Design and performance evaluation of a solar-assisted drying system

Abstract

A solar 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 ten hours a day, has been developed. The system, which combines flat plate solar collector heat exchanger and blower, was evaluated by drying Aonla and Cabbage using air at 60°C and 90 m3/h. The Aonla was dried from 80.0% moisture (w.b) to 7.29% over 20 hours of continuous drying. The dryer reduced the drying time by 70% compared to open sun drying, and provided 92.5% load fraction during the ten-hour operation. The temperature of hot air supplied was stable at 60±3°C for about ten hours for two days during the entire drying duration. © 2010 Inderscience Enterprises Ltd.