Determination of thermal conductivity of highly conducting materials by comparative method using parameter estimation technique

Determination of thermal conductivity of solids by stationary comparative methods may be inaccurate when thermal conductivity of the standard material is significantly different than thermal conductivity of the measured material. This may happen in case of highly conducting materials when the proper reference material is lacking, heat fluxes are high, drops of temperature in the measured material are low and thermal contact resistance and heat losses may be also important. This paper presents study of accuracy of the comparative method on ratio of the sample to reference sample thermal conductivities. The investigation is carried out by numerical simulation of two-dimensional temperature field in the sample and use of the solution of the inverse heat conduction problem and parameter estimation technique. The results were verified by respective measurements on samples of known thermal conductivity. It was also found that increase in accuracy of measurements can be achieved by changing shape of the sample from a cylinder one to the form of a spool. The results were also experimentally checked by carrying out respective measurements on copper sample using N1019 steel as the reference material.