Enhanced scale-up performance on residence time distribution by integrated microcapillaries with high size uniformity

Continuous tubular flow reactors are widely used by virtue of their simple structures, controllable reaction conditions, enhanced heat and mass transfer, etc. Microreactors present specific microscale characteristics including laminar flow, reduced diffusion path, enhanced mixing degree and high surface area to volume ratio. Microcapillary reactors combined the advantages of continuous processing and microscale reactions. However, the scale-up of microreactions is still a very challenging task for the loss of enhanced transport characteristics in microscale. Residence time distribution (RTD) is a vital research method to investigate the flow behaviors of microreactors. Microcapillary films (MCFs) containing several parallel microcapillaries provide a strategy to multiplex the microreactions. Nevertheless, the low size uniformity of microcapillaries in MCF strips hinders their application in microreactions. We carried out Computational Fluid Dynamic (CFD) simulations with experimental RTD validation to investigate the effects of dimension, convection and diffusion on RTD and the relationship between the RTD diversity and the size uniformity of microcapillaries under fixed velocities and volumetric flow rates. MCFs with high size uniformity were manufactured by liquid-assisted extrusion, and the coefficient of variance of the mean residence times of the microcapillaries in the MCF strip was only 2.8%. Neutralization reaction also showed the consistence of reaction performances among microcapillaries. With the enhanced scale-up performance on RTD and microreactions, MCFs are expected to have broad applications in large-scale microreactions in chemical engineering industry.

Automated summary

Continuous tubular flow reactors are widely used due to their simple structures and controllable reaction conditions. Microreactors with microscale characteristics offer enhanced mixing and high surface area to volume ratio. Microcapillary reactors combine the advantages of continuous processing and microscale reactions, but scaling up microreactions remains challenging. Residence time distribution (RTD) is a crucial method to study flow behaviors in microreactors. Microcapillary films (MCFs) provide a strategy for multiplexing microreactions, but the uniformity of microcapillaries in MCF strips limits their application. Computational Fluid Dynamic (CFD) simulations and experimental validations were carried out to investigate the effects of dimension, convection, and diffusion on RTD. MCFs with high size uniformity were manufactured, showing enhanced performance in RTD and microreactions, and suggesting broad applications in large-scale microreactions in the chemical engineering industry.