高温气冷堆球床等效导热系数实验装置模拟计算

Modeling of the heat transfer characteristics of the effective thermal conductivity test facility for high temperature gas-cooled reactors

球床等效导热系数是反映高温气冷堆球床型堆芯宏观热量导出能力的特征参数。为提高中国高温气冷堆设计计算及安全分析能力,清华大学核研院研制了高温气冷堆堆芯全尺寸球床等效导热系数测量实验装置,可进行静态石墨球床在真空及氦气条件下的等效导热系数测量实验。通过对该实验装置的结构进行适当简化,建立了模拟其高温、真空条件下辐射、导热传热特性的二维模型。利用该模型计算了实验装置内的稳态、动态传热特性,可以对球床区径向温度分布、上下保温层材质不同带来的影响、中心发热体超温情况、升降温过程等作出先期理论评估,给出进一步实验的指导性建议。

The effective thermal conductivity is a characteristic parameter which represents the macroscopic heat transfer ability of the pebble bed type core of the high temperature gas-cooled reactor.A full-scale effective thermal conductivity measurement facility was developed by the Institute of Nuclear and New Energy Technology of Tsinghua University to improve calculations and safety analyses of the Chinese high temperature gas-cooled reactor design using experiments in a static graphite pebble bed in a vacuum or helium environment. A simplified two-dimensional model was used to simulate the thermal conduction and radiation characteristics of the facility under vacuum and at high temperatures.The steady and transient heat transfer characteristics were calculated to assess the radial temperature distribution in the pebble bed zone,the influences of different materials in the top and bottom insulating layers,overheating of the central heaters and temperature increases and decreases to guide operation of the experimental facility.