Computational Fluid Dynamic Simulation of Mixing in Circular Cross Sectional Microchannel

Abstract

The application of process intensification has been catching up with the trend already observed in the chemical engineering area, where the use of microfluidic devices has already been elevated to production scale. Microreactor technology, an element of process intensification, offers potential benefits to the future of chemical engineering for its well-defined high specific interfacial area available for heat and mass transfer resulting in higher transfer rates and enhances safety due to its low hold-ups. In relation to the time-scale of chemical kinetics, diffusive transport in micro-devices is faster than in conventional mixers. Since mixing has a crucial impact on the overall performance of micro reaction processes, the need for measuring and comparing mixing performance have also increased. To exploit the resulting potential, the mixing behaviour of flow mixers on micro-scales need to be further investigated. In this work, three-dimensional Computational Fluid Dynamics (CFD) model with circular cross section micro channel has been developed instead of rectangular cross section done by other researchers as circular micro channel can withstand large pressure difference without undergoing any significant distortion where non-circular cannot. The CFD simulation was carried out using COMSOL Multiphysics 4.2a software to investigate the effects of “T” and “Y” micro channel configurations, inlet velocity and diffusion coefficient towards the mixing quality in the micro reactor. The results demonstrated that inlet velocity and diffusion coefficient has significant effects on mixing performance where low inlet velocity and high diffusion coefficient value resulted in better mixing performance. It was found that “Y”-shaped micro channel showed complete mixing at a shorter distance as compared to “T”-shaped micro channel and the minimum mixing length of micro channel needed for complete mixing is 20 mm.