(34d) Experimental and Numerical Studies On the Gas-Liquid Distributions in Microchannels

Microchannel reactors have attracted more and more attentions recently for processes integration and intensification, reactor safety and ?number-up?. The hydrodynamic information inside the narrow space of microchannel was proved to be utmost important for the whole performance of transport and reaction. However, the corresponding experiments carried out in micro-setups with certain geometry could not obtain detailed data for describing multiphase flow and mixing easily. In this paper, gas-liquid two-phase flows in microchannels with different geometries were simulated by using the method of computational fluid dynamics for observing how the hydraulic diameters of microchannel from 50micron~1mm, cross-section shapes of circular and square, as well as the entrance styles of angle between two inlets from 60 to 180 degree affected the distributions and movements of gas bubbles and liquid slugs inside. Meanwhile, necessary experiments were carried out for comparison. The both results were agreed well with each other, and then concluded that channels of larger hydraulic diameters made gas bubbles and liquid slugs longer mainly because of the larger flow rates; In square channels longer bubbles and liquid slugs were formed more easily since for the same hydraulic diameter, square channel had larger cross sectional area, and the gas bubble emergence from four corners of square channel was slower than circular channels; The channels with larger angles between two inlets produced smaller gas bubbles and liquid slugs. Based on the above information, two mathematic models were established for predicting the gas-liquid distributions in microchannels of different geometries such as in non-transparent microchannels and parallel of multi-micro channels.