Compatibility Study Between Synthetic Oil and Vitrified Wastes for Direct Thermal Energy Storage

Compatibility tests were conducted between synthetic oil and potential solid filler materials in a thermocline tank built at the PROMES-CNRS laboratory. These experiments consisted of placing the oil and the solid materials together in small crucibles (2.3 L) and performing compatibility tests at 300 °C and accelerated ageing tests at 330 °C for 500 h. The mutual influence of the oil and the solid materials was assessed through different measurements: X-ray diffraction and scanning electron microscopy. The influence of the solid on the oil was assessed by measuring thermo-physical and chemical properties. While no significant degradation of the oil is measured at 300 °C, at 330 °C, an increase in the oil degradation rate was observed. Its density, thermal conductivity and specific heat did not change, but its viscosity showed a significant increase. However, after accelerated ageing tests at 330 °C, the oil still shows good heat transfer performance. The solid crystalline structure did not change during the test but some of the samples seemed to absorb oil.