Numerical Study On Combined Thermal Storage Performance By Combined Aluminum Alloy And Molten Salt Phase Change Materials

Concentrated solar power(CSP).which uses a solar collector to produce high temperature and pressure steam that can drive a turbine to generate electric power,is one of the most promising forms of renewable energy.The technology has numerous advantages,such as emitting no pollution or greenhouse gases and possessing huge energy reserves.Many believe that actively developing CSP technology is one of the most effective ways to solve current global energy supply problems.Phase change thermal energy storage(TES)is a promising technology due to the large heat capacity of phase change materials(PCM)during the phase change process and their potential thermal energy storage at nearly constant temperature.Although a considerable amount of research has been conducted on medium and low temperature PCMs in recent years,there has been a lack of a similar systematic and integrated study on high temperature PCMs and high temperature thermal energy storage processes.In this paper,a composite phase change heat storage scheme combining aluminum alloy and molten salt phase change heat storage material is proposed.Aluminum alloy metal plate with heat storage function is added to the molten salt phase change material to enhance heat transfer.Two kinds of aluminum alloy materials AL-34Mg and AL-12.5Si were selected as aluminum-based metal plate.The influence of structural parameters and inlet velocity on the heat storage characteristics of the box-type heat storage unit was analyzed by numerical simulation.The numerical results show that the addition of aluminum alloy floor greatly reduces the heat storage time.Aluminum-based floor can quickly transfer heat to low-temperature inorganic salts.Metal PCM has a large heat storage capacity,which can ensure that the total latent heat is not reduced;the aluminum alloy and molten salt composite phase change heat storage heat transfer process is divided into three stages:sensible heat transfer stage,phase change melting stage,sensible heat transfer stage after melting,but the three stages of boundary line is not necessarily obvious;in the new composite phase change heat exchange,when the thickness of PCM-AL is the same as that of PCM-NA,the heat transfer rate is the best,and the smaller the thickness of the phase change material,the faster the heat transfer rate.The higher the inlet velocity of the heat exchanger,the higher the heat transfer rate of the aluminum composite plate and the NaCl/52MgCl2 new composite phase change heat storage heat exchanger.