Performance analysis of a novel thermal energy storage integrated solar dryer for drying of coconuts

The drying of food products is an essential step in the preservation of crops and agricultural by-products that serve as raw materials for numerous end applications. Solar drying with phase change materials (PCMs) is an efficient low-energy consumption process in the post-reaping stage, reducing food deterioration. A customized solar dryer setup was assembled using Cudappah (black) stones as the base of the drying chamber to facilitate the absorption of solar energy on its surface. The organic paraffin wax, with a melting point of 60 ℃, was used as PCM in the solar dryer. The novelty of the study is the application of a PCM in a solar dryer to improve the effectiveness of drying and decrease the absolute drying period and the microbial content in the dried coconut. The study compared the drying characteristics between open sun drying and solar drying without and with PCM (100 and 200 g). The fabricated setup was utilised for drying coconut using a PCM-based solar drying method. The coconut was dried from an initial moisture content of 55.5% to a final moisture content of about 9%. The prototype dryer model minimized the use of the workforce, avoided improper drying, and decreased the absolute drying time. A total plate count (TPC) test was conducted to characterize the microbial content in the dried coconut. The microbial count decreased with the use of 200-g PCM as the use of PCM retained the heat for a longer time in the chamber. The drying time of coconut decreased by about 28 and 52 h on using 100 and 200 g of PCM, respectively, compared to open sun drying. The sensory characteristics like colour, taste, flavour, quality, and texture of the solar-dried coconut sample were superior to the sun-dried coconut sample.