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Feasibility of Poly House Solar Bulk Drying System for Turmeric (Curcuma longa) in Humid Condition of North-East India

MANAS JYOTI BAROOAH, LAXMI NARAYAN SETHI, ABHIJIT BORAH AND AJITA TIWARI
Department of Agricultural Engineering, Triguna Sen School of Technology, Assam University, Silchar-788 011 (Assam), India
*(e-mail: mbarooah15@gmail.com; Mobile: 99576 97548)
(Received: February 6, 2024; Accepted: March 14, 2024)

ABSTRACT

North-East India (NEI) annually produces 110.68 thousand tonnes of quality turmeric, which is around 10% of national production. Freshly harvested turmeric is spoiled in one week at an ambient temperature of 27 to 30°C. Considering the climatic condition of the region, the present study explored the feasibility of an environment-friendly drying system for storage and value addition. Poly-house Solar Dryer (PSD) is one of the cost-effective, bulk drying systems among various systems for minimal processing of turmeric at the farm level. The existing structural design dimensions were improvised and the system automated to attain higher hot air circulation and thermal efficiency. The structural system is standardized from segmented to a hemi-cylindrical section of span 10.2 m and radius 2 m, with a capacity of 1000 kg (with racks), moisture-reducing silica gel embedded passive dehydrators during the night at air inlets, insulated heat storage, and rubber cladding for air outlets. A preliminary trial under no-load test exhibited that the system generated hot air ranging from 42.70 to 54.32°C at an ambient temperature of 28.50 to 34.60°C. Sliced turmeric dried in 22 to 23 hours in February. The initial and final moisture content of turmeric ranged from 78-89% to 10-11% (wb), respectively. At an average solar radiation of 521.46 watt/m², the thermal efficiency of the dryer was 24.89%. After testing several thin-layer drying models, the Page model proved to be the most accurate when simulation was performed on all of the drying data.
Key words: Poly-house solar dryer, embedded sponge, thermal efficiency, bulk drying, solar radiation