Employing a Combination of a Double-Glazed Flat Solar Collector and Sensible Heat Storage for Drying Agricultural Products

Convection heat collector technology is a promising technology for drying agricultural products. The study aimed to determine the temperature characteristics, energy efficiency, and thermal discharging of a flat plate-type collector using double-glazing technology integrated with heat storage material in the state of iron scraps in passive and active modes. Investigation was conducted for seven hours of exposure under the sun (08:00–15:00 local time). Ten temperature sensors and four humidity sensors were used during measurements to determine the thermal characteristics of the heat collector. The density of iron scraps as heat storage material is 250 kg/m3 with an irradiation time of seven hours. The results indicate that the passive mode of operation has a higher temperature characteristics than the active mode. During irradiation process, the highest temperatures on the absorber in active and passive modes were 63 °C and 55 °C, respectively. Meanwhile, the highest temperatures on the TES in passive and active modes during irradiation were 55.6 °C and 50.6 °C, respectively. The energy efficiency of the collector ranges from 23.3–55.1% (passive) and 18.6–40.7% (active). The energy efficiency of the TES (Thermal Energy Storage) has a range of 7.4–22.7% (passive) and 7.4–13.0% (active). During discharging process, it shows that the TES in passive mode can store heat for 275 minutes and active mode for 95 minutes. Heat collectors that used double glazing technology and heat storage materials using iron scraps with a density of 250 kg/m3 have a significant potential to extend the drying duration of agricultural products with limited exposure to sunlight and environmentally friendly heat collectors.