真空低温防护热板法导热系数测量仪的研制

Design and fabrication of a double-sided Guarded-Hot-Plate apparatus on cryogenic thermal conductivity measuring in a controlled gas atmosphere

建立了一套可应用于真空条件下的双试件防护热板法导热系数测量装置,装置中设计了真空调节装置和低放气率的多层隔热结构,可实现真空度为10^(-4)Pa量级~常压下的环境压力调节;通过液氮(或恒温浴)降温和电加热共同控温,可实现-160—280℃的温度控制和导热系数测试。而后通过国家标准样品检验了装置的测量准确性,表明本装置对国家标准样品的测试偏差小于1%;并测量了不同真空度和不同温度条件下的样品导热系数;最后给出了装置的不确定度分析,计算表明本装置在全量程的测量不确定度优于±5%。

A double-sided Guarded-Hot-Plate(GHP)device was established,which could be used for measuring steady-state thermal conductivities of insulation material.The device was designed with a vacuum regulator and multi-layer thermal insulation structure,which could realize the test in a controlled atmosphere from 10^(-4)Pa to 1.013×10^(5)Pa.The test temperature ranged from-160℃to 280℃by combining electric heating and cooling with liquid nitrogen(or thermo bath).The validity of the instrument was verified by standard samples,indicating an experimentally observed accuracy of about±1%.Then thermal conductivities of samples at different gas atmosphere and different temperatures were measured.Finally,the uncertainties for the measurement were also discussed,showing that theoverall calculated uncertainty is better than±5%.