Study On The Non-equilibrium Heat Transfer Process Of Porous Skeleton Structure Composite Phase-change Material

The porous skeletal structure composite phase-change material is prepared through the combination of porous media and phase-change materials,and is a highly promising composite phase-change material.Porous media can not only realize the encapsulation of phase-change materials,but also strengthen the heat transfer process of phase-change materials.Due to the significant difference in thermal diffusivity between the porous framework and the phase-change material,the heat transfer process of this type of composite phase change material is a non-equilibrium heat transfer process with local temperature imbalance.In this paper,the influence of the parameters of the porous skeleton and the thermal physical properties of the material on the non-equilibrium heat transfer process was studied by means of numerical simulation.According to the structural characteristics of porous phase structure composite phase change materials,and neglecting the microscopic differences of its internal structure,a three-dimensional geometric model was established.The geometrical characteristics of porous phase framework composite phase change materials are attributed to the volume fraction and surface coefficient of phase change materials.According to the sensible heat method,a three-dimensional heat transfer model of composite phase-change material with porous framework structure was established,and the model was dimensionlessly processed.The FLUENT software was used to numerically solve the dimensionless heat transfer model.The influence of the volume fraction of phase change material and the parameters of thermal properties on the local temperature difference under constant temperature and periodic temperature boundary conditions was analyzed.Research indicates:(1)Under the constant temperature boundary conditions,when the dimensionless action time is less than 1.4,the non-equilibrium effect of the model is obvious,and the temperature rise is greater than 1%.(2)Under periodic temperature boundary conditions,the smaller the period,the more obvious the non-equilibrium heat transfer of the model and the shallower the heat transfer depth;when the dimensionless period is less than 0.5,the non-equilibrium effect of the model is obvious,and the maximum temperature difference is grater than 5%.When the dimensionless period is the same,the non-equilibrium heat transfer and heat storage of the model is consistent with the boundary condition of constant temperature.The research of this project is helpful for the establishment of effective characterization methods the non-equilibrium heat transfer porous of porous skeleton structure composite phase-change materials.It is also of great significance for the measurement of physical properties,and then provides a theoretical basis for the preparation and application of these phase-change composites.