的燃烧性能,所选带氧化铁涂层燃气热效率为63.6%～65.4%,较原燃气灶提高2%。测试数据表明应用高发射率涂层可以提高燃气红外辐射器的热效率,改善燃气红外辐射器的燃烧性能。     

碳纳米管高温红外隐身特性的研究

研究了碳纳米管粉末在3～5μm、8～13μm波段内的平均红外发射率,分别考察了单壁碳纳米管(L-SWNT-1*)、双壁碳纳米管(L-DWNTs)及多壁碳纳米管(L-MWNT-10)在上述2个波段内发射率随温度的变化。研究结果表明,随着温度的升高,实验所用碳纳米管粉末在上述2个波段内的平均红外发射率随之降低,尤其是在波段3～5μm内,温度为190℃时碳纳米管的平均红外发射率与70℃相比降低了35%左右。同时,对环氧树脂基碳纳米管涂层的红外发射率随温度的变化也进行了考察。结果表明,随温度的升高,涂层的红外发射率也随之降低。说明碳纳米管具有一定的高温红外隐身特性,且碳纳米管在中波3～5μm比在长波8～13μm具有更明显的负温度系数效应。     

NaBa1-xAxPO4（A=Mg，Ca，Sr）材料的制备和红外辐射特性

用高温固相法合成了NaBaPO4结构材料．NaBaPO4是一类常用于荧光粉基质的材料,本实验通过X射线衍射、红外光谱吸收和发射率表征了材料的结构特性和红外辐射性能,发现NaBaPO4具有很好的辐射性能,当掺杂Mg2＋、Ca2＋和Sr2＋后,引起NaBaPO4晶体的金属离子和氧离子的键长改变,使分子间振动改变,发射率改变．其中以NaBa0.85 Mg0.15 PO4的红外辐射性能最佳,8～14μm波段的发射率可达0.924．     

PBT／PET共聚酯及其纤维的热性能

本文利用差示扫描量热分析（ＤＳＣ）研究了ＰＢＴ／ＰＥＴ共聚酯及其纤维热性能与形态结构的关系．实验结果表明ＰＢＴ／ＰＥＴ共聚酯高温稳定性好，其结晶结构为ＰＢＴ／ＰＥＴ共晶结构，随ＰＢＴ含量增加，其熔融热增加，熔点下降，ＰＢＴ／ＰＥＴ共聚纤维的熔融热随拉伸倍数增加而增加，这表明纤维结晶度随拉伸倍数而增加．适宜于ＰＢＴ／ＰＥＴ共聚纤维的拉伸温度为８０℃．     

木质素快速热裂解试验研究

在红外辐射加热反应器中对生物质的主要组分木质素进行了热裂解试验研究，分析了木质素热裂解产物的产量随温度的变化规律。试验结果表明，在350～800 ℃，焦炭产量随温度升高而降低，最后趋近质量分数稳定值约为26%；焦油产量随温度升高而增大，在550 ℃出现质量分数为27%的最大产量，温度进一步升高，部分挥发分的二次裂解使焦油产量降低而轻质气体产量大大增加；气体产物主要有H2、CO、CO2、CH4以及CnHm，其产量随着温度的升高都呈增长趋势。结合木质素热裂解焦油的色谱傅立叶红外光谱（GC-FTIR）分析，发现焦油中主要是含有甲氧基、烷基、羟基等官能团的苯酚和酸、酮类化合物，甲酸和乙酸随着温度升高二次裂解加剧导致产量降低。对比纤维素热裂解试验结果可以发现，纤维素对焦油的生成贡献最大，而木质素热裂解主要是生成轻质气体和焦炭。     

Multispectral thermometry based on neural network

0　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｔｅｃｈｎｏｌｏｇｙｏｆｍｕｌｔｉｓｐｅｃｔｒａｌｔｈｅｒｍｏｍｅｔｒｙｈａｓｂｅｅｎｍａｉｎｌｙｕｓｅｄｆｏｒｄｙｎａｍｉｃｍｅａｓｕｒｅｍｅｎｔｏｆｔｒｕｅｔｅｍｐｅｒａｔｕｒｅａｎｄｔｈｅｒｍｏｐｈｙｓｉｃａｌ ｐｒｏｐｅｒｔｉｅｓｏｆｈｉｇｈｔｅｍｐｅｒａｔｕｒｅａｎｄｕｌｔｒａｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｔａｒｇｅｔｓ ,ｉｎＥｕｒｏｐｅａｎｄＡｍｅｒｉｃａｓｉｎｃｅｔｈｅｅｉｇｈｔｉｅｓ .6 ｗａｖｅｌｅｎｇｔｈｐｙｒｏｍｅｔｅｒｓｗｉｔｈｏｐｔｉｃａ…     

Methods of data processing in multi-wavelength thermometry

Several kinds of multi-wavelength pyrometers havebeen designed and widely used since 1954[1 -4]. Butthe processing of multi-wavelength pyrometer data is aproblem that needs further improvements. The solutionsdeveloped in earlier decades generally assumed oneparticular mathematical relation for emissivity versuswavelength in the wavelength range of the measure-ments. Sometimes this assumption worked and pro-duced acceptable results, but in many other cases thisapproach provided wrong results. I…     

Preparation of high emissivity NiCr2O4 powders with a spinel structure by spray drying

Spray-drying was used to produce the high emissivity NiCr2O4 powders with a spinel structure. Preliminary investigations focused on fabricating the high emissivity powders for infrared radiation coatings and finding the relationship between microstructure and emissivity. The NiCr2O4 powders were characterized for composition, microstructure, and infrared emissivity by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared radiant instrument, and Fourier transform infrared spectra (FT-IR). Thermogravimetry and differential thermal analysis show that the appropriate baking temperature for NiCr2O4 powder preparation is about 1200?C. The emissivity measurement and FT-IR spectra show that, because of the special spinel structure, the NiCr2O4 powders have a high emissivity about 0.91. Spray-drying is a suitable method to produce the high emissivity ceramic powders.     

Preparation of ZAO powder and investigation on its infrared emissivity

According to the basic infrared stealth mechanism of low infrared emissivity powders,the ZAO powder materials were prepared by liquid coprecipitation method,and the starting materials were Zn( NO3) 6H2O and Al( NO3) 39H2O. The process parameters were obtained,and the relationship between technology parameters and infrared emissivity was investigated. The temperature of thermal treatment,crystal structure and surface micrograph of ZAO powder was analyzed by the help of TG-DTA,XRD and SEM. The infrared stealth performance of ZAO powder was studied by IR-2 emissivity spectroscopy. Results showed that the infrared emissivity was the lowest when pH was 8. 0,calcination temperature was 1100 ℃,calcination time was 2 h,and the Al2O3doping content was 3% ( mass percentage) . The crystal structure of doped ZAO powder was lead-zinc, and there exists distortion of crystal lattice in nanocrystalline ZnO. The average particle size was 10 μm. The lowest infrared emissivity reached to 0. 61 at between 8 μm and 14 μm. It means that the ZAO powders will be excellent infrared stealthy materials.     

Microstructure and properties of high emissivity coatings

A new coating on lining in industrial furnace for energy saving has been developed. Properties and microstructure of the coatings were revealed by emissivity instrument,X-ray diffraction (XRD),transmission electron microscope (TEM) and scanning electron microscope (SEM),respectively. The result indicates that the emissivity of coatings is higher than 0.90 and the thickness of coatings is about 200 μm. ZrO2,Cr2O3 and SiC in the coating benefit practical applications of coatings at high temperature with du-ra...     

表面粗糙度对辐射温度计测量误差的影响

辐射式温度计的测量结果需要根据物体的发射率进行修正.在实际应用中,物体的发射率受到很多因素的影响,粗糙度就是其中之一.通过比较不同粗糙表面的计算结果,发现粗糙度对二向反射分布函数和法向发射率的影响不可忽略.在对温度的测量精确性要求较高的场合,由粗糙度造成的温度测量误差需要引起足够重视.     

MICROSTRUCTURE AND INFRARED EMISSIVITY AT NORMAL TEMPERATURE IN TRANSITIONAL METAL OXIDES SYSTEM CERAMICS

The fabrication of Fe_2O_3—MnO_2—Co_2O_3—CuO system ceramics, and the com posite system ceramics of transititmal metal oxides-cordierite and transitional metal oxides-kaolinit are presented in this work. The research was carried out with the main attention to the infrared emissivity in the band of 8～14p'm at room temperature, the microstructure of the ceramics and the relation between them. High infrared emissivities exceeding 0.9 in the band of 8～14pm at room temperature were gained in the transitional metal oxide ceramics and the composite system ceramics. It is suggested that the formation of inverse spinels and partially inverse spinels, such as Fe_3O_4, CoFe_2O_4, CuFe_2O_4 and CuMn_2O_4, is beneficial to the enhancement of the infrared emissivity of the transitional metal oxide ceramics. The transitional metal oxides play an important role in determining the infrared emissivity of the composite system ceramics.     

凸起黑体辐射元件对锻压炉炉膛辐射换热的影响

开展了利用黑体凸起结构强化钢厂热锻压炉炉膛辐射传热的数值研究.采用Gambit软件设计出模拟炉膛段,利用Fluent软件对炉膛段内辐射传热过程进行了耦合数值模拟,获得了炉膛内烟气的流场、温度场以及锻钢表面辐射热流密度.分析了炉壁表面黑度以及不同凸起结构对辐射传热效果的影响规律.结果表明,提高炉膛内壁黑度以及加装凸起辐射元件对炉膛内辐射传热有显著的强化作用.通过Gambit模拟改变辐射元件的尺寸、形状,得到最佳的安装方案可以提高炉膛内烟气15%的辐射传热效率.     

等温圆柱型空腔表面辐射传递方向分布特性

用蒙特卡罗法计算了圆柱型空腔底面与管内壁面单元之间的辐射传递系数,研究了底面为黑体表面、管内壁面为等温灰体、漫发射、漫反射时,管内壁发射率、管长与半径比的变化对管口表面定向发射率的影响,结果表明:管长与半径比增加,管口表面定向发射率极值点向小角度的天顶角方向移动,管长与半径比超过30,管口表面最大定向发射率对应天顶角<2°;管内壁发射率为变量时,距离管出口1倍管内直径处的发射率对管口表面最大定向发射率的影响较大;管内壁的发射率越小,管口表面定向辐射集中特性越好.     

冲天炉铁水连续测温的新方法

利用辐射法对冲天炉铁水进行连续测温,其关键是解决铁水表面发射率的不确定性,因此采用新的测温方法的研究势在必行。其中一种途径即利用一个空芯导管插入铁水中,形成一个近似灰体腔,使腔内铁水表面发射率基本不变,然后利用光纤比色测温仪示出温度。理论计算与实验表明,该方法在很大程度上提高了测温精度,减小了误差。