Convective heating or cooling of granular solids or porous media is of interest in the design of thermal energy storage systems. The solutions to the energy initial boundary value problems governing convective heat transfer between a fixed bed of granular solids and a steady flow of heating or cooling fluid are presented. The storage system is considered to be initially in thermal equilibrium at a uniform temperature, a step change in the inlet temperature of the working fluid is imposed, and the thermal response of the system predicted. The results are valid for gases and liquids when the temperature gradient in the solid material is small and axial conduction effect is negligible in comparison with the convective heat transfer. Unlike the previously available solutions to this problem, the results presented are in closed form. This greatly simplifies evaluation and design of thermal energy storage systems of this general type.
Numerical investigation of the influence of mushy zone parameter Amush on heat transfer characteristics in vertically and horizontally oriented thermal energy storage systems
