Supercooling characteristics of mannitol phase transition system under heterogeneous nucleation

文献类型： 外文期刊

第一作者： Ji, Jun

作者： Ji, Jun;Wang, Yinghui;Zhang, Xuelai;Chen, Yue;Munyalo, Jotham Muthoka;Liu, Sheng

作者机构：

期刊名称：JOURNAL OF MATERIALS SCIENCE （ 影响因子：4.22； 五年影响因子：3.69 ）

ISSN： 0022-2461

年卷期： 2020 年 55 卷 7 期

页码：

收录情况： SCI

摘要： Supercooling of phase change materials (PCMs) during solidification is a major problem in cold thermal energy storage (CTES), which reduces energy efficiency and aggravates energy waste. This study focuses on the supercooling characteristics of PCMs under heterogeneous nucleation, which provides a new idea for researching the influence of different dispersants on the supercooling degree of aqueous solution. The optimal ratios of CNTs water dispersant (TNWDIS) and polymer polyacrylic acid sodium (PAAS) to multi-walled carbon nanotubes (MWCNTs) in mannitol aqueous solution are determined through microstructure and cooling characteristics. How these two surfactants and MWCNTs with different concentrations and particle sizes influence the supercooling degree of nanofluids are investigated. The results indicate that the effect of PAAS is greater than that of TNWDIS. Furthermore, under the action of two dispersants and particle sizes of MWCNTs, the fitting equations of supercooling changing with the concentration of MWCNTs are obtained. In the light of the heterogeneous nucleation theory, with the enlargement of the particle size and the diminution of the contact angle affected by the dispersants, the interfacial free energy of heterogeneous nucleation of PCMs on the surface of nanoparticles is reduced. The supercooling degree therefore decreases. Specifically, the nucleation mechanism is deduced and analyzed through the contact angle and nucleation free energy formula.

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