加热式热电偶液位测量传感器的研究

压力容器内的水位是反应堆运行中的重要参数,针对传统的传感器难以实现液位测量,提出了一种加热式热电偶传感器,它是基于发热体在气(汽)体和液体中放热系数的显著差异,研制的一种变液位测量为温差测量的加热式铠装热电偶。试验表明,本液位测量传感器原理正确,结构可行,性能可靠,能够准确的判断出液气(汽)界面的位置,推广该传感器在压力容器内应用很有必要。     

加热式差分热电阻水位传感器的研制与试验

加热式差分热电阻水位传感器由加热热电阻和不加热热电阻构成,可连续测量水位。理论分析表明水位与差分热电阻ΔRt呈线性关系。水位传感器没有运动部件,热式原理直接敏感水位,测量精度高,工作安全可靠,寿命长。试验结果表明,传感器的测量精度可达±1.5%~±2.0%,该水位传感器尤其适用于核场或其他高可靠应用的场合。     

巴基斯坦核电机组C3/C4堆芯测温用铠装热电偶的研制

介绍了巴基斯坦核电机组C3/C4堆芯测温铠装热电偶的研制。堆芯测温铠装热电偶用于测量反应堆堆芯冷却剂出口温度,用来计算平均温度、最高温度和区域温度最高差值等信息,并参与堆芯液位密度补偿和堆芯过冷度裕度的计算。堆芯测温铠装热电偶已通过核级性能和环境鉴定试验,证明其满足核安全(1E)级的要求,并成功地应用于中国援巴核电项目C3/C4核电机组。堆芯测温铠装热电偶的研制成功填补了国内空白。     

自加热式差分热电阻水位传感器的研究

自加热式差分热电阻水位传感器由一支自加热的热电阻和另一支不加热的热电阻组成,可连续测量水位。理论分析表明,水位与差分热电阻ΔRt之间的关系为线性关系,实际应用时也可以用二次方关系来描述。水位传感器没有运动部件,热式原理直接敏感水位,测量精度高,工作安全可靠且寿命长。试验结果表明,传感器的测量精度可达±1.5%,该类型水位传感器尤其适用于核场或其他高可靠应用的场合。     

工业用铠装热电偶技术发展研究

铠装热电偶作为石油化工、光伏军工等重大装备制造领域中的重要测温传感器,其用量大、用途广、寿命长。综述了工业用铠装热电偶技术研究现状,以贵、廉金属铠装热电偶为例,分析了工艺方法对其使用寿命和测温性能的影响,探讨了铠装热电偶中存在的问题,并基于当前发展趋势,结合新型单管多点式铠装热电偶技术阐述了今后重点研究方向,以期为铠装热电偶的高性能/轻量化制造提供理论依据。     

分段加热的热电偶水位传感器和格雷码制信号处理技术

为适应压水堆核电厂的压力容器、乏燃料池和火力发电厂的高温高压汽包,或其他高可靠性要求的压力容器、储水池/罐内水位监测的需求,该文运用热扩散原理,将分段加热的热电偶作为水位检测的敏感元件,借助于水/气(汽)传热性能的明显差异,检测水位所在的位置.传感器采用格雷码(Gray code)技术,将若干个传感器的敏感元件分组,并将组内敏感元件的热电偶差分连接,将组内加热丝串联连接,研制成功了分段加热的热电偶水位传感器.该传感器信噪比高,信号引出线少,抗干扰能力强,可靠性高和寿命长,适用于高温高压环境,可广泛地应用于核电等多个领域.     

网络仪表与计算机构成的水电站水位监控系统

水位和水头的测量是水电站水力监测的重要内容。为保证水电站的安全运行并实现经济运行，必须对水电站及机组的有关水利参数进行测量和监视。文中介绍了一种远距离水位监控系统，它由新型的潜入式液位传感器、网络仪表和计算机组成。采用新型的潜入式液位传感器作为水位的测量元件，具有体积小、精度高、价格低、结构简单和长期稳定性好等特点，它与新一代的网络仪表和计算机组成的水位监控系统，能准确地远距离测量多点水位。     

磁致伸缩效应在高精度液位测量中的应用研究

简述了磁致伸缩效应及其在液位测量中的应用。针对储油罐液位测量的特点：大量程至20多m，同时要测量油位、水位、温度及储油量等参数，并且液位测量的允许误差小于几mm，介绍了能满足要求的磁致伸缩液位传感器，并从该传感器的测量原理、信号转换和检测、以及温度对测量的影响等方面进行了详细的分析，对该传感器能够实现高精度液位测量方法进行了研究，供有关研究及应用的技术人员参考。     

计算法计量不满管污水流量的研究

本文介绍的不满管污水流量测量是根据管道中液位的测量值直接计算出污水流量。论述了测量原理和流量计算公式，介绍了一种适用于污水液位测量用的电量检测式抗沾污电容传感器。最后，简述了污水流量计的构成及其在实验室的实验结果和现场运行情况。     

小直径铠装热电偶保护管的焊接新技术

铠装热电偶、铠装热电阻是应用十分广泛的测温传感器,但小直径(Φ2～Φ3mm)铠装热电偶和热电阻至今在生产上仍比较困难,其原因是小直径保护管的焊接问题没有过关。 有些生产厂曾从国外引进全位置焊机来焊接这类小直径薄壁管的对接接头,效果不理想。现在有个别厂采用激光焊,但生产成本很高。为解决Φ3mm铠装热电偶和Φ3mm铠装热电阻保护管的对接焊问题,我     

浅析热电偶在检定时应注意的问题

热电偶是目前各种测温场所普遍使用的温度传感器,为使热电偶在测温过程中能够准确测量温度,要对热电偶进行检定。在检定过程中有很多因素影响检定结果的准确性,如热电偶本身的长度、外观、弯曲度、绝缘电阻以及检定操作上的插入深度、升温速率、补偿导线的引用等,对以上因素进行了整理和分析,使热电偶在检定中避免了检定结果的不准确性。     

单片机的炭素焙烧窑多点温度监测系统

介绍以MCS-51单片机为核心,利用K型热电偶作温度传感器,用MAX6675热电偶温度数字传感器进行温度采集,对炭素焙烧窑中64点温度测量的系统。此系统通过485总线通信,将数据传输给工控机(IPC)。     

切削区热电偶测温刀具的制备及其性能测试

由于切削测温温感器无法直接接触切削区,故在铂铑丝表面喷涂耐热绝缘层制作耐热热电偶,把表面覆盖耐热绝缘层的热电偶埋入硬质合金粉末,压制、烧结成热电偶测温刀片。通过恒温箱测温实验判定热电偶的测温性能,用性能正常的热电偶测温刀具进行切削测温实验,测温实验结果及切削刀具镜测结果表明,热电偶测温刀具能直接、可靠地进行切削区温度的测量,但是用此工艺制作的刀具切削寿命较短;实验结果还表明直径越大的铂铑丝制作的热电偶测温刀具的成品率越高,但是铂铑丝直径越大,刀具寿命越短;实验进一步揭示切削区内各点的温差较大,但是一次切削切削区温度场处于稳态时切削测温点的温度是稳定的,温度场处于稳态时切削温度的变化能迅速反映刀具的磨损状态的变化。     

基于NANMAC热电偶的时间常数测试技术研究

本文介绍了热电偶时间常数的测试理论,提出了运用瞬态表面温度传感器动态校准系统实现对NANMAC热电偶时间常数的测试方法。该系统对红外探测器和热电偶进行了静态校准和动态校准,得到两者的温度一时间曲线。由于红外探测器的频率响应优于被校准热电偶的频率响应,因此,以红外探测器测得的值作为真值,用热电偶测得的值与红外探测器测得的值相比得到-条归-化的曲线,并由归-化曲线求得热电偶的时间常数。利用该方法对NANMAC热电偶进行时间常数的测试实验,得到了该热电偶的时间常数。实验结果表明：该时间常数测试方法是可行的,可以实现对微秒、毫秒量级热电偶的动态校准,这对于NANMAC热电偶温度传感器的研究和应用具有一定的参考价值。     

Small diameter fiber Bragg gratings and applications

Small diameter optical fibers are preferred in sensing systems as they have less influence on mechanical performance of smart composite. The static and dynamic monitoring capabilities of the small-diameter fiber Bragg gratings (FBG) are experimentally studied in this paper. Firstly, a small-diameter FBG is used as a strain sensor. Secondly, a temperature sensor is fabricated using a specific FBG. Thirdly, a simple sensing system is proposed in order to discriminate temperature at sensing point. Finally, utilization of these small diameter FBGs for vibration monitoring is discussed. The experiments revealed that the central wavelengths of the small-diameter fiber Bragg gratings shift linearly with strain or temperature. The FBG is more sensitive than a thermocouple inside the thermostat. Acquisition and analysis of the dynamic signal indicates that the designed FBG can be used for dynamic signal monitoring.     

In situ response time testing of thermocouples

Response time information is important in most applications involving transient temperature measurements with thermocouples. Traditionally, the response time of a thermocouple is measured in a laboratory at a reference condition. The laboratory response time information is useful for comparative evaluation of thermocouples but may have little relationship with the response time for the sensor in service. This is because of the effects of installation and process operating conditions on response time.

A method has been developed and validated for response time testing of thermocouples as installed in an operating process. The details are reviewed in this paper. The method is referred to as the Loop Current Step Response Test. The test involves an internal heating of the thermocouple by applying an electrical current to the thermocouple extension wires. The current is then terminated and the thermocouple output is monitored as it returns to ambient temperature. This transient output is analyzed to identify the time constant of the thermocouple. A mathematical transformation is used to convert the internal transient data to the response of the thermocouple for an external temperature perturbation.     

Ultrasonic thermometry for friction stir spot welding

This investigation presents the feasibility of ultrasonic temperature measurement of friction stir spot welding (FSSW). FSSW is an automated solid state joining process. Thermal profiles of the weld zone are crucial for implementing informed process changes to improve weld quality. Ultrasonics present a novel and non-invasive method of monitoring changes in temperature.Ultrasonic time of flight (TOF) measurement method is used to calculate the temperature of Al 6061 as it is heated. Comparisons of the ultrasonic temperature calculations with thermocouple readings confirm the accuracy of the ultrasonic system. The ultrasonic signal is then recorded during spot welding and processed. The results show that ultrasonic technology is a feasible method of monitoring the heating and cooling profiles of the weld zone during welding. The paper also discusses challenges presented by the system as well as recommendations for its future implementation in the friction stir welding manufacturing industry.     

EXPERIMENTAL ANALYSIS OF TEMPERATURE IN GRINDING AT THE GLOBAL AND LOCAL SCALES

The purpose of the article is the experimental estimation of the global and local heat fluxes and the corresponding energy partition to the workpiece for regular grinding of 100Cr6 steel with aluminium oxide wheel. By using a grindable thermocouple, the temperature and the real contact length allow determination of the global heat flux and the partition ratio at the wheel scale. The high frequency analysis of the signal has shown maximum flash temperatures of about 1000°C corresponding to the local temperature under the chip-grain unit with very high heating speed of about 100°C/µs. The comparison between theoretical temperature decay and experimental cooling has demonstrated that the time response of the sensor is fast enough for the estimation of the local temperature and power due to the sliding of grain and to the plastic strain of ground materials.