Numerical and experimental analysis of a flat-plate indirect solar dryer with pebble-based thermal storage

This work examines an enhanced flat-plate solar air collector equipped with pebble-based thermal storage elements. Mathematical modeling of natural air convection was performed using boundary conditions derived from the collector’s design. Experimental data were approximated via regression analysis. The airflow, driven by buoyancy forces, was modeled with unsteady partial differential equations derived from conservation equations for mass, momentum, and energy using the Boussinesq approximation. These dimensionless equations were solved numerically using the finite difference method with an implicit scheme. Temperature and velocity fields were visualized by comparing simulation results with experimental measurements taken at the inlet, outlet, and surface of the thermal storage throughout the day. Model validation was conducted by comparing steady-state profiles computed here with those reported in previous studies. The results demonstrate that the proposed collector achieves efficient convective heat transfer while maintaining compact dimensions.