Abstract
Microfluidic systems undergo rapid expansion of its application in different industries over the few decades as its surface tension-dominated property provides better mixing and improves mass transfer between two immiscible liquids. Synthesis of biodiesel via transesterification of vegetable oil and methanol in microfluidic systems by droplet flow requires separation of the products after the reaction occurred. The separation technique for multiphase fluid flow in the microfluidic system is different from the macro-system, as the gravitational force is overtaken by surface force. To understand these phenomena completely, a study on the hydrodynamic characteristics of two-phase oil-methanol system in microchannel was carried out. A multiphase Volume of Fluid model was developed to predict the fluid flow in the microchannel. An inline separator design was proposed along with its variable to obtain effective separation for the oil-methanol system. The separation performance was evaluated based on the amount of oil recovered and its purity. The capability of the developed model has been validated through a comparison of simulation results with published experiment. It was predicted that the purity of recovered oil was increased by more than 46% when the design with side openings arranged at both sides of the microchannel. The highest percentage recovery of oil from the mixture was simulated at 91.3% by adding the number of side openings to ensure the maximum recovery. The oil that was separated by the inline separator was predicted to be at 100% purity, which indicates that no methanol contamination throughout the separation process. The purity of the separated product can be increased by manipulating the pressure drop across the side openings. Hence, it can be concluded that the separation in a large diameter microchannel system is possible and methodology can be tuned to achieve the separation goal. Finally, the simulation results showed that the present volume of fluid model had a good agreement with the published experiment.
Highlights
Liquid-liquid two phase separation is an important aspect when it comes to the usage of microchannel in performing certain chemical reactions that involve two immiscible liquids 1
It can be concluded that the separation in a large diameter microchannel system is possible and methodology can be tuned to achieve the separation goal
The flow behaviour of two immiscible liquids in microchannel is studied using the Volume of Fluid (VOF) model that is available in ANSYS Fluent software
Summary
Liquid-liquid two phase separation is an important aspect when it comes to the usage of microchannel in performing certain chemical reactions that involve two immiscible liquids 1. The capillary effect and viscous force overcome the gravity and inertial force, causing the fluid to behave differently. Separation is done by exploiting the gravitational effect and the difference in density of the multiphase. In microscale, the effect of gravitational force is overtaken by the surface force, and the density difference of the two phases are small 7. It was found that the microfluidics have app√aratus length scale below the Laplace length scale ( γ/(ρg)), which later proved that the effect of gravitational forces is negligible in microchannel 8. By exploiting the surface forces in microfluidics, two phase separation is possible to perform in a single step. Pcap is a critical parameter in the microscale separation process to induce and maintain
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
