Contribution to the Transient Plane Source Method for Measuring Thermophysical Properties of Solids

The transient plane source method of measuring the thermal conductivity and thermal diffusivity uses a sensor in the shape of a thin disk, which simultaneously serves as the heat source and thermometer. This study describes improvements of the experimental apparatus, providing some details of the electrical bridge with the aim to obtain maximum reliability of the measurement results. The aim of the temperature function analysis is to find the optimal time of measurement. The relation between the data time window used for fitting, the uncertainty of the sensor temperature measurement, and the uncertainty of the results is presented and graphically illustrated using numerical simulation of the experiment. The theory was confirmed by the evaluation of real measurements on polymethylmetacrylate. The temperature function analysis revealed that a decrease of the temperature measurement uncertainty need not always lead to a fall in the total uncertainty of the results but to shorter experiments and smaller specimens.