An Accuracy Analysis of the Steady-State Thermal Conductivity Measurement Method With Single Constant Temperature Region

The newly developed method for steady-state thermal conductivity measurement with single constant temperature region is experimentally proven accurate within 3% compared with the guarded hot plate method. The method is suitable for in-situ non-destructive evaluation of insulation materials. However, there are factors that affect the accuracy of measurement yet to be closely studied. In this paper, we present a theoretical analysis of the accuracy of the method by varying the relative size of the heating plate, the thickness of the test specimen, the location of the temperature sensors at the lower temperature side, and different thermal convection coefficients for the free convection boundary condition. In the study, the temperature distribution in a homogeneous material is solved numerically. The thermal conductivity is evaluated from the temperature distribution and the heat flux measured according to the method. By comparing the results with that given in the numerical model, the accuracy can be expressed as functions of the three variables in the analysis. The results are consistent with that of the experiment. They are considered beneficial in providing information to the optimal design and the measurement correction of a commercialized apparatus using the method.