Reduction in the Degree of Supercooling of the PCM D-mannitol Using Zeolite as a Nucleating Agent

In this study, to alleviate the problem of low heat utilization efficiency caused by extreme supercooling of D-mannitol when used as a phase change material (PCM), we selected eight typical zeolites as nucleating agents and formed the corresponding D-mannitol-based PCMs through the melt blending method. The X-ray diffraction and Fourier transform infrared spectroscopy results reveal that no new compounds other than zeolite and D-mannitol were formed before and after melt blending, and the two were relatively chemically stable throughout the experiment, except for the composite PCM with“Zeolite HS-690 H-Mordenite.”Differential scanning calorimetry (DSC) analysis was used to investigate the effect of the addition of different types and quantities of zeolite on the crystallization behavior of D-mannitol. The results demonstrate that A- and mordenite crystal-type zeolites induce the crystallization of D-mannitol effectively, and the optimal mass ratio is approximately 10% mass fraction. This study provides long-term experimental data that will guide the practical application of PCMs. The results of the subsequent cyclic experiment reveal that the“Zeolite HS-690 H-Mordenite”additive caused the melting enthalpy of D-mannitol to decrease significantly, and the crystallization temperature also decreased over multiple cycles. In contrast, Zeolite HS-642 Sodium-Mordenite”demonstrated better enthalpy stability in the cyclic experiment than the two A crystal-type zeolites, with a decrease in melting enthalpy of only 1.0%. © 2023 Japan Institute of Energy. All rights reserved.