Numerical Simulation of a Curved-Based Passive Microreactor to Produce Biodiesel

The advancement of sustainable and efficient chemical processes has increasingly focused on the integration of microreactor technology, a promising approach in process intensification and green chemistry. This study assesses the performance of three novel curved microreactor geometries, labeled Case ۱, Case ۲, and Case ۳, for biodiesel synthesis, involving two immiscible fluids, oil and methanol, with distinct thermophysical properties. Using COMSOL Multiphysics software, simulations based on incompressible Newtonian fluid dynamics and convection–diffusion equations are conducted to assess Mixing Index (MI), pressure drop (Δp), and Figure-of-Merit (FoM). Results demonstrate that curved microchannels enhance mixing quality by increasing the interfacial area and utilizing centrifugal effects. Among the designs, a microreactor with two three-quarter circular microchannels achieves the highest MI but at the cost of increased Δp, while a shorter channel configuration provides a better balance of MI and Δp. Applying the no-slip boundary condition leads to higher wall shear stress due to viscous friction, causing increased energy dissipation and elevated Δp. Conversely, implementing the slip boundary condition reduces the velocity gradient near the walls, resulting in a decrease of MI from ۷۵.۲۸% to ۶۹.۱۰%. The study further reveals that mixing quality improves as the inlet velocity (Uin) to the microchannel decreases. Additionally, FoM drops sharply from ۲.۱۳۳ at ۰.۰۰۰۰۱ m/s to ۰.۰۰۰۰۰۴ at ۱.۵ m/s, highlighting the superior efficiency of the proposed microreactor at low flow velocities. Moreover, higher molecular diffusion coefficients of the alcohol enhance mixing quality. Narrower channel geometries improve mixing by increasing the velocity gradient and reducing the molecular diffusion distance, thus facilitating better fluid interaction.

کلیدواژه ها:

Microreactor ، Curved microchannel ، oil ، Methanol ، Biodiesel