Investigation On Standard Apparatus For Measuring Thermal Conductivity Of Solid Materials

As an important thermophysical property of materials, thermal conductivity plays a key role in scientific research and engineering applications. The guarded hot-plate(GHP) apparatus was established for measuring thermal conductivity of solid materials in National Institute of Metrology (NIM) of China, which is ready to set up the standard apparatus for measuring thermal conductivity of materials.The dissertation aimed at the systemic experiment research on the measurement apparatus of thermal conductivity of solid material for the purpose of verifying the reliability of this device. The thermal conductivity of PTB reference material (polymethyl methacrylate) was measured in the temperature range from 30℃to 70℃. 17 European laboratories had measured the thermal conductivity of PTB reference material by GHP, other steady-state and transient apparatus, but the maximum relative deviation of their measuring results is 24%. The comparison between NIM and 17 European laboratories showed that the measurement results in NIM located in the middle of European measurement results and were close to the PTB measurement results. The thermal conductivities of granite and optical glass were measured in the temperature range from 60℃to 530℃. And the heat loss errors were analysed, the numerical simulations of the GHP device were presented in this dissertation. By curve fitting of the results of the thermal conductivity of PTB reference material, the fitting standard deviation is 1.1×10-3 W/(m·K), the combined relative standard uncertainty(1σ)is 1.0×10-2, and the expanded uncertainty(k=2)is 2.0×10-2. The comparison showed that the measurement results of the device in NIM were comparable with those developed countries, and the measurement results of the device were well credible.