Thermal conductivity measurement of an individual fibre using a T type probe method

Abstract

A method was developed to measure the longitudinal thermal conductivity (TC) of an individual fibre using a T type probe. In the T type probe, a hot wire was supplied with a constant direct current, whose ends were connected to heat sinks to maintain the initial temperature. The test fibre was attached to the centre position of the hot wire at one end and the other end was connected to another heat sink. Based on a one-dimensional steady-state analysis of the heat conduction in the probe, the TC of the fibre and the thermal contact resistance at the junction between the fibre and the hot wire were simultaneously obtained, by changing the fibre length in the same contact condition at the junction. This method was verified by measuring the Pt wire as a reference sample, and good agreement was achieved between the measurement data and reference value. The TC of a pitch-based carbon fibre was obtained to be 490 W m−1 K−1 at room temperature, and the measurement uncertainty was analysed and compared with that of the previous T type probe method.