Convective drying of chilies using a concentrating solar collector

A concentrating solar collector was developed for convective drying of green chilies by providing optimum drying environment. a temperature in the range of 45-65°c and relative humidity of less than 10% was observed during the drying period provided by the solar collector from 9.00 am to 5.00 pm. different levels of drying temperature and air mass flow rates were tested to find their effect on drying time of the chilies. the experiment was laid out as a randomized complete block design with a factorial arrangement of the treatments consisting of 3 levels of temperature and 3 levels of air mass flow rate,replicated 3 times. drying temperature and air mass flow rates effected the drying time significantly. the means comparison showed that minimum drying time of 17.96 h was recorded at high temperature of 65°c followed by a drying time of 20.27 and 21.43 h at temperatures of 55 and 45°c. the means of air mass flow rates showed that minimum drying time of 18.49 h was noted at high air mass flow rate of 3.50 kg min-1 followed by 20.32 and 20.86 h at air mass flow rates of 1.5 and 2.30 kg min-1. chilies dried at temperature of 65°c and air mass flow rate of 3.5 kg min-1 showed an average drying rate of 0.02 g(h2o) hr-1 cm-2 as compared to the slow drying rates at 55 and 45°c. it was concluded that chilies must be dried at high temperature and high air mass flow rates to get on time quality dried chilies. © pakistan academy of sciences.