发射率结合辐射光强实时测量高温辐射源2维温度场

提出了一种由光纤光谱仪与黑白CCD相机构成的新型实时在线高温温度场测量系统.该系统用光纤光谱仪和黑白CCD相机同时测得高温辐射源的真实发射率和光强场,然后根据发射率和光强场计算得到高温辐射源的温度场.利用该系统对高温发光物体——卤素灯灯丝的温度场进行测量,得到了不同电压值下卤素灯灯丝的温度场分布图,并将所得温度场的最高温度与相应工况下发射光谱法测量得到的最高温度进行比较.结果表明:两者相对偏差在5%以内;所提出的测量方法既弥补了发射光谱法不能获得场分布的缺陷,又避免了比色法测温中单色波长带宽和发射率瞬时变化带来的误差,是一种有效的温度场测量方法.     

Application of spectral technology in flame measurement

Spectral technology has become an important detection method due to its advantages such as nonintrusive measurement and on-line analysis. In this paper, two applications of spectral technology in thermal detection were proposed. First, a novel spectroscopic method based on Planck’s law for measurement of emissivity was introduced. The emissivity, obtained by comparing the radiation intensity of the blackbody which had the same temperature as the flame with the detected intensity of the flames, could be used for on-line measurements and had a relatively higher upper temperature limit. Then, a spectroscopic method for composition detection of blended fuels was proposed based on the emissivity measured. By comparing the spectra of blended fuels and single fuels, the ratio of single fuels of the blended fuel could be calculated. The measurement system proposed in this paper, which consists of a spectrometer and a computer, is very compact.     

A new technique to measure the temperature of a rotating motor shaft

In the present study, a new technique has been developed for the measurement of the temperature of a motor shaft rotating at high speed. A radiation thermometer could be useful as one of the methods of measuring the surface temperature of said shaft. However, if the cross-sectional diameter of the motor shaft is small, it is necessary to closely approach the shaft rotating at high speed when measuring the temperature. The present paper reports the successful measurement of the local surface temperature and the temperature rise time of a motor shaft with a diameter of 10 mm diameter, rotating at high speed, by utilizing the potential of the melting points of different chemical reagents. The measurements were carried out at a distance of 1 m from the shaft, overcoming the difficulty in the use of a radiation thermometer.     

Measuring transient temperature of the medium in power engineering machines and installations

Under steady-state conditions when fluid temperature is constant, there is no damping and time lag and temperature measurement can be made with high accuracy. But when fluid temperature is varying rapidly as during start-up, quite appreciable differences occur between the true temperature and the measured temperature because of the time required for the transfer of heat to the thermocouple placed inside a heavy thermometer pocket. In this paper, two different techniques for determining transient fluid temperature based on the first and second order thermometer model are presented. The fluid temperature was determined using measured thermometer temperature, which is suddenly immersed into boiling water. To demonstrate the applicability of the presented method to actual data, the air temperature which changes in time, was calculated based on the temperature readings from the sheathed thermocouple.     

Measurement of Transient Fluid Temperature in a Pipeline

The aim of this paper is to develop a method of determining the heat transfer coefficients on the inner surface of the pipeline and outer surface of the thermometer used to measure the temperature of a fluid flowing under high pressure. The method is based on the solutions to the inverse heat conduction problems for the thermometer and the pipeline wall. The heat transfer coefficients are determined based on the measurement of the temperature of a cylindrical metal thermometer and the temperature of the wall of a cylindrical pipeline. The temperature sensor is located in the pipeline wall close to the inner surface. The correlations for the Nusselt numbers used to determine heat transfer coefficients on the outer surface of the thermometer and the inner surface of the pipeline contain unknown coefficients which are found using the least squares method. The unknown coefficients are selected so that the sum of the squares of differences between the fluid temperature determined based on the measurement of the temperature of the pipeline wall and the fluid temperature obtained from measurements inside the thermometer, calculated for several dozen set time points, is as small as possible.     

Gas-controlled heat-pipes for accurate temperature measurements

Several gas-controlled heatpipes are operating at IMGC for primary temperature measurements from 100 to 962 °C. One consists of a stainless steel heat-pipe with a single thermometer well and uses 7N-pure mercury as working fluid; another is made in Inconel with six thermometer wells and uses 3N5-pure sodium as working fluid. Both heat-pipes are connected in parallel to the same accurate helium pressure control system made at IMGC. These heatpipes realize a very uniform and stable temperature zone, adequate for measurement at the millikelvin level with platinum resistance thermometers. The paper describes the two heat-pipes and their thermal characteristics, such as the temperature uniformity along the thermometer wells and their temperature response to a pressure change.For the study on the capillary structure, the heating system and the working fluids, heat-pipes in Pyrex glass with a conical connection for their opening and with three thermometer wells have been made. Some results, using pure water and a 3M™ speciality fluid for heat transfer applications, showed that a stability and uniformity of a few millikelvin can be obtained for short-term periods (about 10–15 min) without any pressure control, around the boiling temperature.     

Temperature Determination Using Multispectral Radiation Thermometry Algorithms for Aluminum Alloys

Multispectral radiation thermometry (MRT) was applied to predict the aluminum surface temperature. Experiments were conducted to measure the spectral intensity values for five different aluminum alloys, AL1100, AL2024, AL5083, AL6061, and AL7005, at 600 K, 700 K, and 800 K. The experimental work is coupled with six MRT emissivity models encompassing mathematical and analytical functions to infer surface temperature. Assessment of the MRT emissivity model is subject to parametric effects of number of wavelengths, alloy composition, and temperature. Results show that increasing wavelength number does not significantly improve measurement accuracy while applying MRT. If the emissivity model can represent well the real emissivity behaviors, a more accurate inferred temperature can be achieved. Overall, most models achieve high accuracy in temperature prediction, except two emissivity models. One particular emissivity model provides the best compensation for the aforementioned parametric influences.     

Measurements of brake disc surface temperature and emissivity by two-color pyrometry

A fiber optic two-color pyrometer was developed for brake disc surface temperature and emissivity measurements. The two-color pyrometer consists of a fluoride glass optical fiber, two HgCdTe detectors equipped with bandwidth filters and a data conditioning and acquisition device. The two-color pyrometer measures the brake disc temperature in the 200–800 °C range with a time resolution of 8 μs. The calibration formula for the signals obtained using a blackbody of known temperature is used to compute the true temperature. The uncertainty estimation for temperature and emissivity was obtained from the calibration results. Tests were carried out on known temperature target and a good correlation was found between results obtained with our two-color pyrometer and those obtained with a commercial two-color pyrometer. Hold braking and deceleration braking tests performed on a braking test bench enabled us to reach the brake disc surface temperature and emissivity during braking. Experimental results show a significant variation of emissivity during braking. Direct measurement of emissivity was carried out on the brake disc after braking and shows the emissivity dependence with the surface quality.     

A survey of hemispherical total emissivity of the refractory metals in practical use

The applicability of the hemispherical total emissivity measurement for metals those have a thin protective layer (passive scale) on its surface was investigated at high temperatures (above 1000 °C) using a modified hot-filament method. In this method, the Joule heat and the temperature of the specimen were measured by two sets of electrodes (two sets of thermocouples) spot-welded at the middle portion of the specimen, in order to reduce the influence of heat loss from the water cooled electrodes at both ends of the ribbon specimen.The measured hemispherical total emissivity for type 304 stainless steel and molybdenum above 1000 °C showed a few times higher value compared with the data obtained from polished metals given in the literatures. This result indicated that the emissivity of the metals with protective layer including oxide scale must be carefully considered not only in measuring temperature with the radiometric method but also the designing various devices where radiation phenomena were critical. The measured hemispherical total emissivity above 1000 °C decreased due to the vaporization of the protective layer on the specimen surface during the measurements. Thus, the upper limit of the measuring temperature in this method is ruled by the stability of these surface products in a vacuum at high temperatures. Therefore, such pulse heating methods those enable the more rapid heating within nano- or picoseconds are strongly recommended for the measurements of the emissivity of the metals those having the protective layer.     

汽轮机转子表面温度测量的模拟试验研究

汽轮机转子表面温度是对其进行高温蠕变损伤分析及转子热应力、热疲劳分析的关键数据之一,为解决精确测量汽轮机转子表面温度的难题,通过理论与试验相结合研究了热电偶和光纤等接触式测量、红外辐射式非接触测量等不同方法的特点,及转子旋转、振动对红外方式测温的影响.结果表明:采用传统热电偶等接触式方式测量转子表面温度存在响应时间长、信号引出困难等固有缺陷;红外测温响应速度快,能够在一定程度上较准确地测量汽轮机转子的表面温度并且能长期对转子表面温度进行在线监测,转子的旋转及振动对红外测温系统影响很小.     

Development of RTP for industrial solar cell processing

Rapid Thermal Processing (RTP), originally developed for processing microelectronic devices has been investigated in the recent decade for its potential in the production of Si solar cells. This paper will discuss the use of RTP for industrial Si solar cells with screen-printed contacts. Printed metal contacts require adapted emitters when good fill factors should be achieved. Multi-crystalline Si substrates require to adapt the temperature ramps of RTP to avoid minority carrier lifetime degradation from activated defect centres. Finally, industrial processing requires high throughput that cannot be achieved with conventional RTP equipment. This paper will present an advanced selective emitter process and a recently developed continuous RTP system that meet for the first time the requirements to make RTP compatible with industrial solar cell processing. The limits of industrial RTP solar cell processing will be discussed.     

A new experimental apparatus for measurement of spectral emissivity of opaque materials using a reflector as the dummy light source

A new experimental apparatus has been developed, which can be used to accurately measure the spectral emissivity of opaque materials using a reflector as the dummy light source. The experimental apparatus is mainly composed of the optical detection system, heating system, temperature-controlling system, angle-adjusting system and signal-controlling and data-computing system. The optical system works at 1.5 μm and the bandwidth is 20 nm. The sample can be heated up to about 1200 K by the sample heater. The temperature of sample surface is measured by the two highly accurate platinum–rhodium thermocouples and is controlled by means of a microcomputer-controlled proportional–integral–derivative device. The temperature-controlling error is within 2 K over the experimental range from 700 to 1200 K. A reflector is used as the dummy light source to realize the single-wavelength measurements of spectral emissivity. The present apparatus can be used to perform the measurements of spectral emissivity as a function of temperatures and emission angles. The spectral emissivity of several opaque materials has been measured by the apparatus. As an example, the spectral emissivity results of polished aluminum sheet over the temperature range from 788 to 1028 K have been reported here. The analytic dependence between the spectral emissivity and temperature has been determined. The temperature determined by the two thermocouples is employed to assess the accuracy of spectral emissivity measured here. The comparison between the temperatures measured by the thermocouples and those calculated by the emissivity obtained here demonstrates that the results measured by the apparatus achieve much high accuracy and that the proposed measurement technique is reliable.     

Emissivity characteristics of polished aluminum alloy surfaces and assessment of multispectral radiation thermometry (MRT) emissivity models

Emissivity characteristics were measured for several polished aluminum alloy samples over the spectral range of 2.05-4.72 μm and temperatures of 600-800 K. Overall, aluminum alloys buck the general trend of increasing emissivity with increasing temperature for metallic surfaces in the infrared range. Only AL 7150 follows the expected trend, while the emissivity of the other alloys decreases between 600 and 700 K and increases between 700 and 800 K, and the emissivity of commercially pure aluminum (AL 1100) decreases monotonically with increasing temperature. The experimental results are used to assess the accuracy of popular multispectral radiation thermometry (MRT) emissivity models for temperature measurement. It is shown that drastic changes in the shape of emissivity distribution preclude the use of a single function to accurately represent every band of the measured spectrum. Better predictions are achieved using the simplest form of MRT emissivity models and minimum number of wavelengths required by the model. Two relatively simple models are identified for best overall predictions for different alloys and temperatures. Despite the relative success of these two models, this study clearly demonstrates that improvements are required in both instrumentation and emissivity models to achieve acceptable accuracy in the implementation of radiation thermometry in the aluminum industry.     

碳氢火焰辐射特性快速判定方法研究

针对比色法计算碳氢火焰温度时要判定其是否为灰体，提出了一种基于图像处理的辐射特性判定方法。该方法用黑体炉标定CCD相机，拟合得到三基色值与单色辐射强度的函数关系，再根据普朗克定律和比色法测温原理计算蜡烛火焰的温度以及三基色值下的辐射率，计算三个辐射率的均方差并进行辐射特性判定。实验结果表明，三个快门速度下，计算温度的相对误差均小于0.500%，计算辐射率的相对误差均小于5.000%，说明标定实验的有效性；以蜡烛火焰为研究对象，其辐射率的均方差均大于0.024，可判定蜡烛火焰为非灰体。     

Solution of radiative transfer in a one‐dimensional anisotropic scattering media with different boundary conditions using the DRESOR method

The DRESOR method was applied to analyze the radiative transfer process in anisotropic scattering media with different boundary conditions in this paper. The method was validated by the integral formulation of the radiative transfer equation at first. Some variation regulations about the emissivity were obtained by extensive numerical simulations. When the optical thickness of the media became very large, the emissivity converged to a constant value. The converged emissivity in the forward scattering medium was the largest and that for the backward scattering medium was the smallest. Also the converged emissivity was associated with the scattering albedo of the media. The greater the scattering albedo was, the smaller the converged emissivity was. When the scattering albedo decreased to zero the converged emissivity reached the blackbody emissivity at the same temperature. Furthermore, different boundary conditions were considered. The results showed that if the temperature of the medium and the boundary was equal, the intensity at boundary was the same as that for the blackbody emission at the same temperature, whether the boundary reflectivity was 1.0 or not. When the temperature of the boundary was lower than that of the medium, the boundary emissivity can reach 1.0 only if ρ=1.0. Finally, the radiation flux was studied with different phase functions and different boundary conditions. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(3): 138–152, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20198     

Simple method for spectral evaluation of radiant energy emitted from far infrared heaters

It is necessary to know the spectral emissivity of a heater to ensure efficient heating. This paper proposes a useful method for spectral evaluation of radiation energy emitted from far infrared heaters. The measurement device consists of one radiometer and two band‐pass filters. In order to confirm the experimental results, numerical simulations were also carried out with the spectral emissivity of the heaters and the respective spectral sensitivities of the radiometers. The results obtained by these methods show that the far infrared heater radiates high amounts of energy in the far infrared region even at high temperature. It means far infrared heaters can transmit power effectively to materials which exhibit high emissivity in the far infrared region. This method can classify a type of far remote infrared heaters with the near infrared/far infrared energy ratio. By using this data, the authors also proposed a simple identification method of spectral emissivity of far infrared heaters. This inverse method can obtain a rough value of the spectral emissivity of commercial heaters while maintaining the heating conditions. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20396     

Infrared Thermography for True Temperature Measurement of the Main Board in Personal Computer

This paper presents a way to measure the true temperature of the electronic devices without disturbing their normal operating conditions, which involved with estimating target emissivity, background temperature correctly and choosing infrared transparent material and its transmission estimation. The temperature distributions of the main board in personal computer were measured by the method presented here with infrared thermography in several different running conditions. The measurement errors and their possible remedies are also discussed.     

Measurement of monochromatic emissivity of cement clinker with various Fe2O3 content at high temperature

An applicatiopn of the optical pyrometer is studied for measuring monochromatic emissivities of cement clinker with various Fe2O3 contnet.The idsa of using “brightness temperature” is introduced into the eimssivity measurement.In this method,there is no need for measuring an actual temperature of sample surfaces,only with determining both brightness temperatures of a sample and a blackbody can the required emissivity be evaluated according to Wien‘s radiation law.In practice,the cement clinker is regarded as a greybody,the monochromatic emissivity is approximately equal to the total emissivity,so a single-colour optical pyrometer is applied for this purpose,Test measurements are carried out on 10 kinds of cement clinkers,Experimental data are treated by the least square method.As a result ,the emissivity variation with temperature at a certain Fe2O3 content is quite well represented by εn=a+bT.Furthermore,this work first reported that the eimissivities of cement clinker change consierably with Fe2O3 contents.In multiple cement production this conclusion is very important.     

Investigation of steel emissivity behaviors: Examination of Multispectral Radiation Thermometry (MRT) emissivity models

Steel emissivity behaviors were investigated in this study. Experiments were conducted to measure emissivity. Six emissivity models were then applied to examine Multispectral Radiation Thermometry (MRT) on inferring surface temperature. The data show that emissivity decreases with increasing wavelength. For steel containing high chromium, emissivity is usually lower than others because of the chromium oxide protection layer. Two emissivity models provide the best overall compensation for different alloys, number of wavelengths, and temperatures. The results reveal that if the emissivity model can well represent the real emissivity behaviors, the more accurate inferred temperature can be achieved.     

具有温度分布的半透明平板的发射特性

从半透明体的内部介质辐射出发，采用正、逆向光线跟踪法对具有温度分布的半透明大平板的发射特性进行了研究，得到了表面的方向有效发射率的解析表达式，利用该式对有线性温度分布的半透明大平板的发射特性进行了计算，分析了温度分布、光学厚度以及介质折射率对方向有效发射率和半球有效发射率的影响。