高温气冷堆用碳毡材料导热系数测量及反问题计算

碳纤维材料已成为核能、航天等领域不可或缺的重要功能材料，在高温气冷堆及其相关实验中需要使用大量碳纤维保温材料。但由于目前测试方法的限制，相关材料物性参数测量数据严重不足，尤其是缺乏高温1000℃以上的热物性参数，致其使用受到限制。为此，清华大学核能与新能源技术研究院研制了模拟高温气冷堆温度、环境氛围的材料测试装置，可提供1600℃以下的材料性能测试。根据该装置一次典型实验过程的测量数据，详细介绍了采用非线性导热反问题方法确定材料温度相关导热系数的完整过程和具体算法。提出了一种依据稳态、非稳态热传导原理求解反问题的简明算法，该方法既可单独使用，也可为其他反问题算法提供良好的迭代初值。实验确定了高温气冷堆用碳毡保温材料在1600℃以下的导热系数，将为高温气冷堆相关实验和其他特高温条件下的应用提供重要参考。

Thermal Conductivity Measurement of Carbon Felt Used in High Temperature Gas-cooled Reactor and Inverse Problem Calculation

Carbon fiber material has become an indispensable function material in nuclear and aerospace fields. Researches and designs of the high temperature gas-cooled reactor (HTGR) require a large amount of this kind of heat insulation material. Due to limitations of current measuring techniques, thermo-physical property data of carbon fiber material are gravely insufficient, especially for the data of high temperatures above 1000 ℃, which limits the application of this material. For this purpose, a material performance test apparatus simulating the high temperature and ambient atmosphere in the HTGR core was built by Institute of Nuclear and New Energy Technology (INET) of Tsinghua University, which can conduct material performance tests at temperatures up to 1600℃. With the measuring data from a typical experimental process in this apparatus, a complete procedure and detailed algorithm of estimating the temperature-dependent thermal conductivity of carbon insulating felt by means of inverse nonlinear heat conduction problem method were introduced. A concise algorithm of solving inverse problem based on the law of steady and transient heat conduction was proposed, which could either work alone or provide ideal initial values for other inverse problem methods. Finally, values of thermal conductivity of carbon felt used in the HTGR below 1600 ℃ were determined in the experiment, which could be used as reference in HGTR related experiments and other ultra-high temperature applications.