Abstract Thermochemical storage is based on a reversible chemical reaction; energy can be stored when an endothermic chemical reaction occurs and then, energy is released when it is reversed in an exothermic reaction. According to literature and based on the energy storage density (esd), MgCl2·6H2O is a promising candidate material for thermochemical energy storage. Bischofite is an inorganic salt obtained as a by-product material from extraction processes of non-metallic minerals, from Salar de Atacama in Chile, containing approximately 95% of MgCl2·6H2O. Thus, the purpose of this study was to characterize the dehydration reaction of bischofite ore, studied as a low-cost thermochemical storage material. Thermogravimetric data for bischofite were obtained using a TGA instrument coupled to a DSC, at four different isotherms 70 °C, 80 °C, 90 °C and 100 °C. The results of conversion reaction (α-t) from the thermal dehydration experiments, demonstrated the first phase of dehydration with the loss of two water molecules. The study showed a typical sigmoid curve with a significant acceleration in the conversion at the beginning of the reaction until it reaches a maximum rate, where the curve keeps constant. The same behavior was observed for all the temperatures used. The kinetics of bischofite dehydration model was determined using the isothermal kinetics method. For this, the thermogravimetric data were fitted to the most used kinetic models (D, F, R, A) and then their respective correlation coefficients R were evaluated. The results indicated that the dehydration reaction of bischofite was described by the kinetics of chemical reaction of cylindrical particles R2. The rate of dehydration reaction and esd of bischofite are lower as compared to synthetic MgCl2·6H2O, at temperatures higher than 80 °C. However, the cost of materials to store 1 MJ of energy is three times lower for bischofite, which is an evident advantage to promote the reuse of this material left as waste by the non-metallic industry.

中文翻译：

---

开发低成本无机盐水合物作为热化学储能材料

摘要 热化学储存基于可逆的化学反应；当发生吸热化学反应时可以储存能量，然后当它在放热反应中逆转时释放能量。根据文献和基于储能密度（esd），MgCl2·6H2O 是一种很有前途的热化学储能候选材料。Bischofite 是一种无机盐，作为非金属矿物提取过程的副产品材料，来自智利的阿塔卡马盐沼，含有约 95% 的 MgCl2·6H2O。因此，本研究的目的是表征双菱镁矿的脱水反应，作为一种低成本的热化学存储材料进行研究。Bischofite 的热重数据是使用与 DSC 耦合的 TGA 仪器在四个不同的等温线 70 °C、80 °C、90 °C 和 100 °C。来自热脱水实验的转化反应 (α-t) 的结果证明了脱水的第一阶段，失去了两个水分子。该研究显示了典型的 S 形曲线，在反应开始时转化率显着加速，直到达到最大速率，在此曲线保持恒定。对于所有使用的温度都观察到相同的行为。使用等温动力学方法确定了双菱镁矿脱水模型的动力学。为此，将热重数据拟合到最常用的动力学模型（D、F、R、A），然后评估它们各自的相关系数 R。结果表明，红菱镁矿的脱水反应可以用圆柱颗粒R2的化学反应动力学来描述。与合成 MgCl2·6H2O 相比，在高于 80 °C 的温度下，双氯镁石的脱水反应速率和 esd 较低。然而，存储 1 MJ 能量的材料成本比双菱镁矿低三倍，这对于促进非金属工业作为废物留下的这种材料的再利用具有明显的优势。