基于Hot Disk方法测量热导率的影响因素

Influence Factors Analysis of Thermal Conductivity Measurement with Hot Disk Technique

基于hot disk方法测量材料的热导率时,探头热容及时间延迟的存在会直接影响热导率测量的准确度.为了有效地评估这种影响的程度,本文基于探头表面平均温升理想模型提出了一种可实现热容补偿及时间补偿的修正模型,并利用hot disk热物性分析仪的数据采集系统分别搭载两个不同半径的探头对Pyroceram 9606标准材料在常温常压条件下的热导率进行了测量.实验结果表明,对于测试时间比较短的情况,对理想模型进行探头热容补偿及时间补偿能够较大幅度地提高热导率的测量准确度,并且与hot disk热物性分析仪的测量结果非常接近,探头四线电阻散热的影响是造成差距的主要原因.

The effects of the heat capacity of a hot disk probe and the time delay of the hot disk thermal constants analyser on thermal conductivity measurement were investigated theoretically and experimentally in this paper. Based on the ideal model of the transient plane source technique,a model for correcting the effects of heat capacity and time delay was presented. The thermal conductivity of Pyroceram 9606 standardized material at normal temperature and pressure was measured and analyzed by using the developed model and the hot disk analyser data acquisition system with two different radius probes. The results clearly demonstrate that the thermal conductivity measurement accuracy is improved, and the results obtained agree with the hot disk measurement results well. The estimated relative error caused by heat capacity and time delay is sensitive to different choices of test parameters ,and is mainly influenced by the length of measuring time. It is possible to conclude that the elimination of heat from the four wire resistance is the main reason for accuracy disparity with the hot disk analyser, and it is essential to implement heat capacity and time delay bias for short time measurement situation.