A switched vibrating-hot-wire method for measuring the viscosity and thermal conductivity of liquids.

A method involving a vibrating hot wire is proposed for measuring the viscosity and thermal conductivity of liquids. A platinum wire is bent into a semicircular shape and immersed in the sample liquid in the presence of a static magnetic field. Alternating current is then applied to the wire, causing it to vibrate and generate heat. At low frequency, the frequency response of the vibration is used to calculate the viscosity. At high frequency, the vibration amplitude of the wire is less than the molecular free path, and the thermal conductivity of the sample is obtained from the temperature dependence of the resistance. The proposed method is validated using water, toluene, anhydrous ethanol, and ethanediol as the test samples. The measurement uncertainty is estimated to be 1.5% (k = 1) for thermal conductivity and 0.7% (k = 2) for viscosity.