Experimental evaluation of an indirect type solar dryer for agricultural use in rural communities: Relative humidity comparative study under winter season in tropical climate with sensible heat storage material

Abstract

This research study presents the experimental assessment of two sensible heat materials originating from the State of Yucatán, Mexico, which were incorporated into three compartments within an indirect type solar dryer with a storage system (ITSD-TSS). The experimental tests were carried out under different environmental conditions and were compared with the results obtained from a conventional solar dryer without thermal storage. Temperature and humidity were measured during the different tests and various indicators were used to compare both drying systems. The results revealed that the solar dryer that used limestone as storage material indicated better performance than the dryer that utilized beach sand, since the drying efficiency with limestone was higher by 1.55% and allowed to extract 0.0257 kg more water per unit kWh. Similarly, beach sand stored 1.5 times more energy than limestone, however, this material is very susceptible to variations of solar radiation, so it is not recommended to implement it in areas with high cloudiness. Finally, the implementation of the three storage compartments in the ITSD-TSS allowed an increase between 3 and 4% of the drying efficiency as compared to the conventional solar dryer. The findings of the work can contribute to sustainable development in the agricultural drying process in rural communities.