Evaluating properties of Arabian desert sands for use in solar thermal technologies

Sand has been utilized as a sensible thermal energy storage medium, heat transfer material, and solar absorber material for different solar thermal technologies. In this study, we examine Arabian desert sands (Nafud, Dahna, and southwestern AlRub'AlKhali deserts) to identify optimal thermal energy storage and solar radiation absorption properties. Samples were grouped into three classes: quartzose feldspar-bearing (AlRub'AlKhali desert), quartzose carbonate-bearing (eastern Dahna corridor), and pure quartzose sands (occupying most of Nafud and Dahna deserts). Feldspar in quartzose sand causes a decrease in specific heat capacity, decrease in vitrifying temperature, and decrease in spectral absorbance relative to pure quartzose sand. Calcite in quartzose sand causes a significant reduction of specific heat capacity, change in grain-size distribution, and decrease in spectral absorbance relative to pure quartzose sand. The purest quartzose sands (≥99% quartz) have the best thermo-physical and thermo-optical properties. These pure quartzose sands have the highest specific heat capacity, do not agglomerate up to 1200 °C, and have the highest spectral absorbance after heating to 1200 °C. The purest quartzose sands occupy the southwestern part of the Nafud desert. Sand of this area is proposed to be the best candidate of all Arabian sands to be used as a sensible thermal energy storage medium and solar absorber material.