Improving the performance of an indirect solar dryer using moisture adsorbent materials

Hassanein, Reda Hassanein Emam; Altomy, Eman Osman; Abd Elhay, Yossry Bayoumy

doi:10.21608/ejchem.2023.139935.6148

Improving the performance of an indirect solar dryer using moisture adsorbent materials

Document Type : Original Article

Authors

Agriculture Engineering Department, Faculty of Agriculture, Cairo university, Cairo, Egypt

10.21608/ejchem.2023.139935.6148

Abstract

This article presents a Modified Indirect Solar Dryer (MISD) with the integration of polyvinyl chloride tube (PVC) for recycling the hot air in a close circulation system. Meanwhile, a Silica gel beds (SGB) were used between trays of drying chamber at the air outlet to adsorb moisture. In addition, the basil leaves were dried in MISD, Unmodified Indirect Solar Dryer (UMISD) and Direct Solar Dryer (DSD) as well as the drying parameters were investigated. The indirect solar dyers were a forced convection of hot air by an electric fan operated by a photovoltaic panel and installed on top of them to maximize the utilization of solar energy at any remote area. Results revealed that the drying times for DSD, UMISD and MISD were 12 h, 9 h, and 7 h, respectively. While, the Specific energy consumption for MISD, and UMISD were 0.35 kWh/kg, and 0.48 kWh/kg, respectively. Furthermore, the internal air temperature inside the MISD solar dryer was higher than that in the UMISD by 2 ᵒC. Meanwhile, the average relative humidity during the day time in MISD was higher than that of the UMISD by 3 %. The moisture content (wet basis) of basil leaves reduced from 87% (w.b) to be 14% in MISD, 20% in UMISD, and 25% in DSD. Moreover, the MISD dryer increased the thermal performance efficiency by 51.4 % comparing to the DSD. In conclusion, the indirect solar dryer integrated with PVC tube and silica gel as an absorbent material for reusing the waste heat energy of hot air and absorbing its moisture, could reduce the drying time by 41.6% with a high quality of dried basil which significantly higher in total volatile oils comparing to the direct solar dryer.

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