Returning to classic conditions of THW-technique: A device for the constant heating power mode

The transient hot wire method is widely used in studies of thermal conductivity for gases, liquids and solids. A crucial point for its application is the design of experimental conditions that meet the requirements of the idealized model in the best way. In this paper, we have returned to the requirement of a constant heating power per unit length of the wire and developed the appropriate device, which is free of limitations reported earlier. The device implements electrical power control directly during the pulse with an error of regulation less than 0.03%. The validity of its application in the practice of thermophysical measurements is based on the stable reproducibility over a wide range of power values and is illustrated by test experiments on three n-paraffin hydrocarbons.