热电偶温度自动测量及预测系统研制

在利用热电偶对石油、石化等场所的设备进行温度测量时,由于某些测试环境的特殊性,这就要求热电偶对测温点进行"瞬态"测量,而热电偶的热接点由于受热惯性的影响,短时间很难对测温点进行准确测量.考虑到热电偶测温的阶跃响应特性,利用计算机及A/D转换装置研制了热电偶温度自动监测系统并编制了温度测试系统"预测"软件,在对部分采样的数据进行线性回归后,可实现对温度信号的自动采集及对测量值的跟踪"预测",缩短了测试时间并降低了测试强度.     

高超声速风洞M_a=5中劈尖试件的红外测温

目前,红外测温技术在高温非稳态下的应用研究还不成熟,而红外测温技术的关键在于发射率的准确测量。为了测量高超声速气流下试件的温度,同时采用MCS640高温红外热像仪和GH3030高温合金热电偶对风洞马赫数5(M_a=5)中的超高强度合金结构钢D6AC劈尖试件进行温度测量。首先,通过热电偶和红外热像仪组合的匹配法校正试件的发射率,再设置热像仪的发射率,测得试件驻点的温度变化曲线和试件在不同时刻的热图。实验测得试件驻点的最高温度为2 019.3℃,对分析材料的烧蚀性能和防热结构的可靠性提供了参考。实验证明,该测温方法可以用来测量高超声速风洞中试件的温度。     

非接触式激光测量真空状态下温度的方法

研究了一种利用激光干涉原理进行非接触式测温的方法,该方法能在不破坏样品表面的前提下,准确、方便、廉价地获取玻璃在真空中的真实温度.在相关实验中以Pilkington TEC系列钠钙玻璃为样品,在150～500℃之间同时对样品进行热电偶测温和激光干涉测温,实验数据表明,非接触式激光测温方法得到的温度数据与热电偶直接接触样品表面测得的温度数据在误差10℃范围内基本相同.证明了这种非接触式的方法可用于以玻璃为基底的太阳能电池生产领域.     

接触法测温的几个特殊问题

使用误差很小的普通热电偶高温计,不一定能准确测得某些特殊对象的温度。本文以挤压制造用的测温热电偶为例,说明在用接触法测量特殊对象的温度时,热电偶的测量端结构及测量方法等应满足的一些特殊要求。挤压铸造时,铝合金熔液的温度对挤压铸件质量影响极大。特别是由于挤铸机内的铝液很浅、温度下降很快,故需进行液体浅层测温、阶变测温和迅变测温这样具有三个特点的特殊测温。用普通结构的热电偶(如WREU-110型)根本无法读出被测温度。在此,我们结合实际,分析三种特殊情况下造成测温误差的原因并说明减小误差的方法。 1.液体浅层测温挤铸机内铝液很浅,只能允许热电偶垂直插入50mm。测温时,沿热电偶保护管、热电极的导热损失,使测量端温度t_c低于被测介质温度t_e而造成导热误差为:     

基于热成像的软包锂电池导热系数测试方法

为给软包锂电池热设计提供准确的导热系数值,提出了一种基于热成像技术的测试方法。通过热像仪记录电池表面温度场的演变数据,可同时反演电池的纵向和面向导热系数,避免了传统接触式表面测温引入的不确定因素。测试了多块不同规格的三元聚合物软包锂电池样品,并对其中一种样品进行了稳态法导热系数测量作为参考。结果显示,纵向和面向导热系数测试的相对标准差均在3%以内,纵向导热系数的测试结果与稳态法测量结果的相对偏差为3.1%,表明该方法具有较高的可靠性,可为电池的热设计提供参考。     

热电偶热传导测温中的动态响应时间和误差估计

热电偶是常用的测温元件.文中假设裸露热电偶的热端为一球形温度计,建立裸露热电偶热传导测量空气温度的数学模型,从理论上给出其热传导测量空气温度的动态响应时间和最大温度误差估计式,从而可知只要球形温度计在接触式测量温度时得到其动态响应时间和最大温度误差即可满足所求公式.在实际中,应用裸露热电偶温度传感器测试装药中孔隙内气体爆炸时的温度,可以满足测试要求,说明理论上提出的公式是正确的.     

真空热实验中热电偶测温系统不确定度的评定

热电偶测温系统是真空热试验中最常用的温度测量系统。该测温系统使用热电偶数量多,同时受内置参考点温度场变化的影响,不适合对其系统进行校准。文章依据热电偶测温系统的工作原理和计算公式,对该测温系统的不确定度进行了分析和评定,对某一批次热电偶的不确定度进行了计算。通过试验与铂电阻测温的比对,对热电偶测温系统的不确定评价进行了验证。     

热电偶温度计量常见问题的处理措施探讨

工业生产对周围环境的温度要求很高,为了确保温度能够在控制范围以内,就需要使用仪器来对环境进行测温。而我们普遍使用的测温仪器就是热电偶温度计。热电偶有很多的优点,它可以更准确地测出环境的温度来帮助生产工作的进行。但它很容易受到很多因素的影响。研究热电偶温计量问题可以很好的帮助工业生产。本文简单说明了热电偶的测温基本操作原理,分析了热电偶温度计测量产生误差的原因,还找出了热电偶误差校正的方法和一些使用注意事项,同时也为热电偶的维护和保养提供了一些参考。     

利用原位集成热电偶技术精准测量涡轮叶片表面高温温度的方法探究及误差分析

为实现航空发动机涡轮叶片表面高温温度的精准测量,首先需要对涡轮叶片表面薄膜热电偶进行精确校准,而校准误差主要起源于被校准热电偶与标准热电偶之间存在的温度迟豫。为此,该文在测试样品表面成功原位集成薄膜热电偶和铂点热电偶,进行高温重复循环试验,以铂点热电偶为校准基准,对多次重复循环的实验数据进行整体拟合,形成热电压与温度的校准曲线。并且对每一个测量数据进行误差分析,对校准误差范围形成有效的预估。结果表明:采用上述方法可以减少标准热电偶和被校准热电偶之间的温度迟豫,使涡轮叶片表面集成的薄膜热电偶校准相对误差可以有效地控制在±3%之内。     

非金属表面温度的测量技术

非金属材料具有耐高温、抗烧蚀、抗疲劳、重量轻、隔热性能好等优点,在宇航上得到了广泛的应用。精确测量非金属表面的瞬态温度是工程和科研中迫切需要解决的课题。本文讨论了玻璃钢、微晶玻璃、防热涂层、碳一碳复合材料表面的测温技术。非金属表面测温需要解决温度传感器在非金属表面的安装技术和标定传感器指示的温度讯号。文中介绍了热电偶在玻璃钢、微晶玻璃表面的安装方法,图示了粘贴式微型热电偶的结构和各种胶粘剂的使用方法。本文电点介绍三种标定瞬态表面温度的方法。对于玻璃钢,可以采用分层预埋热电偶的方法,通过测量玻璃钢剖面的瞬态温度分布曲线来"外推"玻璃钢表面的真实温度。第二种方法:采用"表面测温探头"作为标准的瞬态表面温度计对其它温度传感器进行现场标定。表面测温探头是一种能对导热误差进行自动补偿的测温装置。第三种方法:测量试件背面的瞬态温度加上理论计算的试件板厚温差作为标准的瞬态表面温度。采用这种方法检验了"表面测温探头"的精度。文中讨论的瞬态温度为10℃/秒、100℃/秒,试验是在碘钨灯加热器中进行的。文中也介绍了国外进行非金属表面温度测量的设备:热像仪,扫描式红外测温仅,表面测温探头和光导纤维测温装置等。     

基于红外热成像技术的复合式温场测温方法

针对测量目标发射率和吸收率估计不准确将造成红外热像仪测量温场误差较大的问题,提出了用热电偶作为标准建立红外热像仪修正模型的方法.建立热电偶所在位置的修正模型后,用其修正热像仪在其它位置的测量结果,从而提高了热像仪测量温场的准确度.30～200℃的实验证明其修正值具有较好的重复性和复现性.     

航空发动机热端表面温度场测量

航空发动机热端温度场的测量和监视对延长发动机的使用寿命具有重要意义.文章简要介绍了目前采用的各种温度测量方式,如热电偶、光电高温计、红外热像仪和示温漆,并详细介绍了多波长温度测量和谱色温度测量两种新型的温度测量方法.两种方法大大降低了温度测量对被测物体表面发射率的依赖性,适用于1000～3000℃温度范围内高温物体表面温度的测量.     

基于CFD技术的薄膜热电偶热阻修正模型研究

针对薄膜热电偶表面温度测量问题,以选定的薄膜热电偶模型为研究对象,开展不同表面温度下胶层厚度引入的测量误差的CFD数值仿真和试验研究,得到表面温度、胶层厚度与热阻修正之间的对应关系,在此基础上建立热阻修正模型,并设计试验进行验证,结果表明:在相同胶层厚度下,测温偏差大小随着表面温度与环境温度差值增大而增大,与试验结果一致;在相同表面温度下,胶层厚度越薄,测温偏差越小,与实际情况相符。     

Analysis of Thermal Imagers

A thermal imager with a microbolometer focal plane array (FPA) detector which does not require cooling is a relatively new type of instrument. With increasing use of thermal imagers for absolute temperature measurements, there is also an increasing need for their calibration. Five thermal imagers from three manufacturers were evaluated to identify parameters which affect their performance for accurate temperature measurements. Evaluation methods and measurements of parameters such as accuracy, temperature resolution, drift between internal calibration, non-uniformity, size-of-source effect, and distance effect are discussed. Based on the results, it is indicated which parameters should be evaluated in the calibration procedure as well as the uncertainty budget. The suitability of a blackbody for calibration was also addressed, especially in terms of dimensions related to the field of view of a thermal imager at the minimum focal distance.     

Thermocapillary Convection Experiment Facility of an open Cylindrical Annuli for SJ-10 Satellite

Thermocapillary convection has always been a hot topic of great importance in either crystal growth or thin films science. A space experiment about thermocapillary convection in an open cylindrical annuli pool will be done on SJ-10 satellite. A payload for space experiment has been established, which includes a cylindrical annuli thermocapillary convection system, a thermocouple temperature controlling system and measurement system, a thermal infrared imager, a high-precision displacement sensor, and an experiment controlling system. Some experiments have been done on the ground in order to compare with the results of space experiment. Some results from the ground experiment are shown, such as temperature oscillation, surface oscillation, and flow pattern transfer.     

光功率热分析仪的温度校准方法研究

薄膜材料相变温度的准确测量是相变材料的应用关键。光功率热分析仪是基于薄膜材料相变前后光反射率发生突变的原理测量相变温度的新型仪器,采用真空红外加热方式达到相变温度。为了测量得到准确可靠的相变温度,通过对光功率热分析仪测量相变温度方式、标准热电偶原位校准仪器测温热电偶方法的研究,实现将相变温度溯源至SI单位,并且对在测温区间100～1000℃内的温度进行了不确定度评定,得到校准拟合公式,相关系数为0.9997。     

Method for high-accuracy reflectance measurements in the 2.5-microm region

Reflectance measurement with spectroradiometers in the solar wavelength region (0.4-2.5 microm) are frequently conducted in the laboratory or in the field to characterize surface materials of artificial and natural targets. The spectral surface reflectance is calculated as the ratio of the signals obtained over the target surface and a reference panel, yielding a relative reflectance value. If the reflectance of the reference panel is known, the absolute target reflectance can be computed. This standard measurement technique assumes that the signal at the radiometer is due completely to reflected target and reference radiation. However, for field measurements in the 2.4-2.5-microm region with the Sun as the illumination source, the emitted thermal radiation is not a negligible part of the signal even at ambient temperatures, because the atmospheric transmittance, and thus the solar illumination level, is small in the atmospheric absorption regions. A new method is proposed that calculates reflectance values in the 2.4-2.5-microm region while it accounts for the reference panel reflectance and the emitted radiation. This technique needs instruments with noise-equivalent radiances of 2 orders of magnitude below currently commercially available instruments and requires measurement of the surface temperatures of target and reference. If the reference panel reflectance and temperature effects are neglected, the standard method yields reflectance errors up to 0.08 and 0.15 units for 7- and 2-nm bandwidth instruments, respectively. For the new method the corresponding errors can be reduced to approximately 0.01 units for the surface temperature range of 20-35 degrees C.     

红外辐射温度计专用数字表的研制及评价

日本CHINO公司生产的IR-RST系列标准辐射温度计由于没有设计温度显示装置,无法实时显示温度,针对此类型温度计设计了一款专用的电压测量和温度显示,同时可提供24V直流电压的电测显示仪表。利用高等级的电压源和数字电压表,修正了本专用数字表的误差系数,并考核了稳定性,得到其最大相对误差不超过0.03%。与一款名义波长为0.65 μm的IR-RST辐射温度计配合使用,通过TG HT-9500型高温炉对其组合进行内插分度,实验结果证实分度后校准准确度优于0.03%,1 300 ℃时系统测量结果的扩展不确定度为0.62 ℃。     

飞机环控系统管道气流温度的测量

根据实际使用中出现的问题，对各种实用的管道气流温度传感器的误差进行了计算，对电阻式和热电偶式温度传感器的误差原因作了定量分析。由于带密封罩的温度传感器在实际使用中存在着明显的缺点，建议今后使用热电偶测量飞机环控系统管道气流温度，并提出了一种实用热电偶温度传感器的结构形式，同时也介绍了如何减小由于热传导和热辐射引起的误差。     

Evaluation of Flat Surface Temperature Probes

The objective of this paper is elaboration of elements related to metrological analysis in the field of surface temperature measurement. Surface temperature measurements are applicable in many fields. As examples, safety testing of electrical appliances and a pharmaceutical production line represent case studies for surface temperature measurements. In both cases correctness of the result of the surface temperature has an influence on final product safety and quality and thus conformity with specifications. This paper deals with the differences of flat surface temperature probes in measuring the surface temperature. For the purpose of safety testing of electrical appliances, surface temperature measurements are very important for safety of the user. General requirements are presented in European standards, which support requirements in European directives, e.g., European Low Voltage Directive 2006/95/EC and pharmaceutical requirements, which are introduced in official state legislation. This paper introduces a comparison of temperature measurements of an attached thermocouple on the measured surface and measurement with flat surface temperature probes. As a heat generator, a so called temperature artifact is used. It consists of an aluminum plate with an incorporated electrical heating element with very good temperature stability in the central part. The probes and thermocouple were applied with different forces to the surface in horizontal and vertical positions. The reference temperature was measured by a J-type fine-wire (0.2 mm) thermocouple. Two probes were homemade according to requirements in the European standard EN 60335-2-9/A12, one with a fine-wire (0.2 mm) thermocouple and one with 0.5mm of thermocouple wire diameter. Additional commercially available probes were compared. Differences between probes due to thermal conditions caused by application of the probe were found. Therefore, it can happen that measurements are performed with improper equipment or in an improper way for a particular application. Therefore, knowledge and awareness regarding all facts related to the used measuring equipment are essential to avoid the risk of a wrong decision on safety measures.