Design and Performance Analysis of a Conical Fluidized Bed Dryer for Small-Scale Coffee Drying

Small-scale coffee producers require drying systems that reduce dependence on weather, improve moisture uniformity and remain technically feasible at laboratory or farm scale. This work presents the design and performance analysis of a conical fluidized-bed dryer (FBD) for parchment coffee, focusing on the reactor geometry, air-distribution strategy, heating-chamber configuration and electric-resistance arrangement. The experimental stage included blower characterization from 10 to 60 Hz, with measured outlet air velocities from 4.8 to 35.5 m/s and volumetric flow rates from 0.0098 to 0.0725 m3/s. Fluidization observations were performed with parchment-coffee masses of 0.5, 3.0, 4.0 and 5.0 kg. The numerical stage, developed in SolidWorks Flow Simulation, compared cylindrical and conical reactor configurations, distributor alternatives, conical opening angles of 20°, 25° and 30°, heating-chamber geometries, baffle arrangements and electrical-resistance layouts. The cylindrical prototype showed non-uniform fluidization because the incoming jet expanded poorly and remained attached to one side of the reactor, producing localized high-velocity regions and stagnant zones. In contrast, the conical reactor promoted grain recirculation toward the lower high-velocity region and was therefore selected for the final design. The proposed dryer uses a 25° conical reactor, a 50.8 mm inlet section, a 152.4 mm heating chamber with conical inlet and outlet sections, a flat baffle and four 900 W spiral electrical resistors. The ideal heating demand was estimated as 3.40 kW for increasing the air temperature from approximately 30 ℃ to 70 ℃, while the installed 3.60 kW heater capacity provides a 5.9% margin relative to the ideal requirement. The results demonstrate the design feasibility of a 5 kg parchment-coffee fluidization capacity. However, drying kinetics, pressure drop, energy consumption, final moisture uniformity and calibrated uncertainty must still be validated experimentally in the constructed prototype.