线热源法测量冻土热参数的适用性分析

提出了应用线热源法测量冻土热参数存在的问题,冻土中未冻水含量随温度的变化是导致线热源法测量误差产生的根本原因。对二维无限大——点热源热传导方程进行简化得到一维中心对称——热流边界热传导方程。采用双针法对不同温度的环刀土样进行了测试并对冻土传热过程进行数值试算,反演得到不同温度的相变热容和未冻水含量。结果表明:当温度大于-0.7℃时,相变热容值远远大于冻土体积热容并且随温度急剧变化,线热源法测量的结果严重失真;当温度介于-0.7^-4℃时,线热源法测量结果仍有较大的误差;当温度低于-4℃时,相变热容值很小且比较稳定,线热源法测量的热参数能满足一定的精度要求。

线热源法测定金属材料导热系数的原理与测试系统

在经典线热源法的基础上提出了一种测量金属材料导热系数的新方法,论述了线热源法测量金属材料导热系数的原理,并用所设计的线热源法金属材料导热系数测试系统测量了部分金属材料的导热系数,取得了满意的结果。

线热源法测导热系数的智能化测试系统

介绍了一种采用线热源法测量材料导热系数的智能化系统。论述了系统测试原理和软硬件结构，该系统具有测量精度高、自动化程度高和操作方便等特点。测试结果表明，本文设计的硬件电路可靠性高、软件算法合理、具有一定的普遍性，可应用到其它智能化仪器仪表的设计中。

地温未恢复时热响应试验的线热源叠加法

针对热响应试验中2次测试间地温未恢复的情况,提出了一种基于线热源叠加法计算岩土平均导热系数的方法,根据时间函数和流体平均温度之间的线性关系计算得到岩土导热系数。建立了地埋管换热器的线热源模型,对3个钻孔分别依次进行了高、低2种输入功率的热响应测试,2次测试间地温未完全恢复至初始地温。分别采用常规线热源法和线热源叠加法对第2次测试结果进行分析,采用线热源叠加法2次测试结果偏差明显减小。

再生骨料混凝土导热系数试验研究

本实验研究再生骨料混凝土的导热系数,利用基于线热源法的热特性分析仪(KD2Pro)测试各类混凝土试件的导热系数,探讨不同再生骨料替代率(0%、30%、60%、100%)、不同水泥量(354.5kg/m3、433.3kg/m3和557.1kg/m3)对再生混凝土导热系数的影响。通过对本试验结果的分析可知:随着再生骨料替代率和水灰比的增大,混凝土的导热系数减小。

Influence of heat loss through probe electrical leads on thermal conductivity measurement with TPS method

The transient plane source(TPS)method is developed recently to measure the thermal conductivity of materials.In the measurement,the heating power is influenced by the heat which is transferred via the probe electrical leads.This fact further influences the measurement accuracy of thermal conductivity.To solve this problem,the influence of heat loss through the electrical leads on the heating power is studied theoretically.The mathematical formula of heat loss is deduced,and the corresponding correction model is presented.A series of measurement experiments on different materials have been conducted by using the hot disk thermal constant analyzer.The results show that the influence of the heat loss on the measurement is sensitive to different test materials and probes with different sizes.When the thermal conductivity of the material is greater than 0.2 W/(m·K),the influence of the heat loss is less than 0.16%,which can be ignored.As to the lower thermal conductivity materials,it is necessary to compensate the heat loss through the electrical leads,and the accuracy of thermal conductivity measurement can be effectively improved.