After more than a decade of research, the Kalyan Solar Tunnel Dryer by the Sardar Patel Renewable Energy Research Institute (SPRERI) has now been commercially available. According to SPRERI, the first dryers were sold two years ago. Since then, the number has increased to currently 14 units in operation. The photo shows a unit at the National Research Centre for Medicinal and Aromatic Plants in the city of Anand, Gurajat.
The Kalyan dryer has been commercially available for the past six months. Among others, it is offered by the two solar thermal specialists Steelhacks Industries and NRG Technologists in Gujarat State. The technology is licensed on a non-exclusive basis for a period of five years to both collector manufacturers. “We are very satisfied with the technology and plan to increase the number of sold dryers because of growing demand,” Chintan Pandya, owner of Steelhacks Industries, confirms. According to Pandya, the Kalyan dryer pays back in less than 3 years.
SPRERI's Kalyan system has already dried fruits, vegetables, spices and medicinal plants successfully. The agricultural products are placed on trays in a chamber covered with toughened glass. The trays, made of black-painted aluminium sheets, are equipped with wheel tracks for rolling them one by one. A stainless steel wire mesh is put above the agricultural products to ensure they are not being scattered during the drying process. The chamber is insulated with 50 mm thick glass wool.
The hot air generated in the drying tunnel is forced to circulate using an AC-driven, single-phase exhaust fan supplied by either a PV module or electricity from a grid. The ducts inside the tunnel distribute the hot air equally over the material to be dried.