Characterization of electrical properties of phase change materials for liquid fraction sensing via electrical tomography

Electrical impedance tomography could be an accurate and non-intrusive alternative to estimate liquid fraction in phase change materials (PCMs). However, the electrical properties of most PCMs have not yet been characterized. In the present study, Rubitherm RT54HC and Sodium Acetate Trihydrate (SAT) are characterized via electrical impedance spectroscopy. The measurements are performed in liquid and solid state in a temperature range close to the melting point and a frequency range between 4 Hz to 500 MHz. Rubitherm RT54HC is found to be a dielectric with low electrical conductivity and low electrical permittivity in both liquid and solid phases. Hence, material development strategies are required to make electrical tomography sensing feasible. On the other hand, SAT is electrically conductive due to ion transport and presents an innate contrast in electrical conductivity between the liquid and solid phases. Consequently, SAT seems to be better suited for electrical tomography sensing.