Monday, November 9, 2015
Ballroom F (Salt Palace Convention Center)
Bubble uniformity of Taylor flow in a T-junction microchannel was investigated by the bubble length variation coefficient (CVb) via both experiments and theoretical derivations. On the one hand, the detailed relationship between bubble uniformity and the Capillary number (Ca) changing from 0.00027 to 0.0071 was established at operating conditions with different gas and liquid flow rates and various liquid phases. As Ca decreasing, the CVb increased slightly at first. When the Ca further decreased, a sudden rise of CVb was observed indicating compromised bubble uniformity. The reason of this sudden change was explored by pressure sensor and a high-speed camera, which was attributed to bubble fracture process at outlet. As Ca was smaller than 0.0008, a large pressure variation was generated during bubble breakup process which seriously affected the gas flow rate and bubble uniformity. On the other hand, a pressure model was derived to quantize pressure variation and to estimate CVb, which was in good agreement with experimental results. Moreover, the model for calculating CVb can also be used to optimize operating conditions and ensure the bubble uniformity.