Numerical Simulation Of Thermal Energy Storage/Release Characteristics Of Energy Storage Container Use Multiple Phase Change Materials

With the improvement of human living standards, human dependence on energy is increasingly intensified. The contradiction between energy shortage and environment pollution intensified. More and more people focus on energy conservation and the development of renewable energy. In order to make rational use of energy, how to solve the energy intermittent and the adjustment with valley equality issues can provide a broad prospect for the energy storage technology. As an important way of energy storage, latent heat storage has the advantage of thermal storage and exothermic temperature constant, high storage density, smail thermal storage and so on. So scholars began to study in the1970s and it has been so far, enduring. Since the thermal conductivity of the heat storage material is generally low, so most of the scholars have focused on strengthening the capacity of thermal conductivity of the materials, while ignoring the effects of heat transfer fluid temperature change on thermal energy storage process. In this article, based on the temperature distribution of heat transfer fluid along the direction of the fluid flow in the thermal energy storage container with a single phase change material(PCM), a thermal energy storage container use multiple phase change material is proposed. The characteristics of heat transfer during the thermal energy storage process are investigated by using numerical method. The variation of some physical parameters with time are analyzed during thermal energy storage process, such as the temperature of heat transfer fluid, the temperature of multiple phase change material, and the percentage of liquid formation. And a thermal energy storage container of multiple phase change material is optimized to find the best conditions. The main contents are as follows:First of all, we established a two-dimensional physical model and mathematical model about the thermal energy storage container of single phase change material and multiple phase change material, In the calculation process, the nature convective of liquid phase change thermal storage material is taken into account and coupled heat transfer boundary conditions in the interface is used to ensure that the heat transfer model is consistent with the actual article.Secondly, focus on energy storage container use only one phase change material. We calculate the heat transfer fluid velocity and inlet temperature on the influence of the heat storage and heat release process. The calculation results show that:the increasing heat transfer fluid velocity within a certain range can greatly speed up the melting of phase change heat storage material (or frozen). But when the heat transfer fluid flow rate increases to a certain degree, phase change heat storage material melting or solidification rate with the increase of the heat transfer fluid flow speed is very slow. Heat exchange fluid inlet temperature rise can significantly speed up the melting heat storage material, in the meanwhile, along with the increase of heat transfer fluid inlet temperature, regenerative rate will continue to improve. The reduced heat transfer fluid inlet temperature can significantly accelerate the solidification of the heat storage material and with the heat transfer fluid inlet temperature decrease, the heat release rate will also continue to improve.Thirdly, studied and analyzed the heat transfer fluid temperature distribution along the flow. The results shows that in the process of heat storage, heat transfer gradually reduced when the heat transfer fluid temperature gradually drops. The exit temperature change near the outlet is minimal and the heat transfer is the least. In the process of heat release, heat transfer gradually reduced when the heat transfer fluid temperature gradually rises. The exit temperature change near the outlet is minimal and the heat transfer is the least.Fourthly, thermal energy storage container use multiple and single phase change materials are comparative analyzed. Phase change materials are studied under different working conditions about its storage and heat release performance. As a result, in the process of heat storage, melting time of the thermal energy storage container of multiple phase change material shortened by about46minutes than that of single phase change material, which also means the melting time shortened by near15%. When the heat transfer fluid flow direction and the gravity direction are in the opposite directions, multiple phase change materials melt fast and the heat storage is larger per unit time.When the heat transfer fluid flowing in the opposite process of thermal storage and heat release, phase change materials solidifies quickly and has a larger heat release per unit time.