J. Mater. Sci. Technol. ›› 2018, Vol. 34 ›› Issue (2): 379-386.DOI: 10.1016/j.jmst.2017.06.003

• Orginal Article • Previous Articles     Next Articles

Preparation and characterization of capric-palmitic-stearic acid ternary eutectic mixture/expanded vermiculite composites as form-stabilized thermal energy storage materials

Weiyi Zhanga, Xiaoguang Zhanga, Zhaohui Huanga(), Zhaoyu Yina, Ruilong Wena, Yaoting Huangb, Xiaowen Wua, Xin Mina   

  1. aSchool of Materials Science and Technology, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, China University of Geosciences, Beijing 100083, China
    bSchool of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China
  • Received:2017-02-15 Revised:2017-04-13 Accepted:2017-05-12 Online:2018-02-10 Published:2018-02-10

Abstract:

In this study, a composite of form-stable phase change materials (FSPCMs) were prepared by the incorporation of a eutectic mixture of capric-palmitic-stearic acid (CA-PA-SA) into expanded vermiculite (EV) via vacuum impregnation. In the composites, CA-PA-SA was utilized as a thermal energy storage material, and EV served as the supporting material. X-ray diffraction and Fourier transform infrared spectroscopy results demonstrated that CA-PA-SA and EV in the composites only undergo physical combination, not a chemical reaction. Scanning electron microscopy images indicated that CA-PA-SA is sufficiently absorbed in the expanded vermiculite porous network. According to differential scanning calorimetry results, the 70 wt% CA-PA-SA/EV sample melts at 19.3 °C with a latent heat of 117.6 J/g and solidifies at 17.1 °C with a latent heat of 118.3 J/g. Thermal cycling measurements indicated that FSPCMs exhibit adequate stability even after being subjected to 200 melting-freezing cycles. Furthermore, the thermal conductivity of the composites increased by approximately 49.58% with the addition of 5 wt% of Cu powder. Hence, CA-PA-SA/EV FSPCMs are effective latent heat thermal energy storage building materials.

Key words: Capric-palmitic-stearic acid, Expanded vermiculite, Form-stable composite phase-change material (PCM)