Drying of carrot slices in a triple pass solar dryer

Abstract

An indirect triple pass forced convection solar dryer was developed and its per-formance was evaluated for drying of carrot slices. The drying experiments were carried out under the meteorological conditions of Coimbatore city in India dur-ing the year 2016. The experimental set-up consists of a blower, triple pass packed bed air collector (using sand) with wire mesh absorber plate, and a drying chamber. The air mass flow rate was optimized to 0.062 kg/s. The initial moisture content of the carrot slices was reduced from 87.5% (on wet basis) to the final moisture content of 10% (wet basis) in 6 h duration. The thin layer drying charac-teristics were analyzed using twelve mathematical models available in open litera-ture. The results showed that the pick-up efficiency of the dryer was varied in the range between 14 and 43% with an average air collector thermal efficiency of 44% during the experimentation. The drying characteristics of carrot slices was predicted with good degree of accuracy using Wang and Singh drying model.