ABSTRACT

The convective drying of a cocoyam cylinder in a convective dryer is presented. The study was conducted in the laboratory with a convective dryer. The Central composite Design (CCD) approach was adopted to design the experiment and investigate effect of varying drying conditions: drying air temperature (50, 60 and 70°C), air velocity (1.0, 1.5 and 2.0 m/s), and sample thickness (10, 15, and 20 mm) on the total energy consumption, drying efficiency of the system, product drying energy, drying efficiency, and drying time of a cocoyam cylinder samples. Results obtained show that the total and specific energy consumption ranges between 2.28 — 36.4OkWh and 6.92 — 62.76 kW/kg, respectively. The mean system drying efficiency ranges from 6.73 - 35.14%, The drying time, Td ranges from 125.5 -1 7 T1205.5 ± 10 mins. The desirability index technique was used in predicting the optimal drying variables. At the optimum drying conditions of 70°C air temperature, 1.88 rn/s air velocity and 14.31 mm sample thickness and desirability of 0.994, the total energy consumption, drying efficiency, shrinkage, and drying time were obtained as 4.03kWh, 20.46%, 67.05% and 183.8 mins, respectively. The predicted models had R2-values ranging between 0.9928 R2 0.9989, which were verified and validated for accuracy using diagnostic plots and percentage error deviations.