Research On Heat Transfer Performance Of The Heat Accumulator For Solar Thermal Power System

As abundant solar energy makes it easy to develop solar thermal power generation,and the phase change thermal storage technology is the key to solve the discontinuity of it,it has become a hot research topic,and it is most important to design a reasonable and efficient phase change heat storage device.Therefore,the heat transfer performance of the heat storage device in the solar thermal power generation system is studied in this paper.In this paper,the high temperature phase change material of aluminum silicon alloy is selected,and the composite material of ceramic and steel is chosen.The thermal performance of double wall heat storage units is simulated by using FLUENT software.Firstly,under the premise of ensuring the heat storage capacity,third thermal boundary condition is applied to simulate heat storage characteristics of the double wall heat storage units under different diameters.Then the changes of temperature and liquid fraction,as well as liquid fraction distribution nephogram along with time,have been got.The effect of natural convection on the phase change process is also discussed.Secondly,the Fourier number,Stefan number and Reynolds number are introduced,and the physical model and mathematical model of the whole heat storage device are established,at the same time the heat transfer performance under different numbers are simulated.Heat Transfer Empirical Formula fitted by least squares principle criterionand is compared with the existing empirical formula.Finally,the heat storage device is designed,and the experimental system and method are described,too.Those lay a certain foundation for the experiment.The simulation results show that the heat transfer efficiency can be increased by properly reducing their diameter.In addition,natural convectioncan speed up the melting but slow down the solidification.The liquid fraction is positively correlated with Fourier number increasing function in the melting process,but it's opposite in the solidification process.And the performance also can be enhanced when Reynolds number and Stefan number are on the increase.But it should be restricted in application.The simulation research and analysis in this paper provide important reference value and theoretical basis for the optimization design of the heat storage device used in solar thermal power generation system.