Thermal Conductivity Enhancement Of Phase Change Materials And Phase Change Transformation Study By Numerical Method

Metal foam is widely used in heat sink,heat exchanger and energy storage system.The thermal property of metal foam is mainly affected by the micro-topology.Based on the micro-structure characteristics of metal foams,the metal foam model of two kinds of micro-structure are established,W-P model and 3DVoronoi model to predict the overall effective thermal conductivity.W-P model is an ideal regular periodic model,and the3 DVoronoi model is close to the actual structure.Based on the above two models,the overall effective thermal conductivity of paraffin phase change materials filled with different metal foam was simulated.The results show that the porosity is not only factor influence the effective thermal conductivity of metal foam.The prediction results of3 DVoronoi model compared to the W-P model is more accurate,because the pore size distribution is uneven and the skeleton structure and micro structure is more close to the real.In the case of very high porosity,metal foam can also be very effective to improve the effective thermal conductivity of paraffin phase change material.In order to understand the heat transfer mechanism of the solid liquid phase change material in the metal foam,it is very necessary to explore the new experimental method and the theoretical method on the pore scale.In this paper,the phase transition process of foam metal / paraffin composite phase change materials based on pore scale is studied by using the method of W-P model and the finite element method.The results show that the metal foam can strengthen the paraffin phase change heat transfer process,and it is mainly affected by the micro-structure.The wax,which is near the heat source and the foam metal skeleton,is the first to melt.The melting rate of the paraffin wax decreases with time and the melting phase has a tendency to be in parallel with the structure of the foam metal skeleton.Using the numerical simulation method,we can quickly and effectively obtain the phase change heat transfer process of the paraffin phase change material in the complicated structure.The expected results provide researchers with a more research methods to understand the mechanism of heat transfer inside the porous media directly,but also by optimizing the structure parameters of the metal foam in the actual application process can achieve more efficient heat transfer.