Drying of Refuse-Derived Fuel (RDF) using Solar Tunnel Dryer Integrated with Flat-Plate Solar Collector: An Experimental Approach

Solar energy can be effectively used for drying, especially when the cost of fuel used for conventional dryers is high. The drying of refuse-derived fuel (RDF) is a complicated process involving mass and heat transfer and depends on external variables such as humidity, temperature, and air velocity as well as internal variables, e.g., material surface, physical structure, chemical composition, size, and shape. Herein, a solar tunnel dryer integrated with a flat-plate solar collector was designed and fabricated at the Faculty of Engineering, Suez Canal University, Egypt. The experiments were performed during July 2019. The weather characteristics as well as the variation in moisture content with time were recorded continually. The results indicated that the maximum efficiencies of the solar collector were 46.6%, 53.4%, and 40.0% on 2, 4, and 6 July, 2019, respectively. Moreover, on these days, the moisture content of RDF decreased from 35.6% to 9.6%, from 28.3% to 8.5%, and from 43.5% to 14.0%. The dryer efficiency varied over 14.1–29.5% depending on the drying air stream temperature. The maximum dryer efficiencies recorded were 23.8%, 29.5%, and 25.8% on 2, 4, and 6 July, 2019, respectively.