Experimental investigation for the simultaneous estimation of the thermal conductivity and specific heat capacity using a two-wire method

A prototype apparatus that uses two platinum wires for the simultaneous estimation of the thermal conductivity and specific heat capacity of liquids is described. The first wire is used both as a hot wire and a resistance thermometer, while the second one is used as a resistance thermometer. The aim of the work was to experimentally verify the advantages of employing a second wire to improve the reliability of the estimation of the properties. Three different liquids: water, propylene glycol, and a mixture of these are considered. An analytical solution with a changing heat flux is adopted. The thermal conductivity and the specific heat capacity are simultaneously estimated with a nonlinear regression (Maximum Likelihood) of the experimental data, using two-wire measurements or only hot-wire measurements. A comparison between these two approaches is reported and discussed.