Abstract

Glauber’s salt (sodium sulfate decahydrate) is a phase change material (PCM) with promising thermal and physical properties. Moreover, it is very interesting from an economic point of view because it is possible to recover it as a waste product after the disposal of lead batteries. Nevertheless, it is restricted in its applications because of supercooling and phase segregation which require suitable additives that decrease the melting temperature and latent heat of fusion. The obtained mixtures are dispersions of powders in liquids, complex energy storage systems with properties depending not only on composition but also on preparation method. This last aspect is poorly addressed in literature for PCMs. Moreover, these systems are thermodynamically unstable, therefore information about the destabilization kinetic is necessary. The thermal analysis was based on the T-history method, considered by many authors as a more suitable method than Differential Scanning Calorimeter (DSC) for heterogeneous materials, since it requires larger-size samples. Nevertheless, long-term destabilization phenomena were not sufficiently investigated in literature, but they are very relevant because they influence the dispersion stability, homogeneity and energy performances. For this same reason, an optical light scattering method, based on the use of an innovative instrument, the Turbiscan^®, was proposed in this work to study the stability of such heterogeneous PCMs. Two different compositions of Glauber’s salt/borax/bentonite were prepared under controlled sonication conditions and analyzed, as a case study. Transmission and backscattering profiles were studied, explained and correlated with thermal properties and sample compositions and preparation.

摘要

芒硝盐（十水硫酸钠）是一种具有良好热学和物理性能的相变材料（PCM）。此外，从经济角度来看非常有趣，因为在处理铅电池后可以将其作为废品回收。然而，由于过冷和相分离，其在应用中受到限制，这需要合适的添加剂来降低熔融温度和熔化潜热。所获得的混合物是粉末在液体中的分散体，复杂的能量存储系统，其性质不仅取决于组成，而且取决于制备方法。在PCM的文献中，这最后一个方面没有得到很好的解决。此外，这些系统在热力学上是不稳定的，因此需要有关失稳动力学的信息。热分析是基于T历史方法的，因为它需要更大尺寸的样品，因此许多作者认为它比异质材料的差示扫描量热仪（DSC）更合适。然而，长期的不稳定现象在文献中并未得到充分研究，但它们非常相关，因为它们会影响分散稳定性，均质性和能量性能。出于同样的原因，一种基于光波散射法的光学仪器，基于一种创新的仪器Turbiscan 但是它们非常相关，因为它们会影响分散稳定性，均匀性和能量性能。出于同样的原因，一种基于光波散射法的光学仪器，基于一种创新的仪器Turbiscan 但是它们非常相关，因为它们会影响分散稳定性，均匀性和能量性能。出于同样的原因，一种基于光波散射法的光学仪器，基于一种创新的仪器Turbiscan在这项工作中提出了^®，以研究这种异构PCM的稳定性。作为案例研究，在受控的超声处理条件下制备了两种不同的Glauber盐/硼砂/膨润土成分，并进行了分析。对传输和反向散射剖面进行了研究，解释并与热性质，样品组成和制备相关联。