Next Article in Journal
Low Temperature Plasma Nitriding of Inner Surfaces in Stainless Steel Mini-/Micro-Pipes and Nozzles
Previous Article in Journal
Enhanced Sensitivity of MoTe2 Chemical Sensor through Light Illumination
Open AccessArticle

Wide Range Simulation Study of Taylor Bubbles in Circular Milli and Microchannels

Centro de Estudos de Fenómenos de Transporte, Departamento de Engenharia Química, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
Author to whom correspondence should be addressed.
Academic Editor: Joost Lötters
Micromachines 2017, 8(5), 154;
Received: 6 March 2017 / Revised: 6 May 2017 / Accepted: 8 May 2017 / Published: 12 May 2017
A deep knowledge of the hydrodynamics of two-phase flow in millichannels and microchannels is relevant to the design and control of micro structured equipment. While there is plenty of work published in this area, there is a lack of studies over a wide range of dimensionless numbers and some factors have not been properly addressed, such as the role of the Reynolds number, the features of recirculation regions in the liquid slug and the liquid film development length. Therefore, a wide range parametric study of isolated gas Taylor bubbles flowing in co-current with liquid in circular milli- and microchannels is presented, in a wide range of Capillary (CaB) (0.01–2) and Reynolds numbers (ReB) (0.01–700). The shape and velocity of the bubbles are, together with the flow patterns in the flowing liquid, analyzed and compared with numerical and experimental correlations available in the literature. For low values of CaB, the streamlines (moving reference frame (MRF)) in the liquid slug show semi-infinite recirculations occupying a large portion of the cross-section of the channel. The mean velocity of the fluid moving inside the external envelope of the semi-infinite streamlines is equal to the bubble velocity. For high values of CaB, there are no recirculations and the bubble is moving faster or at least at the velocity of the liquid in the center of the tube; this flow pattern is often called bypass flow. The results also indicate that the liquid film surrounding the bubbles is for low CaB and ReB numbers almost stagnant, and its thickness accurately estimated with existing correlations. The stagnant film hypothesis developed provides an accurate approach to estimate the velocity of the bubble, in particular for low values of CaB. The asymptotic behavior of the studied parameters enables the extrapolation of data for CaB lower than 0.01. In addition to the simulations of isolated bubbles, simulations with two consecutive bubbles were also carried out; coalescence was only observed in very specific conditions. The results obtained in this study are directly applicable to co-current slug flow in milli- and microchannels for 0.1 < ReB < 1000 and 0.02 < CaB < 2. View Full-Text
Keywords: Taylor bubble; gas-liquid slug flow; microchannels; millichannels; Newtonian liquids Taylor bubble; gas-liquid slug flow; microchannels; millichannels; Newtonian liquids
Show Figures

Figure 1

MDPI and ACS Style

Rocha, L.A.M.; Miranda, J.M.; Campos, J.B.L.M. Wide Range Simulation Study of Taylor Bubbles in Circular Milli and Microchannels. Micromachines 2017, 8, 154.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Back to TopTop