Hydration kinetics of K2CO3, MgCl2 and vermiculite-based composites in view of low-temperature thermochemical energy storage
Hydration kinetics of K2CO3, MgCl2 and vermiculite-based composites in view of low-temperature thermochemical energy storage
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DOI：
10.1016/j.est.2021.102561
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发表时间：
2021-06
影响因子：
9.4
通讯作者：
R. Fisher;Yulong Ding;A. Sciacovelli
中科院分区：
文献类型：
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作者：
R. Fisher;Yulong Ding;A. Sciacovelli
热化学能量存储（TCES）可以在高能量存储密度下存储热量理论上不确定的时间量。它是实现季节性热能储存（TES）的理想手段。无机吸湿盐在大气压下的水合引起了科学界的广泛关注：在30 °C-150 °C范围内的TES是可实现的，并且适合于家庭供暖应用，例如空间供暖。虽然在材料和反应堆规模上都取得了进展，但对两者之间的关系仍然缺乏基本的了解，而这对于充分发挥TCES的潜力和开发技术解决方案是必要的。研究了无机盐K_2CO_3和MgCl_2及其复合材料在蛭石中的浸渍行为。实验测量（动态蒸汽吸附）和数值优化已知的固态动力学模型相关的吸附被用来推导不同的固态反应动力学模型的动力学系数，并阐明可能的限速机制的水合作用的每种材料。碳酸钾（K2 CO 3）水化被发现是动力学受阻的什么似乎是在粒子间水平的扩散障碍。根据最佳拟合动力学模型，K2 CO 3的浸渍导致在25 °C下通过成核控制和40 °C下通过相边界控制显著改善的水合。MgCl 2水化最好由一阶模型和扩散型模型模拟，指向颗粒内扩散控制。最后，浸渍到蛭石的氯化镁水化最好的模拟相边界控制模型，在不同的温度下没有显着的速率限制阶跃变化。
Thermochemical energy storage (TCES) may store heat for a theoretically indefinite amount of time at high energy storage density. It is an ideal means to achieve seasonal thermal energy storage (TES). Hydration at atmospheric pressure of inorganic hygroscopic salts has attracted much attention from the scientific community: TES in the range 30 °C-150 °C is achievable and suitable for domestic heating applications such a space-heating. While progress at both material and reactor scales have been made, there is still a lack of fundamental understanding of the relationships connecting the two, which is necessary in order to enable full TCES potential and develop technical solutions. We investigated inorganic salts K2CO3and MgCl2, and composites consisting in these salts impregnated into vermiculite. Experimental measurements (dynamic vapour sorption) and numerical optimization of known solid-state kinetic models relevant for sorption were used to derive kinetic coefficients for different solid-state reaction kinetic models and to shed light on the possible rate-limiting mechanisms of the hydration of each material. Potassium carbonate (K2CO3) hydration was found to be kinetically hindered by what appears to be a diffusion barrier at the interparticle level. Impregnation of K2CO3lead to a significantly improved hydration, controlled at 25 °C by nucleation and 40 °C by phase-boundary control according to the best fitting kinetic models. MgCl2hydration was best modelled by first-order model and diffusion-type models, pointing towards intraparticle diffusion control. Finally, the hydration of MgCl2impregnated into vermiculite was best modelled by phase-boundary control models, with no notable rate-limiting step change at different temperatures.