Performance Evaluation of a Solar TUNNEL Dryer for Paddy Drying at Prathum Tani, Thailand

Abstract

A paddy solar tunnel dryer was designed, constructed and fabricated with a 2.112 m2flat plate collector with drying chamber volume of 0.113 m3, this design was improved to satisfy the drying desires of small farmers. The collector-dryer system has been equipped with data acquisition system to evaluate the performance, such as a data logger, K-type thermocouples, and air velocity measuring equipment. No load tests on the dryer; with 1000 cfm (DC) driven fans have been conducted. The performance of the dryer during drying of paddy has also been analyzed for the two configurations. The results, shown by plotting the variation of air temperature, moisture content indicated that the dryer performs better with DC driven fans, as they considerably reduce the fluctuations in the drying air temperature with fluctuating solar radiation. The moisture content reduced from 49.96 to 17.64 MC (% w.b.) in 6 hours. The average drying temperature was 67.75 °C. The heated air was approximately 344.47 W, with the incoming heat in the solar tunnel dryer of 1738.34 W. The thermal efficiency of a solar tunnel dryer was on the average of 22.72%.