The Study On Preparation And Performances Of Nano-composites Phase Change Materials

Phase change materials?PCMs?were widely used in latent heat storage system.However,the poor thermal conductivity of most organic phase change materials is one of the obstacles to their practical application.In this paper,the incorporation of silver nanoparticles into polyethylene glycol,the composite phase change material was prepared by adsorption of paraffin wax or fatty acid by manganese dioxide nanowires/tubes,the thermal conductivity was 115.3 % 377.16 % higher than that of organic phase change materials,the preparation process is simple and green.And a variety of analysis methods of SEM,TEM,XRD,DSC and TGA were performed to measure the pore characteristics and thermal stabilityof the porous materials and thermal properties of the PCMs composites.1.In situ reduction of silver nitrate by polyethylene glycol,the preparation of nano silver composite phase change material,nano Ag particles can be dispersed uniformly in polyethylene glycol by SEM and TEM.The DSC and TGA tests show that the nano silver composite phase change material has higher thermal storage capacity,and the enthalpy of phase change heat storage is between 121.9 and 141.9 J g^-1,and it has good heat resistance.Analysis of the measured thermal conductivity coefficient of thermal conductivity in 0.300 0.635 W m-1 K-1,results show that silver nanoparticles can effectively improve the thermal conductivity of organic phase change materials.2.The use of manganese sulfate?MnSO₄?,potassium acetate?CH3COOK?,potassium chlorate?KCl O3?and acetic acid?CH3COOH?preparation of MnO₂ nanowires?MnO₂ NWs?as carrier materials,and fatty acid and paraffin to prepare nano composite phase change material.The XRD images show that the prepared MnO₂ nanowires was ?-MnO₂.Through SEM and TEM observation and analysis show that MnO₂ nanowire surface adsorption amount of fatty acid.The DSC test shows that the latent heat of the composite phase change material has high value.Through TGA test,the nanocomposite phase change material has no thermal decomposition at 260 oC and has good thermal stability.The thermal conductivity of nanocomposite phase change material can be obtained by nano composite phase change material.The thermal conductivity is between 0.258 and 0.611 W m-1 K-1.The result shows that MnO₂ nanowires can improve the thermal conductivity of organic phase change obviously3.Using the manganese dioxide nanotubes?MnO₂ NTs?which was prepared by Potassium Permanganate?KMnO₄?and 37 wt% hydrochloric acid?HCl?as carrier material and MA,SA and paraffin wax were use as phase change materials to prepared nanocomposites PCMs.The XRD images shows that the prepared MnO₂ nanotubes carrier material was ?-MnO₂.The SEM and the TEM images show that the phase change materials were loaded at the outer and inner surface of MnO₂ nanotubes.The thermal storage properties of nanocomposite phase change materials were tested by DSC.It is proved that nanocomposite PCM has good thermal storage capability.The TGA results suggested that the nanocomposite phase change material is almost weightless and has good thermal stability under the condition of medium and low temperatureThe thermal conductivities of the MnO₂ NTs/PCMs nanocomposites,suggesting that the MnO₂ nanotubes could enhance the thermal conductivities of PCM composites.