Design and Performance of a Solar Tunnel Dryer with

Abstract

A solar tunnel dryer with a polycarbonate cover was designed and constructed. The dryer consists of two parts, namely a solar collector and a drying tunnel. Both parts are connected in series on the same structure. A polycarbonate cover is used to reduce heat losses while allowing the incident solar radiation to transmit into the dryer. Loading and unloading of products to be dried are undertaken through windows at a side wall of the dryer. A dc-fan driven by a 15-watt solar cell module is employed to ventilate the dryer. To investigate its performance, the dryer was used to dry five batches of jackfruits. For most cases, the temperature of the drying air in the dryer varied between 35 to 60 °C from 9 A.M. to 5 P.M. This dryer can be used to dry 30 to 70 kg of jackfruits from an initial moisture content of 80% (wb) to a final moisture content of 30% (wb) within 3 days, compared to 4 to 5 days with natural sun drying in the same weather condition. High quality products in terms of flavor, colour and texture were obtained. The payback period of this dryer is approximately 3 years.