Power Corrections in the Transient Plane Source Method

Abstract

The transient plane source (TPS) is a well-known method for measuring the thermal conductivity, thermal diffusivity, and specific heat capacity of solids, liquids, pastes, and powders. The method assumes that the heat source delivers a constant power throughout the measurement. However, in real-world measurements, the effective power is reduced due to the temperature coefficient of resistance (TCR) and the heat capacity of the sensor. In this paper, we present first-order corrections to the average temperature of the sensor, accounting for the power reduction caused by the TCR and the heat capacity of the TPS sensor. To verify the corrections, TPS measurements were performed on Pyroceram 9606 at multiple initial powers. The measured properties without the corrections showed a significant trend with the power used. The first-order corrections significantly decreased the trend of the measured thermal conductivity with power, validating the improvements the corrections make to the TPS method.