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Experimental Study on Two-Phase Flow Characteristics in Micro-Channels

Yavari, Hadi | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39358 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Nouri, Ali
  7. Abstract:
  8. The present study provids an experimental investigation on two-pase flow characteristics in microchannels. Experiment were conducted with a mixture of air and water in horizontal circular pyrex channel with 400µm inner diameter. The pressure drop and flow rates of the liquid and gas were measured using new method and images of the flow patterns recorded by high shutter speed camera. The gas and liquid superficial velocity ranges were 0.025-12.5m/s and 0.016-3.6m/s, respectively. The flow pattern map is developed from the observed flow patterns based on phases superficial velocity as wel as We numbers of liquid and gas phases. The flow pattern map is compared with those of larger channels. Compared to conventional channels some flow patterns like stratified flow were not observed which implies that in microchannels buoyancy effect is suppressed by surface tension. Compared to channels with D_h≅1mm bubbly-slug and slug-annular transition lines were shifted to higher liquid and lower gas superficial velocities respectively. The homogeneous folw model α=β, provided better prediction of the experimental void fractions compared to Armand corrolation, α=0.8β. On the other hand homogeneous flow model showed poor agreement with measured pressure drops though the seperated flow model showed much better results. The two-phase pressure drops are also used to calculate the frictional multiplier. The multiplier data show a dependence on flow mass flux
  9. Keywords:
  10. Microchannel ; Two Phase Flow ; Flow Patterns ; Pressure Drop

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