Preparation And Characterization Of Paraffin/Graphene Sponge Composite Phase Change Materials

With the development of technology and the improvement of people’s life,the demand for the application of phase change energy storage materials has also increased.Among them,organic solid-liquid phase change energy storage materials have become a research hotspot because of the characteristic of no super-cooling and no phase separation(precipitation)during the phase change.At present,there are two technical problems in organic solid-liquid phase energy storage materials: low thermal conductivity and poor stability.In order to solve the above problems,a directional freeze-drying method was used to prepare a graphene sponge macroscopic body with high orientation,anisotropy and three-dimensional porosity.Then,the paraffin wax is poured into the graphene sponge by a vacuum impregnation method to prepare a composite phase change energy storage material.Two composite phase change energy storage materials with different properties were prepared in this paper: high phase transition heat and high thermal conductivity.For high phase transition thermal composite phase change energy storage materials,the material has electro-thermal conversion capability.The thermal conductivity of this material is 3 times the thermal conductivity of paraffin.The phase transition temperature of the material is the same as pure paraffin,the latent heat of melting and latent heat of solidification is 10% and 21% higher than pure paraffin.The material is thermally stable below 240 ℃.After 100 cycles of thermal cycling,there was no change in the chemical structure and phase transition temperature inside the sample,and the latent heat of melting and latent heat of solidification were only reduced by 9% and 13%,but it is still higher than pure paraffin.The high phase transition thermal composite phase change energy storage material prepared in this experiment has good cycle stability.For high thermal conductivity composite phase change energy storage materials,the thermal conductivity of this material is 126 times the thermal conductivity of paraffin.The material has a very fast response to heat.The phase transition temperature of the material is the same as pure paraffin,and the latent heat of phase change decreases with the decrease of paraffin content in the material.The material is thermally stable below 270 ℃.After 100 cycles of thermal cycling,there was no change in the chemical structure and phase transition temperature inside the sample,and the latent heat of melting and latent heat of solidification were only reduced by 2%.The high thermal conductivity composite phase change energy storage material prepared in this experiment has excellent cycle stability.