Grated coconut drying using an industrial microwave-hot air shaker dryer

Small community enterprises produce dried grated coconut for bakery applications; however, the conventional two-stage drying process (microwave followed by hot air) is labor-intensive, time-consuming (10–12 h), and energy intensive. Simultaneous microwave–hot air drying offers a promising approach to improve productivity and reduce specific energy consumption (SEC). This study presents the design and industrial-scale performance evaluation of an industrial microwave–hot air shaker dryer (IMHASD). The system integrates a multi-magnetron configuration with a mechanical shaker to enable efficient and uniform drying. The two-tray drying chamber was optimized using COMSOL Multiphysics simulations of electric field and temperature distributions. The chamber (0.6 × 2.04 × 0.5 m) was equipped with 12 magnetrons, delivering a total microwave power of 9,600 W at 2,450 MHz. Simulation results confirmed uniform microwave distribution and safe leakage levels. Drying experiments were conducted at 600 W microwave power and 75 °C hot air using grated coconut layers of 1, 2, and 3 cm. The 1-cm layer achieved the fastest drying, while the 3-cm layer resulted in the lowest SEC due to higher product loading. Economic analysis indicated strong feasibility, with an NPV of USD 6,590, IRR of 26%, and a payback period of 3.48 years.