Study On The Effect Of Micro-nano Structure On Heat Transfer And Storage Characteristics Of Microencapsulated Phase Change Materials

Large latent heat is absorbed or released in the process when phase change materials change its phase, and it is an isothermal or approximately isothermal process, for this reason phase change energy storage becomes an effective way of heat storage. Microencapsulated phase change material is a composite material, which makes the use of microcapsule technology to encapsulate PCM. It can effectively resolve the phase change material easy leakage, phase separation, corrosion and some other problems. As film forming techniques become more sophisticated and efficient assembly technology developed, the form of microencapsulated phase change material has evolved from the traditional form of a core-shell structure to more micro-nano structures inside. The difference of micro-nano structures influence the heat transfer and storage characteristics of microencapsulated phase change materials directly.This paper bases on the effect of micro-nano structures on heat transfer and storage characteristics of microencapsulated phase change materials, concludes the differences of micro-nano structures as the changes of cavity wall structure volume fraction η and phase change material surface coefficient σ. Then build a two-dimensional physical model that can be approximatly indicated some microencapsulated phase change materials has different micro-nano structures inside,and this model can fully embody the effect of η and σ on the heat transfer and storage characteristics of microencapsulated phase change materials.This paper gets a dimensionless processing to the model, and Finite Volume Method is used for numerically solving it. According to calculation results, discusses the effect of changing cavity wall structure volume fraction η, surface coefficientσ,and dimensionless thermal conductivity κ on the temperature field, averages temperature, and surface heat flux of the model during the heat transfer and storage process under the first boundary condition; in the same way, analyze the effect of changing cavity wall structure volume fraction η, surface coefficient σ, dimensionlessthermal conductivity κ and Biot Number on the temperature field, average temperature, and surface heat flux of the model during the heat transfer and storage process under the third boundary condition. Then derived the effect of the changing micro-nano structures on heat transfer and heat storage characteristics of microencapsulated phase change materials.