Packed bed thermal energy storage system is a promising alternative to reduce the overall investment cost of a concentrating solar power plant. However, the choice of suitable filler materials depends on different steps and criteria in order to satisfy the requirements of the target application (e.g. operating temperatures, charging/discharging thermal power, thermal and mechanical stabilities, etc.). Most of the previous experimental investigations have focused on the lifetime stability of rocks at high-temperature up to 500°C. However, they have not discussed the suitability of the unsuccessful ones and their application for medium temperatures (up to 300°C). In this scope, the main aim of the present experimental work is to correlate the petrographic properties of the investigated rocks with their effect on their thermophysical properties, and their thermal stability for a medium-range temperature between 100°C and 300°C. To achieve this objective, four natural rocks (two varieties of pegmatite, cipolin and garnetite) are subjected to several experimental characterizations: At first, a petrographic analysis is done in order to identify the mineralogical composition and the texture of the samples. Secondly, chemical and structural analyses are conducted on the rocks using scanning electron microscopy, energy-dispersive x-ray and x-ray power diffraction techniques. Their thermophysical properties (density, specific heat capacity, thermal conductivity and diffusivity) are also measured. Finally, a thermo-gravimetric analysis is performed in order to test the thermal stability of the investigated rocks. The obtained results suggest that all the studied rocks are potential candidates to be used as filler materials in a packed bed configuration for a medium-range temperature.

填充床热能存储系统是减少集中式太阳能发电厂的总投资成本的有前途的替代方案。但是，合适的填充材料的选择取决于不同的步骤和标准，以满足目标应用的要求（例如，工作温度，充电/放电热功率，热和机械稳定性等）。以前的大多数实验研究都集中在岩石在高达500°C的高温下的寿命稳定性上。但是，他们没有讨论不成功的方法的适用性以及它们在中等温度（最高300°C）下的应用。在此范围内，当前实验工作的主要目的是将被调查岩石的岩石学性质与其对其热物理性质的影响相关联，以及在100°C至300°C的中等温度范围内的热稳定性。为了达到这个目的，对四种天然岩石（两种伟晶岩，方铁矿和石榴石）进行了几个实验表征：首先，进行岩相分析以鉴定样品的矿物学组成和质地。其次，使用扫描电子显微镜，能量色散X射线和X射线功率衍射技术对岩石进行化学和结构分析。还测量了它们的热物理性质（密度，比热容，热导率和扩散率）。最后，进行热重分析以测试所研究岩石的热稳定性。