Research On Preparation And Properties Of Palmitic Acid-based Phase Change Heat Storage Materials

Phase change thermal storage stores/releases heat by using endothermic/exothermic process of phase change materials during their phase change process.Phase change materials for thermal storage have some advantages,such as high heat storage density,small temperature variation during charge and discharge process.They have been widely concerned by scholars at home and abroad.Palmitic acid?SA?is not only cheap,non-toxic,but also has excellent performance,especially good thermal stability,which makes it an ideal phase change material.Expanded graphite?EG?has properties including low density,high thermal conductivity and so on.Its porous structure,which can adsorb palmitic acid,makes it remains its shape when melting.Carbon nanotubes?CNTs?have the following characteristics:large specific surface area,good adsorption performance,good thermal stability and chemical stability.Co₃O₄ derived from ZIF-67 is rich in pore structure and large in specific surface area,which can increase the contact area with palmitic acid and enhance the thermal conductivity of palmitic acid.In this paper,palmitic acid is used as the matrix material,Co₃O₄/expanded graphite and Co3O4/carbon nanotubes are thermally enhanced phase.The composite phase change heat storage material is prepared by melt blending,vacuum adsorption and ultrasonic dispersion.The performance of the prepared phase change heat storage material is studied by scanning electron microscopy,thermal constant tester,integrated thermal analyzer,Fourier transform infrared spectrometer.The results show that the Co₃O₄/carbon material composite has rich pore structure and high specific surface area,which can increase the contact area with palmitic acid and improve the thermal properties of palmitic acid.The synergistic effect between the high thermal conductivity of the carbon material and the porous structure of Co3O4 can increase the heat transfer capacity of the palmitic acid and improve heat charge and discharge efficiency.Heat charge and discharge time can directly reflect the heat transfer capacity of the palmitic acid composite phase change material.Co3O4/expanded graphite composite can greatly reduce heat charge and discharge time.Co₃O₄/carbon nanotubes composite can only slightly increase the thermal conductivity in the solid state,and the charge and discharge time decreases little.