The performance of a solar tunnel dryer and evaluation of the quality of dried and dehydrated fish

Abstract

A solar tunnel dryer is designed and developed to study its performance and evaluate the quality of the dried and dehydrated fish. The solar tunnel dryer was developed by locally available raw materials. The dryer consisted of a flat plate air heating collector, a tunnel drying unit and two solar driven DC fans. The collector and the drying unit were covered with transparent plastic foil. The fishes to be dried were placed in a thin layer of bamboo splitted net within the dryer. The whole system was placed horizon-tally on a raised platform. The inside drying air temperature of the solar tunnel dryer was controlled by the air velocity created by operation of two DC fans connected with a solar panel of 40 Watt. During three experimental runs in the month of June, 2004 the inside drying temperature varied from 36 to 49⁰C as against the outside drying temperature of 25 to 35⁰C. The relative humidity inside the tunnel dryer varied from 36 to 63% and with and without that of outside varied from 64 to 93%. The solar radiation recorded was 28 to 866 W/m² in the month of June, 2004 cloud cover. Twelve and 28 drying hours were needed for complete dehydration of Amblypharyngodon mola and Pampus argenteus, respectively. The solar tunnel dryer also took less drying period in comparison with the drying time required for the sun dried fish. It has been observed that the performance of the solar tunnel dryer for improved quality dehydrated fish was better in comparison with the sun dried fish in terms of physical and chemical variables.