Study On Energy-Storage Composite Materials Of Paraffin And Erythritol Filling Graphite Foam

Thermal storage of PCM has become a very active frontier research direction in the field of energy science and materials science in recent years, because of its many outstanding advantages such as approximate isothermal process and controllable energy absorbing and release. However, two main faults of a single phase change materials limit the wide application of phase change materials, one liquid flow phenomena in the process of solid-liquid phase change and the other low thermal conductivity. Due to its low density and high heat conductivity and its porous structure graphite foam can realize the physical encapsulation of phase change materials, this paper adopt foam graphite as matrix, paraffin and erythritol as phase change materials, and prepare phase change materials/graphite foam composite energy-storage materials by the technology of spontaneous molten infiltration.Firstly, in this paper, the organization and performance of graphite foam are characterized, including SEM, mercury intrusion porosimetry(MIP), mechanical property testing, XRD and Raman spectroscopy analysis. The density and volume expansion rate of the phase change materials selected are tested. The infiltration technology of the paraffin and erythritol infiltrating graphite foam is researched by considering infiltration temperature and time and vacuum degree. Finally the best infiltrating conditions are determined, paraffin 60℃, 40min under the normal pressures, erythritol 150℃, 10min under the vacuum conditions.Secondly, Phase change materials/graphite foam composite energy-storage materials'microstructure, phase transformation temperature and latent heat and combination of state are analyzed by SEM, DSC, XRD and Fourier transform infrared spectroscopy (FT-IR). The results indicate that under the best infiltrating technology conditions phase change materials can reach infiltrating saturation, and form physical combination between graphite foam, and not produce new groups. Composite's phase-change temperatures are equivalent to phase change materials'and the latent heat of composite PCM is equivalent to the calculated values based on the mass fraction of PCM in the composite materials. The thermal cycle experiment of composite energy-storage materials is made, and the results showed that paraffin/ graphite foam composite energy-storage materials'weightlessness rate is 5.14% after the thermal cycle of 40 and that erythritol/ graphite foam composite energy-storage materials'weightlessness rate is 14.56% after the thermal cycle of 6. In addition, mechanical performance testing of the composite energy-storage materials is made, and the results showed that compared with graphite foam, compressive strength of composite energy-storage materials of paraffin and erythritol filling graphite foam has 80% and 26% increase respectively and can be used as self supporting composite materials.