基于热电偶的精密环境温场测量的关键问题研究

Research on Some Key of Thermocouple Used to Detect the Temperature of Precision Measurement Environment

分析了热电偶温度测量不确定度、温场稳定度测量不确定度和温场均匀度测量不确定度,为精密环境的温场参数测量和控制提供理论保障.分析表明,热电偶测温不确定度与热电偶热电动势、参考端温度传感器的测量不确定度密切相关;温场均匀度测量不确定度与热电偶热电动势的测量不确定度密切相关;温场稳定度测量不确定度与热电偶热电动势和温差拟合函数的关系密切,在一次线性拟合的条件下取决于拟合函数的斜率.针对测量过程中存在的脉冲噪声和热电偶非线性的干扰,结合精密环境温度信号变化缓慢的特点,提出综合运用均值滤波和中值滤波处理热电偶热电动势测量数据去除测量中脉动噪声和热电偶非线性对测量结果的影响.

Uncertainty of temperature measurement by thermocouple is analyzed,at same time,the uncertainty of stability and uniformity of temperature measurement are analyzed as well.The analysis brings forward the theoretical support for the parameters measurement and control of temperature field under precise environment.It shows the uncertainty of temperature measurement is closely related to the measurement uncertainty of both thermocouple EMF and the sensor temperature at reference-side.The measurement uncertainty of the uniformity of temperature is closely related to the uncertainty of EMF of the thermocouple,while the uncertainty of the stability of temperature is closely related to both EMF and the fitting function of temperature difference,which depends on the slope when the fitting function is a linear fitting.Taking the character that temperature change slowly in precise environment into account,the average filter combined with the median filter are used to remove or weaken the pulse noise and nonliner interference of the thermocouple during the EMF measurement.