Design and performance evaluation of a solar-assisted biomass drying system with thermal storage

A solar biomass hybrid air heating system that does not require a conventional auxiliary heater but can still provide a daily load fraction exceeding 90% and supply hot air at a steady temperature and flow rate continuously for 24h a day has been developed. The system, which combines an unglazed transpired solar collector, rock bed, and a biomass gasifier stove with heat exchanger, was evaluated by drying chilli using air at 60 degrees C and 90m3/h. The chilli was dried from 76.7% moisture (w.b.) to 8.4% over 32.5h of continuous drying. The dryer reduced the drying time by 66% compared to open sun drying and provided 91.6% load fraction during the 24-h operation. The temperature of hot air supplied was stable at 60 +/- 3 degrees C for about 21h during the entire drying duration.