Research On Preparation And Properties Of Stearic Acid/3D Porous Carbon-based Phase Change Materials

Thermal storage technology plays an important role in energy storage and transformation.The composite phase change thermal storage material with good heat storage property has attracted wide attention in the field of thermal storage.Stearic acid,one of fatty acid,has suitable phase transition temperature and high latent heat of phase change.It is suitable for phase change heat storage material applied in mid low temperature solar thermal utilization,electronic heat dissipation and building thermal insulation.Stearic acid has the disadvantage of low thermal conductivity,which limits the internal heat transfer of materials and the heat release efficiency in the melting/solidification phase transition process is low.At present,the most commonly used method to solve the low thermal conductivity is to add materials with high thermal conductivity in the phase change material to increase the heat transfer capacity of the matrix.This paper is mainly reported that three-dimensional porous carbon materials with high thermal conductivity was filled toincrease the heat transfer capacity of the stearic acid,and improve the efficiency of heat and heat release.The morphology,phase,phase transition temperature,phase transition enthalpy and thermal stability of the composite phase change samples were characterized by SEM,XRD,FTIR,DSC,TG and other instruments.The specific surface area and pore size distribution of the additives were determined by BET.The charge and heat release time and speed of the composite phase change sample and pure stearic acid were measured by the charge and heat release experiment.Calcinations of the product of ZIF-67（ZIF:zeolitic imidazolate framework）in-situ deposit on expanded graphite（EG）,a hierarchical porous structure of ZIF-67derived hollow porous Co₃O₄ on EG to synthesis Co₃O₄/EG,and dispersed in stearic acid to obtain a novel compositephase change material（PCM）with excellent thermal properties.Co₃O₄/EG shows a 3D interconnected network structure featured with abundant porous structure and high specific surface area.It can play a certain role in adsorption and increase the contact area with stearic acid,and exhibit an efficient enhancement on the thermal properties of SA.The three-dimmensional reduced graphene oxide（3DRGO）was prepared by adding the ascorbic acid into the obtained graphene oxide（GO）with a heating process.The 3DRGO was filled to stearic acid,and a composite phase change material with excellent thermal properties was prepared.The three-dimensional graphene skeleton can provide effective heat transfer channels in stearic acid,and the high specific surface area and the porous structure of 3DRGO can increase the contact area with stearic acid,inproving the heat transfer area of PCMs and the heat transfer efficiency.Adding two kinds of three-dimensional porous carbon material does not affect the phase transition temperature of stearic acid,but with the addition of three-dimensional porous carbon materials increased,the enthalpy of stearic acid composite PCMs is reduced.Owing to the abnormal interaction of stearic acid and the inner surface of the porous structure,the actual measured enthalpy is slightly less than the theoretical enthalpy.The heat transfer ability of stearic acid composite PCMs is the most intuitionistic performance of heat release time.The two kinds of porous carbon materials such as Co₃O₄/EG and 3DRGO can greatly reduce the charge and heat release time.