Preparation And Performance Study Of Agglomeration CNTs Loading Paraffin For Phase Change Materials

At present,organic phase change materials?particularly solid-liquid phase change materials,SLPCMs?have been comprehensively studied because of the advantages of large latent heat.However,the SLPCMs are limited in practical application due to the poor thermal conductivity and the problems of leakage.Therefore,research and development of a shape-stabilized SLPCMs can not only make up for the inherent shortcomings of organic phase change materials,but also improve the thermal performance of the phase change material,such as the heat transfer rate and the stability during the phase change.Therefore,the exploration of high stability and high thermal performance of shaped-stabilized SLPCMs has become a hot topic in the field of organic phase change material.In this work,aggregated CNTs?A-CNT?are used as the carriers of loading SLPCMs?e.g.paraffin?,which are prepared by chemical vapor deposition using Fe/Mo/Mg O-based catalysts through pyrolysis of propylene.Due to the presence of shear stress,carbon nanotubes will bend and entangle with each other during the growth process,forming a porous network structure like cocklebur to provide an effective space for loading paraffin.Then,they are mixed together by simple impregnation mathod to obtain shaped-stabilized SLPCMs with different load ratios.The shaped-stabilized SLPCMs are characterized by SEM,XRD,TGA,FT-IR,and the thermal properties of shaped-stabilized SLPCMs are measured by DSC and temperature-time response profiles.The experimental results show that the heat storage density of the prepared shaped-stabilized SLPCMs exceeds its theoretical value,which indicates that the composites have high heat storage capacities.The absorption enthalpy retention rate of 88 wt.%paraffin/A-CNT is as high as 98.2%within 300 DSC cycles,indicating excellent thermal cycling stability.The thermal conductivity of 88 wt.%paraffin/A-CNT is 2.5 times of pure paraffin,which shows that the thermal conductivity of composite phase change materials has improved greatly.In addiction,the thermogravimetric weight loss starting temperature is increased by about 40°C under N₂ atmosphere,which indicates that the addition of the CNTs greatly improves the thermal stability of composite phase change heat storage materials.This study found that agglomerated carbon nanotubes are expected to be used as a carriers of SLPCMs in the field of thermal management.