Energy Storage Science and Technology ›› 2024, Vol. 13 ›› Issue (8): 2634-2648.doi: 10.19799/j.cnki.2095-4239.2024.0172

• Energy Storage Materials and Devices • Previous Articles     Next Articles

Determination of the kinetic parameters of fatty acid phase-change materials based on the T-history method

Silin LIU(), Xiaoling CAO(), Peilu ZHANG, Ziyu LENG   

  1. School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
  • Received:2024-03-01 Revised:2024-03-21 Online:2024-08-28 Published:2024-08-15
  • Contact: Xiaoling CAO E-mail:liusilin@my.swjtu.edu.cn;xlcao@swjtu.edu.cn

Abstract:

Existing phase transition models artificially set the phase fraction to be linearly related to the temperature interval, failing to consider the influence of the temperature change rate on the phase transition process and resulting in a low prediction accuracy. In this study, to investigate the two-phase transformation law under the joint effect of temperature and the temperature change rate, a theoretical analysis of the phase change process is conducted and a solidification-melting kinetic model is established through the reversible reaction between the PCM components in the solid and liquid phases using the phase fraction as the key parameter. The Avrami equation was set as the reaction function in the model, and the Arrhenius equation was used as the rate function. Fatty acid phase change materials commonly used in the construction field (i.e., n-decanoic acid, lauric acid, and octanoic acid) were selected as experimental materials, and the Avrami equation was fitted and verified via isothermal crystallization experiments using the T-history method. After verifying that the Avrami equation shows a high degree of consistency and reliability with the data obtained from isothermal crystallization experiments, the thermodynamic characteristics of the phase-change materials at different temperatures and rates of temperature change were evaluated using non-isothermal experiments. The key kinetic parameters in the model were investigated and obtained in conjunction with the kinetic thermal analysis method. The results show that the activation energy and constant factor change via the same trend and exhibit a complementary relationship. Moreover, the activation energy and constant factor differ between different phase-change materials, and these changes vary depending on the phase transition process. The number of reaction levels decreases with increasing temperature change rate, and the number of reaction levels during the solidification process is generally larger than that during the melting process.

Key words: Avrami model, phase transition kinetic model, T-history method, kinetic parameters

CLC Number: