Study On The Thermophysical Properties Of Pentaerythritol Solid-solid Phase Change Energy Storage Materials

Energy problem is related to human survival and social development.In the face of the gradual depletion of non-renewable energy,the development of new energy and energy storage technology is particularly important.Energy storage material is the core of energy storage technology,and low thermal conductivity is a big problem that limits the practical application of energy storage material.The thermal conductivity of energy storage material can be effectively improved by using thermal conductive filler and energy storage material as composite materials.Pentaerythritol is a kind of typical new amyl polyol,which has long carbon chain,high molecular weight,stable ether bond,and its solid-solid phase change is accompanied by a lot of heat,thus,it is an ideal phase change energy storage material.Graphene is a kind of two-dimensional carbon nano material,which is composed of carbon atoms with hexagonal honeycomb lattice.It has excellent thermal conductivity and is an ideal thermal conductive filler.In this paper,pentaerythritol is used as matrix material,graphene and alumina are used as thermal conductive fillers,and the effects of graphene and alumina on the thermal conductivity and other thermal physical parameters of composite phase change materials are studied by combining molecular dynamics simulation and experimental research,and the internal mechanism of action is explored.The main research contents and results are as follows:With Materials Studio software,PE/GE,PE/Al₂O₃ composite phase change material model was built.And the simulation data was sorted out and analyzed through non-equilibrium simulation method for simulation calculation.The simulation results show that the addition of graphene and alumina increases the specific heat capacity of the composite phase change material,and the specific heat capacity increases with the increase of the mass ratio of the heat conducting filler,so that graphene has a better overall improvement effect on the material;The thermal conductivity and interface thermal conductivity of PE/GE,PE/Al₂O₃ composite phase change material increase with the increase of graphene or alumina mass fraction,and graphene as the thermal conductive filler has a better effect improvement;The change of interaction energy of PE/GE and PE/Al₂O₃composite phase change materials is consistent with the change trend of thermal conductivity and interfacial thermal conductivity of PE/GE and PE/Al₂O₃ composite phase change materials.It can be seen from the analysis of radial distribution function that the structure of graphene and alumina in PE/GE and PE/Al₂O₃ composite phase change with the increase of graphene and alumina mass fraction,which changes in the direction of more uniform molecular dispersion and better combination with pentaerythritol,while the molecular structure of pentaerythritol basically does not change.In the process of improving the overall thermal conductivity of the material,the structural change dominates.The experimental samples of PE/GE and PE/Al2O3 composite phase change materials with different mass fractions were prepared by mechanical mixing method.Their micro morphology and thermophysical properties were observed and measured.It can be seen from the experimental results that the micro morphology of PE/GE and PE/Al₂O₃ composite phase change materials observed by SEM change with the increase of the mass fraction of graphene and alumina,and the combination with pentaerythritol is getting better and better,which is consistent with the change of the thermal conductivity of the composite phase change material;The specific heat capacities of PE/GE and PE/Al₂O₃ composite phase change materials all increase with the increase of the mass fraction of the heat conducting filler,and the changes are consistent with the simulation results.The addition of graphene and alumina not only improves the thermal conductivity and specific heat capacity of the composite,and has little effect on the phase transition temperature and latent heat of the composite.Moreover,the effect of graphene as thermal conductive filler is better than that of alumina.