Solar air-heating system with packed-bed energy-storage systems

This article reviews a solar air-heating system comprising single- and double-pass packed-bed energy-storage systems. Critical reviews on the effects of the packing material and the geometrical parameters on the performance of the packed-bed solar air heater (SAH) are performed. The size and geometries of the packing materials and the void fraction of the packed bed significantly affect the performance of the system. The performance difference between the single- and double-pass packed-bed SAHs is also addressed. A review of the literature indicates that the double-pass packed-bed SAH has a higher thermal efficiency than the single-pass packed-bed SAH.