Optimization of a Geothermal Maize Dryer for Minimum Drying Time

Efficient drying of maize plays a crucial role in preserving its quality and ensuring food security. This study investigated the performance of an experimental geothermal maize dryer under various drying conditions and optimized its parameters for improved drying time. The objective was to identify the best combination of drying air velocity, air temperature, and grain layer depth using the Taguchi method implemented in Minitab 20 statistical software. Analysis of Variance (ANOVA) was conducted using R-4.2.3 software to test the significance of varying the selected parameters on the drying time. Tukey’s Honestly Significant Difference (Tukey’s HSD) was used to establish whether the relationship between two sets of selected parameters was statistically significant. The selected parameters were varied within predetermined ranges to assess their individual and combined effects on the drying time of the geothermal maize dryer. Results for the optimal combination of parameters using the Taguchi Method found the optimal combination to be a drying air temperature of 50ºC, a drying air velocity of 0.5 m/s, and a grain depth of 0.1 m, resulting in the minimum drying time. ANOVA and Tukey’s HSD analysis confirmed there was a significant effect on the drying time when velocity and temperature were varied. Optimal parameter values can serve as practical guidelines for designing and operating geothermal maize dryers to reduce drying time.