Performance evaluation of solar tunnel dryer for chilly drying

Abstract

One unit of solar tunnel dryer of 18 m X 3.75 m size was commissioned at farmer’s field in Kotnekal village of Raichur district of northern Karnataka and evaluated its performance for chilly drying. A maximum temperature of 58.5 °C was recorded at 14:00 hours inside the solar tunnel dryer during drying process which was 41.02 per cent higher than the maximum ambient temperature (34.5 °C) at the same time. On an average, a total drying time of 50 drying hours (6 – 7 sunny days) were required for solar tunnel dryer to reduce the moisture content of chilly from initial value of 76 per cent (w.b.) to a final moisture content of 9 per cent (w.b.) while the open sun drying required on an average 105 drying hours (13 – 14 sunny days) to obtain same level of moisture content which resulted in a net saving in drying time of 52.38 per cent for solar tunnel dryer over open sun drying.