Modeling on heat storage performance of compressed air in a packed bed system

Compressed Air Energy Storage (CAES) incorporates a Packed Bed Thermal Energy Storage (PBTES) represents a promising larger scale storage technology. The heat storage performance of compressed air (CA) in PBTES is presented and numerically analyzed in this paper. Phase change material (PCM) particles are used as the filler. The unsteady two-phase energy conservation equations considering the phase change phenomena inside the PCM particles are developed and solved numerically by finite difference method. This model has been validated with Izquierdo-Barrientos' experimental data. Then, the effects of porosity (ε), PCM particle diameter (d_p), CA inlet pressure (P) and filling approach on PBTES thermal behaviors (such as temperature profiles, heat storage capacity and charge efficiency) are investigated.It was found that increasing particle diameter results in a decrease in the charge efficiency, and the charge efficiency increases with an increase in CA inlet pressure. The PBTES filled with three kinds of materials has better charge efficiency compared with the packed bed filled with single PCM or rock.