Investigation of the efficiency of a solar dryer with thermal storage by rock salt and by pebble bed

Storage materials by salt rocks and pebbles were introduced in an indirect solar dryer. Experiments were carried out by using rock salt and pebbles (0.076 m3) as thermal storage materials. To overcome the thermal behaviour with storage materials, the solar dryer was modelled by SolidWorks flow simulation. Rock layers were arranged as superimposed sphere beds. The maximum reached temperature during the sunny period and the duration of the thermal discharge phase are strongly affected by the location of rocks in the drying chamber. These storage media maintained consistent the drying chamber temperature in the absence of the solar radiation by four more hours. Experimental tests were performed on lemon with and without the storage medium. Finally, the insertion of storage medium could increase the dryer efficiency by about 13.83%. Pebbles seem to be more suitable for thermal storage not for their thermal capacity but especially for their density.