Thermal characteristics of the multilayered structural MOF-EG/OC composite phase change material in thermal energy storage

Abstract

At present, low heat storage capacity of organic phase change materials (PCMs) becomes a common problem, and the addition of matrix can contribute to its application in practical engineering. Mixing the porous expanded graphite (EG) with Co3O4 via carbonation of ZIF-67 uniformly, the composite materials PVP@Co3O4/EG were prepared by crosslinking the agent PVP (polyvinyl pyrrolidone), simultaneously the multilayer structure porous OC-PVP@Co3O4/EG composites were prepared by melt-blending method with octadecanol (OC). The thermophysical properties of the composite PCMs appeared the difference by adjusting the ratio of OC to Co3O4. The micromorphology, phase transition enthalpy and phase transition temperature of composite PCMs were determined by scanning electron microscope (SEM) and differential scanning calorimeter (DSC). The multilayer structure prepared by Co3O4 and EG is conducive to the effective transmission of phonons around the axial point, and achieves the goal of efficient heat transfer between PCMs and the external environment. The obtained OC-PVP@Co3O4/EG (Co3O4:EG = 1:8) PCMs exhibited excellent thermal conductivity (11.4 W∙m−1∙K−1), large phase change enthalpy (187.04 kJ∙kg−1). The infrared imaging verified that the infrared light intensity of two thermally conductive substrates (Co3O4:EG = 1:4, 1:8) in the exothermic stage was less than the ratio of Co3O4:EG is 1:4 and 1:8, which was in accordance with the results of the charging/discharging experiments.