多通道数据采集系统测试导热系数的研究

Study on Thermal Conductivity Using Multimeter/Data Acquisition System

基于线热源瞬态模型,根据铜电阻与温度之间相关关系的特性,对微热探针内部的细小铜漆包线加以恒定的加热电压,通过多通道数据采集系统对惠斯登电桥平衡电压进行测试,从而得到了微热探针内部、探针、待测样品的温度变化,进而得出被测样品的导热系数。该测试方法具有线性相关度高>0.999 9,标定偏差小的特点,最大偏差仅为2.5%,采用该测试方法测试液体以及松散材料导热系数,测试的最大误差<3.5%。该测试方法具有测量时间短,通常<20 s;试样温升<2℃,对被测样品的影响较小的特点。

Based on the linear thermal resource model, the thermal conductivity of experimental sample was determined. The balance voltage of Wheatstone bridge was measured when a constant copper temperature varied with resistance variance. The thermal conductivities were determined by the variance of the tiny probe inner temperature, the tiny temperature and the experimental sample temperature. The following conclusion could be drawn, the linear correlation of this method is higher than 0.9999 and the measurement err is less than 2.5%. Using this experimental set to determine thermal conductivities of some samples, the max err of measurement is less than 3.5%. The experiment sample were got less affect for test,and the test time were less than 20 s and the temperature risen is less than 2℃.