Experimental investigation on micro-scale phase change material based on sodium acetate trihydrate for thermal storage

•The micro-porous of EV can provide micro-spaces for SAT phase change.•The CPCM had good thermal stability for heating thermal storage.•The thermal conductivity of the CPCM was enhanced by EV during phase.•change process.•The super-cooling and phase separation problems were effectively improved. A n...

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Veröffentlicht in:Solar energy 2019-11, Vol.193, p.413-421
Hauptverfasser: Liu, Jianwei, Zhu, Chenhao, Liang, Wenzheng, Li, Yanhui, Bai, Hongcun, Guo, Qingjie, Wang, Cuiping
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Sprache:eng
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Zusammenfassung:•The micro-porous of EV can provide micro-spaces for SAT phase change.•The CPCM had good thermal stability for heating thermal storage.•The thermal conductivity of the CPCM was enhanced by EV during phase.•change process.•The super-cooling and phase separation problems were effectively improved. A new composite phase change material (CPCM) for heat storage was prepared via the vacuum impregnation method. The material was based on sodium acetate trihydrate (SAT) adsorbed in micro-porous expanded vermiculite (EV), to form the micro-scale phase change of SAT in each EV micro cell acting as an independent phase change unit. The adsorptive capacity of SAT in EV is up to 600 wt%, while with 2 wt% borax added as a nucleating agent in the CPCM. The micro-structure of EV occupied by SAT was characterized by scanning electron microscopy (SEM) images. X-ray diffraction (XRD) tests indicated good chemical compatibility among the different components of the CPCM. The phase change temperature and heat storage density of the CPCM were 57.6 °C and 270.6 kJ/kg respectively, and the thermal conductivity was higher than that of each component in the compound. Thermogravimetry (TG-DSC) results showed that the insurmountable super-cooling and phase separation problems were almost overcome, and the thermal performance test system results showed that the CPCM was stable over 150 melting-solidification cycles. The performance improvement of SAT is attributed to the micro-scale phase change and heat transfer in EV cells.
ISSN:0038-092X
1471-1257
DOI:10.1016/j.solener.2019.09.050