Use of the Transient Plane Source Technique for Rapid Multiple Thermal Property Measurements

This paper describes work at NPL to evaluate the capability of the transient plane source (TPS) technique using various sensor sizes and different types of materials that include solids (Perspex, alumina, extruded polystyrene, agar gel, and ice) and liquids (water and silicone oil). The aim of the present work is to investigate use of the TPS technique on materials where probe size, contact, and internal specimen convection are potentially important issues. Following validation of the technique on the NPL solid reference materials, measurements were carried out on ice using TPS and the NPL guarded hot plate (GHP) to illustrate the probe-to-sample thermal contact resistance issue. Measurements on silicone oil were compared to GHP and the NPL transient hot wire (THW) technique where the probe size/short times are crucial. In addition, measurements on water and agar gel were made to illustrate the influence of natural convection. Although the TPS is a multi-property technique, the focus of this work was on thermal conductivity.