Optimization of natural-convection, solar drying systems

We present a technique for optimization of natural-convection, solar driers. The physical simulation is combined with a cost prediction and a search technique, which finds the constrained minimum of total cost per unit moisture removal. The optimum design for typical Bangladesh conditions is a relatively long collector, a thin grain bed and negligible chimney height. Sensitivity analyses have shown that the design geometry is not very sensitive to material or fixed costs but grain capacity has some effect. Turning the grain has almost no effect on drying but greatly reduces over-drying at the bottom of the bed.