The Transient Hot Wire (THW-L1) unit is widely used for the accurate measurement of thermal conductivity, thermal diffusivity and specific heat capacity of liquids, pastes, and powders.
The THW-L1 was designed with speed and operational simplicity in mind. With a single measurement of 1 second in duration, small sample volume can be accurately and precisely measured. The THW-L1 sensor consists of a thin heating wire 40 mm in length and is completely inserted into the sample to be tested. The sensor wire is heated using a constant current source (q) and the temperature rise is recorded by monitoring the change in electrical resistance of the wire. The slope (m) from the plot of temperature rise vs. logarithm of time is used in the calculation of thermal conductivity (λ).