Modeling sensible thermal energy storage in solid blocks for concentrating solar power

In concentrating solar power plants, the mismatch between solar energy availability and energy demand requires the development of thermal storage systems. This study analyses a solid thermal energy storage module made of alumina. The block has a honeycomb pattern where the air flows through hexagonal channels. A transient 1D model, based on the finite difference method, is implemented and verified against CFD simulations. Such a simplified model considers the temperature dependence of thermodynamic properties for air and alumina. With the same boundary conditions, a 3D RNG k-ε turbulence CFD model is built, whose mesh and time step are assessed by means of sensitivity analyses. The average temperature difference between both models is as low as 14.8 K, even though the simplified one is around 300 times faster than the detailed CFD model.