Abstract
Two-phase gas-liquid flow in microchannels occurs in a variety of modern industrial applications. Using high-speed video recording, laser scanning and method LIF the characteristics of upward gas-liquid flow in rectangular microchannels with inlet T-mixer are considered. Statistical characteristics of gas-liquid flow and distributions of the phases in cross-section of a microchannel, with hydraulic diameter less than the capillary constant, were identified in a wide range of liquid and gas flow rates. Experiments were carried out for the flow of water-nitrogen in microchannels with cross section 42×280 μm and 720×1500 μm.
Highlights
Multiphase microsystems based on microchannels are of great interest for a variety of applications
It was observed that the elongated bubbles flow, transition flow and annular flow are the main flow patterns for rectangular microchannel with hydraulic diameter substantially less than the capillary constant
It was shown that the perspective method to define the boundary of corresponding flow patterns is statistical processing of the data obtained by laser scanning
Summary
Multiphase microsystems based on microchannels are of great interest for a variety of applications. Important parameters for optimizing the heat and mass transfer processes in microchannels are the length of the bubble, the liquid film thickness and their distribution. The liquid film thickness for the Taylor bubbles in square and rectangular capillaries was measured in [6, 7]. It was shown that the dimensionless film thickness in round and rectangular microchannel has different dependence on the capillary number. The main objective of the present work is experimental study of the multi-scale upward gas-liquid flow characteristics in rectangular microchannel of the microfluidic devices. The statistical parameters of the flow were defined and local film thickness was measured in microchannels with cross section 420x280 ȝm and 720x1500 ȝm using dual laser scanning and laser-induced fluorescence method. Distilled water and nitrogen were used as the working fluids
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