GLM-based optimization of a 3D-Printed spiral milli-reactor for biodiesel synthesis using a design of experiments framework

This study presents a GLM-based optimization strategy for biodiesel production in a continuous-flow 3D-printed spiral stainless-steel milli-reactor. A Design of Experiments (DoE) framework evaluated the effects of methanol-to-oil (MTO) ratio, KOH concentration, reaction temperature, flow rate, and reactor geometry on biodiesel yield and triglyceride (TG) conversion. Catalyst concentration, MTO ratio, and channel design emerged as dominant factors, while flow rate and temperature exhibited comparatively weaker yet interconnected effects. The SSY45 spiral reactor, featuring a 45° Y-junction inlet, enhanced mixing and phase dispersion for efficient biodiesel synthesis. The GLM model identified optimal conditions: 94 % biodiesel yield at 60 °C, 3.27 wt% KOH, 6:1 MTO ratio, and 3 mL/min flow rate; and 96 % TG conversion at 50 °C, 4.1 wt% KOH, 12:1 MTO ratio, and 3 mL/min flow rate. Both targets were achieved within ∼63 s, demonstrating the reactor's process efficiency. GLM predictions matched experimental results closely, confirming the model's reliability. This work highlights the potential of spiral milli-reactor design combined with statistical optimization for efficient, continuous biodiesel production.