Experimental and numerical investigation of potential filler materials for thermal oil thermocline storage

The present paper highlights the thermal energy storage potential of six rocks (quartzite, basalt, granite, hornfels, cipolin and marble) proposed as filler material for thermal oil thermocline storage concept. These rocks were chosen according to their abundance in Morocco. Different technical methods were performed in order to assess the rocks properties (physical, chemical and thermal) at temperatures up to 350 °C (temperature operating conditions using linear Fresnel reflectors or parabolic trough). The thermal performances of the studied rocks inside a thermocline storage system were evaluated using a validated numerical model. Based on the experimental investigation two rocks (Quartzite and Cipolin) were identified as the most suitable filler materials to be used in direct contact with the studied HTF (synthetic oil). While, the numerical analysis revealed that Basalt rock has the best thermal performances inside the studied thermocline storage system concept, but it isn't chemically compatible with synthetic oil. Hence, it can be used advantageously with other heat transfer medium (e.g. Air).