Numerical research on performance comparison of multi-layer high temperature latent heat storage under different structure parameter

A series of two-dimensional axis models with structure mesh were created to simulate the charging process inside a multi-layer latent heat storage system (LHTES) that applied in disk solar thermal power system. 60% NaNO3 mixed with 40%KNO3 were taken as phase change materials (PCMs). PCMs were separated into three ring-shape volume, which made it necessary to balance the heat transfer of the three volume and maximize the proportion of latent heat in energy storage. The phase change material reserves, liquid fraction, latent heat fraction (the proportion of latent heat in total absorbed energy), volume difference of melting fraction (parameter defined to describe the melting difference between three volumes) and volume difference of latent heat fraction (parameter defined to describe the latent heat fraction difference between three volumes) of 4 models with different structure parameter were taken into comparison. The result showed that the phase change material reserve reach to max, melting difference and latent heat fraction difference are minimum when the thickness ratio of the three volume in radial direction are 11:18:8 (when volume ratio was 231:1044:736). The best configuration made the ratio of heat exchange area to heat storage volume optimum and made the heat transfer for charging process close to balance in three volumes.