Experimental Evaluation of an Automatic Cabinet Dryer

Abstract

An automated dryer has been developed, fabricated and evaluated for its efficiency at Landmark University, Omu-Aran, state of Kwara, Nigeria. The dryer comprises a heating chamber, two trays, a 0.5 Hp blower, two 1800W heating elements, a data logger consisting of temperature, relative humidity, and load sensors. Evaluation of the dryer was performed with okra at three levels of temperature (50, 60, and 70°C), load (200, 300, and 400 g) with a constant air velocity of 0.7m/s and average moisture content 88% (wet basis). The data logger device was programmed to record and store readings of weight loss (moisture losses) at 10 minutes intervals. The results showed that the dryer's maximum drying efficiency was 23.3%, whereas moisture losses and drying rate extended as the air temperature increased from 50 to 70°C. The drying rate increased as load decreased from 400 to 200g while okra at lower tray was observed to dry faster than those at the upper tray and moisture content at lower tray decreased faster with time in comparison with moisture content at the upper tray. The drying efficiency decreased with temperature, but increases as load increases.