The effect of fluid dynamics conditions and combustion reactions on the performance and heat and mass transfer distribution of dual-phase oxygen transport membranes

Abstract

A 3-D model based on CFD approach was developed to explore the effect of fluid dynamic conditions and combustion reactions on oxygen transport, in which the distribution of parameters such as oxygen partial pressure, temperature, velocity, and oxygen permeability were considered. After meshing the geometric model with poly-hexcore method, a series of user defined functions written in C++ were compiled and hooked to FLUENT to solve for oxygen permeation of dual-phase oxygen transport membranes. The results showed that oxygen permeability can be improved by pressurizing the feed side or vacuuming the permeate side, and the increased kinetic effect under evacuation conditions can increase the oxygen permeability by 69.85% at a vacuum pressure of 10 kPa and by 270.94% at 90 kPa. Due to the phenomenon of differential concentration polarization, the effect of oxygen concentration on oxygen permeability is more significant when the oxygen concentration on the feed side is lower than 0.17. Combustion reaction of CH4 promotes oxygen permeation, and the effect of the gap height between the fuel inlet and membrane is determined by several trade-off factors including momentum effects, reaction rate and temperature, and optimal oxygen permeability is achieved with a gap height of 3 mm.