TEMPERATURE MEASUREMENT ERROR BY RADIAL INSERTION OF THERMOCOUPLE IN THERMAL CONDUCTIVITY MEASURING DEVICE

To measure the temperature of the inner part of a material, an axially inserted thermocouple is often used. But, when the measurement by an axially inserted thermocouple is difficult, we must insert the thermocouple radially. In the case of radial insertion, a measuring error usually exists. To know the true temperature by the method of radial insertion of a thermocouple, we must conduct numerical calculations.

In this report, numerical calculations have been conducted for the temperature measuring error by radial insertion of thermocouple in a gas thermal conductivity measuring device.^2-5     

聚丙烯保压注射成型冷却过程温度场的研究

采用数值模拟结合实验验证的方法,对聚丙稀（PP）注射成型（保压和不保压）冷却过程实验和数值模拟进行分析。用数据采集器对不同共混物注射冷却过程中的温度变化进行数据采集,并将采集所得温度的实验值与根据改进焓法用Matlab软件对聚丙烯冷却过程中温度分布进行数值模拟计算所得的值进行了比较分析,结果表明聚丙烯在液体冷却段温度分布的实验值与理论值几乎完全吻合,在结晶段和固体冷却段实验值略有不同。     

Numerical analysis of the temperature profile in the melt conveying section of a single screw extruder: Comparison with experimental data

The prediction and measurement off the developing radial temperature profile in a single-screw extruder is essential since excessive extrudate temperature and poor temperature uniformity at the die affect the quality of coextrusion and film/sheet extrusion processes. A finite-difference scheme is used to predict the development of the radial temperature profile in the metering section of a single-screw extruder for power-law fluids. A finite-element analysis of the flow around the screw-tip transposes this temperature profile onto an on-line temperature measuring device consisting of 10 thermocouples for a comparison of numerical results with experimental data on polycarbonates.     

Precise Temperature Measurement in Debye-Scherrer Specimens at Elevated Temperatures

A general method was developed for precisely measuring the temperature of a Debye-Scherrer specimen at elevated temperatures. The method consists of measuring the lattice parameters versus temperature of a primary standard which forms one leg of a calibrated thermocouple, with both specimen and thermocouple junction in the X-ray beam, and then mixing the internal standard in powdered form with the powdered Debye-Scherrer specimen so that the lattice parameters of the internal standard directly indicate temperature. Gold was used as the primary standard, platinum as the other thermocouple leg, and magnesium oxide as the Debye-Scherrer specimen. The platinum/gold thermocouple was calibrated from 0° to 1000°C by the National Bureau of Standards. The lattice parameters (in angstroms; corrected for refraction in Ni Kα radiation) versus temperature are expressed by the equations: Gold (25° to 1000°C)

Magnesium oxide (25° to 932°C)

The temperature precision attained with the gold standard was estimated to be 1.5°C.     

化工温度控制系统的安装和维护

阐述了热电偶配线不当对温度测量环节所造成的影响;热电偶补偿电缆绝缘层带电致使测量失真;对于搅拌设备,分析了温度检测保护套管的断裂原因,并提出了合理的安装方法。     

The Influence of the Variation of Combustion Chamber Volume under pressure load on the determinational of thermodynamic characteristics of solid propellants in pressure bombs

Detailed combustion studies in high-pressure bombs show that the measured maximum gas pressures are always lower than theoretically calculated values and that these differences increase more than proportionally with rising loading densities. By means of experiments and calculations we show that a considerable part of the pressure difference is brought about by the expansion of the combustion chamber during pressure load. The expansion of the combustion chamber is responsible for pressure measurements that are about 5% too low at currently used pressures of 500 MPa. Furthermore the covolume yields an error of about 12% if the constants of the Abel state equation are determined using the standardized method for loading densities of 0.20 g/cm³ and 0.22 g/cm³. The error of the force constant remains under 1%. As the values determined from pressure bomb measurements are to be introduced into further calculations, they must be corrected according to the combustion chamber expansion, or new measuring methods will be necessary.     

Prediction of error estimates for thermocouple attached to a surface using differential inequalities

An analysis is proposed to estimate the measurement error when determining the temperature of a surface with an attached thermocouple. The sensing element is assumed to be a point in a domain that is a circular segment of an infinitely long cylinder. The temperature distribution in the segment which models the medium used to attach the thermocouple is found approximately by using an embedding technique and the method of weighted residuals. The construction of bounds on the unknown exact solution is outlined and results are presented for Biot numbers up to 10.     

热像仪替代热电偶测量气化炉壁温的探讨

描述常规铠缆式热电偶测量水煤浆气化炉壁温时存在的问题和原因,探讨利用红外热像仪代替热电偶测量炉壁温度的可行性,对热像仪测温方式的优点和其具体安装测温过程中可能存在的不利因素进行分析,提出相应的解决方法。     

Predicting conversion using temperature as the measured variable in the RIM process. Part I: Simulation and measurement structure

In general the monitoring and control of many industrial processes is so complicated by problems associated with the on-line measurement of the desired objectives that they must be inferred from available measurements. This leads to a state estimation problem in which the selection and adaptation of the structure of the measurements plays an important role. In particular, in the reaction injection molding (RIM) process, an accurate on-line estimate of the conversion field is highly desirable. Since conversions cannot be determined readily by direct measurements, and a thermocouple can provide reliable dynamic temperature data, we can predict the conversion field from the solution of a state estimation problem using temperature as the measured variable. In this article, we describe an algorithm for designing the optimal arrangement of measuring sensors and analyze the RIM process dynamics which influence the structure depending on the operating conditions. The search for the optimal measurement structure for the purpose of state estimation makes up the bulk of the results. No particular estimation-control strategy is investigated in this paper. Work is underway to develop the on-line corrective system, which will use the temperature measurements to correct model predictions. The results of that work will appear in part II of this series.     

Blackbody-based calibration for temperature calculations in the visible and near-IR spectral ranges using a spectrometer

This paper presents, the results of a method used to create a blackbody-based referenced calibration curve for a spectrometer in the visible and near-IR range. This method would allow the use of optical temperature measurements in high temperature furnaces when distance, environment, and emissivity effects are not accurately known. A probe containing a lens connected to a fiber-optic cable is inserted into a furnace and aimed toward a hot wall source. Spectral intensity data is fed back to a spectrometer and then to a monitoring computer. Initial data is taken along with another method to measure the source temperature, usually a thermocouple or IR-gun. The spectral data is compared to the blackbody intensities generated from the source temperature to create the calibration curve. This calibration curve is then used to correct intensities for temperature calculations using a spectrometer where furnace conditions are similar to those of the calibration data. This calibration method provides much more accurate temperature measurement results than the common practice of using a halogen reference. The results in the visible range compare favorably with those taken in the near-IR range under the same conditions.     

基于USB-4716的工业热电偶自动检定系统设计

针对工业中常用的温度采集、处理系统的分析,利用USB-4716数据采集模块对热电偶检定过程中加热炉温度进行采集和处理,通过对热电偶锌、铜和铝3个检定点热电动势的采集和误差分析,判定被检热电偶是否合格,进而给出检定报表。整个过程结合计算机控制技术,实现了热电偶自动检定、数据存储、报表打印以及历史记录查询等功能。     

Design of dedicated instrumentation for temperature distribution measurements in solid oxide fuel cells

A thermocouple was designed for temperature distribution measurements in solid oxide fuel cells. A theoretical model, based on mixed convective–radiative heat transfer was used to predict the thermocouple response. The proposed flat type thermocouple was shown to be a high sensitive, low error temperature sensor, capable of satisfying the requirements for solid oxide fuel cell thermal behaviour research. Thereafter, a purpose-built, thin, flat-type thermocouple has been used for temperature distribution measurements at the cathode side of a planar solid oxide fuel cell. High temperature conditions of 1223K have been tested. Beside temperature mapping, local hot spots have been easily located.     

Heterogeneous Gas-Phase Catalysis Under Microwave Irradiation—a New Multi-Mode Microwave Applicator

The microwave-assisted gas-phase oxidation of propane over perovskite-type catalysts was studied with an intention of investigating the feasibility of the new multi-mode microwave applicator. Temperature measurement was made with IR-pyrometer and thermocouple by insertion technique. Radial and axial temperature gradients are unavoidable and partially responsible for observed rate enhancement under microwave irradiation.     

Temperature distribution within the moving bed of rotary kilns: Measurement and analysis

Inadequacies in the temperature measurement within the moving bed have hindered a thorough understanding of the processes occurring within rotary kilns. A new measuring system, consisting of thermocouple arrays, a radio-transmitter, a radio-receiver and a computer monitor is introduced in this paper. With it, the 3D temperatures within the moving bed, as well as the temperatures of the freeboard gas and the kiln wall, can be measured and saved automatically. Experiments with sand on a co-current pilot kiln demonstrated that, in the passive layer of the moving bed, the temperatures were approximately constant in the circumferential direction. In the radial direction, however, large temperature difference was observed within the bed near the feed end of the kiln, and the difference became smaller as the bed went progressed through the kiln. This temperature measuring system can be used to obtain data over a wide range of operating conditions for use in engineering design. The obtained results may give new thoughts in theoretical modeling of heat transfer within the moving bed of rotary kilns.     

用热电偶测量流体介质温度的误差分析

在工业应用中,普遍采用热电偶传感器来进行温度测量。讨论了热电偶在测量温度过程中,由于热传导和热辐射的作用,使其测量误差存在的影响因素,并就提高测量精度介绍了一些措施和几种有针对性的改进热电偶装置。     

Predicting conversion using temperature as the measured variable in the reaction injection molding process. Part II: Implementation of the on-line corrective algorithm

In the reaction injection molding process, we need to know the evolution of the conversion field with a high level of confidence in order to minimize the mold opening time. Thus, the mold can be opened as soon as there is conversion everywhere in the mold above the value needed for the part to become dimensionally stable. Since conversion can not be determined readily by experimental measurements, and since a thermocouple can provide reliable dynamic temperature data, it is best to predict the conversion field from the solution of a state estimation problem using temperature as the measured variable. Here, we develop an on-line corrective system which uses temperature to correct the model predictions. It is shown that by measuring at the center and at the mold wall, both of which are physically possible, the performance of the corrective algorithm is fairly good.     

Experimental measurement of temperature profiles of molten flowing polymers in a heat exchanger

Molten polymer was pumped through an isothermal-wall heat exchanger and the temperature at four radial positions was measured with a hypodermic thermocouple. Temperature profiles were obtained for heating, cooling, and isothermal flow of polyethylene, polystyrene and polypropylene at Graetz numbers from 1.7 to 9.2. The results show large viscous heating effects, particularly for cooling.     

基于光纤Bragg光栅的管道压力在线监测

介绍了基于光纤Bragg光栅的管道压力测量方法.液压实验结果表明,沿环向粘贴在管道外壁的光纤Bragg光栅的实验灵敏度为188.1pm/MPa,非线性误差为4.89%Fs;沿轴向粘贴在管道外壁的光纤Bmgg光栅的实验灵敏度为26.7 pm/MPa,非线性误差为6.25%FS.传感器适用于设计压力低于10MPa的中低压管...     

A12O3-W金属陶瓷用于金属熔体温度测量可行性研究

采用高纯氧化铝和不同含量金属钨制成的Al2O3-W金属陶瓷作为热电偶两极,直接浸入金属熔体中进行连续测温实验.结果表明:该金属陶瓷热电偶输出的热电动势较大,在金属熔化温度范围内其热电动势与温度的线性关系明显.金属陶瓷具有良好的耐热态金属及熔渣侵蚀性能,可实现对高温熔体温度的连续测量.     

Swirling flow of natural gas in supersonic separators

The supersonic swirling separator is a new apparatus for offshore and subsea natural gas separation, due to its lightweight and the viability of unmanned operation. A new supersonic swirling separator was designed for the numerical calculation, in which a central body was inserted based on the principle of conservation of angular momentum. Axial and radial distribution of the main parameters of natural gas flow was investigated with RNG K-? turbulence model. The effects of the shock waves on the natural gas flow fields were analyzed in the supersonic separator. The results show that water and heavy hydrocarbons can be separated from natural gas due to the low temperature and high centrifugal field. The non-uniformity of radial distribution of the gas dynamic parameters significantly affects the gas/liquid separation. The position of the shock wave determines the distribution of the temperature, which has a great influence on the re-evaporation of liquid droplets.