Design of a Solar Tunnel Dryer Combined Heat with a Parabolic Trough for Paddy Drying

Abstract

This paper presents the design, build and performance test of a solar tunnel dryer combined heat with a parabolic trough for paddy drying. A 2.27 m² parabolic trough stainless steel made with a single-axis solar tracking system produced hot water and delivered to the cross flow heat exchanger equipped with a solar tunnel dryer with the size of flat plate collector of 2.112 m2. The system received solar radiation and reflected sunlight to the receiver at the focal point of a parabolic trough. At this point, a copper heat pipe with the inside diameter of 25.4 mm for water heating is placed. A parabolic trough is covered with plastic sheets for protecting the wind in order to prevent the heat loss by convection. The produced hot water is used to warm the air and is sent to the heat exchanger and the blower passes hot air through the drying chamber of solar tunnel to dry paddy. The average drying temperature was 57.73 °C. The paddy moisture content was assessed in a reduction from 49.96 to 15.61 MC (% d.b.) in 6 hours. The heated air was around 245.87 W, with the incoming heat in the solar tunnel dryer of 1271.84 W. The thermal efficiency of a solar tunnel dryer, a parabolic trough, and the overall efficiency were on the average of 28.31%, 8.73%, and 3.80%, respectively.