Energy Storage Science and Technology ›› 2022, Vol. 11 ›› Issue (12): 3836-3844.doi: 10.19799/j.cnki.2095-4239.2022.0414

• Energy Storage Materials and Devices • Previous Articles     Next Articles

Crystallization kinetics of stearic acid and stearic acid/MXene composite phase change materials

Bochao YANG(), Jie LÜ, Ziwei ZHEN, Jianjun WANG, Yuxia SHEN, Yu ZHANG, Yi WANG()   

  1. School of Petrochemical Engineering, Lanzhou University of Technolgy, Lanzhou 730050, Gansu, China
  • Received:2022-07-25 Revised:2022-08-08 Online:2022-12-05 Published:2022-12-29
  • Contact: Yi WANG E-mail:baochaoyang2022@163.com;wangyi@lut.edu.cn

Abstract:

The confined molecules exhibit different physicochemical properties and crystallization behavior from the bulk. Therefore, to explore the effect of confinement on the crystallization behavior of confined phase change materials (PCMs), stearic acid/MXene (SA/MXene) composite PCMs were prepared by hydrothermal method using stearic acid (SA) and MXene as the heat storage medium and matrix, respectively. The crystallization behavior was analyzed using a differential scanning calorimeter (DSC) and polarized microscopy (PM), and the SA and SA/MXene crystallization kinetics were studied by the Avrami, Jeziorny, Mo, and Kissinger models. The effects of confinement on the crystallization behavior of confined stearic acid were also analyzed. The results show that SA and SA/MXene exhibit opposite temperature-dependent crystallization behavior during the isothermal crystallization process. SA presents a larger crystallization rate than SA/MXene at low temperatures, while SA/MXene exhibits a shorter half-crystallization time and a faster crystallization rate at higher temperatures. In the non-isothermal crystallization process, MXene has dual effects on the crystallization behavior of stearic acid, which include promoting heterogeneous nucleation under a low cooling rate and inhibiting the confinement effect at a high cooling rate. The confinement effect increases the energy barriers of the confined molecules during the crystallization process. Therefore, the crystallization activation energy of SA increases from 174 kJ/mol to 208 kJ/molin SA/MXene. Finally, this study can provide a theoretical basis for designing and optimizing shape-stabilized composite phase change materials.

Key words: stearic acid, MXene, crystallization kinetics

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