Mathematical Modeling of Solar Tunnel Dryer for Ginger Drying

Abstract

The drying of fruits, vegetables, ginger, tea, coffee, fish flesh, and herbs can be accomplished with a solar tunnel dryer. It was mathematically modeled for drying ginger products. The solar tunnel dryer comprises of a transparent UV-stabilized plastic-coated chamber and a flat plate solar collector covered in glass. An exhaust fan with solar photovoltaic modules is provided to evacuate the moist air from the dryer. The designed dryer has length, and width area of 8.5, 2 m, and 11 m², respectively. The average daily efficiency of the solar collector over eight hours was about 32%. The dryer can dry 50 kg of ginger per batch. The ginger has a starting moisture content of 90.4% (w.b) and the ultimate moisture level is about 11.8% (w.b). Ginger was selected because it is a major agricultural commodity in Ethiopia, where it is utilized both fresh and dried forms. The dried ginger is utilized for commercial applications. It is used as a local medication and as a flavoring spice in most families. It is quite important in the country’s traditional eating patterns. The ginger was sliced into average length of 9.5 cm, thickness of 1.5–2 mm, and a weight of 7.5–9.2 g pieces. The design improved the Cost of fuel and electricity saved per season. A non-linear regression analysis was used to develop drying models for ginger. The models were compared using the correlation coefficient (R²), the residual sum square (RSS), and standard error of estimates (SEE) analysis to determine the one that best represented the thin layer drying characteristics of ginger. The results show that the Page model satisfactorily described the drying of ginger with R² of 0.995, the Standard error of estimate (SEE) is 0.003 and the residual sum square (RSS) is also 0.006. The drying time of the dryer is 3.33 days. The overall efficiency of the dryer is about 36%.