Optimization of LiNO3-Mg(OH)2 composites as thermo-chemical energy storage materials
Optimization of LiNO3-Mg(OH)2 composites as thermo-chemical energy storage materials
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DOI：
10.1016/j.jenvman.2020.110258
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发表时间：
2020-05-15
影响因子：
8.7
通讯作者：
Zhang, Huili
中科院分区：
文献类型：
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作者：
Li, Shuo;Liu, Jia;Zhang, Huili
为了减少温室气体的排放，用可再生能源替代化石燃料越来越重要。然而，需要使能源供应和需求相匹配，如果采用间歇性可再生能源，则更是如此。因此，热能储存具有显著的优势。利用可逆反应的热化学储能系统具有高的反应焓，超过了显热和潜热模式的储能能力。氢氧化镁是这种系统的候选TCES材料，温度约为300摄氏度，并且适用于用金属盐掺杂Mg（OH）（2）。研究了纯Mg（OH）（2）及其与1、3、6和10wt%LiNO3的复合物。目前的工作验证了这TCES过程，并开发其设计所需的反应速率方程。LiNO 3掺杂显著降低了脱水的起始温度。对于纯Mg（OH）（2），温度为325 ℃。当存在1重量%的LiNO 3时，其降低到289摄氏度，并且在10重量%的LiNO 3剂量下进一步降低到269摄氏度。然而，纯Mg（OH）（2）的脱水是缓慢的，在300 ℃下的速率常数k为1.72 × 10（-5）s（-1），当存在10wt%LiNO3时，添加增加量的LiNO 3逐渐增加反应速率常数，在300 ℃下接近10（-2）s（-1）。动力学表达式能够预测转化率和对于任何期望的温度和热诱导脱水的选定持续时间存储或释放的热量。当热源在250至400摄氏度之间的温度下可用时，掺杂LiNO 3的Mg（OH）（2）在TCES应用中具有高潜力，因为可以通过添加不同重量%的LiNO 3将平衡温度和脱水Mg（OH）（2）的程度调节到所需的温度范围。
To reduce the emission of greenhouse gases, the substitution of fossil fuel by renewable energy sources is increasingly important. Matching energy supply and demand is however required, even more so if intermittent renewable energy sources are employed. Thermal energy storage then offers significant advantages. Thermo-chemical energy storage systems, using reversible reactions, have a high reaction enthalpy that exceeds the storage capacities of sensible and latent heat modes.Magnesium hydroxide is a candidate TCES material for such a system at temperature around 300 degrees C, and adaptable when doping Mg(OH)(2) with metal salts. Both pure Mg(OH)(2) and its composites with 1, 3, 6 and 10 wt% LiNO3 are studied. The present work validates this TCES process and develops reaction rate equations needed for its design. The LiNO3-doping significantly reduces the onset temperature of dehydration. For pure Mg(OH)(2), the temperature is 325 degrees C. It is reduced to 289 degrees C when 1 wt% LiNO3 is present, and further reduced to 269 degrees C at a dosage of 10 wt% LiNO3. Whereas the dehydration of pure Mg(OH)(2) is slow, with a rate constant k of 1.72 10(-5) s(-1) at 300 degrees C, adding increasing amounts of LiNO3 progressively increases the reaction rate constant to similar to 10(-2) s(-1) at 300 degrees C when 10 wt% LiNO3 is present. The kinetic expressions enable to predict the conversion yield and amount of heat stored or released for any desired temperature and selected duration of the heat-induced dehydration. LiNO3- doped Mg(OH)(2) have a high potential in TCES applications when the heat source is available at temperatures between 250 and 400 degrees C, since the equilibrium temperature and the extent of de-hydration Mg(OH)(2) can be tuned to the required temperature range by adding different wt% of LiNO3.