稳态法测量导热系数的误操作影响分析

Analysis on the Misoperation of Steady-state Method for Thermal Conductivity Measurement

在稳态法测量导热系数的实验中模拟了常见的误操作,包括样品与加热盘和散热盘未对齐、样品与两盘接触过紧、未达到稳态时测试、未进行强迫对流换热、热电偶与两盘接触不充分等,分析了误操作对导热系数数值的影响。通过模拟误操作实验,发现除了样品与两盘接触过紧的影响较小外,其他误操作引起的偏差均较大。样品与两盘未对齐10%,低于稳态温度3℃时测试、加热过程未开风扇、热电偶与两盘接触不充分等常见误操作引起的导热系数百分差分别为6.7%、35.8%、48.6%、38.0%。误操作导致两盘温差和散热盘稳态点处曲率的改变,进而影响导热系数。

The misoperation of stead-state method for thermal conductivity measurement was simulated. The effect of misoperation on thermal conductivity was investigated. Experimental results showed that all the misoperation caused large deviation, which tightly contacted with the sample. A misalignment between the sample and the plate caused 6.7% difference in thermal conductivity. The test with lower steady temperature or without fan caused 35.8% and 48.6% difference in thermal conductivity, respectively. An insufficient contacting with thermocouple caused 38.0% difference in thermal conductivity. The changes in the temperature of radiating plate and the curvature of steady-state point, which resulted from the misoperation, were identified as the origin for the changed thermal conductivity. The analysis of misoperation was useful for optimizing the experimental method and serving the college experimental teaching.